Abstract
In investigations of the general altitude performance of combustors for aircraft gas-turbine engines at the Cleveland laboratory of the National Advisory Committee for Aeronautics (NACA), the combustors have been instrumented with a large number of thermocouples for determining average temperatures, temperature distributions, and combustion efficiencies. Presented herein is a discussion of the thermocouple installations used, some of the construction details of typical thermocouples, and representative temperature and combustion-efficiency measurements made in combustors. The results of numerous investigations of the general altitude performance of combustors for gas-turbine engines have indicated that air temperatures at the inlet to the combustors can be adequately measured with common bare-wire thermocouples, and that, at the combustor outlet, large variations in temperature distributions, nonuniform velocity distribution, and fluctuations in the temperatures are among the possible sources of errors in measuring the average combustor-outlet temperatures. In addition, the results indicate that the temperatures measured at the combustor outlet, although admittedly not accurate, are generally satisfactory for evaluating the altitude performance of combustors, and that the values of combustion efficiencies obtained from temperature measurements are satisfactory approximations of combustion efficiencies and serve to show the effect of primary variables on combustion efficiency.
