Design And Performance Analysis Of A New Type Of Swirl Ramjet Engine Compressor

Ramjet engine is simple in structure and has a large high-thrust ratio,but it cannot start by itself and requires the booster to accelerate to a certain speed before it can work.However,when it is combined with turbojet engine or turbofan engine to be used as an aero-engine,it loses the advantages that ramjet engine has simple structure and so on.This paper is based on the invention patent that a distributed compression,swirl ramjet engine.It can solve the problem that the existing ramjet engine can not start at low speed and adapt to various working conditions by means of swirl stamping.Based on the compressor of a micro turbojet engine,a coaxial two-stage centrifugal compressor was designed and its performance was studied by numerical calculation.The main contents are as follows:1.Designed with ANSYS Bladegen,and adjusted the inclination Angle and thickness of the impeller blade with bezier curve,first stage centrifugal impeller is generated.Simulated different static pressure outlets to get the highest pressure ratio and efficiency,the results show that it close to the working point.2.The tip clearance of 0%,3% and 6% blade height was studied respectively.The results show that the existence of tip clearance will lead to the leakage of the impeller's shroud surface and aggravate the influence of secondary flows.However,the existence of tip clearance can weaken the high-speed jet flow at the impeller outlet.Through the design of the first stage centrifugal compressor and the numerical simulation of the first stage,the outlet temperature and the outlet pressure are obtained.3.The return channel is designed and the flow condition inside the return channel with the number of blades 8,9 and 10 was analyzed.The results show that the outlet pressure and velocity distribution of return channel are more uniform,but the outlet pressure decreases more.4.The design of the second stage centrifugal compressor is completed and the numerical simulation of the two-stage centrifugal compressor is carried out.it is found that the total pressure ratio reach 10.6.Meanwhile,In the combined simulation,the gas pressure atthe outlet of the second stage diffuser and the outlet of the volute are smaller than that at the stage of the fractional simulation,because of the uneven flow of fluid on the connection surface.5.In the high pressure condition,the simulating nozzle is designed and the inlet conditions with different flow rates are given for numerical simulation.It is found that when two groups of compressors are operating,the velocity of nozzle outlet could reach the sound velocity,which provide conditions for the normal operation of ramjet engine.The results show that velocity of the nozzle can reach the sound velocity when the two groups of two-stage centrifugal compressor are combined with the simulating nozzle,that is,the ramjet can start statically.It can provide technical support for the research and development of distributed compression and swirl ramjet.