Features of combustion product flow structure in a spherical semi-open cavity

Results are presented from an experimental study of features of escape of high temperature combustion products of acetylene- and hydrogen-air flames through a compact circular nozzle device with a semi-open cavity to the rear. The experiments were carried out within a shock tube apparatus. Conditions for development of pressure pulsations were determined and their frequency was measured. The reactive force was measured as a function of nozzle critical section and oxidizer/fuel ratio. The circular nozzle's specific impulse was determined from equilibrium thermodynamic calculations of combustion product parameters for the fuels used and the measured reactive force values.