Design And Experiment Investigation Of Dynamic Adjustable Supersonic Diffuser

Supersonic diffusers are widely used in supersonic wind tunnels,high energy chemical lasers and any supersonic device that operates at a statics pressure below ambient.The conventional supersonic diffusers adopt fixed geometry structure,because they are relatively simple in design.However,there is a contradiction between the starting characteristics and pressure recovery performance and at this condition,variable geometry diffuser is required.In this paper,a dual-channel supersonic diffuser is designed.Using numerical simulations and exprimental studies as well as theoretical analysis,the paper carries out a series of reserches involving supersonic diffuser design methods,the flow field analysis,the test model design and experimental operations.Firstly,in this paper,the design methods of the conventional second throat supersonic diffuser are systematically studied,and the selection principles of structual parameters are determined.Two different unconventionality supersonic diffusers are designed in order to improve the pressure recovery efficiency.Based on the researches on the fixed geometry diffuser,the dynamic adjustable dual-channel supersonic diffuser is designed,whose throat area can be adjusted simplely and effectively.Then,the feasibility and validity of the dual-channel supersonic diffuser are examed preliminarily through numerical simulations.Results show that the dynamic adjusting progress doesn't change the nornal working states of the diffuser,and after the accessory channel closed,the ability to resisitance back pressure get enhanced.However,starting progeress is diffucult to study through numerical simulations,it's necessary to conduct experimental research.Finally,the test bench is builded up and experiments are carryed out to test the practice performance of the dual-channel diffuser.With the wall pressure measurements,the starting and adjusting progress as well as the steady working state are studied,and the practical working characteristics are researched.Results show that the design method is available,raising the starting characteristics and at the same time,improving the pressure recovery performance.Based on the engineering application,this paper focus on the design of the variable geometry diffuser.CoMPared to other variable geometry stucture,the dualchannel diffuser has the advantages of simple designed,small volume and easy realization.This study have reference value and practical value,though the performance of dual-channel supersonic diffuser can be improved further.