ベンチュリ管スロート部におけるキャビテーションの衝撃エネルギーに及ぼす噴射条件の影響の評価

抄録

For hydrodynamic cavitation produced by a Venturi tube, cavitation bubble is collapsed at downstream of a nozzle and its intensity is influenced by upstream pressure and downstream pressure. In order to investigate the effect of the upstream pressure p₁ and the downstream pressure p₂ on aggressive intensity of hydrodynamic cavitation, an experiment measuring acoustic power by an AE sensor was conducted. Relationship between pressure conditions and acoustic power P_A was studied. The higher the upstream pressure p₁, the higher the acoustic power P_A. Acoustic power had a maximum value at the upstream pressure p₁ = 1.6, 2.1, 2.6, 3.1 and 3.6 MPa. At the upstream pressure p₁ = 2.6 MPa and the downstream pressure p₂ = 0.5 MPa, the aggressive intensity of hydrodynamic cavitation increased to be 36 times larger of the value corresponding to the atmospheric downstream pressure. While the optimum downstream pressure depended on the upstream pressure, the cavitation number was nearly constant for all upstream pressures. It was concluded that increasing the downstream pressure is an effective means to increase the aggressive intensity of the hydrodynamic cavitation without increasing the input energy.