Front edge design method for optimizing suction surface wave system and suppressing fan shock wave noise

Abstract

The invention discloses a front edge design method for optimizing a suction surface wave system and suppressing fan shock wave noise. The front edge design method comprises an element blade front edgeoptimum design method, a three-dimensional fan/rotor blade design method based on element blade front edge optimum design and a three-dimensional fan/rotor blade design method through combination ofelement blade front edge optimum design and bending modeling. On the existing ultrasonic blade basis, the shape of the front edge and the shape of a suction surface are fast changed, air flow turningangle distribution of the suction surface between the front edge point and the point E is reasonably distributed, and therefore distribution of compression waves and expansion waves on the suction surface is optimized, the interference function of the wave system and forward-stretching shock waves on the suction surface is improved, and then the effect of reducing the transonic fan shock wave noise is achieved; and the shock wave noise of an ultrasonic blade of an original round front edge can be effectively reduced by about 1.5-3.5 dB, the method can be combined with the bending three-dimensional modeling technology, the noise reduction effects of a near field and a far field are achieved at the same time, and high engineering application value is achieved.

Description

technical field [0001] The invention relates to the field of shock wave noise control of a transacoustic fan with a large bypass ratio, in particular to a leading edge design method for optimizing a suction surface wave system to suppress fan shock wave noise. Background technique [0002] With the increasing awareness of environmental protection, the international control of jet noise is becoming more and more stringent, and European and American aviation giants also regard noise indicators as one of the main technical fortresses to squeeze out competitors; All large Russian civil airliners will automatically withdraw from the international civil aircraft market. It is expected that the fifth stage of noise trial flight regulations, which is expected to be implemented around 2020, is likely to be 10 to 15 decibels lower than the current standard. And the commercial airliner C919 presents a severe test of survival. [0003] At present, commercial airliners widely use aeroen...

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Problems solved by technology

[0004] Reducing aircraft noise, especially engine noise, has become a popular research topic and a major technical challenge in the aviation field; currently, the widely used methods for engine noise reduction mainly include the use of lobe-shaped nozzles, reasonable design of the number of rotor-stator blades, and increasing the number of rotor-stator blades. The axial distance between the rotor and the stator, the use of acoustic lining and blade bending and sweeping, etc., among which the lobe nozzle is used to reduce the jet noise, the number of rotor-stator blades is reasonably designed, the axial spacing of the rotor-stator is increased, and the use of acoustic lining can reduce the sub-acoustic state to a certain extent Downturn static interference noise and broadband noise, but the effect on low-mode shock wave noise is very limited, and the research on noise reduction of curved and swept blades has been accumulated for nearly 20 years. The technology is relatively mature, and it is difficult to have a large-scale effect There is an urgent need for a new simple, effective and mechanism-specific noise reduction method for shock wave noise of transacoustic fans, which is compatible with existing noise reduction techniques

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