Problems of flow, heat release, and mixing in gas turbine combustion chambers are discussed and analyzed. The analysis is based on an idealized or equivalent chamber in which the end result is the same as in the conventional chamber, but in which the functions are separate and distinct. A large primary zone is advantageous, but the combustion process still is burdened by an inverse relationship between primary air and fuel. Conditions favorable to combustion in the primary zone over the whole range of operation are realized by means of a mechanical control. Agreement between analysis and experiment was demonstrated by tests of a chamber with a mechanical control. Comparison of the field of mixing of primary flame gas and secondary air with other studies of mixing revealed a general similarity, but a slower rate of mixing that is ascribed to the effects of a large difference of temperature or density in these experiments. Although jet propulsion for aircraft has become a practical reality, many problems connected with it are still only partially solved. One of these problems is the development of combustion chambers for turbojet engines that will give satisfactory performance under all service conditions. Satisfactory performance implies that a continuous supply of exhaust gas at the desired temperature is furnished the turbine, and that response to demands for changes of conditions is positive and occurs in a minimum of time. Other desirable characteristics are high combustion efficiency, small loss of pressure, uniformity of temperature in the exhaust, minimum size and weight consistent with required performance and life, and ease of manufacture and maintenance. Some compromises have been necessary in designing combustion chambers, since some of these features have been found to be obtained only at the expense of others. Problems of flow and combustion in conventional combustion chambers are so complicated and interrelated that development of chambers has progressed largely by empirical methods. Although development by these methods has produced immediate results, in the long run a fundamental understanding of the problem is advantageous and will promote design on a more rational basis. It is the purpose of this paper to separate and examine some of the functions of conventional gas turbine combustion chambers in an attempt to arrive at a better understanding of their influence on the performance of the chamber as a whole. 2. Nomenclature A — Area, ft2. c— Effectiveness of mixing. C= Coefficient in mixing length equation. Cp = Specific heat at constant pressure, Btu/lb°F. d,D= Diameter, ft. g=Standard acceleration of gravity, ft/sec2. /= Mixing length, ft.