Aerodynamic Optimization Design Of The Thrust Reverser System Of The Civil Aircraft

The cascade thrust reverser is the most effective form of braking used by large commercial aircraft to shorten the aircraft’s landing distance.Currently,the thrust reverser device of the large civil aircraft in China lacks independent research and development capabilities.Based on the problems,this paper conducts the means of numerical simulation combined with wind tunnel experiments for the thrust reverser device,and adopts the optimization design method.A systematic research has been carried out from components to the whole system.Firstly,according to the experimental design of the thrust reverser cascade,experiments and numerical simulations were performed under three typical conditions of Mach number before the cascade.The aerodynamic performance and flow characteristics of the thrust reverser cascade were obtained.The numerical simulation method of the thrust reverser cascade was calibrated.Secondly,a parametric modeling method was developed for the two-dimensional thrust reverser cascade,and the optimization design variables were selected rationally.The total pressure recovery coefficient and reverse thrust were the optimization objectives,and a thrust reverser cascade aerodynamic simulation model and optimization design platform were established.Optimization designs of thrust reverser cascades with different solidities were finished.Finally,an integrated numerical simulation study of the thrust reverser cascade and the air intake system was carried out.Two thrust reverser devices of the circumferential angle layout were designed.The integrated calculation modeling including mesh generation and numerical simulation were completed.The flow fields of thrust reversers were compared and analyzed under the four typical motion conditions of an aircraft.A set of procedures and methods for the integration numerical simulation of the thrust reverser and the intake system are established.The main conclusion of this paper is as follows:(1)The comparisons between the numerical simulation and experimental result of the twodimensional thrust reverser cascade show that the numerical simulation accurately predicts the performance of the thrust reverser cascade.The average relative maximum error of the total pressure recovery coefficient at the outlet of the thrust reverser cascade is less than 1.3%.The absolute error of the deviation average is 1.64°.The reason for some errors in numerical simulation is that there are two low-speed separation zones in the flow field.The two separation flows caused by the flat structure of the leading and trailing edges of the thrust reverser cascade,and the separation flow of the cascade suction surface near the leading edge.(2)The optimization results of the thrust reverser cascade show that the inlet airflow angle and the outlet airflow angle have a great influence on the aerodynamic performance.Better performance is obtained when the front transition curve of the bullnose is shortened appropriately,which is consistent with the inlet airflow angle of the thrust reverser cascade.The optimal value of the solidity after increasing the bullnose as the optimization variable is lower than the solidity regardless of the bullnose.(3)The numerical simulation of the integration of thrust reverser and air intake system shows that the design of the circumferential angle used in this paper achieves the purpose of avoiding aircraft components,reducing fan inlet distortion and the possibility of reingestion,and broadening the working range of the thrust reverser.But some of the reverse-thrust forces are sacrificed at the same time.When the landing speed is 60 knots,the reverse thrust is reduced by 25.94% compared with the case without the circumferential angle.