Three-dimensional Numerical Simulation Of An Entire Micro Turbojet Engine

Micro turbojet engines are widely used in model aircraft and unmanned aerial vehicles because of their small size,high thrust-to-weight ratio,high energy density,and easy maintenance.Centrifugal compressors,combustion chambers,turbines and tail nozzles are the main core components of micro-engines,and their performance has a great impact on the overall performance of the entire micro turbojet engine.In order to study the overall performance parameters of the micro turbojet engine more comprehensively,the numerical calculation and analysis of each core component and the whole machine were carried out.Based on the KJ66 turbojet engine model,the commercial software FLoEFD is used to calculate the performance characteristics of the centrifugal compressor.The centrifugal compressor has a mass flow of 0.214kg/s and a pressure ratio of 2.1 at the maximum design speed.Then the numerical calculation and comparative analysis of the combustion chamber of the engine are carried out.The results show that the main combustion zone has reached the chemically proportional combustion temperature.And the Outlet temperature distribution coefficient OTDF of the combustion chamber outlet is as high as 0.2912,and the radial temperature distribution coefficient RTDF is 0.1164.It shows that the internal combustion of the combustion chamber is even worse,which will have a negative impact on the turbine.Then the performance characteristics of the engine turbine are calculated and analyzed.When the pressure fall ratio is 1.8,the mass flow rate of the calculation result is different from the experimental result by 0.005kg/s,and the turbine efficiency error is 2.3%.The calculation error is small,which shows the good agreement with the experimental results.According to the above calculations,the three-dimensional machine calculation of the turbojet engine is carried out,and the calculation results of engine variable speed,speed characteristics and height characteristics are analyzed.The results show that as the engine speed increases,its thrust gradually increases,but at low speeds,its thrust is small;its speed characteristic is that as the number of flying Mach increases,the thrust of the engine reduced first and then increased.The fuel consumption rate has been increasing;the height characteristic is that as the flight altitude increases,the thrust of the engine decreases significantly,and the fuel consumption rate of the engine also gradually decreases.Through the above calculation and analysis,a relatively complete 3D machine performance researchsystem is established,which provides technical means and ideas for the future research of turbojet engine.