基于位置特征和螺旋方向的柱面气膜密封槽型控漏能力评价

Evaluation of Leakage Control Capability of Cylindrical Air Film Seal Groove Based on Position Characteristics and Spiral Direction

为探究轴套侧开槽新型柱面气膜密封在控制泄漏方面的能力,首先,采用有限差分法对不同位置特征和螺旋方向的新型柱面气膜密封槽型建立数值模型,通过对比各槽型气膜压力分布和密封性能参数,揭示位置特征和螺旋方向对不同槽型密封特性的影响机理。然后,针对反向“人”字槽型进行了参数化分析,探究螺旋槽角度、槽长坝长比、槽宽台宽比、槽深比对反向“人”字槽泄漏量、浮升力、摩擦力等密封性能参数的影响规律,同时对特定结构参数组合的反向“人”字槽逆流泵送控制泄漏的能力进行评价。结果表明:气膜厚度阶梯变化和偏心收敛楔效应在密封面形成高压气膜区域,有效阻止轴向泄漏,实现轴套侧开槽柱面气膜密封主泄漏通道的密封,且随着转速的增加,新型柱面气膜密封沿轴向间隙的泄漏量呈现下降趋势,该特性对于泄漏控制具有重要意义,特别是在高速运转的工况下。此外,通过合理的槽型参数调控可以使压差流造成的沿轴向间隙密封气体泄漏正好被反向“人”字槽逆流泵送作用导致的密封气体流动补偿,从而实现反向“人”字槽型柱面气膜密封的气体零泄漏甚至负泄漏,为柱面气膜密封槽型结构设计提供理论参考。

To assess the leakage control capability of a newly developed grooved cylindrical air film seal on the sleeve side,a numerical model was established using the finite difference method.The model encompassed various positional features and spiral directions.By comparing the air film pressure distribution and sealing performance parameters across different groove types,the impact mechanisms of positional features and spiral directions on various groove types were elucidated.Subsequently,a parametric analysis was conducted for the reverse dovetail groove type,exploring the influence of parameters such as spiral groove angle,groove length-to-ridge length ratio,groove width-to-ridge width ratio,and groove depth ratio on leakage,buoyancy force,friction force,and other sealing performance parameters.Simultaneously,an assessment was made regarding the ability of the reverse dovetail groove with specific structural parameter combinations to control leakage through reverse flow pumping.The research findings indicate that the stepped change in air film thickness and the eccentric converging wedge effect create a high-pressure air film region on the sealing surface,effectively preventing axial leakage and sealing the main leakage channel of the grooved cylindrical air film seal on the sleeve side.Moreover,with an increase in rotational speed,the leakage along the axial gap of the new cylindrical air film seal shows a decreasing trend,a crucial characteristic for effective leakage control,especially in high-speed operating conditions.Furthermore,it was observed that a rational structural design for the reverse dovetail groove type can achieve zero or even negative gas leakage for the cylindrical air film seal.Adjusting groove parameters appropriately compensates for the leakage of sealing gas along the axial gap caused by pressure differential flow,precisely counteracted by the reverse dovetail groove’s reverse flow pumping effect.This enables the reverse dovetail groove type of cylindrical air film seal to achieve zero or even negative gas leakage,providing valuable theoretical guidance for the design of grooved cylindrical air film seal structures.