In order to reduce pressure fluctuation and improve Mach number stability in continuous trans-supersonic wind tunnel

it is necessary to study the Mach number control model of second throat.In view of the few descriptions involved in existing literature

taking 0.6m continuous transonic wind tunnel as an example

the principle of the Mach number control with second throat was analysed

then the precise position control of second throat was realized based on the double PID(proportion-integral-derivative) control mode of motion controller plus servo driver

and the combined control sequence of second throat and compressor speed was presented

and then the algorithm of segmented variable parameter fuzzy PID and cascade control was proposed to control the Mach number. Finally

experiments were carried out. The results show that the Mach number control accuracy can be better than 0.001

and the time of each Mach number polar curve (9 attack angles) can be controlled within 4minutes

proving that the control strategy proposed is effective

and can provide reference for the design and construction of continuous trans-supersonic wind tunnel.