Acoustic test device, air intake turbulence control device calibration method and system

Abstract

The purpose of this invention is to provide an acoustic testing apparatus, a calibration method and system for an intake turbulence control device, comprising the following steps: placing the intake turbulence control device to be calibrated in a fully anechoic test environment, with airflow directed towards the device under intake conditions; calculating the pressure loss coefficient of the device; calculating the Reynolds number of the device; changing the parameters of the intake conditions to obtain multiple combinations of pressure loss coefficients and Reynolds numbers under different intake conditions; fitting a calibration curve based on the combinations of pressure loss coefficients and Reynolds numbers under multiple different intake conditions; and calibrating the intake turbulence control device based on the calibration curve. This intake turbulence control device calibration method enables accurate on-site calibration of the pressure loss of the device.

Description

Technical Field

[0001] This invention relates to the field of acoustic testing, and more particularly to an acoustic testing apparatus, an intake turbulence control device calibration method and system. Background Technology

[0002] With the continuous increase in bypass ratio of civil aircraft engines, fan noise has become increasingly prominent, and has become a major noise source for civil aircraft engines. In the engine development process, fan acoustic testing plays a crucial role in the engine development system, and is key to verifying and testing fan noise levels and noise reduction designs.

[0003] For ground noise testing of aero-engine fans, the inlet turbulence control device is a key piece of equipment for ensuring the success of fan noise testing and research. Its function is to rectify the incoming airflow to the fan, preventing additional noise generated by the interaction of turbulent vortices generated on the floor of the anechoic chamber during intake and ensuring the directivity of the fan's forward-propagating noise. Due to the structural characteristics of the inlet turbulence control device, a certain pressure loss occurs as the airflow passes through it. If the pressure loss of the inlet turbulence control device is not considered when calculating the inlet flow rate, the accuracy of the fan's inlet flow rate during acoustic testing may not meet the requirements. Therefore, how to calibrate the pressure loss characteristics of the inlet turbulence control device is a crucial issue in fan noise testing.

[0004] There is an urgent need to provide a calibration method for an intake turbulence control device to enable on-site calibration of the pressure loss of the intake turbulence control device. Summary of the Invention

[0005] The purpose of this invention is to provide a calibration method for an intake turbulence control device, which can achieve accurate on-site calibration of the pressure loss of the intake turbulence control device.

[0006] The calibration method for the intake turbulence control device to achieve the aforementioned objective includes the following steps:

[0007] The intake turbulence control device to be calibrated was placed in a completely silent test environment, with the intake airflow directed toward the intake turbulence control device to be calibrated under the condition of intake flow.

[0008] The total ambient pressure, total ambient temperature, and relative humidity of the anechoic test environment were obtained.

[0009] Along the direction of the incoming flow, a detection flow tube is installed downstream of the intake turbulence control device to be calibrated, and a total pressure differential sensor is installed at the inlet of the detection flow tube to obtain the total pressure differential of the intake turbulence control device to be calibrated.

[0010] The actual flow rate of the incoming airflow to the intake turbulence control device to be calibrated is obtained from the detection flow tube.

[0011] The initial diameter of the intake turbulence control device to be calibrated is corrected based on the total ambient temperature to obtain the corrected diameter.

[0012] The corrected gas constant is calculated based on the relative humidity, total pressure, and total temperature of the environment.

[0013] The pressure loss coefficient of the intake turbulence control device to be calibrated is calculated based on the corrected gas constant, the total ambient pressure, the total ambient temperature, the total pressure difference, the corrected diameter, and the actual flow rate.

[0014] The Reynolds number of the intake turbulence control device to be calibrated is calculated based on the actual flow rate and the corrected diameter.

[0015] By changing the parameters of the intake airflow condition, multiple combinations of pressure loss coefficients and Reynolds numbers under different intake airflow conditions can be obtained;

[0016] A calibration curve is obtained by fitting the pressure loss coefficient and Reynolds number combination under multiple different intake flow conditions, and the intake turbulence control device is calibrated based on the calibration curve.

[0017] In one or more embodiments, the corrected diameter is calculated using the following formula:

[0018] D t =D ref [1+α(T t0 -T ref )];

[0019] Among them, D ref T is the initial diameter of the inlet turbulence control device to be calibrated. t0 For the total ambient temperature, T ref The ambient temperature during the calibration test of the intake turbulence control device to be calibrated, α is the coefficient of thermal expansion of the intake turbulence control device to be calibrated, and D is the ambient temperature. t The diameter is corrected for temperature.

[0020] In one or more embodiments, the corrected gas constant is calculated using the following formula:

[0021]

[0022] Among them, R f To correct for the gas constant, R is the air gas constant, RH is the ambient relative humidity, and P... t0 Total environmental pressure.

[0023] In one or more embodiments, the pressure loss coefficient and Reynolds number are calculated using the following formula:

[0024]

[0025] Where ζ is the pressure loss coefficient, Re is the Reynolds number, and m in Δp represents the actual flow rate, μ represents the aerodynamic viscosity, and Δp represents the total pressure difference of the intake turbulence control device to be calibrated.

[0026] In one or more embodiments, a calibration curve is obtained by fitting a combination of pressure loss coefficient and Reynolds number under multiple different inlet flow conditions using a nonlinear least squares method.

[0027] On the other hand, the present invention also provides a calibration system for an intake turbulence control device, characterized in that the intake turbulence control device is calibrated using the intake turbulence control device calibration method described above, and the intake turbulence control device calibration system includes:

[0028] Anechoic chamber, providing the aforementioned anechoic testing environment;

[0029] The intake unit provides a uniform inflow of air toward the intake turbulence control device to be calibrated;

[0030] An ambient total temperature probe is positioned upstream of the intake turbulence control device to be calibrated, along the direction of the incoming flow, to detect and obtain the ambient total temperature.

[0031] An ambient total pressure probe is positioned between the ambient total temperature probe and the intake turbulence control device to be calibrated to detect and obtain the ambient total pressure.

[0032] A flow detection tube is installed downstream of the intake turbulence control device to be calibrated, along the direction of incoming flow, to detect and obtain the actual flow rate.

[0033] A total pressure differential sensor is installed at the inlet of the detection flow tube to detect and obtain the total pressure differential; and;

[0034] The exhaust unit is located downstream of the flow detection tube along the direction of the incoming flow.

[0035] In another aspect, the present invention also provides an acoustic testing apparatus, which uses an intake turbulence control device calibrated by the intake turbulence control device calibration method described above to conduct acoustic tests.

[0036] In one or more embodiments, the acoustic testing apparatus is used for fan acoustic testing.

[0037] The beneficial effects of this invention are as follows:

[0038] This calibration method for the intake turbulence control device obtains the total pressure difference of the device under test using a total pressure differential sensor. It also considers the effects of temperature, the diameter of the device under test, and humidity on the air constant R, and corrects for these factors. Furthermore, by combining the relationship between the pressure loss coefficient ζ and the Reynolds number of the intake turbulence control device, a least-squares fitting curve is obtained, providing accurate calibration results and curves for the pressure loss of the intake turbulence control device in fan acoustic testing.

[0039] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0040] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0041] Figure 1 This schematically illustrates a calibration system for an intake turbulence control device according to some embodiments of the present application;

[0042] Figure 2 A schematic diagram of the curve obtained by fitting the calibration method of the intake turbulence control device according to some embodiments of this application is shown. Detailed Implementation

[0043] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0044] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0045] In view of the fact that there are currently no clear requirements and methods for calibrating the pressure loss of intake turbulence control devices, this application provides a calibration method for intake turbulence control devices and a calibration system for intake turbulence control devices calibrated using this calibration method, based on some embodiments of this application.

[0046] Please see Figure 1 , Figure 1 A schematic diagram of an intake turbulence control device calibration system according to some embodiments of this application is shown, such as... Figure 1 As shown, the intake turbulence control device 6 to be calibrated is installed in the intake turbulence control device calibration system. The intake turbulence control device calibration system also includes an intake unit 1, an ambient total temperature probe 2, an ambient total pressure probe 3, a flow detection tube 4, a total pressure differential sensor, and an exhaust unit 5.

[0047] The intake turbulence control device calibration system, not shown in the figure, also includes a fully anechoic chamber. This chamber provides a completely anechoic test environment for acoustic testing. The intake unit 1 provides a uniform inflow to the intake turbulence control device 6 to be calibrated, with the inflow direction indicated by arrow a in the figure. Along the inflow direction a, the ambient total temperature probe 2 and the ambient total pressure probe 3 are both positioned upstream of the intake turbulence control device 6 to be calibrated. For example, as shown in the figure, the ambient total pressure probe 3 is positioned between the ambient total temperature probe 2 and the intake turbulence control device 6. The flow detection pipe 4 is positioned downstream of the intake turbulence control device 6, the total pressure differential sensor is positioned at the inlet of the flow detection pipe 4, and the exhaust unit 5 is positioned downstream of the flow detection pipe 4.

[0048] The calibration method for the intake turbulence control device using the aforementioned intake turbulence control device calibration system includes the following steps:

[0049] First, the intake turbulence control device 6 to be calibrated is placed in a fully anechoic test environment. The intake unit 1 provides a uniform inflow to the intake turbulence control device 6, for example, by providing a uniform inflow to the intake turbulence control device 6 with intake inflow operating parameters. Specifically, in one embodiment, it is as follows: Figure 1 As shown, the intake unit 1 provides a uniform inlet airflow to the intake turbulence control device 6 to be calibrated. It can be understood that the test system can supply air to the flow tube to be calibrated under different inlet airflow conditions. By adjusting parameters such as intake flow rate, intake pressure, and inlet flow velocity, different inlet airflow conditions can be obtained.

[0050] Subsequently, the total ambient pressure, total ambient temperature, and relative humidity of the anechoic test environment are obtained. Specifically, in one embodiment, the total ambient temperature is detected by the total ambient temperature probe 2, the total ambient pressure is detected by the total ambient pressure probe 3, and the relative ambient humidity is detected by a humidity sensor (not shown in the figure) installed in the test environment.

[0051] Subsequently, along the incoming flow direction a, a detection flow pipe 4 is installed downstream of the intake turbulence control device 6 to be calibrated, and the total pressure differential of the intake turbulence control device to be calibrated is obtained at the inlet of the detection flow pipe 4. Specifically, in one embodiment, the total pressure differential is detected by a total pressure differential sensor installed at the inlet of the detection flow pipe 4.

[0052] Subsequently, the actual flow rate of the incoming airflow to be calibrated turbulence control device 6 is obtained from the flow rate detection tube 4.

[0053] Subsequently, based on the total ambient temperature and the ambient temperature of the intake turbulence control device 6 to be calibrated, the initial diameter of the intake turbulence control device 6 to be calibrated is corrected to obtain the corrected diameter.

[0054] Subsequently, the corrected gas constant was calculated based on the relative humidity, total pressure, and total temperature of the environment.

[0055] Subsequently, the pressure loss coefficient of the intake turbulence control device 6 to be calibrated is calculated based on the corrected gas constant, ambient total pressure, ambient total temperature, total pressure difference, corrected diameter, and actual flow rate.

[0056] Subsequently, the Reynolds number of the intake turbulence control device 6 to be calibrated is calculated based on the actual flow rate and the corrected diameter.

[0057] Subsequently, the parameters of the intake airflow conditions were changed to obtain multiple combinations of pressure loss coefficients and Reynolds numbers under different intake airflow conditions.

[0058] Finally, a calibration curve was obtained by fitting the pressure loss coefficient and Reynolds number combination under multiple different intake flow conditions, and the intake turbulence control device was calibrated based on the calibration curve.

[0059] Furthermore, in one specific embodiment, the corrected diameter is calculated using the following formula:

[0060] D t =D ref [1+α(T t0 -T ref )];

[0061] Among them, D ref The initial diameter of the intake turbulence control device 6 to be calibrated, in meters (m); T t0 Total ambient temperature, in K; Tref The ambient temperature during the calibration test of the intake turbulence control device 6 to be calibrated is given in Kelvin; α is the coefficient of thermal expansion of the intake turbulence control device 6 to be calibrated, in 1 / K; D t To correct for diameter, the unit is meters (m).

[0062] Furthermore, in one specific embodiment, the corrected gas constant is calculated using the following formula:

[0063]

[0064] Among them, R f To correct for the gas constant, the unit is J / (kg K); R is the air gas constant, the unit is J / (kg K); RH is the ambient relative humidity, P t0 Total ambient pressure, expressed in Pa.

[0065] Furthermore, in a specific embodiment, the pressure loss coefficient and Reynolds number are calculated using the following formula:

[0066]

[0067] Where ζ is the pressure loss coefficient, Re is the Reynolds number, and m in Δp represents the actual flow rate, μ represents the aerodynamic viscosity in kg / (m / s), and Δp represents the total pressure difference in Pa.

[0068] Furthermore, in a specific embodiment, a nonlinear least squares method is used to fit the pressure loss coefficient and Reynolds number combination under multiple different intake flow conditions to obtain a calibration curve, so that the distribution of pressure loss coefficient ζ and Reynolds number Re tends to be reasonable, effectively improving the calibration accuracy.

[0069] This method for calibrating an intake turbulence control device uses a total pressure differential sensor to obtain high-precision total pressure differential, and considers the effects of temperature on the flow tube diameter and humidity on the air constant R, correcting for temperature and humidity. Combining the relationship between the pressure loss coefficient and Re number of the intake turbulence control device, the least squares fitting is used to obtain the relationship curve between the pressure loss coefficient ζ and Re, providing the intake turbulence control device pressure loss calibration results and curves that meet the accuracy requirements for fan acoustic testing.

[0070] On the other hand, according to some embodiments of this application, an acoustic testing apparatus is also provided, which uses an intake turbulence control device calibrated by the aforementioned calibration method to perform acoustic tests. The intake turbulence control device calibrated by this method has higher testing accuracy, increasing the reliability of acoustic tests.

[0071] In one or more embodiments, the acoustic testing apparatus is used for fan acoustic testing.

[0072] To further demonstrate the advancements of this flow tube calibration method, an example is provided below for further illustration:

[0073] In one embodiment, for temperature correction, if the inlet air temperature is 40°C and the relative humidity is 80%, the diameter change rate of the inlet turbulence control device to be calibrated before and after temperature correction is 0.04%; the gas constant change rate before and after humidity correction is 0.02%, and the pressure loss coefficient measurement accuracy can be calculated to be improved by 0.14% according to the formula.

[0074] Finally, as Figure 2 As shown, the total pressure loss coefficient ζ and Reynolds number of the multiple sets of collected data on the intake turbulence control device to be calibrated are fitted with least squares. This can convert the discrete calibration results into a curve showing the relationship between the total pressure loss coefficient ζ and the Reynolds number Re. The points in the figure are the data points on the relationship between the total pressure loss coefficient ζ and the Reynolds number of the multiple sets of collected data, and the curve is the fitted curve obtained after least squares fitting. According to the calculation, the calibration accuracy of the total pressure loss coefficient can reach 0.8%.

[0075] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0076] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two).

[0077] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. An air intake turbulence control device calibration method, characterized by, Includes the following steps: The intake turbulence control device to be calibrated was placed in a completely silent test environment, with the intake airflow directed toward the intake turbulence control device to be calibrated under the condition of intake flow. The total ambient pressure, total ambient temperature, and relative humidity of the anechoic test environment were obtained. Along the direction of the incoming flow, a detection flow tube is installed downstream of the intake turbulence control device to be calibrated, and a total pressure differential sensor is installed at the inlet of the detection flow tube to obtain the total pressure differential of the intake turbulence control device to be calibrated. The actual flow rate of the incoming airflow to the intake turbulence control device to be calibrated is obtained from the detection flow tube. The initial diameter of the intake turbulence control device to be calibrated is corrected based on the total ambient temperature to obtain the corrected diameter. The corrected gas constant is calculated based on the relative humidity, total pressure, and total temperature of the environment. The pressure loss coefficient of the intake turbulence control device to be calibrated is calculated based on the corrected gas constant, the total ambient pressure, the total ambient temperature, the total pressure difference, the corrected diameter, and the actual flow rate. The Reynolds number of the intake turbulence control device to be calibrated is calculated based on the actual flow rate and the corrected diameter. By changing the parameters of the intake airflow condition, multiple combinations of pressure loss coefficients and Reynolds numbers under different intake airflow conditions can be obtained; A calibration curve is obtained by fitting the pressure loss coefficient and Reynolds number combination under multiple different intake flow conditions, and the intake turbulence control device is calibrated based on the calibration curve.

2. The air intake turbulence control device calibration method of claim 1, wherein, The corrected diameter is calculated using the following formula: D t = D ref [1 + a(T t0 - T ref )]; Among them, D ref T is the initial diameter of the inlet turbulence control device to be calibrated. t0 For the total ambient temperature, T ref The ambient temperature during the calibration test of the intake turbulence control device to be calibrated, where α is the coefficient of thermal expansion of the intake turbulence control device to be calibrated, and D is the ambient temperature. t The diameter is corrected for temperature.

3. The method of calibrating an air intake turbulence control device of claim 2, wherein, The corrected gas constant is calculated using the following formula: Among them, R f To correct for the gas constant, R is the air gas constant, RH is the ambient relative humidity, and P... t0 Total environmental pressure.

4. The air intake turbulence control device calibration method of claim 3, wherein, The pressure loss coefficient and Reynolds number are calculated using the following formula: where ζ is the pressure loss coefficient, Re is the Reynolds number, m in Q is the actual flow rate, μ is the aerodynamic viscosity, and Δp is the total pressure difference of the intake turbulent flow control device to be calibrated.

5. The air intake turbulence control device calibration method of claim 1, wherein, The calibration curves were obtained by fitting the pressure loss coefficient and Reynolds number combination under several different inlet flow conditions using the nonlinear least squares method.

6. An air intake turbulence control device calibration system, characterized by, The intake turbulence control device is calibrated using the calibration method for the intake turbulence control device as described in any one of claims 1 to 5, wherein the intake turbulence control device calibration system comprises: Anechoic chamber, providing the aforementioned anechoic testing environment; The intake unit provides a uniform inflow of air toward the intake turbulence control device to be calibrated; An ambient total temperature probe is positioned upstream of the intake turbulence control device to be calibrated, along the direction of the incoming flow, to detect and obtain the ambient total temperature. An ambient total pressure probe is positioned between the ambient total temperature probe and the intake turbulence control device to be calibrated to detect and obtain the ambient total pressure. A flow detection tube is installed downstream of the intake turbulence control device to be calibrated, along the direction of incoming flow, to detect and obtain the actual flow rate. A total pressure differential sensor is installed at the inlet of the detection flow tube to detect and obtain the total pressure differential; and; The exhaust unit is located downstream of the flow detection tube along the direction of the incoming flow.

7. An acoustic test apparatus, characterized by Acoustic tests were conducted on the intake turbulence control device calibrated using the calibration method for the intake turbulence control device as described in any one of claims 1 to 5.

8. An acoustic test apparatus as claimed in claim 7, characterised in that, The acoustic testing apparatus is used for fan acoustic testing.

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