| Summary: | 碩士 === 中華大學 === 機械與航太工程研究所 === 91 === In this work, cavitated two phase flows for nozzle and a 2D and 3D curved pipes are simulated. The benchmark test will be focused on the two-phase cavitation simulations for curved tubes and high-pressure convergent-divergent or core cooling channels of pipeline system in power plants by CFD STAR-CD solver. The geometry and operation conditions of the pipeline system will be provided by the related experiments as the test cases. The effect of operation conditions as the flow velocity pressure of pipelines on occurrence of cavitations is studied. Besides, the distributions of the occurrences of cavitation along pipe and nozzle are also discussed.
For example, Nozzle is simulated in different pressure drop. And we can know when in pressure drop 0.79Mpa that Reynolds number between 4.3×104 is critical range of cavitation. Cavitation number is correspond about 1.252.
In this case,the Reynolds number in cavitations critical range of curved pipes is between 1.35×106 and 2.69×106. The sequence of flow field cavitation is no.4 no.3. The cavitations occurs at no.2 curved pipe when Reynolds number is added about 5.38×106. And the cavitation also occurs at no.1 curved pipe when Reynolds number is added about 8.07×106. And the volume of cavitation in no.4 is more larger. In the main of this text we most find out the interrelation between pressure drop and Reynolds number and the timing of cavitation occurring. We can predict the conditions about cavitation in flow field easily. At the same time, we also can calculate the place and distribution for cavitation. Besides, we can find out the corresponding relation and then we also can improve the timing of cavitation occurring.
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