氣體流出に関する熱力學的研究

Abstract

This paper is relate to an experiment to determine the coefficient of discharge of gas through a nozzle and orifice etc. by the method of measuring the time of efflux of air from a vessel. Notwithstanding that the correct measurement of the temperature change of the air in the vessel is the atmost important thing in this mothod, because it affects the coefficient very severely yet the radiation effect fails the measurement almost to nonsense. In this research the author has made an attempt to measure the correct temperature by the following method : the air which is filled in the vessel with certain pressure and temperature is discharged by opening the cock until it reaches to a certain pressure and the cock is then rapidly closed. After the cock is closed, the pressure and temperature of the air rise gradually and reach finally to a steady condition. The pressure and temperature are then read, and the temperature at the instant when the cock was closed is calculated from the perfect gas law by using these values. The vessel is then filled with the compressed air at the original pressure and temperature. Discharge is made again until another pressure is reached and the temperature at that instant is calculated by the same method as above described. The temperature change thus obtained is shown in the Fig. 7 comparing with that obserbed by the oscillograph. Experiments were repeated changing the initial pressure ; and the coefficients calculated both from the observed and calculated temperatures are compared in the Fig. 11 showing the defect of the value calculated from the former. The coefficients of discharge of the nozzle, sharp orifice and flat edged orifice are compared in the Fig. 12. The coefficient of discharge decreases with the pressure, as shown in the Fig. 12,and especially those of the sharp orifices decrease rapidly at about the critical pressure while the decreasing of those of the nozzles and flat edged orifices are not so remarkable.