A test checking method for high supersonic speed friction resistance standard value

Abstract

The present application belongs to the technical field of hypersonic wind tunnel test, and discloses a test checking method of hypersonic frictional resistance standard value. The test checking method of hypersonic frictional resistance standard value is carried out in a hypersonic quiet wind tunnel, and the model is stably kept in a laminar flow state by means of a quiet flow field provided by the hypersonic quiet wind tunnel, so that the interference of flow field noise on the hypersonic frictional resistance is eliminated, real near space flight test data is obtained, and the obtained hypersonic frictional resistance standard value can be used for related test calculation or theoretical analysis, thereby providing technical support for the research on the frictional resistance of a spacecraft.

Description

Technical Field

[0001] This invention belongs to the field of hypersonic wind tunnel testing technology, specifically relating to a test and inspection method for the standard value of hypersonic frictional resistance. Background Technology

[0002] Frictional drag between an aircraft and the air is a significant component of the aerodynamic drag experienced by an aircraft. Studying the surface friction characteristics of aircraft surfaces or key components (such as scramjet engine inlets and aircraft wings) is crucial for improving aircraft drag performance. Frictional drag measurements can be used to calculate the frictional drag of aircraft surfaces, analyze the impact of model surface roughness on drag, or compare with theoretical calculations to verify the feasibility and accuracy of theoretical calculation methods.

[0003] In ground-based wind tunnel tests, the wind tunnel flow field has a significant impact on frictional drag measurements. This is primarily because flow field noise affects the flow regime (laminar, transition, turbulent, etc.) around the aircraft. Turbulent disturbances are too large and completely unpredictable, rendering the resulting values ​​incomprehensible. The transition process, with its various disturbances, also lacks the necessary measurement environment. Only laminar flow closely approximates the space environment during hypersonic flight. Therefore, it is necessary to obtain standard values ​​for hypersonic frictional drag under laminar flow conditions.

[0004] Currently, there is an urgent need to develop a test method for the standard value of hypersonic friction resistance. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a test method for the standard value of hypersonic frictional resistance, so as to overcome the defects of the prior art.

[0006] The test method for checking the standard value of hypersonic frictional resistance of the present invention includes the following steps: S10. Before the test, simulation calculations were performed to obtain the installation position of the friction sensor on the model and the calculated value of frictional resistance under ideal conditions for subsequent comparison. S20. Install friction sensors on the model; S30. Install the model in the hypersonic silent wind tunnel test section, lead out the power line and signal line of the friction sensor, connect it to the hypersonic silent wind tunnel data acquisition system, perform equipment self-check, and after confirming that it is normal, complete the test preparation work. S40. Conduct a test to measure the standard value of hypersonic frictional resistance. The friction sensor converts the noise signal it senses into a voltage signal. The voltage signal is synchronized in real time on the computer of the hypersonic silent wind tunnel data acquisition system, and a noise distribution map of the hypersonic silent flow field is plotted. By comparing the noise level with the noise level, the time period in the silent flow field is obtained. S50. Select a time period for the silent flow field, calculate the signal value of the sensor during the selected time period, obtain the friction resistance value, compare the friction resistance value of the silent flow field with the calculated friction resistance value under ideal conditions, and take the friction resistance value of the silent flow field as the standard value of friction resistance according to the preset error range.

[0007] Furthermore, the friction sensor is a sensor equipped with a semiconductor friction resistance balance; the semiconductor friction resistance balance is a micro-friction resistance balance that employs a temperature-compensated semiconductor strain gauge.

[0008] Furthermore, the model described is a flat plate model or an expanded flat plate model.

[0009] The experimental verification method for the standard value of hypersonic friction drag of the present invention is carried out in a hypersonic silent wind tunnel. Relying on the silent flow field provided by the hypersonic silent wind tunnel, the model is kept in a stable laminar flow state, eliminating the interference of flow field noise on hypersonic friction drag, and obtaining real near-space flight test data. The obtained standard value of hypersonic friction drag can be used for related experimental calculations or theoretical analysis, providing technical support for the study of friction drag of aircraft. Attached Figure Description

[0010] The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this disclosure. It is obvious that the drawings described below are merely some embodiments of this disclosure, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort. Furthermore, the same reference numerals denote the same parts throughout the drawings.

[0011] Figure 1 This is a noise distribution diagram of a hypersonic silent flow field. Figure 2 This is a schematic diagram of the test method for checking the standard value of hypersonic frictional resistance according to the present invention; Figure 3 This is a schematic diagram of a flat plate model; Figure 4 This is a schematic diagram of an expanded flat plate model.

[0012] In the figure, I. Noisy flow field; II. Quiet flow field; 1. Ludwig tube; 2. Flat plate model; 3. Expanded flat plate model; 4. Friction sensor; 5. Diffusion section; 6. Voltage signal; 7. Hypersonic silent wind tunnel data acquisition system; 8. Standard value of friction resistance. Detailed Implementation

[0013] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0014] The test method for checking the standard value of hypersonic frictional resistance of the present invention includes the following steps: S10. Before the test, simulation calculations were performed to obtain the installation position of the friction sensor on the model and the calculated value of frictional resistance under ideal conditions for subsequent comparison. S20. Install friction sensors on the model; S30. Install the model in the hypersonic silent wind tunnel test section, lead out the power line and signal line of the friction sensor, connect it to the hypersonic silent wind tunnel data acquisition system, perform equipment self-check, and after confirming that it is normal, complete the test preparation work. S40. Conduct a test to measure the standard value of hypersonic frictional resistance. The friction sensor converts the noise signal it senses into a voltage signal. The voltage signal is synchronized in real time on the computer of the hypersonic silent wind tunnel data acquisition system, and a noise distribution map of the hypersonic silent flow field is plotted. By comparing the noise level with the noise level, the time period in the silent flow field is obtained. S50. Select a time period for the silent flow field, calculate the sensor signal value during the selected time period to obtain the frictional resistance value, compare the frictional resistance value of the silent flow field with the calculated frictional resistance value under ideal conditions, and take the frictional resistance value of the silent flow field as the standard value of frictional resistance according to the preset error range (the total pressure decreases with time during the test, and the frictional resistance value is calculated by selecting the time period corresponding to the preset pressure value).

[0015] Furthermore, the aforementioned friction sensor is a sensor equipped with a semiconductor friction resistance balance; the semiconductor friction resistance balance is a micro-friction resistance balance that uses a temperature-compensated semiconductor strain gauge. The micro-friction resistance balance can accurately measure the friction resistance on the surface of a hypersonic aircraft and has the characteristics of small size, high sensitivity, and strong temperature compensation capability.

[0016] Furthermore, the model described is a flat plate model or an expanded flat plate model.

[0017] Example: The hypersonic silent wind tunnel in this example is a Φ300mm hypersonic silent wind tunnel. The Φ300mm hypersonic silent wind tunnel is a jet wind tunnel, using suction devices evenly distributed at the front end of Ludwig tube 1 to eliminate noise. The outlet diameter of Ludwig tube 1 is Φ320mm, with nominal Mach numbers of 6.0 and 8.0, a maximum design total pressure of 2.0MPa, and a total temperature of 537K. The gas medium is pure air or nitrogen. The stable operating time of the Φ300mm hypersonic silent wind tunnel is no less than 10s, and the cycle of a single platform is 150ms to 200ms.

[0018] like Figure 1 As shown in the schematic diagram, the Φ300mm hypersonic silent wind tunnel consists of Ludwig tube 1, test section, and diffuser section 5 from front to back. The test section is equipped with... Figure 2The flat plate model 2 shown, or as shown Figure 3 The expanded flat plate model 3 shown has a friction sensor 4 installed on it. The noise signal sensed by the friction sensor 4 is converted into a voltage signal. The voltage signal is synchronized in real time on the computer of the hypersonic silent wind tunnel data acquisition system, and the standard value of friction resistance 8 is obtained through the calculation program.

[0019] The test duration in this embodiment is approximately 12 seconds; the results obtained are as follows: Figure 4 The diagram shows the noise distribution of a hypersonic silent flow field. Figure 4 In the diagram, Ⅰ represents the noise flow field, with a noise value of approximately 2%. At this point, the model surface is in a turbulent state. Figure 4 In the diagram, II represents a silent flow field with a noise level not exceeding 0.05%. Under silent flow field conditions, the flight environment in near space can be realistically simulated. The flow field around the aircraft is stable and in a laminar state, and the frictional resistance value obtained from the silent flow field is the standard value of frictional resistance.

[0020] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. For those skilled in the art, all features disclosed in the present invention, or all steps in all methods or processes disclosed, except for mutually exclusive features and / or steps, can be combined in any way without departing from the principles of the present invention. The present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A test method for checking the standard value of hypersonic frictional resistance, characterized in that, Includes the following steps: S10. Before the test, simulation calculations were performed to obtain the installation position of the friction sensor on the model and the calculated value of frictional resistance under ideal conditions for subsequent comparison. S20. Install friction sensors on the model; S30. Install the model in the hypersonic silent wind tunnel test section, lead out the power line and signal line of the friction sensor, connect it to the hypersonic silent wind tunnel data acquisition system, perform equipment self-check, and after confirming that it is normal, complete the test preparation work. S40. Conduct a test to measure the standard value of hypersonic frictional resistance. The friction sensor converts the noise signal it senses into a voltage signal. The voltage signal is synchronized in real time on the computer of the hypersonic silent wind tunnel data acquisition system, and a noise distribution map of the hypersonic silent flow field is plotted. By comparing the noise level with the noise level, the time period in the silent flow field is obtained. S50. Select a time period for the silent flow field, calculate the signal value of the sensor during the selected time period, obtain the friction resistance value, compare the friction resistance value of the silent flow field with the calculated friction resistance value under ideal conditions, and take the friction resistance value of the silent flow field as the standard value of friction resistance according to the preset error range.

2. The test method for checking the standard value of hypersonic frictional resistance according to claim 1, characterized in that, The friction sensor is a sensor equipped with a semiconductor friction resistance balance; the semiconductor friction resistance balance is a micro friction resistance balance that uses a temperature self-compensating semiconductor strain gauge.

3. The test method for checking the standard value of hypersonic frictional resistance according to claim 1, characterized in that, The model described is a flat plate model or an expanded flat plate model.

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