Strong,normal shock wave,terminating a local supersonic area on an airfoil,not only limits aerodynamic per-formance but also becomes a source of a high-speed impulsive helicopter noise.The application of a passive con-trol system(a cavity covered by a perforated plate)on a rotor blade should reduce the noise created by a movingshock.This article covers the numerical implementation of the Bohning/Doerffer transpiration law into theSPARC code and includes an extended validation against the experimental data for relatively simple geometriesof transonic nozzles.It is a first step towards a full simulation of a helicopter rotor equipped with a noise reducingpassive control device in hover and in forward flight conditions. Strong, normal shock wave, terminating a local supersonic area on an airfoil, not only limits aerodynamic per-formance but also a source of a high-speed impulsive helicopter noise. The application of a passive con-trol system (a cavity covered by a perforated plate should reduce the noise created by a moving shock. This article covers the numerical implementation of the Bohning / Doerffer transpiration law into the SPARC code and includes an extended validation against the experimental data for relatively simple geometries of transonic nozzles. It is a first step towards a full simulation of a helicopter rotor equipped with a noise reducing passive control device in hover and in forward flight conditions.