Universe dynamic measurement device and method for flow field in confined space of turbomachinery

Abstract

The invention discloses a global dynamic measurement device and method for a flow field in a confined space of a turbomachine, and belongs to the technical field of internal flow testing of the turbomachine. A dynamic probe and a hot-wire probe are matched with a surface hot film measurement unit and an oil flow visual measurement unit to obtain the pressure and the flow direction of a main flow area between turbomachinery stages, the blade normal near-wall boundary layer speed, the blade surface quasi-wall surface shear force and an end wall near-boundary layer streamline topological structure; sweeping measurement in a limited blade channel section is realized through a displacement control mechanism, and a synchronous phase locking module and a multi-channel data acquisition and processing module which take a dynamic probe periodic pressure signal as a reference are adopted. After phase sensitive detection and low-pass filtering are carried out on hot line and hot film signals, high signal-to-noise ratio extraction and strict synchronization with a rotor phase are realized, spatial and temporal distribution of a turbomachinery boundary layer is reconstructed, boundary layer separation, reattachment and transition characteristics are identified, and global dynamic measurement of a flow field in a limited space is realized.

Description

Technical Field

[0001] This invention belongs to the field of internal flow testing technology for turbomachinery, and relates to a device and method for full-domain dynamic measurement of flow field within a confined space of turbomachinery. Specifically, it relates to a device and method that combines four technologies to achieve full-domain dynamic measurement of flow field within a confined space of turbomachinery: dynamic probe technology with high-frequency dynamic measurement function, oil flow technology with flow field visualization function, hot wire probe technology with near-wall flow field high-frequency response measurement function, and surface hot film measurement technology with quasi-wall shear force measurement function. The dynamic probe technology and hot wire probe technology, together with a biaxial displacement control mechanism, complete the sweeping measurement process of the flow field. Background Technology

[0002] Under the coupling effect of rotational motion and complex geometric flow channels, the internal flow of modern turbomachinery exhibits significant three-dimensionality, unsteadiness, and strong shearing effects. Furthermore, in pursuit of higher performance, modern turbomachinery often employs high-load blade designs. However, this design introduces flow challenges: the enhanced lateral and flow-direction pressure gradients easily induce boundary layer separation at the suction surface, generating multi-scale vortex structures within the flow channel. The resulting increased flow losses and overall performance degradation become bottlenecks restricting further improvements in turbomachinery efficiency. Against this backdrop, the core challenge in the aerodynamic design of high-load turbomachinery lies in effectively suppressing boundary layer separation and systematically revealing the generation and evolution mechanisms of complex internal vortex structures. Overcoming this bottleneck hinges on a deep analysis of the physical structure and evolutionary laws of the highly unsteady flow within turbomachinery.

[0003] Currently, unsteady flow structures inside turbomachinery are mainly obtained through two methods: CFD calculations and experimental measurements. Because turbomachinery flows are characterized by abrupt transitions, strong shearing, and significant separation, the accuracy of CFD calculations is often low, while existing experimental measurement methods typically struggle to simultaneously capture the unsteady flow characteristics within turbomachinery. Therefore, a high-precision measurement technique is needed to reproduce the full structure of the flow field, thereby improving our understanding of unsteady flows inside turbomachinery.

[0004] Currently, flow measurement methods for high-load turbomachinery mainly include dynamic probe technology, hot-wire probe technology, surface hot film technology, and oil flow technology. A dynamic probe is a sensor specifically designed to capture microsecond to millisecond-level instantaneous changes in fluid flow. It has high spatiotemporal resolution and can accurately analyze key transient phenomena such as blade passage frequency, vortex shedding, and flow instability. However, the probe's large size can disturb the local flow field, making it difficult to accurately measure the flow field near the wall. Furthermore, it is typically fixed to a displacement mechanism, making deployment difficult in rotating environments. Hot-wire probes can effectively capture unsteady signals, but their complex internal structure requires a hot-wire anemometer and temperature correction during operation. When extremely close to the wall, they are easily affected by radiative heat transfer from the metal endwall, leading to significant measurement errors. In addition, both dynamic and hot-wire probe technologies can only perform discontinuous point measurements, resulting in low efficiency. They are also susceptible to blade interference under rotating conditions, making it difficult to transmit boundary layer flow signals in real-time with high fidelity. Both are non-contact measurements, therefore only measuring the boundary layer near the endwall, and are easily damaged by contact with the wall when extremely close. Oil flow technology is relatively inexpensive and can intuitively display complex flow characteristics, but it is difficult to provide quantitative flow field data and has low time resolution, making it difficult to reflect changes in the flow field over time. Surface hot film measurement technology is a contact measurement method that can continuously measure boundary layer data on the blade surface and features high frequency response, high synchronization, and small flow field disturbance. For rotating blades, it can also ensure real-time and high-fidelity transmission of unsteady boundary layer flow signals, thus showing significant advantages in boundary layer measurement. However, it can only measure data on the blade surface and cannot measure near-wall boundary layer flow. Furthermore, like hot-wire probe technology, it has a complex internal structure and requires temperature correction and the use of a hot-wire anemometer. In addition, coupling these four measurement technologies can achieve full-domain dynamic measurement of the flow field within the confined space of turbomachinery. However, when performing multi-cycle flow field measurements, all four technologies suffer from high signal-to-noise ratio and dynamic detail distortion, and lack effective means to strictly correlate the measurement data with the rotor's rotation phase, thus failing to reflect the dynamic evolution of the flow field with the rotor phase.

[0005] In summary, existing methods for testing the internal flow field of turbomachinery generally suffer from problems such as dispersed measurement areas, limited parameter types, insufficient spatial and temporal resolution, and difficulty in coordinating multiple technologies under confined space, high load, and high speed conditions. These limitations make it difficult to meet the need for comprehensive dynamic characterization of the complex three-dimensional unsteady flow field inside turbomachinery. Therefore, how to achieve multi-parameter, high spatiotemporal resolution, comprehensive dynamic measurement of the flow field within the confined space of turbomachinery is a pressing technical problem that needs to be solved in this field. Summary of the Invention

[0006] (a) Purpose of the invention To address the aforementioned deficiencies and shortcomings of existing technologies, this invention combines the advantages and disadvantages of four measurement techniques and proposes a global dynamic measurement device and method for the flow field within the confined space of turbomachinery based on phase-locked loop (PLL) technology. This invention utilizes the small size, low interference, fast response, and high spatiotemporal resolution of hot-wire probes to measure the normal flow field of turbomachinery blades, solving the problem that surface hot-film measurement technology can only measure boundary layer data on the blade surface. It also leverages the ability of surface hot-film measurement technology to continuously measure boundary layer data close to the blade wall, and its high-frequency response, high synchronization, and small flow field disturbance characteristics to address the problems of dynamic probes and hot-wire probes being unable to measure boundary layer data on the blade surface and the difficulty in real-time, high-fidelity transmission of boundary layer flow signals under high-speed blade rotation. Furthermore, it utilizes oil flow visualization technology to address the problem that dynamic probes and hot-wire probes cannot acquire flow information at the endwall. The invention also utilizes the simple structure and high-frequency response of dynamic probe technology to measure the interstage flow field, and leverages the asynchronous averaging characteristics of PLL technology to improve the signal-to-noise ratio and effectively filter out random noise, clearly revealing the dynamic evolution of flow parameters with rotor phase, thus achieving simultaneous and synchronous measurement of the global flow field within the confined space of turbomachinery. This invention is a high-resolution unsteady-state testing technology that couples oil flow, dynamic probe, hot wire probe, and surface thermal film. Combined with a multi-point nonlinear data processing module, a synchronous phase-locked loop module, and a multi-flow field parameter post-processing module, it can realize fully automatic synchronous acquisition of airflow parameters in the confined space of turbomachinery. It can obtain the complex flow field structure between stages, the boundary layer characteristics of the blade surface, and the fluid flow characteristics near the endwall in real time, meeting the internal flow field testing requirements of high-load, high-speed turbomachinery. It has the advantages of high spatiotemporal resolution, simultaneous synchronous measurement of multiple physical parameters, and low interference to the flow field.

[0007] (II) Technical Solution To achieve the objective of this invention and solve its technical problems, the present invention adopts the following technical solution: The first objective of this invention is to provide a global dynamic measurement device for the flow field within a confined space of a turbomachinery, used for multi-parameter global dynamic measurement of the flow field in the interstage mainstream region, the blade normal boundary layer, and the near-endwall region within the confined space of the turbomachinery blade passage, comprising at least: The measurement execution module is used to acquire flow field parameters in different spatial regions of the impeller stage blade passage under test. It includes a displacement control mechanism and a combination of two or more of the following measurement units: (i) a dynamic probe, set on the displacement control mechanism, used to acquire transient total pressure, static pressure and flow direction parameters of the interstage flow field; (ii) a hot wire probe, set on the displacement control mechanism, used to acquire the transient velocity and unsteady pulsation characteristics of the blade normal near-wall boundary layer; (iii) a surface hot film measurement unit, including a hot film element and temperature sensor and lead wire attached to the end wall and / or blade surface, used to acquire the quasi-wall shear force at the corresponding position and its electrical signal changing with time; (iv) an oil flow visualization measurement unit, including an oil film layer coated on the end wall and / or blade surface, used to acquire the streamline topology of the near-wall boundary layer at the corresponding position. The synchronous phase-locked module includes a signal generator and a lock-in amplifier. The signal generator is used to provide an excitation signal to the hot wire probe and / or the surface hot film measurement unit. The lock-in amplifier is used to perform phase-sensitive detection and low-pass filtering on the measurement signal output by the hot wire probe and / or the surface hot film measurement unit, and to establish a synchronous correspondence between the processed signal and the rotation phase of the impeller machinery. The data acquisition and processing module communicates with the above modules and is used to acquire the original signals of the dynamic probe, as well as the hot wire and hot film signals after phase-locked demodulation, the position feedback signals of the displacement control mechanism, and the rotor phase signals of the turbomachinery. It performs spatiotemporal reconstruction of the flow field parameters of the interstage mainstream region, the blade normal boundary layer, and the near-endwall flow field to obtain the global dynamic distribution of the flow field in the confined space of the turbomachinery.

[0008] The second objective of this invention is to provide a high-precision measurement method for the boundary layer of turbomachinery, based on the aforementioned global dynamic measurement device for the flow field within the confined space of turbomachinery, comprising the following steps: Based on the working speed and load conditions of the impeller under test, the dynamic probe and hot wire probe are calibrated, and the zero point calibration and synchronous clock setting of each measurement channel are performed through the data acquisition and processing module. A displacement control mechanism is used to control a dynamic probe to perform transient measurements of the interstage flow field. A displacement control mechanism is used to control a hot-wire probe to perform transient measurements on the normal boundary layer of the blade. Transient measurements of the boundary layer on the blade surface were performed using a surface thermal film measurement unit. The flow field at the endwall is visualized using an oil flow visualization measurement unit; Using a synchronous phase-locked loop module, the measurement signals of the hot wire probe and / or surface hot film are subjected to phase-sensitive detection and low-pass filtering, and a synchronous correspondence is established with the rotation phase of the turbomachinery rotor. The data acquisition and processing module synchronously acquires and unifies the time base alignment of the raw signals from the dynamic probe, the hot wire and hot film signals after phase-locked loop demodulation, the position feedback signals from the displacement control mechanism, and the rotor phase signals. Based on the acquired data, parameters are extracted and comprehensively processed: through dynamic probe sweep measurement, the total pressure and static pressure behind the blade grid are obtained, and then the distribution of total pressure loss and lag angle behind the grid are obtained; through oil flow visualization, the endwall streamline distribution is obtained, and then the motion trajectory and vortex structure of the fluid near the endwall are obtained; through hot wire probe sweep measurement, the pulsation curve of the fluid velocity in the boundary layer of the blade suction surface over time is obtained, and the boundary layer state and boundary layer thickness data are obtained based on its transient velocity fluctuation; through the raw signals obtained by surface hot film measurement, the mean, root mean square and skewness information of the quasi-wall shear force are obtained, and the boundary layer separation and reattachment interval and transition interval data of the blade surface are obtained.

[0009] (III) Technical Effects Compared with the prior art, the device and method for full-domain dynamic measurement of flow field in the confined space of turbomachinery of the present invention has the following beneficial and significant technical effects: (1) The device and method for measuring the dynamic flow field in the confined space of turbomachinery proposed in this invention solves the problem of the difficulty in measuring complex fluid characteristics such as boundary layer separation and radial migration of fluid in the flow field of turbomachinery. It also solves the problem of not being able to achieve real-time and high-fidelity transmission of dynamic signals of the boundary layer on the blade surface at high speeds. It realizes the measurement of steady-state and transient data of the flow field in the end region, near-end region, normal boundary layer and interstage.

[0010] (2) On the one hand, the present invention uses a hot wire probe to perform transient measurement of the blade normal, which solves the problem that surface hot film measurement technology can only measure the boundary layer data on the blade surface. On the other hand, the present invention uses surface hot film measurement technology to solve the problem that dynamic probes and hot wire probes can only measure at breakpoints and have low efficiency. On the other hand, the present invention uses surface hot film measurement technology to solve the problem that dynamic probes and hot wire probes cannot measure the boundary layer data at the blade endwall and that it is difficult to transmit the boundary layer flow signal in real time with high fidelity when the blade is rotating at high speed. The present invention also solves the problem that the flow field on the endwall surface is difficult to measure by oil flow visualization.

[0011] (3) This invention is a high-resolution unsteady-state testing technology that couples dynamic probe, hot wire probe and surface hot film. Combined with multi-point nonlinear data acquisition and processing module and synchronous phase-locked module, it can realize fully automatic synchronous acquisition of airflow parameters between impeller stages and boundary layer of impeller, and obtain the complex flow field structure between impeller stages, the boundary layer characteristics of blade surface and the fluid flow characteristics near the end wall in real time. It meets the testing requirements of internal flow field of high load and high speed impeller and has the advantages of high spatiotemporal resolution, synchronous measurement of multiple physical parameters and small interference to flow field. Attached Figure Description

[0012] Figure 1 A schematic diagram of the architecture of a global dynamic measurement device for the flow field within the confined space of a turbomachinery. Figure 2 This is a schematic diagram illustrating the working principle of the synchronous phase-locked module in this invention. Figure 3 This is a schematic diagram of the dynamic probe structure in this invention; Figure 4 This is a schematic diagram of the hot wire probe structure in this invention; Figure 5 This is a schematic diagram of the displacement control mechanism in this invention; Figure 6 This is a schematic diagram of the surface thermal film structure in this invention; Figure 7 This is a schematic diagram of the hot-wire probe measurement of the blade boundary layer flow field in this invention; Figure 8 This is a schematic diagram of the surface thermal film measurement of the blade boundary layer flow field in this invention; Figure 9 This is a flowchart of the phase-locked synchronous measurement process for dynamic probes, hot wire probes, and surface hot films.

[0013] Reference numerals: 1. Cable; 2. Sensor; 3. Plug; 4. Probe support; 5. Probe head; 6. Left hole; 7. Middle hole; 8. Right hole; 9. Bottom hole; 10. Needle tip bevel; 11. Probe support; 12. Probe head; 13. Metal wire; 14. Hot wire fork; 15. Probe base; 16. Flat plate base; 17. Lateral control unit; 18. First support rib; 19. Longitudinal pulley; 20. Longitudinal slide rail; 21. Second support rib; 22. Longitudinal support platform; 23. Longitudinal lead screw; 24. Longitudinal control unit; 25. Probe holder; 26. Lateral lead screw; 27. Lateral slide rail; 28. Lateral support platform; 29. ​​Lateral pulley; 30. Temperature sensor; 31. Hot film substrate; 32. Wire; 33. L-shaped probe support; 34. One-dimensional hot wire probe; 35. Stator blade; 36. Rotor blade; 37. Surface hot film; 38. Grid plate; 39. Hot film wire; 40. Detailed Implementation

[0014] This invention aims to provide a device and method for full-domain dynamic measurement of flow field within the confined space of turbomachinery. It is used to perform multi-parameter full-domain dynamic measurement of the flow field in the interstage mainstream region, the blade normal boundary layer, and the near-endwall region within the confined space of the turbomachinery blade passage. To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in more detail below with reference to the accompanying drawings of the embodiments. The described embodiments are some, but not all, embodiments of this invention, and are exemplary and should not be construed as limiting the invention. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0015] Example 1: Global Dynamic Measurement Device The main structure of the turbomachinery confined space flow field dynamic measurement device provided in this embodiment is as follows: Figure 1 As shown. The measuring device mainly consists of several parts, including a measurement execution module, a synchronous phase-locked loop module, and a data acquisition and processing module. The measurement execution module is used to acquire the flow field parameters of different spatial regions of the blade channel of the impeller under test. It mainly includes a displacement control mechanism and: (i) a dynamic probe, which is set on the displacement control mechanism to acquire the transient total pressure, static pressure, and flow direction parameters of the interstage flow field; (ii) a hot wire probe, which is set on the displacement control mechanism to acquire the transient velocity and unsteady pulsation characteristics of the near-wall boundary layer in the blade normal direction; (iii) a surface hot film measurement unit, including a hot film element and temperature sensor and lead wire attached to the end wall and / or blade surface, to acquire the quasi-wall shear force at the corresponding position and its electrical signal changing with time; and (iv) an oil flow visualization measurement unit, including an oil film layer coated on the end wall and / or blade surface, to acquire the streamline topology of the near-wall boundary layer at the corresponding position.

[0016] The synchronous phase-locked module mainly includes a signal generator and a lock-in amplifier. The signal generator is used to provide excitation signals to the hot wire probe and / or surface hot film measurement unit. The lock-in amplifier is used to perform phase-sensitive detection and low-pass filtering on the measurement signals output by the hot wire probe and / or surface hot film measurement unit, and to establish a synchronous correspondence between the processed signal and the rotation phase of the impeller machinery.

[0017] The data acquisition and processing module communicates with the above modules and is used to acquire the original signals of the dynamic probe, as well as the hot wire and hot film signals after phase-locked demodulation, the position feedback signals of the displacement control mechanism, and the rotor phase signals of the turbomachinery. It performs spatiotemporal reconstruction of the flow field parameters of the interstage mainstream region, the blade normal boundary layer, and the near-endwall flow field to obtain the global dynamic distribution of the flow field in the confined space of the turbomachinery.

[0018] Specifically, both the dynamic probe and the hot-wire probe in the measurement execution module belong to non-contact measurement technologies. The dynamic probe has a simple structure and high spatiotemporal resolution, but its volume is relatively large. Therefore, the dynamic probe is used to perform unsteady-state measurements of the interstage flow field. The hot-wire probe has a small volume, minimal interference with the flow field, short response time, and high spatiotemporal resolution, which can effectively capture unsteady signals and perform unsteady-state measurements of the blade normal boundary layer. The combination of these two measurement technologies can obtain transient data of the blade surface normal boundary layer and the interstage flow field, solving the problem that the surface hot film measurement technology can only measure the blade surface boundary layer data. Furthermore, the biaxial displacement control mechanism solves the problem that both technologies can only perform discontinuous point measurements, resulting in low efficiency. Both oil flow technology and surface hot film technology are contact measurement technologies. Oil flow technology can reflect the flow information at the endwall, solving the problem that dynamic probes and hot wire probes are difficult to measure the flow field near the endwall. Surface hot film measurement technology is a contact measurement technology. With its characteristics of continuity, high frequency response, high synchronization and small flow field disturbance, it can solve the problems that dynamic probes and hot wire probes cannot measure the boundary layer data on the blade surface and that it is difficult to measure the boundary layer flow in real time when the blade is rotating at high speed.

[0019] Furthermore, this invention, through a synchronous phase-locked loop module, can strictly synchronize data acquisition to a specific phase point of rotor rotation. Repeated acquisition and averaging of a large amount of data at the same phase position significantly improves the signal-to-noise ratio of the measurement signal, effectively filters out random noise, and clearly reveals the dynamic evolution of flow parameters with rotor phase. In summary, this invention organically combines four measurement technologies—dynamic probe, hot-wire probe, surface hot film, and oil flow technology—with phase-locked loop technology to achieve full-domain dynamic measurement of the flow field within the confined space of turbomachinery.

[0020] The working principle of synchronous phase-locked loop technology is as follows: Figure 2As shown, it achieves high signal-to-noise ratio flow field measurement through coherent detection. The phase-locked loop (LLL) mechanism mainly consists of a signal generator and a LLL amplifier. During system operation, the signal generator produces a sinusoidal electrical signal of a specific frequency, which is transmitted in three paths: two paths serve as excitation sources to drive the hot-wire probe and the surface hot film, respectively; the other path serves as a reference input to the LLL amplifier. When fluid flows across the probe surfaces of the hot wire and hot film, changes in flow velocity alter the probe's heat dissipation conditions, thereby modulating the thermal wave amplitude. The LLL amplifier, acting as the core demodulation unit, performs correlation operations on the modulated signal and the reference signal using a phase-sensitive detector. This operation converts the components in the input signal that are in phase with the reference signal into DC signals, while other frequency components are converted into AC signals. Subsequently, a low-pass filter removes all AC components, retaining only the DC output related to the flow velocity. The resulting voltage signal maintains a strictly linear relationship with the instantaneous flow velocity and possesses an extremely high signal-to-noise ratio. For periodic flow fields, the data acquisition system automatically identifies the periodic characteristics of the flow and determines the reference phase by real-time monitoring of the flow velocity signal output by the LLL amplifier. The system uses this benchmark to divide the continuously acquired flow velocity data into periods and performs an arithmetic average on the data from the same phase points within hundreds of periods. For dynamic probes, the signal does not require phase-locked amplification, but periodic flow field information can still be obtained through phase-locked averaging.

[0021] Preferably, in the synchronous phase-locked loop module, the signal generator generates a sinusoidal electrical signal with a frequency of 10Hz to 1000Hz and transmits it in three paths: the first path serves as an excitation source to drive the hot wire probe, the second path serves as an excitation source to drive the temperature sensor of the surface hot film measurement unit, and the third path serves as a reference signal input to the lock-in amplifier; the phase-sensitive detector of the lock-in amplifier performs correlation operations on the modulation signal and the reference signal, converting the component of the input signal that is in phase and frequency with the reference signal into a DC signal, and converting other frequency components into AC signals and filtering them out by a low-pass filter; the cutoff frequency of the low-pass filter is set to 0.1 to 0.5 times the frequency of the reference signal, retaining the DC output voltage that is linearly related to the flow rate; the time constant of the lock-in amplifier is set to 0.1 to 10 seconds to balance the signal-to-noise ratio improvement and time resolution.

[0022] In this embodiment of the invention, the dynamic probe is a porous pneumatic probe, preferably a dynamic porous probe with a four-hole wedge-shaped head at the front end. Multiple sets of pressure measuring holes for measuring total pressure and lateral pressure are arranged along a predetermined angle on the front face of the wedge-shaped probe head. Each pressure measuring hole is connected to a high-frequency response pressure sensor located at the tail end of the probe via an air guide tube inside the probe support rod. The frequency response bandwidth of the pressure sensor is not less than several times the passing frequency of the blades. Using a pre-calibrated probe calibration curve or calibration matrix, the instantaneous pressure signals from each pressure measuring hole are calculated into transient total pressure, static pressure, and flow direction parameters of the interstage flow field of the impeller. More specifically, a four-hole dynamic probe structure is as follows: Figure 3 As shown, this probe uses a high-frequency response micro-sensor 2 to capture instantaneous fluctuations in flow field parameters in real time, thereby analyzing unsteady flow structures. The probe mainly consists of a probe head 5, a probe support 4, a plug 3, and a sensor 2. The probe head 5 is wedge-shaped, a design that makes the probe sensitive to inflow deflection and provides high spatial resolution. The probe head 5 has four measurement holes 6-9, each connected to the high-response sensor 2 at the probe tail, used to measure transient pressure changes within the flow field. The probe support 4 primarily supports and secures the air duct between the holes and the sensor. The plug 3 is located close to the sensor 2 at the tail, its main function being to prevent damage from the probe hitting the wall if it is not securely clamped.

[0023] In this embodiment of the invention, the hot-wire probe is a one-dimensional hot-wire configuration and is used in conjunction with a constant-temperature hot-wire anemometer circuit. The hot-wire anemometer includes a bridge circuit, a gain and compensation circuit, and a feedback control unit for maintaining a basically constant hot-wire temperature. The metal wire of the hot-wire probe is arranged along the blade normal. The convective heat transfer of the hot-wire by the flow field causes a change in its resistance. The transient velocity signal of the normal boundary layer of the blade is obtained by converting the unbalanced voltage output of the bridge circuit with the calibration relationship between the flow velocity and the flow rate. Under multi-cycle measurement conditions, the transient velocity signal is coherently extracted and asynchronously averaged by a synchronous phase-locked module to achieve high signal-to-noise ratio extraction of unsteady pulsating characteristics.

[0024] More specifically, a one-dimensional hot wire probe structure such as Figure 4 As shown, its working principle is based on thermal equilibrium. The hot wire is located in the blade channel. When airflow passes through, heat exchange causes some heat to be carried away by the airflow, creating a temperature difference. The magnitude and rate of temperature change are related to the airflow velocity and the temperature difference between the airflow and the hot wire, thus establishing a relationship between the hot wire temperature and the airflow velocity. The hot wire probe mainly consists of a probe support 11 and a probe head 12. The probe head 12 includes a metal wire 13, a hot wire fork 14, and a probe base 15. The metal wire 13, made of gold-plated tungsten wire, is located between the hot wire forks 14 and is the measuring element of the hot wire probe. The hot wire forks 14 are conical and located on the probe support 11. The two hot wire forks 14 are aligned in a straight line and equidistant. The hot wire forks 14 are made of stainless steel and are used to support and fix the metal wire 13. The probe support 11 is cylindrical and located between the probe head 12 and the hot wire forks 14. Its interior has a circular through-hole for leading the cable of the hot wire fork 14 to the probe head. The probe head 12 is a flat cylinder used to connect the probe base 15 and the probe head 12. The probe base 15 is cylindrical and is used to fix and support the hot wire probe.

[0025] In this embodiment of the invention, the displacement control mechanism is a biaxial displacement control mechanism, which is set outside or near the test section. It includes mutually orthogonal linear guides, screw transmission assemblies that cooperate with each linear guide, and an actuator driven by a stepper motor or servo motor. It is also equipped with a base and a spanwise multi-hole probe support platform. The probe support platform is used to arrange dynamic probes and / or hot wire probes, and is driven by the screw transmission assembly to move controllably in two degrees of freedom planes, so as to ensure continuous sweep measurement of the interstage mainstream area and the blade normal near-wall area within the cross section corresponding to the blade channel.

[0026] Specifically, the biaxial displacement control mechanism is installed on the wind tunnel experimental equipment. It can fix and mount the probe, and drive the probe to move, solving the problem of low efficiency in probe breakpoint measurement. Its structure is as follows: Figure 5 As shown. To enable the probe to move axially and circumferentially on the cross-section of the blade, the biaxial displacement control mechanism includes two degrees of freedom: the X-axis and the Y-axis, including a transverse pulley 30, a transverse support platform 29, a transverse slide rail 28, a transverse lead screw 27, a flat plate base 16, a transverse control unit 17, a first support rib 18, a longitudinal pulley 19, a longitudinal slide rail 20, a second support rib 21, a longitudinal support platform 22, a longitudinal lead screw 23, a longitudinal control unit 24, a probe support platform 25, and a probe holder 26.

[0027] The flat base 16 is used to fix the displacement control mechanism and connect the experimental equipment. The transverse control unit 17 includes a stepper motor, a driver, and a controller, which, together with the transverse pulley 30, the transverse slide rail 28, and the transverse lead screw 27, controls the movement of the probe along the blade axis. A longitudinal displacement control structure is installed on the transverse support platform 29. This longitudinal displacement control structure is fixed and supported by the first support rib 18. The longitudinal control unit includes a stepper motor, a driver, and a controller, which, together with the longitudinal pulley 19, the longitudinal slide rail 20, and the longitudinal lead screw 23, controls the movement of the probe along the blade circumferential direction. A probe support platform 25 is installed on the longitudinal support platform 22. The probe support platform 25 has five oblong through holes, which are equidistantly arranged with a spacing of 75 mm, to adjust the position of the probe in the blade spanwise direction. The probe on the probe support platform is fixed and locked by the probe retainer 26. The probe retainer is split in half with a through hole in the middle. The two retainers are connected to each other and to the probe support platform by countersunk screws.

[0028] The motion control principle of the two-axis displacement control mechanism is as follows: The external testing system outputs a displacement control signal to the controller in the horizontal and vertical control units. The controller performs A / D conversion on the signal, and then determines the number of pulses to be sent to the driver in the horizontal and vertical control units according to the set ratio. The driver performs A / D conversion again and drives the horizontal and vertical stepper motors to rotate the lead screw according to the number of pulses. This causes the horizontal and vertical support platforms to move along the horizontal and vertical slide rails respectively, moving the probe to the designated position. At the same time, the stepper motor will feed back the motor position signal to the controller, and then the controller feeds it back to the testing system to observe whether it has moved into place.

[0029] In this embodiment of the invention, the structure of the surface thermal film measurement unit is as follows: Figure 6 As shown, its working principle is based on thermal equilibrium. A hot-wire anemometer heats the surface thermal film and maintains it at a constant temperature in the flow field. The flow within the boundary layer dissipates some heat through convective heat transfer. To maintain a constant temperature, the hot-wire anemometer continues to supply heat, causing a change in the voltage applied across the surface thermal film. By monitoring this voltage change, the fluid changes within the boundary layer can be obtained. The surface thermal film of this invention has a spatial resolution of up to 2 mm and mainly includes a thermal film measurement unit and a surface thermal film substrate 32. To reduce disturbance to the boundary layer, the thickness of the surface thermal film substrate 32, attached to the predetermined measurement area on the endwall and / or blade surface, is controlled to be less than 0.05 mm. The thermal film measurement unit includes a wire 33 and a temperature sensor 31. The wire 33 transmits current and signals, and the temperature sensor 31 collects the temperature difference caused by convective heat transfer. One surface thermal film has six thermal film measurement units, which can simultaneously monitor fluid changes at different locations on the blade surface.

[0030] In this embodiment of the invention, the oil flow test first requires thoroughly cleaning the surface to be tested and spraying it with matte black paint to enhance contrast. Then, a specific ratio of oil flow material is evenly and thinly coated with a brush to form a translucent oil film. The oil flow material is a mixture of kerosene, oleic acid, and titanium dioxide powder in a certain proportion. After the oil film is ready, the equipment is run stably under target conditions for a period of time, using airflow shear force to drive the oil film to form a streamline pattern. The machine is then stopped and allowed to solidify the pattern. Next, the surface is irradiated with lateral grazing light to highlight the texture, and a high-resolution camera is used to capture and record a clear streamline pattern. Based on this pattern, the flow characteristics of the solid wall surface can be obtained, including identifying key structures such as separation zones, reattachment lines, and vortex core trajectories.

[0031] In this embodiment of the invention, the data acquisition and processing module includes a multi-channel synchronous acquisition unit and a data processing unit. The multi-channel synchronous acquisition unit is used to synchronously acquire the original signal of the dynamic probe, the hot wire signal and hot film signal after phase-locked demodulation, and the position feedback signal and rotor phase signal of the displacement control mechanism at a sampling frequency not lower than several times the highest frequency under test. The channels are time-aligned using a unified clock source. The data processing unit performs periodic segmentation and asynchronous averaging of hundreds of periods on the continuous data based on a unified reference, suppresses random noise and retains the periodic unsteady structure, and calculates the temporal-spatial joint distribution of the total pressure loss distribution and the lag angle distribution, the normal velocity pulsation spectrum, and the quasi-wall shear force statistics behind the gate.

[0032] As a preferred embodiment, the data acquisition and processing module also includes multi-scale spatiotemporal reconstruction of the internal flow field of the turbomachinery, including: reconstructing the total pressure loss coefficient distribution and lag angle distribution under different rotor phases in the interstage mainstream region; reconstructing the velocity profile and its pulsation intensity distribution at different normal positions in the blade normal boundary layer region; reconstructing the secondary flow and vortex structure topology in the near-endwall region by combining oil flow images and quasi-wall shear force distribution; and realizing full-domain dynamic visualization and quantitative analysis of the complex three-dimensional unsteady flow field in the confined space of the turbomachinery under a unified spatial coordinate system and rotor phase reference frame.

[0033] Example 2: Hot wire probe application example This invention uses a combination of a hot-wire probe and a biaxial displacement control mechanism as an example to illustrate the measurement process of the normal boundary layer flow field of a turbomachinery blade. It mainly involves the stator blade 36, the biaxial displacement control mechanism, the displacement control mechanism mounting platform, the L-shaped probe support 34, and the one-dimensional hot-wire probe 35, as follows... Figure 7 As shown.

[0034] Setting up the experimental setup: To measure the boundary layer distribution at the mid-section of the blade, the two-dimensional motion plane of the biaxial displacement control mechanism should be parallel to the plane formed by the axial and circumferential directions of the blade (B2B section), and the metal wire of the hot-wire probe should be perpendicular to the airflow direction. First, install the biaxial displacement control mechanism on the experimental equipment, and then fix the hot-wire probe to the third oblong through hole of the probe support platform using a probe holder.

[0035] Determining the measurement location: The hot-wire anemometer and biaxial displacement mechanism are activated. Under the control of the control unit, the displacement mechanism drives the probe. First, the hot-wire probe moves very slowly towards the blade wall. When the voltage signal measured by the hot-wire probe changes abruptly, the biaxial displacement control mechanism stops moving the probe and transmits the current position coordinates to the external testing system for recording as a wall point. Then, the hot-wire probe is slowly moved circumferentially towards the blade to a suitable position, and its current position coordinates are transmitted to the external testing system for recording as the normal endpoint. Subsequently, the lateral displacement mechanism and the longitudinal displacement mechanism work together to repeat the above process, recording the wall point coordinates and normal endpoint coordinates at multiple axial positions on the blade. This provides a reference for the distribution of measurement points for subsequent spatial sweep measurements of the blade's normal near-wall boundary layer.

[0036] Experimental Measurement: After determining the boundary layer measurement location, the fan is started to introduce airflow into the blade channel. The biaxial displacement control structure drives the hot wire probe to move along the path set in the previous step. The data collected by the hot wire probe is transmitted to the measurement system via the lead wire. After further processing, the unsteady data of the blade normal boundary layer is obtained.

[0037] Example 3: Application of Dynamic Probes This invention illustrates the measurement process of interstage flow field in turbomachinery using a combination of a dynamic probe and a biaxial displacement control mechanism as an example. It mainly involves blades, a biaxial displacement control mechanism, a mounting platform for the displacement control mechanism, and a dynamic probe. To measure the flow field at a specified interstage interface, the two-dimensional motion plane of the biaxial displacement control mechanism should be parallel to the plane formed by the radial and circumferential directions of the blades. The opening of the dynamic probe's head should face the incoming gas flow, and the dynamic probe should be fixed to the third oblong through-hole of the probe support platform using a probe holder. Then, the circumferential and radial coordinates of the interstage measurement position are determined using a method similar to that used in hot-wire probes. After determining the measurement position, the fan is started, and the biaxial displacement control mechanism moves the dynamic probe along the path set in the previous step. The data collected by the dynamic probe is transmitted to the measurement system via a lead wire. After further processing, the unsteady-state data of the interstage flow field measurement is obtained.

[0038] Example 4: Application of Surface Thermal Film like Figure 8As shown, this embodiment of the invention takes the application of a surface thermal film on the surface of a rotor blade as an example to illustrate the measurement process of the transient flow field of the boundary layer on the surface of an impeller blade. The main components involved include: rotor blade 37, surface thermal film 38, thermal film lead wire 40, and grid plate 39. After determining the application position of the thermal film, the thermal film 38 and lead wire 40 are fixed to the blade surface with adhesive. The thermal film lead wire 40 passes through the grid plate 39 and connects to an external hot-wire anemometer and testing system. Subsequently, the motor and hot-wire anemometer are started, causing the rotor blade to rotate while the surface thermal film on the hot-wire anemometer reaches a stable temperature. Then, the fan is started to introduce airflow into the blade channel. The velocity fluctuations at this time will cause changes in the voltage applied across the surface thermal film. The thermal film lead wire transmits this voltage signal to the testing equipment to obtain the flow field within the boundary layer. Through further processing, the quasi-wall shear stress of the boundary layer at the measured position on the suction surface of the blade can be obtained. τ w Its definition is as follows: (1) in E 0 refers to the no-wind voltage measured on the surface heat film when the fan is not turned on. E The mean value of the quasi-wall shear force measured under specified operating conditions reflects the separation and reattachment of the boundary layer, while its root mean square (RMS) and skewness (SKEW) reflect the stability of the boundary layer, thus providing information on boundary layer transition. For rotating machinery, the spatiotemporal distribution of these three statistics can be accurately obtained through phase-locked loop (PLL) technology. After all the quasi-wall shear force information is obtained through Equation 1, the mean value of the quasi-wall shear force can be obtained through Equation 2. : (2) in τ w ( t , n ) is the quasi-wall shear force signal obtained by Equation 2.

[0039] The root mean square of the quasi-wall shear force and the skewness can be further obtained using equations 3 and 4: (3) (4) Example 5: Application of Global Dynamic Measurement Full-range dynamic measurement requires simultaneous and synchronous measurements from the hot-wire probe, hot-film probe, and dynamic probe, which can be achieved through phase-locked loop (PLL) synchronous measurement. Furthermore, a high-precision camera is needed to record end-wall oil flow information, obtaining oil flow images at the start and end of the test. The PLL measurement scheme is as follows: Figure 9As shown in the diagram, the process is as follows: The raw signal output from the dynamic probe is amplified and filtered by a dedicated conditioner, then split into two independent paths. One path is sent to a trigger discrimination circuit, which triggers data acquisition when it receives both the lock-in amplified signal and the dynamic probe signal simultaneously. The other path is directly connected to the analog input channel of the data acquisition system to record the raw physical quantities. Simultaneously, the hot wire / hot film probe signal is modulated and input to the lock-in amplifier, where it is demodulated under the control of an external reference signal. The output flow velocity signal is then synchronously sent to the data acquisition system. Through this architecture, the system can achieve strictly synchronous acquisition of data from the hot wire, hot film, and dynamic probe, ensuring precise phase alignment between the flow velocity and pressure signals.

[0040] More specifically, the high-precision measurement method for the boundary layer of turbomachinery of the present invention, based on the full-domain dynamic measurement device for the flow field within the confined space of turbomachinery of the present invention, mainly includes the following in its implementation: Based on the operating speed and load conditions of the impeller mechanical stage under test, the dynamic probe and hot wire probe are calibrated, and the zero point calibration and synchronization clock setting of each measurement channel are performed through the data acquisition and processing module. The displacement control mechanism is used to control the dynamic probe to perform transient measurement of the interstage flow field. The displacement control mechanism is used to control the hot wire probe to perform transient measurement of the blade normal boundary layer. The surface hot film measurement unit is used to perform transient measurement of the blade surface boundary layer. The oil flow visualization measurement unit is used to visualize the endwall flow field. The phase-locked loop module is used to perform phase-sensitive detection and low-pass filtering on the measurement signals of the hot wire probe and / or surface hot film, and a synchronous correspondence is established with the rotor rotation phase. The data acquisition and processing module synchronously acquires and unifies the time base alignment of the raw signals from the dynamic probe, the hot wire and hot film signals after phase-locked loop demodulation, the position feedback signals from the displacement control mechanism, and the rotor phase signals. Based on the acquired data, parameters are extracted and comprehensively processed: through dynamic probe sweep measurement, the total pressure and static pressure behind the blade grid are obtained, and then the distribution of total pressure loss and lag angle behind the grid are obtained; through oil flow visualization, the endwall streamline distribution is obtained, and then the motion trajectory and vortex structure of the fluid near the endwall are obtained; through hot wire probe sweep measurement, the pulsation curve of the fluid velocity in the boundary layer of the blade suction surface over time is obtained, and the boundary layer state and boundary layer thickness data are obtained based on its transient velocity fluctuation; through the raw signals obtained by surface hot film measurement, the mean, root mean square and skewness information of the quasi-wall shear force are obtained, and the boundary layer separation and reattachment interval and transition interval data of the blade surface are obtained.

[0041] Preferably, during the synchronous phase-locked loop and multi-cycle data acquisition process, phase alignment and coherence extraction are performed on the measurement signals of the hot wire probe and the surface hot film. This includes: dividing one cycle into several equally spaced phase points within each rotor cycle; synchronously acquiring the hot wire velocity signal and the hot film voltage signal at the same phase point in N consecutive rotor cycles; averaging the N samples at the same phase point after phase-sensitive detection and low-pass filtering by the lock-in amplifier to suppress random noise and uncorrelated interference, thereby obtaining the near-wall velocity and quasi-wall shear force time history with a high signal-to-noise ratio under a unified rotor phase reference. In addition, the data acquisition and processing module adopts a multi-channel synchronous sampling and unified time base alignment strategy when performing parameter extraction and comprehensive processing. This includes: assigning independent acquisition channels to the original pressure signal of the dynamic probe, the hot linear velocity signal and hot film signal after phase-locked loop demodulation, the position feedback signal of the displacement control mechanism, and the rotor phase signal, and using a unified high-precision clock as the sampling reference to maintain synchronous sampling of each channel throughout the test. After the test, the position feedback data is used to map each measurement signal to the three-dimensional coordinate system of the blade channel, and the rotor phase signal is used to convert the data of different periods into a standard rotor phase period, so as to realize the unified spatiotemporal calibration and fusion reconstruction of the flow field parameters of the interstage mainstream region, the blade normal boundary layer, and the near-endwall.

[0042] The objectives of this invention have been fully and effectively achieved through the above embodiments. Those skilled in the art will understand that this invention includes, but is not limited to, the contents described in the accompanying drawings and the specific embodiments described above. Although the invention has been described with reference to what is currently considered the most practical and preferred embodiments, it should be understood that the invention is not limited to the disclosed embodiments, and any modifications that do not depart from the functional and structural principles of the invention will be included within the scope of the claims.

Claims

1. A global dynamic measurement device for the flow field within a confined space of a turbomachinery, characterized in that, include: The measurement execution module includes a displacement control mechanism and two or more of the following measurement units: (i) a dynamic probe, which is set on the displacement control mechanism to acquire the transient total pressure, static pressure and flow direction parameters of the flow field between impeller stages; (ii) A hot-wire probe, mounted on the displacement control mechanism, is used to acquire the transient velocity and unsteady pulsation characteristics of the near-wall boundary layer in the normal direction of the blade; (iii) A surface hot film measurement unit, including a hot film element, a temperature sensor, and a lead wire attached to the end wall and / or blade surface, is used to acquire the quasi-wall shear force at the corresponding position and its time-varying information; (iv) An oil flow visualization measurement unit, including an oil film layer coated on the end wall and / or blade surface, is used to acquire the streamline topology of the near-wall boundary layer at the corresponding position. The synchronous phase-locked module includes: (i) a signal generator for providing an excitation signal to the hot wire probe and / or the surface hot film measurement unit; (ii) Lock-in amplifier, used to perform phase-sensitive detection and low-pass filtering on the measurement signal output by the hot wire probe and / or surface hot film measurement unit, and to establish a synchronous correspondence between the processed signal and the rotation phase of the impeller machinery; The data acquisition and processing module communicates with the above modules and is used to acquire the original signals of the dynamic probe, as well as the hot wire and hot film signals after phase-locked demodulation, the position feedback signals of the displacement control mechanism, and the rotor phase signals of the turbomachinery. It performs spatiotemporal reconstruction of the flow field parameters of the interstage mainstream region, the blade normal boundary layer, and the near-endwall flow field to obtain the global dynamic distribution of the flow field within the confined space of the turbomachinery.

2. The apparatus according to claim 1, characterized in that, The displacement control mechanism is a two-axis displacement control mechanism, which is set outside or near the test section. It includes mutually orthogonal linear guides, screw drive assemblies that cooperate with each linear guide, and an actuator driven by a stepper motor or servo motor. It is also equipped with a base and a spanwise multi-hole probe support platform. The multi-hole probe support platform is used to arrange dynamic probes and / or hot wire probes, and is driven by the screw drive assembly to move controllably in two degrees of freedom planes, so as to ensure continuous sweep measurement of the interstage mainstream area and the blade normal near-wall area within the cross section corresponding to the blade channel.

3. The apparatus according to claim 1, characterized in that, The dynamic probe is a porous pneumatic probe. Multiple pressure measuring holes for measuring total pressure and lateral pressure are arranged along a predetermined angle on the front end face of its wedge-shaped probe head. Each pressure measuring hole is connected to a high-frequency response pressure sensor located at the tail of the probe via an air guide tube inside the probe support rod. The frequency response bandwidth of the pressure sensor is not less than several times the passing frequency of the impeller blades. The instantaneous pressure signal of each pressure measuring hole is calculated into the transient total pressure, static pressure and flow direction parameters of the impeller stage flow field through a pre-calibrated probe calibration curve or calibration matrix.

4. The apparatus according to claim 1 or 3, characterized in that, The displacement control mechanism is also used to determine the wall-adjacent limit position based on the abrupt change characteristics of the pressure signal output by the dynamic probe. This includes controlling the dynamic probe to gradually approach the blade endwall along the normal direction. When a significant reduction in the total pressure signal of the dynamic probe is detected within a preset step length, the probe position at this time is recorded as the wall-adjacent reference position. Based on this position, the probe is moved back a preset safe distance into the channel as the measurement starting position. This achieves high-precision non-contact measurement of the near-wall flow field without damaging the probe by hitting the wall.

5. The apparatus according to claim 1, characterized in that, The hot-wire probe is a one-dimensional hot-wire configuration and is used in conjunction with a constant-temperature hot-wire anemometer circuit. The hot-wire anemometer includes a bridge circuit, a gain and compensation circuit, and a feedback control unit for maintaining a basically constant hot-wire temperature. The flow field causes convective heat transfer to the hot wire, resulting in a change in its resistance. The transient velocity signal of the near-wall boundary layer of the blade is obtained by converting the unbalanced voltage output of the bridge circuit with the calibration relationship between the flow velocity and the flow rate. Under multi-cycle measurement conditions, the transient velocity signal is coherently extracted and asynchronously averaged by a synchronous phase-locked loop module to achieve high signal-to-noise ratio extraction of unsteady pulsating characteristics.

6. The apparatus according to claim 1 or 5, characterized in that, The displacement control mechanism is also used to determine the measurement position based on the sudden change characteristics of the hot wire voltage output by the hot wire probe, including: driving the hot wire probe to gradually approach the blade wall at a preset low speed along the blade normal; when a sudden change in the hot wire voltage exceeding a preset threshold is detected in a series of consecutive sampling points, the current position of the probe is marked as the wall point position; then driving the probe to move along the blade circumference to a preset position and using it as the normal endpoint; then the displacement control mechanism repeats the process of the probe approaching the wall and moving circumferentially at multiple axial positions in the blade spanwise direction to obtain the wall point coordinates and normal endpoint coordinates at each axial position, providing a measurement point distribution benchmark for subsequent spatial sweep measurement of the blade normal near-wall boundary layer.

7. The apparatus according to claim 1, characterized in that, The surface thermal film measurement unit includes a thermal film element, a temperature sensor, and leads. The thermal film element is made of a thin film substrate and is attached to a predetermined measurement area on the end wall and / or blade surface. Multiple independent measurement sensitive areas are arranged in the chord and spanwise directions. Each sensitive area is connected to a signal conditioning circuit through an independent temperature sensor and leads, so as to realize high spatial resolution continuous acquisition of the near-wall shear force distribution of the boundary layer near the end wall and / or blade surface.

8. The apparatus according to claim 7, characterized in that, The data acquisition and processing module calculates the near-wall boundary layer quasi-wall shear force and its statistics in the following manner: First, the no-wind voltage measured by the surface heat film when the fan is not turned on. E Using 0 as the reference voltage, the voltage measured under specified operating conditions is: E ,according to The instantaneous quasi-wall shear force signal was calculated. τ w ( t , n ),in n =1~ N The first obtained under phase-locked loop technology n Sample sequence number of the same phase point within each rotor cycle N The total number of rotor cycles included in the statistics; Press again The mean quasi-wall shear force at this phase point was calculated, and further calculated according to... and Calculate the root mean square (RMS) value of the quasi-wall shear force respectively. t ) and skewness (SKEW) t Furthermore, by utilizing the distribution characteristics of the mean value, root mean square value, and skewness of the quasi-wall shear force on one rotor cycle, the separation and reattachment regions and transition positions of the boundary layer on the blade surface are identified, and the stability of the boundary layer is evaluated.

9. The apparatus according to claim 1, characterized in that, In the oil flow visualization measurement unit, the oil film layer is an oil film mixture formed by using kerosene as a solvent, oleic acid as a surfactant, and mixing in titanium dioxide powder. It is coated on the end wall and / or blade surface that has been pretreated with black paint or a dark coating. During the operation of the impeller machinery, oil traces are formed under the action of tangential shear force on the wall surface, which evolves with the flow topology. After the machine stops, the image acquisition device acquires the oil flow image. By analyzing the morphology, density, and distribution of the oil traces, the separation line, reattachment line, and the location of the secondary flow and vortex core in the near-boundary layer are qualitatively identified.

10. The apparatus according to claim 1, characterized in that, In the synchronous phase-locked module, the signal generator outputs a reference sinusoidal excitation to drive the hot wire probe and the surface hot film respectively, and provides a reference reference to the lock-in amplifier. The lock-in amplifier includes a phase-sensitive detector and an adjustable time constant low-pass filter to extract the in-phase and in-frequency components of the measurement signals of the hot wire probe and / or surface hot film measurement units, and asynchronously averages the same phase point over multiple rotor cycles to improve the signal-to-noise ratio of the measurement signal. The dynamic probe signal is amplified and filtered by the conditioner and then divided into two independent paths. One path enters the trigger discrimination circuit, which triggers data acquisition when it receives both the lock-in amplified signal and the dynamic probe signal. The other path directly enters the data acquisition and processing module to achieve strict phase alignment and high signal-to-noise ratio demodulation across channels.

11. The apparatus according to claim 1, characterized in that, The data acquisition and processing module includes a multi-channel synchronous acquisition unit and a data processing unit. The multi-channel synchronous acquisition unit is used to synchronously acquire the original signal of the dynamic probe, the hot wire signal and hot film signal after phase-locked demodulation, and the position feedback signal and rotor phase signal of the displacement control mechanism at a sampling frequency not lower than several times the highest frequency under test. The channels are time-aligned using a unified clock source. The data processing unit performs periodic segmentation and asynchronous averaging of continuous data over hundreds of periods based on a unified reference, suppressing random noise and preserving the periodic unsteady structure. At the same time, it calculates the temporal-spatial joint distribution of the total pressure loss distribution and the lag angle distribution behind the grid, the normal velocity pulsation spectrum, and the quasi-wall shear force statistics.

12. The apparatus according to claim 1 or 11, characterized in that, The data acquisition and processing module also includes multi-scale spatiotemporal reconstruction of the internal flow field of the turbomachinery, including: reconstructing the total pressure loss coefficient distribution and lag angle distribution under different rotor phases in the interstage mainstream region; reconstructing the velocity profile and its pulsation intensity distribution at different normal positions in the blade normal boundary layer region; reconstructing the secondary flow and vortex structure topology in the near-endwall region by combining oil flow images and quasi-wall shear force distribution; and realizing full-domain dynamic visualization and quantitative analysis of the complex three-dimensional unsteady flow field in the confined space of the turbomachinery under a unified spatial coordinate system and rotor phase reference frame.

13. A high-precision measurement method for the boundary layer of turbomachinery, based on the global dynamic measurement device for the flow field within the confined space of turbomachinery as described in any one of claims 1 to 12, characterized in that, include: Based on the working speed and load conditions of the impeller under test, the dynamic probe and hot wire probe are calibrated, and the zero point calibration and synchronous clock setting of each measurement channel are performed through the data acquisition and processing module. A displacement control mechanism is used to control a dynamic probe to perform transient measurements of the interstage flow field. A displacement control mechanism is used to control a hot-wire probe to perform transient measurements on the normal boundary layer of the blade. Transient measurements of the boundary layer on the blade surface were performed using a surface thermal film measurement unit. The flow field at the endwall is visualized using an oil flow visualization measurement unit; Using a synchronous phase-locked loop module, the measurement signals of the hot wire probe and / or surface hot film are subjected to phase-sensitive detection and low-pass filtering, and a synchronous correspondence is established with the rotation phase of the turbomachinery rotor. The data acquisition and processing module synchronously acquires and extracts parameters from the raw signals of the dynamic probe, the hot wire and hot film signals after phase-locked loop demodulation, the position feedback signal of the displacement control mechanism, and the rotor phase signal. Through dynamic probe sweep measurement, the total pressure and static pressure behind the blade grid are obtained, leading to the distribution of total pressure loss and lag angle behind the grid. Through oil flow visualization, the streamline distribution on the endwall is obtained, leading to the fluid's trajectory and vortex structure near the endwall. Through hot wire probe sweep measurement, the pulsation curve of the fluid velocity over time within the boundary layer on the blade's suction surface is obtained, and based on its transient velocity fluctuations, the boundary layer state and thickness data are obtained. Through the raw signals acquired by surface hot film measurement, the mean, root mean square, and skewness information of the quasi-wall shear force are obtained, yielding data on the boundary layer separation and reattachment intervals and transition intervals on the blade surface.

14. The method according to claim 13, characterized in that, During the synchronous phase-locked loop and multi-cycle data acquisition process, phase alignment and coherence extraction are performed on the measurement signals of the hot wire probe and the surface hot film. This includes: dividing one cycle into several equally spaced phase points within each rotor cycle; synchronously acquiring the hot wire velocity and hot film voltage signals at the same phase point in N consecutive rotor cycles; averaging the N samples at the same phase point after phase-sensitive detection and low-pass filtering by the lock-in amplifier to obtain the time history of near-wall velocity and quasi-wall shear force with high signal-to-noise ratio under a unified rotor phase reference.

15. The method according to claim 13, characterized in that, When performing parameter extraction and comprehensive processing, the data acquisition and processing module adopts a multi-channel synchronous sampling and unified time base alignment strategy, including: assigning independent acquisition channels to the original pressure signal of the dynamic probe, the hot linear velocity signal and hot film signal after phase-locked loop demodulation, the position feedback signal of the displacement control mechanism, and the rotor phase signal, and using a unified high-precision clock as the sampling reference to maintain synchronous sampling of each channel throughout the test; after the test, the position feedback data is used to map each measurement signal to the three-dimensional coordinate system of the blade channel, and the rotor phase signal is used to convert the data of different periods into a standard rotor phase period, so as to realize the unified spatiotemporal calibration and fusion reconstruction of the flow field parameters of the interstage mainstream region, the blade normal boundary layer, and the near endwall.

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