油液内气泡半径和含气量模型研究

In view of the air release issue in hydraulic oils, the variation of bubble size and gas content in terms of pressure is studied. Based on the stress balance on the bubble interface, an analytical model of bubble radius and gas content are derived, and from the comparison to numerical results the formula is verified with a high precision. The model takes the influence of gas dissolution and diffusion on bubble radius and gas content into account. The analytical model is validated by the experimental test rig. Measurement of the bubbles with the initial radius of 0.095 mm and 2.9 mm show that gas diffusion makes the bubble shrink more quickly, and the influence is determined by the gas solubility in oil. The bubble distribution is found to conform to the logarithmic normal distribution, and a uniform equation is fitted to match for different cases. At last, the analytical expression of the change rate of gas content is derived according to the proposed model. Results show that the oil pressure and its derivative are the main factors affecting the change of gas content.