Structural Design And Optimization Of Aero-engine Pneumatic Grinding Instrument

Aero-engine is the most important core component of the aircraft.During the working process of the engine,there always some objects such as sand,gravels and others make the engine blades damaged.If such damages are not repaired in time,the whole blades will fracture to be invalid due to their crack propagation.Generally,focusing on the issue of engine blades repair,a kind of pneumatic grinding blade device is designed which can work under the condition of unload the engine in the aircraft.The dynamic mesh technique is used to simulate the passive rotation of the impeller under the air pressure,and the relevant process testing experiments are designed to verify the numerical simulation results.Finally,the optimization result of the impeller structure is calculated by numerical simulation.Firstly,according to the requirements of grinding tasks,the whole system of grinding device system is designed including the grinding head with angle adjustment mechanism,which can realize multi-angle polishing,and the feeding mechanism which can realize the different feeds in the grinding process,and the vision system with an endoscope equipment which can provide the real-time observation of the grinding condition.Under the actual working condition of there exists an angle between the grinding head and the direction of the incoming flow,the passive rotation process of the impeller under unknown motion conditions is simulated by using the passive dynamic mesh method which can define the physical properties of the impeller through the user-defined function.The rationality of the air-dynamic principle is verified by the simulation results of the velocity vector diagram.Based on the rotational speed data from the simulation,the Sigmoid function is used to making the numerical model,and the interpolation method and numerical integration are applied to obtain the empirical formula of the rotational speed versus time under different air pressures.The testing experiment is designed and carried out for the verification.The error is below 10% between the empirical formula and the testing experiment,which verifies the accuracy of the numerical simulation method.Finally,the main parameters affecting the air-dynamic performance of the impeller are given by analyzing the force mathematical model of the impeller,and the geometric parameters of the impeller with the best air-dynamic performance are obtained by analyzing the influence of different blade space and different curvature,therefore the optimization of the impeller is completed eventually.