Abstract: Mixture of cold air flow from annular pass through holes with main flow(cold or hot stream) has been researched experimentally. The momentum exchange for annular pass air flow through plain or plunge circular holes into main flow has been studied experimentaaly on a rectagular test section in a simulated combustion chamber. The momentum exchange increases the pressure loss of the main air stream near the jet holes. The results show that the mixture pressure loss of combustor with plunge circular holes is 1 to 1. 5 time as large as that of the combustor with plain circular holes. Therefore, the combustor with plunge circular holes is favourable to combustion and may reduce the length of the combustor.