Multi Scale Simulation Model for Temparature Prediction of Radial Lip Seals

弹性径向唇形密封用于密封旋转轴。在运行期间，在径向唇形密封件和轴之间的接触区域中产生摩擦热。产生的摩擦热越多，热量散失越差，接触区域就越热。高温对密封系统极为有害。它们会显著加速唇形密封弹性体和润滑剂的老化，并导致密封系统更快失效。为了提供密封系统所需的可靠性，在运行期间温度必须保持在允许的范围内。因此，设计人员必须能够在开发阶段就估计密封接触中的温度。目前，对摩擦热的估算大多是基于经验和专业知识，由于摩擦热的产生和耗散的影响因素众多且相互影响，存在较大的误差。这些估计误差的后果是尺寸过大（这意味着不经济）的密封系统或大规模的故障。因此，在本研究项目中，开发了一个模拟模型来模拟摩擦热的产生和耗散。该仿真模型可以计算出密封系统及其周边的温度分布，并采用多尺度的概念，有效地解决了不同长度尺度上的影响。模拟模型在微观尺度上描述了摩擦热的产生，在宏观尺度上描述了摩擦热的耗散。采用Fortran语言编制了微模型计算程序，利用雷诺方程描述了流体动压密封间隙内的流体流动。仿真模型使用径向唇形密封和轴的真实的表面形貌。宏观模型采用现有的共轭传热模型。该模拟模型允许组合的流体流动和热模拟。该方法不仅对密封系统的流体区域进行传热计算，而且对密封系统的固体区域也进行传热计算，为了解决密封系统的生热和散热的相互影响，将宏观模型和微观模型耦合起来进行迭代求解。通过在多功能试验台上的大量试验，对整个仿真模型及其组成部分进行了验证和优化，并对验证后的仿真模型进行了参数研究，确定了影响接触区温度的因素及其相互作用。基于参数研究和验证实验的结果，开发了一种预测开发阶段接触温度的近似方法。

Elastomeric radial lip seals are used to seal rotating shafts. During operation frictional heat is generated in the contact area between the radial lip seal and the shaft. The more frictional heat is generated and the poorer this heat is dissipated, the hotter the contact area gets. High temperatures are extremely harmful to the sealing system. They significantly accelerate the aging of the lip seal elastomer and the lubricant and cause faster failures of the sealing system.To provide the required reliability of the sealing system, the temperatures must stay in the allowed range during operation. Therefore designers have to be able to estimate the temperature in the sealing contact already in the development stage. Today the estimation is mostly based on experience and expertise.Considerable errors occur due to the multitude and the mutual interactions of the influencing factors on the generation and dissipation of the frictional heat. The consequences of those estimation errors are overdimensioned (this means uneconomic) sealing systems or massive failures.Therefore in this research project a simulation model is developed for simulating the production and dissipation of the frictional heat. With this simulation model the temperature distribution in the sealing system and its periphery can be calculated.A multi scale concept is used for the simulation model to solve the effects running on different length scales efficiently. The simulation model describes the production of the frictional heat on the micro scale and the dissipation of the frictional heat on the macro scale. A Fortran program is developed as micro model, which describes the fluid flow in the hydrodynamic sealing gap using the Reynolds equation. The simulation model uses real surface topographies of the radial lip seal and the shaft. An existing conjugate heat transfer model is used as macro model. This simulation model allows a combined fluid flow and heat simulation. The heat transfer is not only calculated for the fluid domains but also for the solid domains of the sealing system.To resolve the interaction of heat generation and heat dissipation, the macro and the micro model are coupled and are solved iteratively. The whole simulation model and its components are validated and optimized by comparing the simulation results with extensive test runs on a multi-purpose test rig.A parameter study is performed with the validated simulation model to identify the influencing coefficients and their interactions on the temperature in the contact area. Based on the results of the parameter study and the validation experiments, an approximation method is developed for predicting the contact temperature during the development stage.