Improved design of pressure reduction ratio characteristics of a nozzle afterburner regulator

In order to solve the problem that the turbine drop pressure ratio deviates from the design value in the use of a nozzle afterburner regulator with an engine，the gas flow state of one-dimensional steady compressible Laval nozzle was theoretically analyzed and calculated，and the service conditions for the normal operation of Laval nozzle were analyzed according to the continuous working requirements of turbine drop pressure ratio；an improved design method for the secondary decompression Laval nozzle air pressure reducer expansion groove shape was proposed，and the engine test was conducted.The results showed that when the air pressure reducer only worked in supercritical state，and the shock wave was positioned behind the pressure measuring point location，it could ensure that relief was only associated with the position of pin plug，but had nothing to do with the inlet pressure.When the inlet pressure was low，the shock wave position was close to the pressure measuring point，which caused the deviation of the decompression ratio in the relative stable state.Increasing the throat area can make the shock position move backward and away from the pressure measuring point under the same inlet condition，which is conducive to improving the stability of the decompression ratio.Increasing the angle of the back end can make the shock position move forward，which is not conducive to the stability of the decompression ratio.