熱力学的自己抑制効果と壁面加熱がノズル内キャビテーションに及ぼす影響

Abstract

To clarify the thermal aspect of cavitating flow, cavitation experiments were conducted using a heated nozzle with different mainstream temperatures and heating conditions to evaluate two thermal effects that affect the cavity. The decrease in cavity length was observed due to the thermodynamic self-suppression effect by increasing the mainstream temperature, and the cavity length increased by heating from the wall. By comparing the variation of cavity length in the non-heated and heated conditions, the condition balancing the two thermal effect was found. Additionally, the response of each thermal effect to the mainstream temperature was also found. It was also shown that the required wall superheat to cancel out thermodynamic self-suppression effect reaches a maximum value when the mainstream temperature is around 70 °C. The experimental results were compared and discussed with the mathematical model values for the two thermal effects.