| Energy conservation and emission reduction are the long-term basic state policy of our country, while much energy consumption and environmental pollution of our country were caused by the heating system. Therefore, it is imperative to popularize metering heating charge reformation. A large number of good household heat meters are needed when popularizing metering heating charge reformation but the existing heat meter technology in our country cannot well adapt to the heating system. Meanwhile, there exists some technological gap compared with developed countries, so the study of household heat meter is urgently needed. In the paper, the internal flow field characteristics were studied on the basis of the universal DN25 ultrasonic heat meter of U shaped reflecting pillar in the market. Five meter-structure improvement programs which optimize the flow field characteristics are given and compare analyzed in the water both free from impurities and containing impurities. This has a certain theoretical guidance for the design and production of ultrasonic heat meters.In the paper, the numerical simulation was mainly studied by the theoretical analysis and proved correct and advantageous through the experiment. The numerical simulation was compromised by the theoretical analysis which improved and guided it. Draw on the past experience of numerical simulation and use the computational fluid dynamics software.3D numerical simulation was used for the internal flow field in ultrasonic heat meter. The flow field velocity distribution, K coefficient curve, K coefficient of standard deviation of different channels and the pressure loss in the internal flow field was got by the analysis of simulation results and five meter-structure improvement programs which optimize the flow field characteristics were proposed:adding guide plate in front of the inlet side reflected column, adding guide plate after the outlet side reflected column, adding guide plate in both side reflected columns, scrapping part of the top of reflected columns, Integrating of the above measures. Analyzing results of the same simulation of five meter-structure improvement programs, the flow field velocity distribution, K coefficient curve, K coefficient of standard deviation of different channels and the pressure loss in the internal flow field was obtained and compared with the original meter. Finally, the optimal and worst order to five meter-structure improvement programs is obtained.Because the water of the actual heat supply pipeline contains impurities, the discrete phase model in the computational fluid dynamics software was used to simulate the internal flow field characteristics of five meter-structure improvement programs and the original meter in order to preferably mirror the flow field characteristics of the ultrasonic heat meter in actual conditions in the paper. The relationship between the impurity concentration distribution and the flow was analyzed and K coefficient of standard deviation of different channels and the pressure loss in the internal flow field in the water containing impurities were compared with the ones in the water free from impurities. Finally, the flow characteristics in the actual heat supply pipeline were obtained.This paper which researched the relationship between the meter-structure and the flow characteristics in the ultrasonic heat meter provided relevant principle and guidance on the aspect of designing ultrasonic flow meter and improving its precision. And it filled the gap that domestic in this field at present to a certain extent. |
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