掺气减蚀减压模型相似律问题的探讨

通过大朝山水电站表孔减压水力学模型试验结果与原型资料对比分析，对掺气减蚀减压水力学模型与原型之间的相似律问题进行了研究。研究结果表明，传统水力学减压试验方法在掺气减蚀减压模型中，由于存在模型和原型之间掺气不相似、初生空化界限不明确等问题，致使模型水流空化特性试验结果与原型差异比较大，只有通过空化部位水流掺气相似得到的减压模型试验结果才能与原型空化达到基本相似的要求。

Discussion on similarity law of pressure relief model for air entrainment and cavitation prevention

The similarity law between the prototype and the hydraulic model of air entrainment for cavitation prevention and pressure relief is studied herein based on the comparative analysis made between the result from the hydraulic model test for pressure relief of the surface spillway of Dachaoshan Hydropower Station and the observation data from the prototype concerned. The study shows that the result from the model test on the flow cavitation characteristic is quite different from the prototype due to the problems from the dissimilarity of the air entrainment between the model and the prototype and the indefiniteness of the initial cavitation boundary, if the model test for the pressure relief is made with the traditional hydraulic test method. In this way, the basic similarity between both the model test result and the data from the prototype can only be obtained from the similarity of flow air entrainment for the cavitated locations.