On the question of set gas expiration through axisymmetrical holes and nozzles

Real parameters of the gas expiring out of narrowing nozzles of different confi-guration have been calculated knowing the discharge coefficients obtained experimentally. Rather a simple method to calculate the ?second? critical pressure differential dependent on discharge coefficients at cut-off expiration modes has been offered. Using an inviscid fluid one-dimensional model the author has confirmed that it is impossible to receive critical speeds in the output hole. The method makes it possible to estimate the value of the pressure in the separation point (if it is available), where the Laval nozzle section is minimum and knowing ?second? critical pressure differential (or total pressure at cut-off expiration). The received data can be used as initial data to calculate jet flows passing through various kind of holes. The analytical research results of gas discharge regime through the holes (nozzles) have shown, that a one-dimensional model can be used to calculate the parameters of the expiration through holes of different configuration in the nozzle narrowing part precisely enough to estimate changes of the main (basic) flow parameters in the channels of the holes. The analysis of the research indicates that the flow coefficients at flow-off expiration modes for convergent and convergent-divergent holes are identical and the parameters in critical section are identical as well. The total pressure recovery coefficient is approximately equal to the flow coefficient, there being losses of total pressure. The received results can be used in power engineering, metallurgy etc. developing various blowing devices and burners