| Jet ejector based on"jet technology"has been used in a variety of applications including civil engineering construction, aircraft thrust augmentation, heat pumps for refrigeration and air-conditioning system and solid powder transportation due to their simplicity, reliability, and versatility. However, as matters stand, most of Steam-jet ejector was faced with the problem of high noise. To make such system economically competitive it is necessary to improve the performance of the steam-jet ejector they use, not only in terms of pressure lift ratio (PC/PH), but also entrainment ratio (GH/GP) and low noise. Further work is thus required to design the effective steam jet-ejector. The main contributions of the paper are as follows:(1) The state-of-the-art of theoretical, experimental and numerical investigation for ejector was reviewed. Thermodynamic models and air-dynamic function models was investigated.(2) The present test and spectrum analysis was carried out to get the character of high noise of the steam-jet ejector. The result indicated that the character is as follow: wide frequency band; high sound pressure; the highest sound pressure concentrates on frequency band of 1kHz~4kHz; the whole noise frequency spectrum can separate to four different character section.(3) Theoretical study for cause of high noise of the steam-jet ejector indicated that velocity gradient in outlet of nozzle and force gradient by the flow path is the origin of four pole and dipole noise source.(4) A commercial CFD scheme FLUENT was used to simulate the supersonic process of steam jet ejector. The relation between cause of noise and structure parameters of the steam-jet ejector was studied.(5)A perfection design according to theoretical study FLUENT CFD simulating was completed in order to reduce the noise of sound source. By present test, the noise reduces 14dB.
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