An experimental study was undertaken to investigate some of the factors. affecting the behaviour of pressure variations in a straight exhaust pipe attached to a rotary engine. The investigation involved the measurement of engine load, speed, fuel consumption, combustion air properties and flow rate, mean static pressure near the exhaust port, mean temperatures at two locations in the exhaust pipe and transient gas pressures at two locations in the exhaust pipe. A theoretical, nonlinear model of the particle velocity of a gas excited by an acoustic wave propagation was modified to model the transient pressure behaviour of an acoustic wave. The model was correlated with the transient pressure measurements with the aid of an iterative correlation technique and digital signal processing. Standard curve fitting procedures were used to relate the various measurements as functions of engine speed,

The iterative procedure outlined has been found to be a good method for the treatment of data which cannot be correlated by standard linearization and regression techniques. Further, the analysis indicates that the model correlates very well with the pressure pulse created by the rotor chamber blow-down. It is also possible to predict the length through which the pressure pulse must travel before. the leading portion of the pulse distorts into a shock wave.