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排序方式: 共有307条查询结果,搜索用时 218 毫秒
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飞机液压系统依靠被密封的工作介质来传递力和速度,因此,系统密封性的好坏直接影响系统的效率和工作性能,严重时将导致系统不能工作。O型密封圈由于具有优越的密封性能、密封结构简单和拆装方便等优点,被广泛应用于液压系统密封装置中。O型密封圈的参数设计对密封装置的有效密封起到关键性作用。现行有效的HB/Z4-1995适用于21 MPa压力体制液压系统密封结构及密封件设计,以1S243和1S384为基础,对28 MPa压力体制液压系统密封结构及密封件的压缩率、拉伸率等主要参数进行计算,并给出推荐参数选择范围,可以给28 MPa压力体制液压系统密封结构及密封件设计提供依据。 相似文献
243.
《中国航空学报》2021,34(5):554-572
The reliability estimation of mechanical seals is of crucial importance due to their wide applications in pumps in various mechanical systems. Failure of mechanical seals might cause leakage, and might lead to system failure and other relevant consequences. In this study, the reliability estimation for mechanical seals based on bivariate dependence analysis and considering model uncertainty is proposed. The friction torque and leakage rate are two degradation performance indicators of mechanical seals that can be described by the Wiener process, Gamma process, and inverse Gaussian process. The dependence between the two indicators can be described by different copula functions. Then the model uncertainty is considered in the reliability estimation using the Bayesian Model Average (BMA) method, while the unknown parameters in the model are estimated by Bayesian Markov Chain Monte Carlo (MCMC) method. A numerical simulation study and fatigue crack study are conducted to demonstrate the effectiveness of the BMA method to capture model uncertainty. A degradation test of mechanical seals is conducted to verify the proposed model. The optimal stochastic process models for two performance indicators and copula function are determined based on the degradation data. The results show the necessity of using the BMA method in degradation modeling. 相似文献
244.
The complex operating state of aeroengines has an impact on the performance of finger seals.However,little work has been focused on the issue and the dynamic performance of finger seals is also rarely studied.Therefore,a distributed mass equivalent model considering working conditions is proposed in this paper for solving the existing problems.The effects of the fiber bundle density and the preparation direction of the fiber bundle of a C/C composite on the dynamic performance of a finger seal are investigated in rotor tilt based on the proposed model.The difference between the C/C composite finger seal performances under the rotor precession and nutation tilt cases is also investigated.The results show that the fiber bundle density and the preparation direction of the fiber bundle have an influence on the dynamic performance of the finger seal as rotor tilt is considered,and the dynamic performance of the finger seal is different in the two kinds of tilting modes.In addition,a novel method for design of finger seals is presented based on the contact pressure between finger boots and the rotor.Finger seals with good leakage rates and low wear can be acquired in this method. 相似文献
245.
《中国航空学报》2020,33(4):1206-1217
Tooth bending damage resulting from an intense impact by the rotor sometimes occurs in the transient operation. To investigate the influence of after-damage clearance and tooth bending length on the leakage performance and rotordynamic coefficients of labyrinth seals, three tooth bending damages were taken into consideration, including the unbent tooth damage (abbreviated as Unbent), the partial tooth bending damage (abbreviated as Pbent) and the complete tooth bending damage (abbreviated as Cbent). The transient CFD solution was utilized to calculate the leakage flow rates and rotordynamic coefficients of labyrinth seals with clearances of 0.3, 0.4, 0.5, 0.6 mm for three tooth bending damages. The obtained result shows that the Unbent tooth damage leaks least while the Pbent tooth bending damage leaks most, and an increase of 6.1% for Cbent tooth bending damage and an increase of 19.4% for Pbent tooth bending damage are discovered at the tooth clearance of 0.6 mm in comparison with the Unbent tooth damage. Compared to the Unbent tooth damage, the effective damping for Pbent tooth bending damage and Cbent tooth bending damage is lower and drops by 9.7%–33.6% and 8.5%–22.6% respectively at the tooth clearance of 0.6 mm, suggesting that Pbent tooth bending damage or Cbent tooth bending damage tends to weaken the seal stability when compared to the Unbent tooth damage. 相似文献
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为防止燃气入侵涡轮盘腔,提高运行安全性,对盘腔和轮缘密封间隙内非定常流动机理进行了深入研究。采用数值求解三维URANS(Unsteady Reynolds Averaged Navier-Stokes)和SST湍流模型的方法,研究了涡轮径向轮缘密封的非定常燃气入侵和封严效率。数值计算的径向轮缘密封的封严效率和环量比与实验数据吻合一致,验证了数值方法的可靠性。分析了6种冷气流量下径向轮缘密封的非定常压力分布、封严效率和燃气入侵与冷气出流特性。研究表明:冷气流量的增加阻止了径向轮缘密封处的燃气入侵和强化了冷气出流,径向轮缘密封盘腔内的封严效率随着冷气流量的增加而增加;动盘附近的封严效率高于静盘;入侵燃气基本被限制在径向轮缘密封的间隙区域。径向轮缘密封间隙出口处的主流周向时均压力随着冷气流量的增加而增加,周向时均压力最大值与最小值的差值随着冷气流量的增加而减小。当动叶前缘与静叶尾缘距离较近且不断靠近的过程,主流周向压力最大值与最小值的差值增大,动静叶相分离的过程周向压力最大值和最小值的差值减小。在静叶和动叶间非定常干涉作用下,轮缘密封间隙出口区域主流周向压力最大值与最小值差值较大时刻的主流低压区域具有优良的封严效率,同时高压区域的燃气入侵导致封严效率降低。 相似文献
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几何参数对刷式密封泄漏和刷丝尖端力的影响 总被引:1,自引:0,他引:1
建立了一种刷式密封的切片式三维模型,利用计算流体动力学(CFD)方法,计算了刷丝所受的气流力并将其简化为较少量的一系列的集中力.基于力矩平衡和线性叠加原理,提出了气流力引起的刷丝尖端力、转矩的一种定量计算方法.1台刷式密封实验台和1只实验刷环被用于相关理论计算 的实验验证.基于上述理论计算,利用正交实验研究了刷丝长度、刷丝间隙、刷丝排数、安装角、刷丝直径和保护间隙对泄漏率、气流力、刷丝尖端力和转矩的影响.结果表明,总泄漏率及转矩的计算与实验结果基本吻合,各点误差均小于20%.刷丝直径、刷丝间隙、保护间隙及刷丝排数的对总泄漏率影响非常显著,安装角对转矩的影响非常显著. 相似文献