An anechoic chamber for the aerodynamic noise test of the fan booster stage

Abstract

The invention discloses an anechoic chamber for a fan / booster stage aerodynamic noise test, and belongs to the field of anechoic chamber design. The anechoic chamber is of an asymmetric structure, an adjacent wall of a corner of the anechoic chamber is offset towards the inside, and a wall of an offsetting part is in a vertical shape; the wall connected with the offsetting part is in an inclined shape, a fan / booster stage test piece is installed on the inner side of the wall in the vertical shape, and an inner and outer culvert exhaust air system and a tester are arranged on the outer side of the wall; a far field microphone array is arranged on the position of a fan / booster stage test piece diameter which is far away from an inlet of the fan / booster stage test piece and the distance of which is not less than 15 times; and a turbulent flow control panel is arranged on the windward side direction of the fan / booster stage test piece, an air inflowing system is connected with an air inlet of the anechoic chamber, the inner and outer culvert exhaust air system is connected with the anechoic chamber through the fan / booster stage test piece, and the tester is connected with the fan / booster stage test piece. The anechoic chamber for the fan / booster stage aerodynamic noise test satisfies required conditions of an engineering level fan / booster stage noise test study.

Description

technical field [0001] The invention belongs to the technical field of anechoic chambers, and in particular relates to an anechoic chamber used for the aerodynamic noise test of a fan supercharging stage. Background technique [0002] As one of the main noise sources of the aircraft, the fan supercharger test piece is a necessary means to test the low noise design and noise reduction effect of the fan supercharger, and it is also an important link in the engine noise test research system. [0003] At present, there are only 3-4 laboratories for the experimental research on the mechanism of fan aerodynamic noise that have been built or are currently under construction in China, and the foundation is very weak; The size of the acoustic room is relatively small (the height is generally less than 7m, the length and width are less than 10m), and only basic and qualitative experimental research on the generation, propagation and suppression of single-stage fan noise sources can be...

AI Technical Summary

Problems solved by technology

[0005] 1) The lack of consideration of the symmetry of the sound field and the corresponding special design method in the prior art will lead to a huge building area and extremely high cost;

[0006] 2) There is a lack of special vibration isolation design technology for large-scale, high-power, and complex testers in the prior art, and there will be technical difficulties in ensuring good sound and vibration quality of large-scale anechoic chambers;

[0007] 3) The lack of large-span roof design and anechoic wedge installation technology in the prior art will lead to difficulties in the design of large-scale anechoic chambers

Due to the demand for a fully free sound field, the anechoic chamber needs no column support structure, coupled with the self-weight of a large number of roofs and wedges, which brings difficulties to the design of the roof structure of a large-area anechoic chamber;

[0008] 4) In the prior art, there is a lack of consideration of high-frequency sound waves being affected by air absorption and temperature and humidity. When the size of the anechoic chamber becomes larger, the propagation path will become longer, and the noise is affected by air absorption and temperature and humidity. The accuracy of the noise test is reduced or even the test data cannot be used;

Therefore, the prior art lacks an air intake system design method suitable for open type, large air flow, high noise reduction effect, and low noise reflection, which cannot support the design of large anechoic chambers;

[0010] 6) There is a lack of means to control the temperature gradient in the anechoic chamber in the prior art, and it is impossible to avoid the influence of the internal temperature gradient change on the noise test after the size of the anechoic chamber becomes larger;

[0011] 7) There is a lack of methods for controlling intake turbulence in the prior art, and it is impossible to avoid that after the size of the anechoic chamber becomes larger, the interior of the anechoic chamber will be air-intaked from the ground and there will be objective intake turbulence, and it is impossible to simulate the intake conditions of the engine in high-altitude flight , and then lead to the existence of secondary noise sources, resulting in errors in test results;

[0013] 9) There is a lack of testing methods for the sound absorption performance of the anechoic wedge and the full anechoic chamber at frequencies above 20kHz, which cannot meet the precise test requirements for the noise of full-scale or scaled-down fan supercharger components

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