The Design Of The Experimental Device And Experiment Study Of The Jet Characteristics Based On Controlling By Pulse Micro-jets

With the development and utilization of natural gas, the gas has become main source of industrial energy. Rapid mixing of fuel and air is the key to improve the efficiency of fuel combustion.the effective control for the state of the flow of the jet will be able to control the process of mixing and burning process of the jet. This paper aims to design a set of jet combustion experiment device based on the control of high frequency of micro jet. The CFD software was used to carry out numerical simulation experiment for the flow field of jet under different control conditions.the results are as follows:1. A pulsed micro jet experimental device was designed with the help of CAXA and Solidworks of CAD design software, which is of mainly design jet gas processing system,the jet pipe and impulse generate device, the fluid analysis software Fluent Was also used to simulation analysis of the relevant parameters in diffusion and contraction section of the jet pipe. The best scattered Angle in the diffuser was selected as 16°,the best Sinusoidal of the contraction curve and length contraction L=170mm, which ensued that the flow parameters such as the turbulence from the main jet nozzle exit and the thickness of the boundary layer consistent with the test requirements.2. To assemble the experiment device, then to built the experiment bench and to adjust it. Detecting the velocity distribution and the turbulence intensity distribution of the jet exit of the experiment bench. The average turbulence of the jet exit is smaller than 0.5% and the boundary layer thickness ??2.0R, so this results meet the design requirements.3. The analysis of the experiment and simulation of the external flow field under the condition that the mass flow rate Cm=0.1% and the duty ratio φ=10% in each micro jet hole,when the frequency ratio of the main jet and micro jet Fv /FO(FV is the frequency of micro jet,FO is the frequency of the main jet)variety from 0 to 2.0, at the same time the number of the micro jet hole is 2、3、4、6 and in uniform distribution mode. The results showed that,the control effect of the micro jet to the main jet is west when Fv /FO≈1.Under the condition of Fv /FO ≈ 1, the number of the micro jet is 2, the large eddy ceiling and matching process are obviously in the flow field and the mixed degree of the main jet and the external environment fluid is best. Although the number of the micro jet is increasing, the mass transfer and mixing effect of the fluid between vortex ring andthe center area of the main jet are attenuated, so the decay effect of the main jet and it’s mixing effect with the external flow fluid are weakened. By comparison, the control effect of the micro jet is best when the number of the micro jet is 2 and under the symmetric distribution.