To provide data needed for the design of gas turbines and jet engines, the National Bureau of Standards is conducting a broad program of research on the viscosity of gases at elevated temperatures and pressures. Under the sponsorship of the National Advisory Committee for Aeronautics, hydrocarbon mixtures and combustion products composed of various proportions of nitrogen, carbon dioxide, argon, oxygen, carbon monoxide, and water vapor are being studied. In the course of this work, J. C. Westmoreland of the NBS staff has developed a unique type of flowmeter 1 which accurately controls and measures the flow of very small volumes of gas, such as those required in a small capillary tube viscosimeter. As a result of this development, it has been possible to obtain data hitherto unavailable on the viscosity of pure gases and their mixtures.
Accurate data on the viscosity of gases are required in designing transmission and measurement systems for fuel gases and in constructing gas-flow systems in chemical plants. Because the viscosity of a gas is an important factor in the rate of heat transmission between gases and metals, gas-viscosity data are also needed in the design of gas turbines and jet engines. With the continued development of new engines of this kind, the need for information on the viscosity of the exhaust gases at high temperatures is becoming increasingly important.
At present, available data on the viscosity of gases are very meager, particularly at temperatures above 1000 Β° F. To meet this need, the National Bureau of Standards has undertaken to determine the viscosity of pure gases and gas mixtures at pressures from 5 to 10,000 psi. and over the temperature range from 60 Β° to 2500 Β° F.
In the NBS program, viscosities are measured by timing the flow of the gas under study through a very fine capillary tube. If the dimensions of the tube are known, the viscosity can be computed by means of Poiseuille's law 2 from the volume rate of flow through the tube and the pressure drop from inlet to outlet of the tube. The capillary tubes * Communicated by the Director.