| Because of its super-sonic jet characteristics,supersonic nozzles are widely used as core components in cold spraying,air-cooled quenching and converter steelmaking.During the operation of supersonic equipment,the flow field formed by the supersonic nozzle directly contacts the surface of the workpiece,which affects the processing quality and efficiency of the workpiece.Therefore,a reasonable nozzle structure is important to improve the jet performance of the supersonic nozzle and the efficiency of the supersonic equipment.This project takes the air-cooled quenching technology as the research background,aiming at the problem of poor uniformity of the flow field of multi-nozzle joint quenching of flat workpieces,a rectangular supersonic nozzle is proposed,and specific research and analysis are carried out on this nozzle.The main contents of the project are as follows:A design method of double-line rectangular supersonic nozzle based on cavity equivalent principle is proposed.The cavity of the rectangular supersonic nozzle is designed as a shrink first and then expand cavity.The shrinking profile is designed using the Witosinski curve method,and the expanding profile is designed using the Crown analytical method.After determining the cavity curve of the nozzle,the boundary layer of the nozzle was modified based on the boundary layer correction principle of the nozzle.Next,the FLUENT software was used to simulate the internal flow field and free jet flow field of the rectangular supersonic nozzle to verify the correctness of this design method.Rectangular supersonic nozzles with single-line or double-line were designed respectively,and the internal flow field and free-jet flow field of the nozzle were simulated using FLUENT software.The qualitative analysis of the flow field formed by the two nozzles proves the superiority of the double-line rectangular supersonic nozzle,superiority of the double-line rectangular supersonic nozzle was proved.Based on determining that the flow field of the double-line rectangular supersonic nozzle is superior to the single-line rectangular supersonic nozzle,the influence of nozzle inlet conditions,cavity design parameters and outlet design Mach number on the flow field inside the nozzle were studied,the influences of the optimal cavity design parameter combination,inlet pressure,and outlet design Mach number on the internal flow field of the double-line rectangular supersonic nozzle were obtained.After determining the optimal combination of cavity design parameters for the double-line rectangular supersonic nozzle,the effects of nozzle inlet pressure,outlet Mach number,and outlet cross-sectional area on the free jet of the nozzle were studied,the influence of each factor on the free jet flow field of the nozzle were obtained.This research enriches the types of supersonic nozzles,and it is of great significance to study the quenching uniformity of flat workpieces.It also has important reference value for supersonic spraying of slender parts. |
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