The induced injection principle of self-suction type isovelocity fly ash sampling gun has been analysed

the theoritical expresion equation of jet flow rate m for the induced injector being established

obtaining m only from determination of the pressure head ratio ε and of the velocity ratio x and y. The numerical simulation of the induced injecting system for the said sampling gun has been carried out

obtaining the rule of spray nozzle’s exit velocity to be varying along with the variation of the mixing tube’s length L

providing theroritical basis for design

debugging and application of the said sampling gun in the field.