A jet-based method and system for reducing rotor noise

Abstract

The invention discloses a method and system based on jet flow for reducing noise of rotor wings. The method comprises the steps of acquiring rotor wing parameters and working parameters of a helicopter; acquiring the thickness noise characteristics of a first rotor wing at an observation point; obtaining the thickness noise characteristics of a plurality of second rotor wings at the observation point; determining an objective function, wherein the objective function is a function which maximizes the area of a noise reduction region of the observation point; determining the distribution position of applied external force according to the objective function; determining the value of the external force according to a sound field cancellation method; adopting a CFD numerical simulation methodfor determining a function relationship of the jet flow parameters and the external force; determining the jet flow parameters of the distribution position according to the function relationship of the jet flow parameters and the external force and the value of the external force; applying the jet flow to the distribution position according to the jet flow parameters to reduce the noise of the rotor wings of the helicopter. By means of the method and system, the area of the noise reduction region of the thickness noise of the rotor wings can be significantly increased, and the noise reductioneffect is improved.

Description

technical field [0001] The invention relates to the field of helicopters, in particular to a jet-based method and system for reducing rotor noise. Background technique [0002] With the wide application of helicopters in military and civilian fields, the serious disadvantage of helicopter noise radiation has attracted more and more attention, and has become a problem that needs to be considered in the process of helicopter design. Rotor noise is the most important part of helicopter noise. According to the formation principle, it can be divided into thickness noise, load noise, propeller-vortex interference noise and high-speed pulse noise. Among them, the thickness noise of the rotor mainly propagates outward along the plane of the paddle disc, and has many low-frequency components, so the thickness noise has the characteristics of slow attenuation and long propagation. The main composition of noise is a key factor affecting the performance of acoustic stealth for military...

AI Technical Summary

Problems solved by technology

Some researchers have reduced the rotor noise to a certain extent by optimizing the design of the rotor, such as reducing the rotating Mach number, changing the blade shape design (swept tip, tapered blade or thin airfoil), etc., but there are the following Disadvantages: 1) While reducing noise, it also affects the aerodynamic performance of the rotor, and a compromise needs to be made between noise and performance design; 2) There is no targeted noise reduction of rotor thickness noise, resulting in poor noise reduction effect of thickness noise ; 3) This passive noise control method also has the adaptability problem for different flight states, and the helicopter noise reduction under the full-envelope flight state cannot be realized.

In terms of active control, it mainly focuses on the control of rotor propeller-vortex interference noise. Regarding the noise reduction of rotor thickness noise, the existing method uses a separate external force on the tip of the rotor to cancel and reduce the noise of the rotor noise, which can only achieve noise reduction at a single control point. , the noise reduction area is small, the overall noise reduction effect is poor, and it is difficult to meet the noise reduction requirements in actual flight

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