空氣マイクロメータの靜特性(第3報)
高壓式理論
1952 年 18 巻 206 号 p. 83-89
詳細
1952 年 18 巻 206 号 p. 83-89
Generally the frictional loss of pressure of a high speed flow is negligibly small comparing with a large difference of pressure which causes air to flow through a small opening. Considering that, the static characteristics of a pneumatic micrometer of high pressure type was thermo-hydrodynamically calculated neglecting the viscosity.
In the approximate calculation, we found the followings : If the initial pressure is over 3.6 absolute atmospheric pressure, there will be an approximately linear amplification which we could not see with a low pressure type. This linear region being included in the region where the speed of air-flow at the air-escaping opening (clearance to be measured) is equal to that of local sound, have the maximum of very high amplification in its centre. Therefore in this region the performance becomes so stable as to permit us precision measurements.
Figures obtained from theoretical analysis manifest the relations of the amplifying pressure to the section-area of an air-escaping opening and to magnification, where the ratios of the initial pressure to the atmsopheric pressure are taken as parameter. Moreover characteristic regions for practical use are shown, and approximate standards for the instrumental designs are given.
