Gas making in the dilution zone of a combustions chamber

The mixing characteristics of cold air jets injected13; perpendicularly into a hot gas stream were studied experimentally under simulated aircraft gas turbine combustion chamber conditions.The hot gas stream was supplied to a 6.875 in*, diameter mixing duct at the desired temperatures by a modified combustion chamber. The jet diameters were 0.75 in., 1.00 in. and 1.25 in.and the number of jets selected was either 4 or 8. Temperature traverses were made at three cross sections downstream of the jet13; origin, their distances being 0.5, 1.0 and 1.5 duct diameters respectively from the jet origin. The temperatures were all recorded automatically and processed to determine the traverse quality which was expressed as a standard deviation of temperature, 13; Effects of jet to primary stream velocity ratio, flow rate ratio and temperature ratio were investigated. Results indicate that each mixing geometry is associated with an optimum mass flow rate ratio for obtaining best mixing, irrespective of temperature ratio. The importance of the results of such mixing studies in the design of combustion chamber dilution zone system is discussed