Research On Mixing Flow Characteristics Of Mixing Valve Based On Large Eddy Simulation Method

Mixing valves play an important role in fluid transfer piping systems and fluid thermal mixing in energy and chemical industries.During the working process of the blending valve,the high periodic thermal fluctuation of the fluid near the wall of the valve body will cause the thermal fatigue failure of the admixture valve,and the jet velocity of the branch pipe and the plunger stroke will have an important impact on the temperature fluctuation of the flow field near the wall of the admixture valve.The study of the temperature distribution and temperature fluctuation mechanism of the injection speed and plunger stroke of the branch pipe on the mixing valve will provide theoretical support for the safe operation of the mixing valve in the fluid transfer system.The main work of this article is as follows:1.The temperature fluctuation mechanism of the fluid in the mixing valve under different speed ratio conditions was studied.The influence of branch pipe injection speed on temperature fluctuation during hot mixing in the mixing valve was discussed.With the increase of the injection velocity of the branch pipe,the high-temperature fluid of the branch pipe jet penetrates deep into the main basin with the structure of the arclike vortex cluster,and at the same time continuously falls off a large number in the direction of wingspan,when a large number of vortex structures are broken,the surrounding high-pressure fluid quickly flows to the low-pressure vortex core,making the flow field flow more chaotic and the hot mixing more intense.However,under the influence of the low-speed return area of the cylindrical leeward side of the center of the valve body,the temperature of the fluid in the circumferential 90° and 270°circumferential section of the wingspan increased and the temperature fluctuation intensity increased.The temperature power spectrum analysis of the near-wall region fluid with severe temperature fluctuation shows that the frequency signal of 0.2Hz runs through the hot and cold mixing process in the circumferential region of the wingspan section of 270°.2.The temperature fluctuation mechanism of the fluid in the mixing valve under different plunger stroke conditions was studied.The influence of plunger stroke on temperature fluctuations during hot mixing in the admixture valve was discussed.With the increase of plunger stroke,the center of the effective jet section of the branch pipe continues to move to the negative Y axis while the effective jet area decreases,so that the jet angle of the branch pipe changes at the same time the jet vortex structure also changes,different jet vortex structures develop downstream at different angles,and continue to fall off a large number in the direction of wingspan,affecting the flow field disturbance of fluids in different regions,when the plunger stroke is small,there is a higher temperature and strong temperature fluctuation in the circumferential 90° area of the wingspan section,and when the plunger stroke is large,The circumferential area of 270° of wingspan section has higher temperatures and strong temperature fluctuations.The temperature and power spectrum analysis of the near-wall region fluid with severe temperature fluctuation shows that with the increase of plunger stroke,the temperature power spectrum of the fluid in the circumferential 90° region of the wingspan section first increases and then decreases,and the peak frequency of 0.3Hz is identified in the circumferential region of 270° circumferential of the wingspan section of the involute tube.