Application of the water traverse technique to the development of an afterburner

Abstract

A technique was developed for assessing the fuel-air ratio distribution of a reheat burner with the engine run at design conditions, but without reheat in operation. Water is injected from the reheat burner fuel manifold, the associated drop in gas temperatures recorded by thermocouples in traverse planes around the burner being a measure of the water-air ratio distribution. Primary interest was in the radial and circumferential spread of the fuel at these planes, and the location of the jet core. By repeating the tests to cover the operational flow range of the burner, the local fuel-air ratio at the stabilizers can be expressed as a percentage of the total fuel-air ratio, at each condition. The extinction limits of the burner having been established with reheat in operation in terms of total fuel-air ratio, the local stability limits of the flame stabilizers can be estimated. However, as the extinction limits generally occur at jet pipe conditions other than those at which the water traverse tests are carried out, appropriate similarity parameters must be used. These are compared quantitatively with the parameters affecting fuel penetration and dispersion in the literature. A correlation has been done of the extinction limits of a series of different reheat burners from flight and test bed results using the water traverse technique.