针对液压油液内空气析出现象，研究压力变化时气泡尺寸和含气量变化规律。在分析气泡界面受力基础上，推导气泡半径和油液含气量的解析模型，通过与数值计算结果对比验证解析公式具有较高精度，理论分析气体随压力升高而发生的溶解和扩散现象对气泡半径和含气量的影响。搭建气泡尺寸测试试验台验证解析模型可准确计算气泡半径。对初始半径为0.095 mm和2.9 mm的两个气泡跟踪测量结果表明气泡溶解和扩散导致气泡半径缩小加快，其影响程度决定于气体在油液的溶解度；对不同含气率的油液测量表明气泡分布呈现对数正态分布特点，经数据拟合气泡半径分布函数可由统一公式表示。最后，根据含气量模型推导其变化率的表达式，研究表明油液压力及其导数是影响含气量变化的主要因素。
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.
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