DEVICE AND ASSOCIATED METHODS FOR DETECTING MULTIPLE WAVE FRONT FLOWS - Patent application

Abstract

A sensor device, system, and method for measuring different flow components is provided. The sensing arrangement includes a substrate and first and second sensor arrays on the substrate. The sensing elements of the first sensor array are distributed to obtain measurement data indicative of a first property of the operating environment, such as a turbulent component of the fluid flow. The sensing elements of the second sensor array are interspersed between the first sensor array and distributed to obtain measurement data indicative of a second property of the operating environment, such as an acoustic component of the fluid flow.

Description

[Technical field]

[0001] (Priority) This PCT application claims the benefit of and claims priority to U.S. Provisional Patent Application No. 62 / 774,756, filed December 3, 2018.

[0002] FIELD OF THEINVENTION FIELD OF THE DISCLOSURE Embodiments of the subject matter described herein relate generally to electronic test systems. More specifically, embodiments of the subject matter relate to systems that collect data from a sensing arrangement that includes multiple sensor arrays for simultaneously measuring multiple properties of an operating environment. [Background technology]

[0003] The prior art is replete with various electronic systems that generate, collect, and process sensor data. In this context, certain classes of sensor devices may provide digital output information that represents a measurable quantity, element, or phenomenon. For example, such sensors may output data that is inherently digital, such as event counting sensors, or may have analog-digital electronics integrated into the sensor package, such as modern micro electromechanical system (MEMS) microphones. Digital sensor devices may be configured to measure any of the following, including, but not limited to: electromagnetic energy, fluid flow, sound, radio frequency interference, air pressure, temperature, air speed, and the like. The small dimensions of modern digital sensors have enabled the first high spatial resolution measurements, using arrays of many closely spaced sensors to generate not only sample point measurements, but also spatiotemporal images or mappings of the measured quantities.

[0004] One application for measurements using sensor arrays is in the field of aerodynamic vibro-acoustics to measure noise transmission through structures in aerodynamic or fluid dynamic environments, such as wind noise in automobiles. Designs for controlling wind-induced interior noise in automobiles often involve analyzing the external flow relative to the aerodynamic shape. However, wind tunnel testing to analyze the external flow can be expensive, and thus it is desirable to minimize the amount of time or cost incurred in obtaining measurements. It is therefore desirable to provide a sensor array that can measure or otherwise quantify components of multiple different characteristics of flow loads in an efficient manner. Additionally, other desirable features and characteristics will become apparent from the following detailed description and appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background. Summary of the Invention

[0005] An exemplary embodiment of a sensing arrangement includes a substrate, a first sensor array on the substrate, and a second sensor array on the substrate, the first sensor array including a first plurality of sensing elements, a first distribution of the first plurality of sensing elements on the substrate configured to obtain a first set of measurement data indicative of a first property of the operating environment, the second sensor array including a second plurality of sensing elements interspersed among the first sensor array, and a second distribution of the second plurality of sensing elements on the substrate configured to obtain a second set of measurement data indicative of a second property of the operating environment.

[0006] In another embodiment, a method is provided that involves obtaining from a user a required data acquisition time and over-range and under-range levels of sensors, establishing a logical connection with an array instrument RAM controller, providing a user with a graphical display of the logical connections to the array instruments and sub-array components, providing a graphical means for the user to specify a file name and folder and / or path for the results data, providing a graphical means for the user to start and stop data acquisition, providing a means for the user to review the number of sensors that measured over-range signals and the number of sensors that measured under-range signals in each sub-array during the data acquisition period, and providing a means for the user to save the results data to a defined file name after reviewing the number of over-range and under-range instances.

[0007] In another embodiment, a sensor system is provided, comprising: a flexible support substrate configured to conformably mount to a curved surface; and an array of digital sensor devices carried by the flexible support substrate, each of the digital sensor devices configured to generate a respective digital output signal conveying raw digital sensor output data, the array of digital sensor devices comprising a lower wavenumber array comprising a first set of digital sensor devices and a higher wavenumber array comprising a second set of digital sensor devices, the higher wavenumber array comprising a plurality of subarrays comprising respective subsets of the second set of digital sensor devices, the first set of digital sensor devices of the lower wavenumber array being uniformly distributed across the flexible support substrate, and the subarrays of the plurality of subarrays being non-uniformly interspersed among the first set of digital sensor devices of the lower wavenumber array. The sensor system also includes an array of random-access memory (RAM) devices carried by the flexible support substrate, the RAM devices being directly connected to the digital sensor devices during data recording operations of the sensor system whereby the RAM devices directly receive digital output signals, and a controller operatively coupled to the array of RAM devices to synchronously clock the array of RAM devices during data recording operations whereby raw digital sensor output data is synchronously written to the array of RAM devices.

[0008] In another embodiment, a system is provided that includes means for obtaining from a user the required data acquisition time and over-range and under-range levels of the sensors, means for establishing a logical connection with an array instrument RAM controller, means for providing a user with a graphical display of the logical connections to the array instruments and sub-array components, graphical means for a user to specify a file name and folder and / or path for the results data, graphical means for a user to start and stop data acquisition, means for a user to review the number of sensors that measured over-range signals and the number of sensors that measured under-range signals in each sub-array during the data acquisition period, and means for a user to save the results data to a defined file name after reviewing the number of over-range and under-range instances.

[0009] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

[0010] A more complete understanding of the subject matter can be derived by reference to the detailed description and claims when considered in conjunction with the following drawings, in which like reference numerals refer to like elements throughout. [Brief description of the drawings]

[0011] [Figure 1] 1 is a simplified block diagram representation of one embodiment of a sensor system. [Diagram 2] 1 illustrates a perspective view of a conformable sensing array overlying a structure in an exemplary embodiment; [Diagram 3] FIG. 2 is a top plan view of an exemplary embodiment of a compatible sensing array. [Figure 4]FIG. 2 is an exploded perspective view of an example embodiment of a sensing element suitable for use in a compatible sensing arrangement in accordance with one or more example embodiments. [Diagram 5] FIG. 2 is a detailed top plan view of a subarray suitable for use in a compatible sensing arrangement in one or more exemplary embodiments. [Figure 6] FIG. 2 is an exploded perspective view of an exemplary embodiment of a compatible sensing array. [Figure 7] FIG. 1 is a flow diagram of an example multi-wavefront sensing process suitable for use with a compatible sensing array in accordance with one or more example embodiments. [Figure 8] 8 illustrates an example sequence of graphical user interface (GUI) displays suitable for presentation in connection with the multiple wavefront sensing process of FIG. 7 in accordance with one or more embodiments. [Figure 9] 8 illustrates an example sequence of graphical user interface (GUI) displays suitable for presentation in connection with the multiple wavefront sensing process of FIG. 7 in accordance with one or more embodiments. [Figure 10] 8 illustrates an example sequence of graphical user interface (GUI) displays suitable for presentation in connection with the multiple wavefront sensing process of FIG. 7 in accordance with one or more embodiments. [Figure 11] 8 illustrates an example sequence of graphical user interface (GUI) displays suitable for presentation in connection with the multiple wavefront sensing process of FIG. 7 in accordance with one or more embodiments. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The following detailed description is merely exemplary in nature and is not intended to limit the subject embodiments or the application and uses of such embodiments. As used herein, the word "exemplary" means "serving as an example, instance, or illustration." Any implementation described herein as exemplary is not necessarily to be construed as preferred or advantageous over other implementations. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary, or the following detailed description.

[0013] Techniques and technologies may be described herein in terms of functional and / or logical block components and with reference to symbolic representations of operations, processing tasks, and functions that may be performed by various computing components or devices. It should be understood that the various block components illustrated in the figures may be realized by any number of hardware, software, and / or firmware components configured to perform the specified functions. For example, one embodiment of a system or component may employ various integrated circuit components, e.g., memory elements, digital signal processing elements, logic elements, look-up tables, etc., that can perform various functions under the control of one or more microprocessors or other control devices.

[0014] For the sake of brevity, conventional techniques regarding sensor devices, sensor designs, data transmission, data storage, and other functional aspects of the system (and individual operating components of the system) may not be described in detail herein. Furthermore, the connecting lines shown in the various figures contained herein are intended to represent example functional relationships and / or physical couplings between the various elements. It should be noted that many alternative or additional functional relationships or physical connections may be present in an embodiment of the subject matter.

[0015] Embodiments of the subject matter described herein generally relate to sensing arrays for measuring flow-induced loads on a structure. In an exemplary embodiment, the sensing array includes two or more logically separate sensor arrays, where the different sensor arrays are arranged or configured to measure different salient properties or characteristics of the surrounding environment resulting from the interaction between the fluid flow and the structure. In this regard, the number of individual sensing elements associated with each sensor array, and the distribution or positioning of these sensing elements within each sensor array, may be selected to optimize a particular property or characteristic of the surrounding fluid flow. For example, the sensor array may itself be composed of several different subgroups or subarrays of sensing elements, which are distributed, oriented, or otherwise arranged with respect to each other to optimize the ability of the sensor array to capture, measure, or otherwise quantify a property or characteristic of a particular flow component of the operating environment. Furthermore, the different sensor arrays may be provided on a common substrate such that the sensing elements of the different sensor arrays may be interwoven with each other.

[0016] In an exemplary embodiment, the sensor array is provided on a flexible substrate that can conform to the surface of the structure where the flow-induced loads are to be measured to ensure an aerodynamically smooth measurement surface that minimizes flow disturbance. In one embodiment, the pressure sensor array is installed on a flexible printed circuit board or flexible polymer printed circuit that allows for a comb-like or spiral-like configuration of flexible fingers that can allow the sensor array to conform to the shape of the curved surface where the flow measurement is to be performed. The flexible substrate can have a uniform thickness to facilitate an aerodynamically conformal surface for measuring fluid flow in the surrounding operating environment.

[0017] For example, two or more pressure sensor arrays may be integrated into a single measurement instrument to measure two or more components of a flow-induced pressure field that have different characteristics of pressure spectra and / or different characteristics of spatial correlation and that may be separated by wavenumber-frequency spectral analysis. In this regard, one pressure sensor array may have spacing between constituent sensing elements and dimensions, sizes, or other physical arrangements designed to resolve higher wave speed and lower wave number flow components in the wavenumber-frequency spectrum, while another pressure sensor array had different spacing between constituent sensing elements and dimensions, sizes, or other physical arrangements designed to resolve one or more additional lower wave speed and higher wave number components in the wavenumber-frequency spectrum.

[0018] In some embodiments, the distribution, spacing, and / or physical arrangement of the sensing elements allows each sensor array to use a minimum number of sensing elements to measure only the pressure cross spectrum required to compute the spatial correlation of the measured wavefront. For example, a one-dimensional line array of sensing elements to compute the pressure wavenumber frequency pressure spectrum cannot be completely filled, but wavenumber-frequency post-processing and sparse array signal processing techniques can be used to estimate the wavenumber frequency pressure spectrum. Similarly, a two-dimensional rectangular array of sensing elements cannot be completely filled, but wavenumber-frequency dependent post-processing and sparse array signal processing techniques can be used to estimate the wavenumber frequency pressure spectrum. Furthermore, if the amplitude pressure spectrum of one flow component is significantly higher than all other flow components, the sensor array can be further reduced to a simple pair of oriented sensors to quantify the pressure spectrum and spatial correlation directly from the measured cross spectrum without relying on one- or two-dimensional wavenumber-frequency spectrum analysis.

[0019] In some embodiments, a physical structure such as a windscreen can be provided over or covering the exposed surfaces of the sensing elements to effectively provide an anti-aliasing filter that attenuates unwanted high wavenumber signals. In other embodiments, unwanted high wavenumber content of low wavespeed flow components is removed from the high wavespeed, low wavenumber sensor array measurement data by subtracting a curve-fitted empirical model of the high wavenumber content that includes an estimate of the Discrete Fourier Transform aliasing or aliasing error.

[0020] In one or more exemplary embodiments, the sensor array utilizes microelectromechanical system (MEMS) sensing elements, such as digital MEMS microphones. In some embodiments, all of the digital measurement data from the sensor array is stored or buffered in a random access memory (RAM) physically installed on a flexible printed circuit board (PCB) substrate of the sensor array measurement device using conductive traces on the printed circuit board (PCB) substrate to establish electrical connections between the output terminals of the sensing elements and the RAM components. Digital data records recorded from a single data acquisition period can be stored in the RAM installed on the substrate of the measurement device and subsequently downloaded using a high-speed data link. The measurement data acquisition may be digitally controlled by a software application running on a remote computer, which may generate or otherwise provide a graphical user interface (GUI) display that allows a user to see which sensing elements and how many of them went above or below the measurement range within the data acquisition period.

[0021] As described in more detail below in the context of Figures 2-11, the exemplary embodiments described herein provide flow noise surface pressure sensor arrays that are organized in logically separate groups or subarrays that are configured to fully define the input aeroacoustic or hydroacoustic loading conditions of a mathematical model to predict the vibration and strain response and sound transmission of any complex structure subjected to measured flow turbulence loading. Examples of candidate applications include wind noise in automobiles, boundary layer turbulent loading in aircraft or spacecraft, wind noise in high speed trains, underwater flow noise in sonar systems, flow noise in piping systems, and the like. In exemplary embodiments, a sensing array is provided that integrates two or more separate sensor arrays into a single thin "stick / peel" conformable surface blanket that includes a full blanket sized array for low wave number flow loading, plus one or more smaller arrays for high wave number localized flow loading. The sensing array may also include perforated screens and porous materials to attenuate unwanted turbulent noise of the acoustic array sensor.

[0022] The sensing arrangement may also utilize a thin aerodynamic fairing layer with microports between the pressure measurement ports in the fairing layer and the sensing ports in the MEMS sensor. For example, a digitally printed fairing layer with suitable microports allows measurements with the pressure sensing ports spaced closer together than would be permitted by spacing based on the smallest physical dimensions of the MEMS sensor package. Acoustic and aerodynamic calibration procedures may be performed to adjust gain and provide phase correction for the effects of such windscreens and microports.

[0023] In an exemplary embodiment, the adaptive sensor blanket incorporates a global two-dimensional sensor array for low wavenumber aeroacoustic loading, which is acoustic for low subsonic flow velocities and convective turbulence for higher supersonic and hypersonic flow velocities. The adaptive sensor blanket also incorporates multiple smaller sensor arrays for local variations in high wavenumber loading, which is convective turbulence for low subsonic flow velocities and acoustic for higher supersonic and hypersonic flow velocities. The local high wavenumber pressure sensor array may be either a two-dimensional (2-dimensional, 2D) array for directly measuring the local two-dimensional (2D) surface pressure frequency-wavenumber spectrum, or an array of suitably oriented one-dimensional lines, or a simpler concentric circular array that defines the properties of the local directional cross spectrum. The 2D array does not need to be completely filled, and sparse array signal processing methods can be used to estimate the required frequency-wavenumber spectrum. A complete "stick / peel" compatible sensor array can also utilize direct data to memory data acquisition, as described in U.S. Patent No. 9,921,748, the entirety of which is incorporated herein by reference, to eliminate electrical noise and latency in recording measurement data and avoid multiple wired connections to external data acquisition systems. High speed data acquisition and data downloading can be facilitated by network or data bus architectures, high speed data interfaces, and / or high speed communication protocols.

[0024] Sensor system overview

[0025] 1 is a simplified block diagram of one embodiment of a sensor system 100 supporting direct storage of data in a digital memory for an array of digital sensors, as described in more detail in U.S. Pat. No. 9,921,748, the entirety of which is incorporated herein by reference. The sensor system 100 generally includes, but is not limited to, a flexible support substrate 102, an array of digital sensor devices (also referred to herein as a sensor array 104), a random access memory (RAM) architecture that may be realized as an array of physically separate RAM devices (also referred to herein as a RAM array 106), and a controller 108. The sensor array 104 is coupled to the RAM array 106 to facilitate direct writing of digital sensor output data from the sensor array 104 to the RAM devices in the RAM array 106. The RAM array 106 is operably coupled to the controller 108 such that the controller 108 can control data write and read operations of the RAM array 106 as needed. In this particular embodiment, the sensor array 104 , the RAM array 106 , and the controller 108 are all carried by the flexible support substrate 102 .

[0026] The illustrated embodiment of sensor system 100 also includes or cooperates with a data interface (e.g., a universal serial bus (USB) interface 110, a wireless data communication interface, etc.). The USB interface 110 is coupled to at least the controller 108 and is preferably configured to accommodate transfer of stored digital sensor output data from the RAM array 106 to a host computing device 112. As will be well understood by those familiar with modern computer technology, the USB interface 110 is also configured to provide operating voltages and power to at least some of the components of sensor system 100, such as the sensor devices of sensor array 104, the RAM devices of RAM array 106, and the controller 108.

[0027] The flexible support substrate 102 allows the sensor array 104, RAM array 106, and controller 108 to be conformably mounted or affixed to curved surfaces such as vehicle windows, vehicle body structures, aircraft skins, or other contoured surfaces under test. Thus, in effect, a direct data-to-memory array can be mounted on a flexible printed circuit board (PCB) or similar electrical substrate to form a conformal array that can follow the shape and curvature of the test object. The thin assembly of sensors and RAM chips on a flexible PCB can be molded into a thin polymer sheet of uniform thickness to provide a convenient "stick-on" and "peel-off" instrumentation mat or blanket that perfectly conforms to the underlying curved surface. The fact that the system 100 can be scaled by simply adding more RAM devices to support more sensors, while still maintaining a single wired interface to the host, means that the system 100 may be manufactured on a very thin, flexible, conformal circuit board and test installed directly on the surface without the need for additional machining or interface wiring or circuitry.

[0028] The sensor array 104 includes multiple sensing elements. The sensor array 104 preferably includes the same type of digital sensor device (e.g., microphone device, temperature sensor, air pressure sensor, light sensor, etc.), although certain embodiments may support a sensor array 104 having multiple different sensor types. While any suitable type of sensor, transducer, or measurement device may be used in the sensor array 104, the exemplary embodiment described herein utilizes a microphone device. As described in more detail below, in an exemplary embodiment, the sensor array 104 is itself composed of multiple logically separate or distinct groups or subarrays of sensing elements, with the different sensor array groups physically arranged, distributed, or configured to measure different significant flow properties or characteristics resulting from the fluid flow. The number, dimensions, and other physical characteristics of the sensor array groups may vary depending on the needs of a particular application, test subject, test requirements, etc.

[0029] Each sensor device in the sensor array 104 generates a respective digital output signal that conveys raw digital sensor output data for that particular sensor device. In practice, each sensor device in the sensor array 104 may include a data output terminal or pin that is used to convey digital information in the form of high and low voltage levels. Each data output terminal or pin is then connected to a RAM device in the RAM array 106. The RAM devices may be assigned to the sensor devices in any convenient manner. In other words, each of the RAM devices is operatively associated with at least one of the digital sensor devices in the sensor array 104. According to a particular implementation, each physically separate RAM device in the RAM array 106 includes 16 inputs, and thus each RAM device can receive and write sensor output data for up to 16 different sensor devices. It should be understood that this 16:1 arrangement is merely one example of a suitable configuration, and RAM devices having more or less than 16 data inputs may be utilized as desired.

[0030] The controller 108 is operatively coupled to the RAM array 106, the sensor array 104, and the USB interface 110 to initiate, control, and regulate data read and write operations involving the RAM array 106, and, as necessary, to initiate, control, and regulate the transfer (download) of raw digital sensor output data from the RAM array 106 to the computing device 112. During data recording operations, the controller provides a common clock signal to each of the RAM devices in the RAM array 106. This common clock signal may also be provided to the individual sensor devices in the sensor array 104. In this regard, starting, stopping, clocking, and addressing of data storage are handled by the controller 108. To use the system 100 as a test data acquisition system, the computing device 112 may provide one or more user interfaces, software applications, and the like, for resetting the system 100, starting data collection, stopping data collection, and uploading data to a host for post-collection processing. Additionally, the clocking of raw sensor data from the sensor array 104 to the RAM array 106 is dependent on control address generation and clock pulses. These tasks are performed by a controller 108, which may include a microcontroller, addressing circuits, multiplexer circuits, etc., that cooperate to perform the various functions and processes described herein.

[0031] A USB interface 110 allows for retrieval of multi-channel array data from the RAM array 106. Downloading of data from the RAM array 106 to the computing device 112 is handled by the controller 108. In response to appropriate user input commands, the controller 108 initiates data transfer to the host computing device 112 via the USB interface 110. Alternatively, the sensor system may utilize one of many possible high speed interfaces, including, but not limited to, PCI, PCI Express, SATA, RS232, RS485, and CAN.

[0032] The digital data from the sensor array 104 is a digital representation of a measurable quantity or phenomenon that has been converted from some raw analog form to a pure digital form. The digital sensor data is generated by individual sensor devices in the sensor array 104 and made available in a high-speed serial format. The raw original digital output signals from the sensor array 104 are provided directly to the RAM array 106 without any intervening data processing, filtering, data conditioning, or modification. Furthermore, the RAM devices are located in close proximity to the sensor devices to avoid long conductor paths and reduce latency. Thus, the serial data stream is clocked directly into the high-speed RAM devices of the RAM array 106. In other words, there is no sensor conversion or processing in the sensor system 100. The raw sensor data is in digital format, and the system 100 captures the high-speed data stream directly into memory in real time during data recording operations.

[0033] For accurate sensor arrays, the direct data to memory arrangement minimizes the introduction of data acquisition noise and phase errors. Because the system 100 uses a direct sensor to RAM storage system, the sensor data maintains the highest signal-to-noise (S / N) levels possible, i.e., achieved by the sensor device itself. There is no possibility of contamination of the sensor output signal (from power supply noise, analog-to-digital converter noise, etc.), including introduction of phase delay, jitter, or noise. This is important for accurate sensor array measurements.

[0034] For large channel count sensor arrays, the direct data to memory design allows for the most compact wiring that can be completely contained within a multi-layer circuit board. The design is easily scalable and does not require the penalty of multiple data converters or wiring to the host. Additionally, regardless of the number of sensor elements, the flexible support substrate 102 maintains its low profile, conformal footprint, and single-wire interface to the host.

[0035] For near real-time processing of the sensor array processing, a direct data to memory design minimizes latency. As mentioned above, direct storage to memory means that all data channels (no matter how large the sensor array 104 is) are stored simultaneously within a clock and storage jitter window of a few nanoseconds, thereby completely maintaining the phase integrity of the sensor array.

[0036] Furthermore, multiple wired connections to external digital signal processing units are avoided. In fact, the sensor system 100 can be deployed with minimal or no wired connections (wireless) to external devices during the data acquisition phase. For data transfer, only a single digital data port (e.g., USB interface 110) connection is required for data download and post-processing, even for data sets of very high channel count arrays.

[0037] Flow-induced noise and vibrations of multiple wave fronts.

[0038] A major focus in the field of aerodynamic vibroacoustics is the transmission of noise through structures when the external source is an aerodynamic or hydrodynamic environment. The subject matter described herein facilitates physics-based simulation methods, which in turn facilitates engineering design for the control of interior noise. The design problem has two parts. The first part is the simulation of the external flow as influenced by design parameters such as aerodynamic shape and flow control. The second part is the simulation of the transmission of the external surface pressure to the interior sound field as influenced by the shape and physics of the intervening structure. The sound transmission physics of the second part can be used to better define the aeroacoustic requirements from wind tunnel testing and computational processing currently used for the first part of the problem.

[0039] Aerodynamic and hydrodynamic noise transmission have elements in common with the room acoustics problem of sound transmission loss where external sources are assumed to be diffuse acoustic fields. The vibration response of a structure to acoustic excitation may be dominated by its resonant modes, while low frequency sound transmission to the interior is controlled by the acoustically forced response of non-resonant modes.

[0040] Aircraft interior noise transmission can be predicted for high-speed boundary layer noise excitations. An empirical model of the boundary layer surface pressure cross spectrum is convolved with each structural mode to estimate the resonant vibration response. At cruise conditions (e.g., Mach 0.8), the high level of aerodynamic excitation at the convective wave number couples well with the resonant modes of the structure, so that non-resonant transmission can be neglected. Neither the resonant nor the non-resonant responses couple well with the interior acoustics. Problems associated with low-speed flows are more challenging, especially when there are separated flows over irregularly shaped bodies. Typically, the Mach numbers for automotive and submerged vehicle flows are 0.1 and 0.01, respectively. The boundary layer convective turbulent wave number k c =ω / U c (where ω is the radian frequency and U c is the speed of the fluctuating pressure convection) is up to two orders of magnitude larger than the corresponding acoustic and structural wave numbers. Under these conditions, the mode shape Ψ r Structural resonance with (x), where x is the surface coordinate vector x,y, is calculated using the pressure wavenumber-frequency spectrum Φ to predict the vibration response of the structure. p (k,ω) (where k is the wave vector (k x ,k y We present such a powerful spatial filter for excitation that it is necessary to use only the very small amplitude, low wavenumber components of the surface pressure cross spectrum G pp (x,x',jω) and structural resonance mode Ψ r The spatial filter or coupling property between (x) is sometimes called the modal joint acceptance. The main problem is to estimate the low wavenumber cross-spectral components of the flow excitations, since their amplitudes can be small compared to the dominant hydrodynamic turbulence convective wavenumber disturbances.

[0041] The acoustic field component of the boundary layer pressure spectrum represents the natural propagation of pressure disturbances away from each instantaneous and local eddy (at a sufficient distance from the local eddy) where the pressure has decayed to the small amplitude acoustic range. This acoustic component is small in amplitude compared to the pressure created by the convective turbulent eddies, but can be crucial for sound transmission properties or aerodynamic vibro-acoustic problems. A cross-spectral model of low-speed boundary layer flows can be modeled by the sum of two uncorrelated source components. The two components are the convective turbulent source Φ c (k,ω) and the acoustic source Φ0(k,ω), and the equation Φ p (k,ω)=Φ c (k,ω)+Φ0(k,ω), where k is the wave number (rad / m) and ω is the frequency (rad / sec), is obtained. Each source component can be described by a surface pressure cross spectrum. For convenience, it is assumed that the shape of the cross spectrum is generally separable in the frequency and spatial domains. For homogeneous sources, the frequency content is expressed as a spatially averaged autospectrum:

number

[0042] Pressure cross-spectral models of convective turbulence are typically written as follows:

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[0043] The coupling between the pressure field and the mode shapes of the responding structure is given by the equation

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[0044] The product of the typical wavenumber spectrum of a panel mode (simple supported or pinched boundary conditions) and the turbulent boundary layer excitation at a given frequency may result in a spectrum with two main peaks corresponding to the main mode peak and the turbulent boundary layer peak. At aerodynamic coincidence, the two peaks will overlap and the coupling will be at an overall maximum.

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[0045] For structural and boundary layer parameters typical of an aircraft in cruising, the response of a rectangular plate to turbulent boundary layer excitation occurs in resonating, acoustically inefficient plate modes, and the contributions of these plate modes dominate the acoustic radiation, whether or not they are strongly driven by the boundary layer. If the mode is strongly driven by the boundary layer, the excitation level is determined by the convective peak of the wavenumber-frequency spectrum, which is where most of the fluctuating energy resides, and the radiated sound is sensitive to details of the shape and location of the peak. If the mode is weakly driven by the boundary layer, the sub-convective region of the wavenumber-frequency spectrum is significant, and differences between models at low wavenumbers lead to corresponding discrepancies in the prediction of the radiated sound.

[0046] In automotive wind noise applications, the flow velocities are much slower and more isolated than in the aircraft boundary layer case. The sound power transmitted into the interior acoustic space is given by the equation

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[0047] The modal configurations described above can be extended to explicitly include resonant and non-resonant contributions to the transmitted sound. The total sound power radiated inwards is given by the equation

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[0048] For low-speed, highly separated flows (such as wind noise), the external pressure spectrum is proportional to the high-energy turbulence spectrum Φ c (k c ,ω) and the low-level uncorrelated diffuse acoustic spectrum Φ0(k0,ω). The total sound power radiated inside the car can therefore be expanded into four terms:

number

[0049] As shown for the automotive wind noise application above, the vibration, dynamic distortion, and acoustic radiation response of a structure imposed by any nearby flow field depends on both the surface pressure spectrum and its spatial correlation. The spatial correlation is given by:

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[0050] As described in more detail below, the subject matter herein provides a pressure sensing array that is composed of multiple different logical groups or arrays of sensing elements for obtaining different sets of measurement data corresponding respectively to the pressure spectra and spatial correlations of "slow" (high wavenumber) loads and "fast" (low wavenumber) loads.

[0051] Overview of a multi-wavefront flow-sensing array.

[0052] If the wavenumber-frequency spectrum of pressure fluctuations under flow can be measured, flow-induced sound and vibration in a structure can be predicted. Flow can contain both (incompressible) turbulent pressure fluctuations and (compressible) acoustic pressure fluctuations at wavenumbers of significantly different characteristics. The sound and vibration response of a structure to these two different source components depends on the spatial coupling or joint acceptance between the fluid loading and the vibro-acoustic resonance response. The smaller of the two flow pressure fluctuations (convective turbulent, acoustic) very often results in the largest, flow-induced sound or vibration in the structure. This often leads to a signal-to-noise measurement problem, where one component of the flow pressure fluctuation needs to be measured at a low level in the presence of much larger pressure fluctuations in the other component.

[0053] Exemplary embodiments described herein provide a flow noise surface pressure sensing array configured to obtain sets of measurement data that fully define the input aeroacoustic or hydroacoustic loading conditions of the aforementioned mathematical models to predict the vibration response and sound transmission of any complex structure subjected to flow turbulence loading, i.e., a set of measurement data characterizing the pressure spectrum and spatial correlation of "slow" (high wave number) loadings and another set of measurement data characterizing the pressure spectrum and spatial correlation of "fast" (low wave number) loadings. Although the subject matter may be used in the context of measuring any number or combination of properties or characteristics of the surrounding environment, for purposes of explanation, the subject matter is described herein primarily in the context of measuring fluid flows interacting with a structure, such as, for example, wind for an automobile, aircraft, spacecraft, or other vehicle. In this regard, a pressure sensing array includes a first logical grouping or array of sensing elements, the sensing elements being physically arranged or otherwise distributed relative to one another across the substrate in a manner configured to optimize the spectral resolution and signal to noise ratio (SNR) of a measured wavenumber-frequency spectrum characterizing the pressure spectrum of a high wavenumber hydrodynamic load of a fluid flow. A second logical grouping or array of sensing elements, the sensing elements being physically arranged or otherwise distributed relative to one another across the substrate in a manner configured for the spectral resolution and signal to noise ratio (SNR) of a measured wavenumber-frequency spectrum characterizing the pressure spectrum of a low wavenumber acoustic load of a fluid flow. Different groups of sensing elements may be interwoven among one another across a common substrate that is flexible and capable of conforming to the structure being measured.

[0054] In one or more exemplary embodiments, the low wavenumber pressure measurement array of sensing elements is distributed across the substrate in a uniform manner to obtain "global" pressure measurement data, while the high wavenumber pressure measurement array of sensing elements is itself composed of smaller subarrays or subgroups of concentrated sensing elements to obtain "local" pressure measurement data at different locations or regions of the flow on the structure. In exemplary embodiments, the low and high wavenumber sensor arrays each typically include 8-128 individual sensing elements, and the two arrays are integrated on a thin conformable substrate or "blanket" that can be applied in a "stick / peel" manner to any flow-impinging structural surface without significantly altering the flow field. The conformable blanket is fabricated to allow for the encapsulation or mounting of one or more sensor arrays, some or all of the required supporting electronics, and interconnections as described above in the context of FIG. 1. In this regard, the substrate may be flexible to allow compliance of multiple curvatures, while also being capable of supporting the various components provided above, providing strength or durability to allow reliable use and reuse in harsh industrial or testing environments. The edges of the sensor blanket may be aerodynamically and / or hydrodynamically faired to the remainder of the structure with modeling clay or equivalent filler material. Although the subject matter is described herein in the context of pressure sensing elements (microphones), the array may additionally or alternatively incorporate other sensor types, such as temperature sensors or acceleration sensors.

[0055] In one or more embodiments, the low wavenumber sensor array is realized as a 2D array of sensing elements spanning a substrate to measure low wavenumber aeroacoustic or hydroacoustic loadings, which are acoustic for low flow velocities (subsonic) and convective turbulence for higher flow velocities (supersonic and hypersonic). For example, the low wavenumber sensor array may be a rectangular 2D array spanning the entire length and width of the substrate, with the spacing between sensing elements determined by the required Nyquist spatial sampling frequency of the low wavenumber pressure fluctuations. The wavenumber resolution of the array is then determined by the length L of the array: x and width L y For example, for a frequency range of 8000 Hz and a convective velocity of 27 m / s, the maximum wavenumber to be resolved is 1,860 rad / m, and from the Nyquist spatial sampling criterion, the sensor spacing dk is determined to be 1.7 mm. For a one-dimensional array of 64 sensors, the length of the array is 109 mm, which results in a wavenumber spectral resolution dk of 50 rad / m. In this regard, it is noted that completely filling the dimensions of the substrate with the sensing elements of the low wavenumber sensor array maximizes the wavenumber resolution of the array and facilitates direct estimation of the total spatially averaged pressure frequency spectrum over the entire measurement surface. Thus, the 2D array does not need to be completely filled, and sparse array signal processing methods can alternatively be used to estimate the required frequency-wavenumber spectrum.

[0056] When measuring low wavenumber pressure fluctuations in the presence of masking by high wavenumber pressure fluctuations, perforated screens and / or porous materials are applied to each of the sensing elements to physically attenuate the unwanted high wavenumber "noise" on the sensor. This effectively provides a spatial anti-aliasing filter in the wavenumber domain. When applied to the sensor, this attenuates the high wavenumber pressure fluctuations and reduces anti-aliasing errors in the desired low wavenumber pressure spectrum. At moderate levels of high wavenumber masking and higher frequencies, the windscreen may be sufficient to directly measure the low wavenumber surface pressure fluctuations. In applications where high wavenumber masking is sufficient for a pressure sensor on a windscreen, a 1D or 2D array of microphones can be used to support wavenumber filtering.

[0057] In an exemplary embodiment, the adaptive sensing array also incorporates a high wavenumber sensor array composed of multiple smaller sensor subarrays or subgroups for measuring local variations in high wavenumber aeroacoustic or hydroacoustic loadings, which are convective turbulence for low flow velocities (subsonic) and acoustic for higher flow velocities (supersonic and hypersonic). In an exemplary embodiment, the high wavenumber sensor subarray is smaller than the dimensions of the sensing array and sized to provide the required high wavenumber spectral resolution. This allows multiple smaller high wavenumber subarrays to be integrated at different locations on the conformal sensor blanket to measure variations in the local flow frequency-wavenumber pressure spectrum. In this regard, the high wavenumber sensor array (and constituent subarrays or subgroups of sensing elements) may focus measurements on a selected few locations or distinct regions on the surface, rather than spreading, encompassing, or otherwise attempting to obtain measurements across the entire measurement surface.

[0058] To measure high wavenumber pressure fluctuations, conformal sensing arrays utilize a thin aerodynamic fairing that contains microports to accommodate pressure sensing ports at smaller spacings than would be possible based on the tight packing of the MEMS sensor package. The microports can be manufactured to tight dimensional tolerances for very small diameter ports, down to a diameter of 0.1 mm, using digital printing of aerodynamically faired plastic manifolds molded into the conformal sensor blanket.

[0059] As mentioned above, direct data to memory data acquisition, described in U.S. Pat. No. 9,921,748, can be used to eliminate electrical noise and latency in the recorded data and avoid multiple wire connections to an external data acquisition system. Due to the high frequency sampling used by the array elements to ensure high bandwidth acquisition, and the large number of sensing elements, such data acquisition methods are used to ensure simultaneity of all sensor samples and minimize latency so that the sensor data can be synchronized with other external measurement data. In addition, the large amount of data collected per test may be available for analysis with minimal time delay. Such data acquisition techniques may include one or more of the following: Direct parallel storage from the sensors to a single unified memory block under the clock and address control of a microcomputer; High speed interleaved or multiplexed sensor to memory storage (but utilizing multiple data streams from groups of sensors to separate memory blocks); Use of multiple microcomputers, each operating on a group of sensors and a memory storage block. Use of a microcomputer with integrated memory of sufficient size to capture the sensor data from the test (e.g., by direct parallel means or high speed interleaved serial data streams before transmission to a larger computer for analysis via a high speed data communication bus or protocol). Use of multiple microcomputers, each interacting with a group of sensors and providing a high speed data path via a serial communication bus or medium directly to a storage medium such as flash memory, Universal Serial Bus (USB) storage, solid state hard drives, or directly to a computer. The multiple data streams can be reconstructed in the analysis process to provide the entire sensor data set in a synchronized parallel format. The set of measurement data obtained via each sensor array can ultimately be transmitted to a server, laptop, or other computer for post-test processing and analysis.

[0060] The design process for multiple wavefront arrays.

[0061] In an exemplary embodiment, the array of sensing elements of the compatible sensing arrangement is represented by the equation

number

number

[0062] An optimal sensor array provides the spectral resolution and signal-to-noise ratio (SNR) required to quantify the wavenumber-frequency spectrum of multiple spatiotemporal flow components.

number

number

number

number

number

number

[0063] Using the discrete Fourier transform (DFT) method,

number

number

number

number

number

number

number

number

[0064] The high wave number sensor array and its subarrays are designed to accurately measure the slow components of the aeroacoustic or hydroacoustic loading of the flow field. Slow wave speed components, by definition, have higher wave numbers and shorter characteristic correlation lengths than fast wave fronts, and therefore require smaller sensor spacing.

number

number

number

number

[0065] Each high wavenumber measuring sensor subarray can measure a high enough wavenumber that the resulting wavenumber-frequency spectrum contains both fast (low wavenumber) and slow spectral energy. The fast (low wavenumber) content can be filtered out by wavenumber filtering or by curve fitting an empirical model of the fast energy, as shown in the equation

number

[0066] A particular sensor array configuration can be made independently for the fast and slow sensor arrays (or subarrays). The array of sensing elements can be selected as the best application-specific compromise between wavenumber resolution and the number of sensors and / or the cost or complexity associated with the measurement. For example, the low wavenumber sensor array and / or the high wavenumber sensor subarray can be realized as a two-dimensional (2D) sensor array, an oriented one-dimensional (1D) sensor array, a concentric array, or any other combination or topology of sensing element configurations.

[0067] Automotive application examples

[0068] FIG. 2 illustrates an exemplary embodiment of a conformable sensing array 200 provided on an exterior surface of a vehicle 202, such as an automobile window. As discussed above, the sensing mechanism 200 may be fixed or otherwise provided on and in contact with the exterior surface of the window in a stick / peel manner, for example, by using an adhesive provided on the back side of the substrate 210 of the sensing array 200. In an exemplary embodiment, the sensing array 200 includes an array 220 of sensing elements 222 that are uniformly distributed across the length and width of the substrate 210 to provide a 2D low wavenumber sensor array 220. The sensing array 200 includes another array 230 of sensing elements 232 arranged in logical subgroups or subarrays 234 interspersed among the low wavenumber sensor array 220 and distributed across the substrate 210 in a manner configured to provide the spectral resolution and signal-to-noise ratio (SNR) required to quantify the wavenumber-frequency spectrum of a high wavenumber fluid field. In this regard, the sensing elements 232 utilized for the higher wavenumber measurements may be between the evenly spaced sensing elements 222 utilized for the lower wavenumber measurements that would otherwise be adjacent or adjacent to one another according to the minimum spacing of the lower wavenumber array. In such a situation, the spacing or separation distance between the higher wavenumber sensing elements 232 and the lower wavenumber sensing elements 222 may be less than the minimum spacing determined for the lower wavenumber array, as described in more detail below. It should be noted that, in an exemplary embodiment, each of the sensing elements 222, 232 is implemented as a MEMS microphone acting as a sensing element for a fluctuating surface pressure (FSP) load, however, in other embodiments, the sensing elements 222, 232 may be of different types, and the subject matter described herein is not limited to any particular type or combination of sensing elements 222, 232. Thus, for purposes of explanation, the subject matter may be described herein in the context of a MEMS microphone.

[0069] The adaptive sensing array 200 can be utilized to measure the varying pressure loads on a glass window surface (or alternatively, a vehicle body) to quantify the source of interior wind noise. At conventional road speeds of Mach < 0.1, the flow-wise convective velocity of the turbulent loads is at least an order of magnitude greater than the acoustic propagation wavenumber, k c The amplitude of the acoustic component of the fluctuating surface pressure (FSP) is typically 20-40 decibels (dB) lower than the amplitude of the convective turbulent FSP. It is therefore desirable to use array surface microphones and wavenumber analysis to separate the acoustic and convective turbulent flow loading components using wavenumber filtering.

[0070] The adaptive sensing array 200 effectively provides a single FSP array that can obtain all of the required wind noise load data in a cost-effective manner. In this regard, wind tunnel measurement time is costly and it is not cost-effective for an automobile manufacturer to move MEMS FSP array sensors around. In the embodiment of FIG. 2, wind loads from low wave number acoustics are measured using a larger array 220 of uniformly distributed, more widely spaced MEMS microphones 222, and more localized turbulent wind loads are measured using smaller sensor sub-arrays 234 of clustered or concentrated MEMS microphones 232 provided in separate or localized areas or locations.

[0071] In some embodiments, where the high wavenumber FSPs at low wave speeds are of higher amplitude than the low wavenumber acoustics, the array can be reduced to the minimum number of sensing elements required to measure only the pressure cross spectrum between a small number of oriented sensor pairs and compute the spatial correlation of the flow-induced pressure field. In other embodiments, the high wavenumber localized turbulence array can be realized as a one-dimensional line array of sensors, or a two-dimensional rectangular array of sensors. In such embodiments, the array cannot be completely filled, but wavenumber-frequency post-processing can utilize sparse array signal processing techniques on the measurement data obtained from the sparsely filled array to estimate the wavenumber-frequency spectrum of pressure.

[0072] 3-6 depict an exemplary embodiment of a compatible sensing array 300 suitable for use as the sensing array 200 of FIG. 2. The sensing array 300 includes a low wavenumber array of sensing elements 302 (e.g., sensing elements 222) distributed across a flexible electronics substrate 310, with higher wavenumber subarrays 304 (e.g., subarray 234) interspersed among the lower wavenumber sensing elements 302 at distinct locations on the substrate 310. In an exemplary embodiment, the electronics substrate 310 is molded into or otherwise physically integrated with a compatible encapsulation structure 320 that surrounds the electronics substrate 310, which may then be fixed, adhered, or otherwise attached onto a surface where fluid flow is to be measured, such as the surface of a vehicle 202.

[0073] In an exemplary embodiment, the conformable sealing structure 320 is realized as a sheet, blanket, or similar substantially flat layer of flexible material, such as silicone rubber. The sealing layer is selected to be electrically insulating, flexible enough to tightly conform the array to the doubly curved structural surface, and durable enough to allow hundreds of installations and de-installations over the expected life of the array. In an exemplary embodiment, the conformable sealing structure 320 has a substantially uniform thickness to present an aerodynamically smooth surface. As mentioned above, in an exemplary embodiment, the sealing layer 606 can be desirably as thin as practicable, with a uniform thickness, typically in the range of 2-5 mm, to improve the aerodynamic properties of the conformable sensing array and limit or otherwise minimize perturbations of fluid flow due to the geometry of the conformable sensing array.

[0074] In an exemplary embodiment, the electronics substrate 310 is realized as a thin printed circuit board, although in other embodiments the substrate 310 may be realized as a flexible polymer circuit or a network of smaller printed circuit boards connected by flexible polymer circuits or wiring strips. In the exemplary embodiment of FIG. 3, the electronics substrate 310 is cut into a multi-finger configuration to improve conformability to curved structures.

[0075] When utilized in conjunction with the technique of direct storage of data in digital memory described in U.S. Pat. No. 9,921,748, the electronics substrate 310 may also include or otherwise support one or more controllers, memory elements (e.g., RAM arrays) mounted thereon or otherwise provided, and conductive traces between the sensing elements and the memory elements described herein. The electronic controller and RAM array may be separately dedicated to each physical measurement subarray, or may be integrated into a single controller and RAM array to store the digital outputs from all subarrays in a serially encoded manner. The controller and RAM array may be integrated directly onto the array device on the PCB and within an encapsulating conformal layer, or may be implemented on a separate PCB separate from the array measurement device with electrical connections via flexible polymer circuitry or ribbon cables.

[0076] In an exemplary embodiment, the low wavenumber array sensing element 302 is realized as a MEMS microphone or a sensing device of a fluctuating surface pressure (FSP) load. In an exemplary embodiment, the MEMS microphone sensing element 302 is mounted or otherwise secured to the electronics substrate 310 in a manner configured to attenuate turbulence. In this regard, FIG. 4 illustrates an exploded view of an exemplary embodiment of a MEMS microphone 402 (e.g., sensing element 302) mounted to an area of ​​an electronics substrate 404 (e.g., substrate 310) in a manner configured to reduce exposure of the MEMS microphone 402 to turbulence. In an exemplary embodiment, the MEMS microphone 402 is mounted to the backside of the electronics substrate 404, and a hole, bore, or similar cutout area 405 is provided in the substrate 404 to expose the MEMS microphone 402 to fluid flow on an exposed surface of the substrate 404 opposite the MEMS microphone 402. Acoustic foam or similar porous material 406 is affixed or otherwise attached to the exposed surface of substrate 404 and is aligned with or otherwise covering pressure sensing holes 405 so as to attenuate high wave number pressure fluctuations at MEMS microphone 420 from the prevailing low wave speed turbulent loads. A micro-perforated stainless steel windscreen or similar material 408 is provided on the exposed surface of acoustic foam 406 and is similarly aligned with pressure sensing holes 405 so as to minimize self-noise from the microphone sensing ports and / or the aerodynamically rough surface of the acoustic foam layer.

[0077] Referring to FIG. 3 with reference to FIG. 5, in an exemplary embodiment, the high wavenumber subarray 304 includes a plurality of clustered sensing elements (e.g., sensing elements 232) provided at separate and distinct locations of the sensing array 300. As with the lower wavenumber array 302, the sensing elements of the higher wavenumber subarray 304 may be realized as MEMS microphones or sensing devices with varying surface pressure (FSP) loads. For example, FIG. 5 illustrates an exemplary embodiment of a high wavenumber subarray 500 suitable for use as the subarray 304 in the embodiment of FIG. 3. Each high wavenumber subarray 304, 500 may include a plurality of MEMS microphones 502 (e.g., sensing elements 232) that are more densely located relative to one another relative to the lower wavenumber array sensing elements 302 when mounted or otherwise provided on an electronics substrate 504 (e.g., substrate 310). In an exemplary embodiment, the MEMS microphones 502 are arranged in an arc around a central MEMS microphone 502. Similar to the MEMS microphones 402 of the low wavenumber array, the high wavenumber MEMS microphones 502 may be mounted, secured, or otherwise provided on the back surface of the substrate 504 and exposed to the fluid flow through corresponding aligned holes, bores, or cutouts in the substrate 504. In an exemplary embodiment, the MEMS microphones 502 of the high wavenumber sub-array 304 are exposed to the fluid flow without any intervening elements that may attenuate turbulence, i.e., the acoustic foam 406 and windscreen layer 408 do not overlap or otherwise align with the MEMS microphones 502.

[0078] Figure 6 illustrates an exploded view of a compatible sensing array suitable for use as the sensing array 300 of Figure 3. The sensing array includes a flexible electronics substrate layer 602 with a turbulence attenuation layer 604 (e.g., acoustic foam 406 and overlying windscreen 408) mounted, secured, or otherwise provided on an exposed surface of the flexible electronics substrate layer 602. The turbulence attenuation layer 604 includes void or cut-out regions aligned with the high wavenumber subarray regions 603 of the flexible electronics substrate layer 602 to expose the high wavenumber subarray sensing elements (e.g., sensing elements 232) to the turbulent fluid flow while attenuating the turbulent portion from the fluid flow to which the low wavenumber sensing elements 222 are exposed. A conformable encapsulation layer 606 is attached, secured, or otherwise provided over the exposed surface of the turbulence attenuation layer 604 to encapsulate or otherwise seal the flexible electronics substrate layer 602 and the turbulence attenuation layer 604. As mentioned above, in an exemplary embodiment, the encapsulation layer 606 may be desirably as thin as practicable with a uniform thickness to improve the aerodynamic properties of the conformable sensing array and to limit or otherwise minimize fluid flow perturbations due to the geometry of the conformable sensing array.

[0079] FIG. 7 is a flow diagram illustrating an embodiment of a multiple wavefront sensing process 700 suitable for implementation in connection with the sensor system 100 of FIG. 1. The various tasks performed in connection with the multiple wavefront sensing process 700 may be performed by software, hardware, firmware, or any combination thereof. For illustrative purposes, the following description of the multiple wavefront sensing process 700 may refer to elements described above in connection with FIGS. 1-6. In an exemplary embodiment, one or more aspects of the multiple wavefront sensing process 700 are implemented in or by the computing device 112 (e.g., by a software application executing on the computing device 112). It should be understood that the multiple wavefront sensing process 700 may include any number of additional or alternative tasks, and that the tasks illustrated in FIG. 7 need not be performed in the illustrated order, and that the multiple wavefront sensing process 700 may be incorporated into a more comprehensive procedure or process having further functionality not described in detail herein. Additionally, one or more of the tasks illustrated in FIG. 7 may be omitted from an embodiment of the multiple wavefront sensing process 700, so long as the intended overall functionality remains intact.

[0080] An example embodiment of the multiple wavefront sensing process 700 begins by receiving, obtaining, or otherwise identifying desired measurement requirements to be satisfied from a user (task 702). For example, a user may manipulate graphical user interface (GUI) elements on a GUI display (e.g., presented on the computing device 112) to select, input, or otherwise provide values ​​for the nature, characteristics, attributes, or other parameters of the operating environment in which the fluid flow measurements are to be obtained, such as, for example, the size and shape of the measurement domain, minimum and maximum frequencies defining the range of frequencies to be measured, the desired wavenumber resolution for low wavenumber flow components, the desired wavenumber resolution for high wavenumber flow components, the number of components in the wavenumber-frequency spectrum of the flow, the estimated autospectral levels and spatial correlations for each component in the wavenumber-frequency spectrum of the flow, and / or other parameters characterizing low and high wavenumber fluid flow components.

[0081] The multiple wavefront sensing process 700 continues by calculating or otherwise determining constraints for the sensing elements of the low wavenumber array based on the desired measurement requirements (task 704). In this regard, the multiple wavefront sensing process 700 determines the minimum spacing between sensing elements and the minimum number of sensing elements for the low wavenumber array to achieve the desired wavenumber resolution for the low wavenumber flow components, as described above. For example, a spatial array of sensors is required for spatial Fourier analysis of distributed FSP loads that are statistically random in both space and time. Spatial Fourier analysis of the sensor data is required for subsequent wavenumber filtering of the acoustic load spectral components in the total FSP load spectrum.

[0082] As described above, in one embodiment, the multiple wavefront sensing process 700 defines the number of components in the wavenumber-frequency spectrum of the flow to be measured, estimates the autospectral level and spatial correlation of each of the components in the wavenumber-frequency spectrum of the flow, and defines characteristics that describe the fast (low wavenumber) components from the slow (high wavenumber) components. The multiple wavefront sensing process 700 defines parameters of the pressure wavenumber-frequency spectrum measurement of the fast and slow components, such as, for example, the size and shape of the flow measurement domain, the minimum and maximum frequencies of each component, and the desired wavenumber resolution for each component. Based thereon, the multiple wavefront sensing process 700 computes the minimum sensor spacing and number of sensors for the measurement array of the fast component, as described above, and adjusts the array length to accommodate the wavenumber resolution requirements. In an exemplary embodiment, the multiple wavefront sensing process 700 estimates the aliasing of the high wavenumber from the slow component, and identifies or otherwise determines one or more means for minimizing the aliasing error, such as, for example, a physical filter on the sensor, post-processing in the wavenumber domain, etc. An array configuration (or shape) for the fast component measurement array is then selected or otherwise identified (e.g., line, cross, circle, or other cross-spectral curve-fitted array) along with dimensionality or other constraints (e.g., full or sparse placement of sensors, one- or two-dimensional DFT wavenumber analysis components, etc.).

[0083] The example multiple wavefront sensing process 700 continues by identifying or otherwise determining a desired shape or physical configuration for the low wavenumber sensor array (task 706). In one embodiment, the multiple wavefront sensing process 700 generates or otherwise provides a GUI display including a list of selectable array configurations from which a user can select or otherwise identify a desired array configuration for a particular application or structure to be analyzed. For example, based on the minimum spacing and number of sensing elements required to achieve a desired wavenumber resolution for low wavenumber fluid flow components, the GUI display may include a graphical representation of different potential array configurations having the minimum spacing and determined number of sensing elements to allow the user to preview the potential array configurations. In one embodiment, the user may select from among any number of different one-dimensional array configurations, two-dimensional array configurations, curved or arcuate array configurations, multi-finger array configurations, etc. The user can also select whether the low wavenumber sensor array is fully filled (e.g., with a minimum spacing between sensing elements determined uniformly across the area of ​​the shape) or sparsely filled (e.g., with a spacing between sensing elements greater than the minimum spacing), or otherwise choose.

[0084] After identifying the desired low wavenumber array configuration, the multiple wavefront sensing process 700 continues by calculating or otherwise determining constraints for the sensing elements of the high wavenumber array based on the desired measurement requirements for the high wavenumber fluid flow component (task 708). In this regard, the multiple wavefront sensing process 700 determines the minimum spacing between sensing elements and the minimum number of sensing elements for the high wavenumber array to achieve the desired wavenumber resolution for the high wavenumber flow component, as described above. For example, in one embodiment, the multiple wavefront sensing process 700 calculates or otherwise determines the minimum sensor spacing and number of sensors for the slow array, and then calculates or otherwise determines the dimensions of the slow component measurement array based on the wavenumber resolution requirements, the minimum sensor spacing, and the minimum number of sensors. The multiple wavefront sensing process 700 can then review the expected flow field to determine the number and corresponding positions of multiple smaller slow component measurement subarrays to be incorporated into the larger fast component measurement array. In this regard, if the fast component measurement array sensors do not require an anti-aliasing windscreen, the multiple wavefront sensing process 700 can determine a position of the low component measurement subarray that maximizes the reuse (or dual use) of individual sensors in both the low and fast component measurement arrays.

[0085] After determining the sensor constraints for the high wavenumber array, the multiple wavefront sensing process 700 continues by calculating or otherwise determining constraints for the subarrays that make up the high wavenumber array based on the expected high wavenumber components of the fluid flow field (task 710). In this regard, the multiple wavefront sensing process 700 calculates or otherwise determines the number of different subarrays that need to be divided, which determines the minimum number of sensing elements that need to be divided based on the number of sensing elements per group required to achieve the desired high wavenumber resolution. After determining the number of subarray groups to be utilized, the multiple wavefront sensing process 700 also determines the corresponding locations where these subarrays (and their constituent sensing elements) should be distributed and interspersed among the low wavenumber array. In an exemplary embodiment, the multiple wavefront sensing process 700 estimates the amount of aliasing between the low wavenumber and high wavenumber fluid flow components and whether a windscreen or other attenuation mechanism is utilized. In the absence of an attenuating element (e.g., attenuating layer 604), the multiple wavefront sensing process 700 identifies a location for the high wavenumber subarray that maximizes the number of sensing elements that can be used for both the low wavenumber array and the high wavenumber array (e.g., task 706), for example, by maximizing the number of high wavenumber sensing elements that can be otherwise juxtaposed with the low wavenumber sensing elements already in place.

[0086] After the multiple wavefront sensing process 700 identifies or otherwise defines the minimum number of sensors and minimum sensor spacing for the low wavenumber array, the shape or configuration of the low wavenumber array, the minimum number of sensors and minimum sensor spacing for the high wavenumber array, the number of sensors per high wavenumber subarray, and the spatial distribution of the high wavenumber subarray, a corresponding sensing array can be constructed as described above. For example, a flexible PCB can be cut or otherwise patterned to achieve a desired shape for the low wavenumber array, and sensing elements can be provided on the flexible PCB at determined locations and / or with determined sensor distribution and spatial arrangement relative to each other. As described above in the context of FIG. 6, an optional turbulence attenuation layer having cut-out areas corresponding to the high wavenumber subarray can be provided on the flexible PCB and encapsulated with the PCB using a compatible encapsulation layer.

[0087] 7, the exemplary embodiment of the multiple wavefront sensing process 700 continues by receiving or otherwise obtaining test parameters and programming or otherwise configuring the sensing system in accordance with the test parameters (tasks 712, 714). In this regard, a user may manipulate or otherwise interact with GUI elements on the GUI display to input or otherwise provide values ​​for parameters that define the test procedure to be performed, such as, for example, duration of the test, desired sampling frequency, etc. Based on the input test parameters, the multiple wavefront sensing process 700 may calculate or otherwise determine corresponding settings for the controller 108, RAM array 106, etc., such as, for example, digital data block size, digital data block download time, data block download rate, etc. Thereafter, at the start of the test procedure, the controller 108 may be commanded, signaled, or otherwise instructed to initiate the capture of measurement data from the sensor array 104 in accordance with the input test parameters. In one embodiment, the multiple wavefront sensing process 700 identifies or otherwise determines a record of a required measurement time and calculates a digital data block size based on the required measurement time. The multiple wavefront sensing process 700 then calculates or otherwise determines a required data block download time and a required data download rate, and in an exemplary embodiment, selects or otherwise utilizes a high speed data link with the required data download rate. In some embodiments, the multiple wavefront sensing process 700 can program the downloaded controller application according to the test parameters.

[0088] As described in U.S. Pat. No. 9,921,748, the RAM array 106 may be initialized or formatted by the controller 108 to ensure that new data is ready to be recorded and that a data recording operation is initiated, for example, by an attached computing device 112, which may be utilized to issue commands to the controller 108 or otherwise schedule the initiation of a data recording operation at the controller 108. During a data recording operation, the digital sensor devices (e.g., sensing elements 222 and 232) generate respective digital output signals that convey the raw digital sensor output data of interest to a RAM device assigned to the respective source sensor device, which serves as an input to the RAM device. To synchronously sample the digital output signals, a common clock signal may be provided to the RAM device and / or the digital sensor device, as needed, thereby synchronously writing the raw sensor output data to the RAM device. The raw digital sensor data may be maintained in the RAM array 106 until it is time to read or download the sensor data. In certain embodiments, the data recording operation terminates when the RAM array reaches its data capacity. In other embodiments, the data recording operation is terminated after a predetermined time. In yet other embodiments, the data recording operation is terminated in response to a user command or instruction. The raw digital sensor output data may then be transferred from the RAM array 106 to the computing device 112 via the controller 108. As mentioned above, the USB interface 110 may be utilized to transfer the raw sensor data to the host computing device 122 where it may be processed, analyzed, filtered, or otherwise manipulated as desired. Delaying post-recording processing in this manner allows the RAM device to efficiently and effectively capture raw sensor data from a large number of sensor devices in real time with minimal latency.

[0089] 8-11 depict exemplary GUI displays that may be presented by or on a computing device, such as computing device 112, in connection with the multiple wavefront sensing process 700 and related subject matter discussed above. FIG. 8 depicts a setup GUI display 800 that may be presented on computing device 112 that includes a GUI element 802 that allows a user to input test parameters, such as test duration (or data acquisition time), along with other thresholds or parameters for the test (e.g., task 712). The exemplary setup GUI display 800 also includes a graphical representation 804 of the sensing array, along with a graphical representation 806 of the connection status of different arrays of the sensing array. The setup GUI display 800 also includes a GUI element 808 that allows a user to manage the storage of measurement data on or in the computing device 112 after it has been transferred from the RAM array 106 to the computing device 112.

[0090] 9 illustrates a measurement review GUI display 900 that may be presented during or after data acquisition. The measurement review GUI display 900 includes a bar graph or similar GUI display 902 that depicts low wave number (acoustic) measurement data, such as, for example, a numerical value or proportional distribution of low wave number fluid flow component measurements from the measurement array 220 (or sensing elements 222) during a test period that are above an upper threshold value, below a lower threshold value, or within a range defined by upper and lower threshold values. Similarly, the measurement review GUI display 900 includes a second bar graph or similar GUI display 904 that depicts high wave number (turbulent) measurement data, such as, for example, a numerical value or proportional distribution of high wave number fluid flow component measurements from the measurement array 230 (or sensing elements 232) during a test period that are above an upper threshold value, below a lower threshold value, or within a range defined by upper and lower threshold values.

[0091] FIG. 10 illustrates another example of a measurement review GUI display 1000 that may be presented during or after data acquisition. The measurement review GUI display 1000 includes a graphical representation 1002 of a sensing array including individual sensing elements depicted at respective locations. In this regard, in some embodiments, the sensing elements may be rendered using different visually distinguishable characteristics to indicate different attributes or status associated with each sensing element. For example, the sensing elements may be color coded to indicate whether the fluid flow component of each wavenumber measured by each sensing element is above an upper measurement threshold, below a lower measurement threshold, between an upper and lower measurement threshold, etc., thereby providing a graph showing how the effect of fluid flow varies with location. Similarly, the sensing elements may be color coded or otherwise rendered using different colors or visually distinguishable characteristics to indicate a connection or operational status, a logical group or subarray to which each sensing element belongs, etc.

[0092] 11 illustrates another example of a measurement review GUI display 1100 that may be generated or otherwise presented at a computing device (e.g., computing device 112) based on an analysis of measurement data obtained from different sensor arrays. For example, a software application at computing device 112 may provide GUI elements 1101, 1103, such as list boxes, drop-down menus, etc., that allow a user to select or otherwise identify the arrays 220, 230 and corresponding wavenumbers of fluid flow components that the user would like to analyze, as well as allow a user to select or otherwise indicate the type of representation of the measurement data that the user would like to analyze. For example, in response to selecting an autospectral presentation of the measured responses captured by the high wavenumber array 230, the computing device 112 (or a software application running thereon) can analyze the measurement data captured by the sensing elements 232 of the high wavenumber array 230 to calculate or otherwise compute an autospectrum, power spectral density, or similar representation of the measured responses to the high wavenumber components of the fluid flow with respect to frequency and provide a corresponding graphical representation 1102 of the measured responses to the high wavenumber components of the fluid flow with respect to frequency on the GUI display 1100. In an exemplary embodiment, the GUI display 1100 also includes a graphical representation 1104 of the measured responses to the high wavenumber components of the fluid flow with respect to time. It should be noted that FIG. 11 merely illustrates some exemplary representations of measured responses captured using the sensing arrays described herein, and the subject matter is not intended to be limited to any particular GUI display or the graphical representation(s) provided thereon.

[0093] It will be appreciated that the subject matter described herein allows all of the required data to be conveniently obtained in a single test on the vehicle body, either on the road or in an aeroacoustic wind tunnel. Measurement data from the different sensor arrays can be post-processed to define the loading of exterior wind noise sources on a vibro-acoustic (VA) model of the vehicle, which can then be used to predict interior wind noise sound pressure levels (SPL). In this regard, to evaluate interior wind noise early in a new vehicle development program, the sensing configuration described herein can be used on reduced-scale clay or similar models of the vehicle's aerodynamic styling to facilitate the design of the vehicle in a manner that achieves the desired acoustic performance prior to manufacturing and assembly. If the predicted structural vibration or interior SPL levels exceed the design targets, the described process allows an aeroacoustic engineer to apply aerodynamic design modifications using modeling clay or equivalent materials to find an aerodynamic design that has lower measured levels of wind acoustic loading and / or wind hydrodynamic turbulence loading, and therefore lower levels of structural vibration and / or interior noise.

[0094] Additionally, the following exemplary embodiments are provided, which are numbered for easier reference:

[0095] Example 1: A sensing array comprising: a substrate; a first sensor array on the substrate, the first sensor array including a first plurality of sensing elements, a first distribution of the first plurality of sensing elements on the substrate configured to obtain a first set of measurement data indicative of a first property of an operating environment; and a second sensor array on the substrate, the second sensor array including a second plurality of sensing elements interspersed between the first sensor array, a second distribution of the second plurality of sensing elements on the substrate configured to obtain a second set of measurement data indicative of a second property of the operating environment.

[0096] Example 2: The sensing arrangement of example 1, wherein the second sensor array includes a plurality of subarrays, each of the plurality of subarrays including a respective subset of the second plurality of sensing elements.

[0097] Example 3: The sensing array of example 2, wherein a spacing between sensing elements of each subset of the second plurality of sensing elements of each subarray is smaller than a second spacing between each subarray and another subarray of the plurality of subarrays.

[0098] Example 4: The sensing array of example 1, wherein the first property comprises a first response to a lower wavenumber component of the fluid flow and the second property comprises a second response to a higher wavenumber component of the fluid flow.

[0099] Example 5: A sensing array as described in Example 4, wherein the first distribution includes at least one of a minimum sensor spacing to achieve wavenumber resolution of the lower wavenumber component and a number of sensing elements to achieve wavenumber resolution of the first response to the lower wavenumber component.

[0100] Example 6: A sensing array as described in Example 5, wherein the second distribution includes a number of subarrays having a second minimum sensor spacing and a number of sensing elements per subarray to achieve a second wavenumber resolution of a second response to a higher wavenumber component.

[0101] Example 7: The sensing arrangement of example 4, further comprising an attenuation layer covering the first plurality of sensing elements of the first sensor array.

[0102] Example 8: A sensing array as described in example 7, wherein the attenuation layer includes a windscreen configured to provide an anti-aliasing filter that attenuates higher wavenumber components.

[0103] Example 9: A sensing array as described in Example 4, wherein modeled data of higher wavenumber components is subtracted from the first set of measured data to remove the higher wavenumber components, and the modeled data includes an estimate of at least one of discrete Fourier transform aliasing or foldback errors.

[0104] Example 10: The sensing array of example 1, further comprising a conformable encapsulating layer covering the substrate, the first sensor array, and the second sensor array.

[0105] Example 11: The sensing array of example 10, wherein the conformable sealing layer comprises a removable adhesive material.

[0106] Example 12: A sensing array as described in Example 1, comprising a plurality of subarrays, wherein a first sensor array is optimized to obtain a first set of measurement data indicative of a higher wave speed and lower wave number flow component of a flow-induced pressure field, and a second sensor array is optimized to obtain a second set of measurement data indicative of a lower wave speed and higher wave number flow component of a flow-induced pressure field.

[0107] Example 13: The sensing array of Example 1, wherein the substrate comprises a flexible printed circuit board.

[0108] Example 14: A sensing array as described in Example 13, where the flexible printed circuit board is cut or patterned for compatibility.

[0109] Example 15: The sensing array of Example 14, wherein the flexible printed circuit board is patterned into a multi-finger structure or a spiral.

[0110] Example 16: The sensing array of Example 1, further comprising: a random access memory (RAM) architecture coupled to the first and second plurality of sensing elements; and a controller operably coupled to the RAM architecture to control read and write operations of the RAM architecture, wherein during data recording operations, each sensing element of the first and second plurality of sensing elements is electrically and physically directly connected to the RAM architecture to facilitate synchronous writing of digital sensor output data comprising first and second sets of measurement data.

[0111] Example 17: A method comprising: obtaining from a user the required data acquisition time and sensor over-range and under-range levels; establishing a logical connection with an array device RAM controller; providing a user with a graphical display of the logical connections to the array devices and sub-array components; providing a graphical means for the user to specify a file name and folder and / or path for the results data; providing a graphical means for the user to start and stop data acquisition; providing a means for the user to review the number of sensors in each sub-array that measured over-range signals and the number of sensors that measured under-range signals during the data acquisition period; and providing a means for the user to save the results data to a defined file name after reviewing the number of over-range and under-range instances.

[0112] Example 18: The method of example 17, further comprising: providing a graphical means for a user to see which sensor positions within each subarray were over-ranged; providing a graphical means for a user to see which sensor positions within each subarray were under-ranged; and providing a means for a user to save the resulting data to a defined file name after reviewing the number and positions within the array of the over-range and under-range instances.

[0113] Example 19: A flexible support substrate configured to be conformably mounted to a curved surface; and an array of digital sensor devices carried by the flexible support substrate, each of the digital sensor devices configured to generate a respective digital output signal conveying raw digital sensor output data, the array of digital sensor devices including a lower wavenumber array including a first set of digital sensor devices and a higher wavenumber array including a second set of digital sensor devices, the higher wavenumber array including a plurality of subarrays including respective subsets of the second set of digital sensor devices, the first set of digital sensor devices of the lower wavenumber array being uniformly distributed across the flexible support substrate, and the plurality of subarrays including a first set of digital sensor devices and a second set of digital sensor devices. an array of digital sensor devices, where a subarray of the digital sensor devices is non-uniformly interspersed among a first set of digital sensor devices of a lower wavenumber array; an array of random access memory (RAM) devices carried by a flexible support substrate, the RAM devices being directly connected to the digital sensor devices during data recording operations of the sensor system whereby the RAM devices directly receive digital output signals; and a controller operatively coupled to the array of RAM devices to synchronously clock the array of RAM devices during data recording operations whereby raw digital sensor output data is synchronously written to the array of RAM devices.

[0114] Example 20: The sensor system of Example 19, wherein each digital sensor device in the array of digital sensor devices includes a microelectromechanical microphone device.

[0115] Example 21: A system comprising: means for obtaining from a user the required data acquisition time and sensor over-range and under-range levels; means for establishing a logical connection with an array device RAM controller; means for providing a user with a graphical display of the logical connections to the array devices and sub-array components; graphical means for a user to specify a file name and folder and / or path for the results data; graphical means for a user to start and stop data acquisition; means for a user to review the number of sensors in each sub-array that measured over-range signals and the number of sensors that measured under-range signals during the data acquisition period; and means for a user to save the results data to a defined file name after reviewing the number of over-range and under-range instances.

[0116] Example 22: The system of Example 21, further comprising: a graphical means for a user to see which sensor positions within each subarray were over-ranged; a graphical means for a user to see which sensor positions within each subarray were under-ranged; and a means for a user to save the resulting data to a defined file name after reviewing the number and locations within the array of over-range and under-range instances.

[0117] Although at least one exemplary embodiment has been presented in the foregoing detailed description, it should be understood that a vast number of variations exist. It should also be understood that the exemplary embodiment(s) described herein are not intended to limit in any way the scope, applicability, or configuration of the claimed subject matter. If anything, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing the described embodiment(s). It should be understood that various changes can be made in the function and arrangement of elements, including equivalents known and foreseeable equivalents at the time of filing this patent application, without departing from the scope defined by the claims.

Claims

1. A surface pressure sensing array for measuring flow induced loads on a structure due to a fluid flow, including an acoustic component and a convective turbulent component, interacting with a surface of the structure, comprising: a flexible substrate conformable to said surface; a low wavenumber sensor array on the flexible substrate, the low wavenumber sensor array including a first plurality of pressure sensing elements, a first distribution of the first plurality of pressure sensing elements on the flexible substrate configured to obtain a first set of measurement data indicative of a low wavenumber component of the fluid flow interacting with the surface of the structure; a high wavenumber sensor array on the flexible substrate, the high wavenumber sensor array including a second plurality of pressure sensing elements non-uniformly interspersed among the low wavenumber sensor array in a plurality of localized regions, a second distribution of the second plurality of pressure sensing elements on the flexible substrate configured to obtain a second set of measurement data indicative of a high wavenumber component of the fluid flow interacting with the surface of the structure.

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