Experimental Investigation On The Performance Of The Combustor's Diffuser

.For the high performance of aero-engine,the high pressure ratio is required with respect to a high performance of the diffusor.In order to ensure a stable and efficiency combustion of the gas flow in the combustor,it is necessary to improve the performance of the difFfuser.At present,the use of single-channel short diffusers is widely used at home and abroad.The predecessors have conducted much research on them,but there are few analyses on the internal flow field structure,and there are still areas that can be improved;In addition,three-channel diffuser has potentials to meet our need.Yet the current experimental data on the three-channel diff:user is far more not sufficient.Therefore,the present research work aims at the design of a single-channel short bulge diffuser that has been used in China,and compares the design of a three-channel diffuser model with advanced Particle Image Velocimetry(PIV)for the internal flow,as well as pressure measurement of the diffuser.Flow field information and pressure performance were systematically studied.The experiment focuses on the variation of the pressure performance and the internal flow field structure of the single-channel diffuser and the three-channel difuser under different relative dump gap and airflow distribution ratios,obtains the best relative dump gap and flow distribution through comparison.Through experimental research,it has been found that for a single-channel diffuser,when relative dump gap and the inside of the flame cylinder is constant,the flow rate of the outer ring is increased,the performance of the diffuser increase first and then decreases.When the flow distribution ratio is 0.31:0.365:0.325,the total pressure loss is the lowest;the change in the sudden expansion gap will have a blocking effect on the main flow.In a certain range,this kind of obstruction is beneficial to the diffuser to improve the performance.The obstruction effect is reduced,too small expansion gap will cause the fluid to bend when entering the corresponding channel;at the same time,when the sudden expansion gap ratio is in the range of 1.6 to 1.8,the pressure performance of the diffuser is best.At the same time,the experiment shows that the pressure performance of the three-channel diffuser is generally better than that of the single-channel diffuser,and the Reynolds stress distribution in the flow field is relatively uniform;in addition,the change of the flow distribution ratio mainly affects the distortion of the exit velocity of the pre-diffuser.,thereby affecting the ability of the diffuser to recover static pressure.Compared with the single-channel diffuser,the distortion of the flow field caused by the change in the flow distribution ratio of the three-channel diffuser is small.