摘要
以某重型柴油机的连杆轴承为研究对象,引入运动边界和动网格smoothing网格光顺方法来探究不同入口条件对油膜空化现象的影响,研究了用于抑制轴承润滑空化现象的轴瓦开槽方法,对比开槽数量、深度及开槽形式对抑制油膜空化现象的影响.研究发现,润滑空化的范围和程度是一个动态变化的过程,引起空蚀的并非在空化形成阶段,而在空化溃灭的过程中.因而如果空化现象频繁发生和溃灭,相比持续存在的稳定空化状态,将更易破坏轴瓦表面,引发明显空蚀现象.由于重型柴油机的连杆轴承润滑油来自于主轴承,连杆轴承润滑油入口压力存在显著波动,导致空化程度波动剧烈,进一步恶化空蚀现象,这也解释了重型柴油机连杆轴承穴蚀损伤往往更甚于主轴承.通过轴瓦开槽可以有效缓解空化,从而达到抑制空蚀的效果;增加开槽数目和深度都可以强化抑制效果,但提升的程度有限.相比全槽模型,半槽模型可以强化油膜的轴向流动,对空化的抑制效果更好,可将油膜的气相体积分数最高值从0.94(未开槽)降至0.39.考虑到轴瓦的厚度与强度需求,选择适当槽深的半环单槽即可有效地抑制轴承运动过程中油膜的空化现象.
Abstract
The influence of different inlet conditions on the oil film cavitation phenomenon of connecting rod bear-ings of a heavy-duty diesel engine was explored through the dynamic boundary calculation.A method of slotting on the bearing bush was proposed to suppress the cavitation phenomenon during the bearing movement.The effects of the number,depth and form of grooves on the suppression of oil film cavitation were further analyzed.It is found that the increase in the number and depth of grooves can improve the effect of oil grooves to inhibit cavitation,but the degree of improvement of the inhibition effect decreases accordingly.If cavitation occurs and collapses fre-quently,it will be more likely to destroy the bearing bush surface and cause obvious cavitation erosion compared with the stable cavitation state.Compared with the full-groove model,the half-groove model has a higher suppres-sion effect,which can reduce the maximum gas phase volume fraction of the oil film from 0.94(ungrooved)to 0.39.Combined with the reliability requirements of the overall structure of the bearing bush,selecting a half-ring single groove with an appropriate groove depth can effectively suppress the cavitation of the oil film during the bearing movement.
基金项目
内燃机可靠性国家重点实验室开放基金资助项目(skler-201908)
国家自然科学基金资助项目(52076193)
维普
万方数据