Experimental Investigation And Numerical Simulations Of Bird Impact On The Helicopter Rotor

Bird impact usually occurs in the airspace below600meters. However, low altitude flying isthe most obvious characteristics of helicopter. Therefore, there is a great possibility that birdimpact occurs to helicopter. Moreover, with the improvement of flying speed, the danger of birdimpact is gradually deepening. Slight bird impact could cause plane body damage, while huge birdimpact could cause plane crash accident. The rotor is the most vital component of helicopter. Oncethe damage occurs, it will cause serious threat to helicopter’s flying safety which needs to beresolved urgently in anti-bird impact research.Anti-bird impact design research of civil helicopterin our country started fairly late and there are also few reports about numerical calculation andbird impact test related to civil bird impact. Therefore, How to meet AACA(Administration of theAirworthiness of Civil Aircraft’s) requirements in design process by adopting effective analysis,design and test means has become the problem that needs to be urgent resolved in thedevelepoment of our country’s new-style civil helicopter.In this paper, the numerical computation methods for bird impact were studied, and therelative theoretical formulas were derived. Combined with the characteristics of the helicopterrotor bird impact,The ALE fluid-structure method was adopted to analyze dynamic response ofone civil helicopter’s rotor bird impact and related bird impact test was carried out. Firstly, thefinite element model of one civil helicopter’s full-scale bird impact was established. Theeffectiveness of rotor finite element model was verified by analysing the inherent characteristics ofrotor blade. Strain rate effect was taken into consideration in blade material’s constitutive model,And the effect of centrifugal force was considered in the form of prestress. The influence of birdimpact parameters, such as impact speed, impact direction, impact part and bird density, on theblade’s dynamic response was analysed, and some conclusions which are of great reference valuewere reached.As for anti-bird impact’s weak aspect of blade trailing edge, some methods ofimproving blade anti-bird impact were proposed under the principle of minimum weight of aircraftdesign, and the contrastive analysis of those method was carried out.A bird impact test device was developed, which includes the fire mechanism, hullingmechanism, bird shot installation mechanism and gelatin birdshot. A test of pigeon and gelatinbird striking cantilever beam was carried out. In pigeon impact test, the pigeon was tied with clingfilm and directly launched to impact the target instead of being killed. The result from high speedcamera showed that the present method was even closer to real bird impact. Fluid dynamicbehavior in bird impact process was well simulated by gelatin birdshot. Thus, a certain foundation for bird replacement research in future’s blade bird impact test is built.The main rotor blade full-scale bird impact test is very hard to be realized due to thefollowing aspects: helicopter’s rotor diameter is larger; during rotating process, rotor consists ofdifferent motion forms such as flap, lag, torsion; boundary conditions are complicated; testcondition and test site are limited. In this paper,it was raised to adopt static bird impact withcentralized loads to replace that of rotating blade, and the effectiveness of this method was verifiedthrough numerical calculation method. Thus, theoretical basis is provided for impact test methodof helicopter’s rotating component.