A review of test medium contamination effects on test article combustion processes

Abstract

Aerospace systems currently in operation demonstrate that good, useful results can be obtained from ground testing in existing test facilities. One of the concerns with ground testing is that the thermochemical characteristics of the flight medium, the standard test medium, are different from the thermochemical characteristic of the ground test medium, a non-standard test medium, (NSTM). This paper is concerned with the effects on hypersonic air-breathing propulsion systems that may be a result of the method used to supply the energy necessary for simulation of hypersonic flight in the atmosphere. A review was begun of published results that address the effects of a NSTM on combustion in the test article. This paper documents the current understanding of the effects of available energy addition processes on the test medium and suggests an approach to make the best possible use of ground test facilities. A second paper is planned to address specific examples. Review of the literature shows that each case is different and must be analyzed individually. A second observation from the review is that all energy addition methods currently used to simulate hypersonic atmospheric flight create a NSTM. The best solution to the problem of the question of NSTM effects is to be aware of the differences between the flight medium and the NSTM and to know how these differences affect the test results. The most detrimental situation is to be unaware of the differences in test media that affect the results of the test. * The research reported herein was performed by the Arnold Engineering Development Center (AEDC), Air Force Materiel Command. Work and analysis tor this research were performed by personnel of Sverdrup Technology, Inc., AEDC Group, technical services contractor for AEDC. Further reproduction is authorized to satisfy needs of the U. S. Government.

Effects of Vitiated Air on Hydrogen Ignition in a High-Speed Laminar Mixing Layer

“…Thus, when providing the required stagnation conditions for testing, it is necessary to heat up air to a high enthalpy level that matches the properties of high-Mach-number flight. There are several heating techniques currently available, including archeated facilities, thermal storage facilities, shock=expansion facilities, and combustion-heated facilities (Huebner et al, 1996;Powell and Stallings, 1998;Tishkoff et al, 1997). Among them, the combustion-heated facilities have been widely used for supersonic combustion studies because of the much higher enthalpy air that is achievable, and also their ease to operate, lower cost, and higher efficiency in generating the required heated air.…”

Effects of Air Vitiation on Scramjet Performance Based on Thermodynamic Cycle Analysis

“…For example, the stagnation temperature of engine airstream is about 1100 K at Mach 4.5 and the corresponding stagnation enthalpy reach over 1 MJ/kg. The methods of air heating are currently as follows [5]: combustion heating, shock tube heating, arc heating, storage heating, and electric heating. Because of the ease of operation, the low operating cost and the supply of long test times, combustion heating has become the most widely used method of producing high-enthalpy air.…”