Browsing by Author "Grün, Jeremias"

Now showing 1 - 5 of 5

Open Access
Computational fluid dynamics of the lubricant flow in the sealing gap of rotary shaft seals
(2022) Grün, Jeremias; Feldmeth, Simon; Bauer, Frank
The lubricant flow in the sealing gap significantly affects the sealing behavior of rotary shaft seals. Computational fluid dynamics (CFD) are applied here to analyze these fluid flows. A decisive input parameter is the sealing gap height respectively the lubricant film thickness. The film thickness is estimated on the basis of several analytical elastohydrodynamic lubrication (EHL) equations. The results for sealing characteristics such as the pumping rate and the friction torque derived from the numerical analyses are compared and discussed with the results obtained from test rig studies. This allows the validity of the applied methods to be verified.
Open Access
Multiphase conjugate heat transfer analyses on the assembly situation of rotary shaft seals
(2023) Hannss, Jacqueline; Grün, Jeremias; Olbrich, Christoph; Feldmeth, Simon; Bauer, Frank
Rotary shaft seals prevent the exchange of fluid at shaft passages. Their function and service life depend decisively on the temperature in the contact area between the sealing edge and the shaft. Since the temperature depends on both the generation of frictional heat in the contact area and the heat transfer to the surrounding sealing system, the design of the sealing system is crucial. Within the scope of this work, multiphase conjugate heat-transfer analyses were performed considering different assembly situations. The computed results were presented and contrasted to experimental data. This resulted in a valid model for predicting the temperature in the sealing system, which provided insight into the influence of the sealing surroundings on the contact temperature.
Open Access
Multiscale structural mechanics of rotary shaft seals : numerical studies and visual experiments
(2023) Grün, Jeremias; Gohs, Marco; Bauer, Frank
Although rotary shaft seals have been used successfully in many industrial applications for decades, their tribological behavior is still not completely understood. In-depth knowledge of the structural mechanics is essential for the design and optimization of such sealing systems. High complexity results from the multiscale interactions in the tribological system rotary shaft seal. Large macroscopic deformations occur due to the hyperelastic material behavior of elastomers coupled with microscopic tangential distortions of the sealing edge surface in the contact area. This paper includes both numerical and experimental studies on the tribological behavior of rotary shaft seals. A multiscale finite element model provides the simulation of the macroscopic deformations and the microscopic displacements. A test rig equipped with a hollow glass shaft enables in situ visual contact analyses, qualitative determinations of pressure distributions and quantitative measurements of elastomer surface distortions. The optical phenomenon of frustrated total internal reflection enables qualitative evaluations of the pressure distribution. Particle image velocimetry (PIV) is employed to quantify the tangential distortions. The test rig enables the measurement of the friction torque with the same configuration. The results of the numerical and experimental investigations for the radial load, friction torque and tangential distortions are compared and discussed. This serves to validate the simulation methods and the correlation of the measured parameters. This finally results in a solid and validated basis for further tribological investigations of rotary shaft seals.
Open Access
Numerische Untersuchungen zum Dichtmechanismus von Radial-Wellendichtungen
(Stuttgart : Institut für Maschinenelemente, 2025) Grün, Jeremias; Bauer, Frank (apl. Prof. Dr.-Ing.)
In numerous applications, the tribological system rotary shaft seal is subjected to various dynamic loads on multiple scales. Trends and challenges towards electromobility have further increased the exposure of rotary shaft seals to extreme operating conditions and loads. The associated increasing demand for shorter development times with simultaneously growing requirements and changing conditions make the use of numerical models for the simulation of tribological systems inevitable. Within the scope of this study, a multiscale model has been developed for the transient simulation of the lubrication and sealing mechanism of rotary shaft seals. A multiscale finite element model divided into two subdomains provides the computation of the structural mechanics. The macroscopic subdomain is utilized to compute the large deformations of the sealing ring during mounting, while the second subdomain is used to determine the microscopic distortions of the surface roughness on the sealing edge. An efficient and automated modeling approach allows the direct integration of physical surface measurement data into the numerical model. A transient computational fluid dynamics model enables the simulation of the dynamic flow processes in the sealing gap on the microscale. Lubricant film thickness equations serve as an indirect coupling between structural mechanics and fluid mechanics. The temperature dependence of the lubricant data is taken into account in the fluid mechanics model and in the determination of the sealing gap height. An empirical model is introduced, in conjunction with the computational fluid dynamics model, to account for mixed lubrication effects, considering only the viscous portion of friction. Established test rig experiments, extended experimental approaches, and data from previous work validate and verify the developed and applied methods. The numerical analyses demonstrate reasonable outcomes and a high level of consistency between the numerical simulation results and experimental data across the scales under consideration. Deviations between the simulation and experimental results increase as the scale moves from macroscale to microscale, potentially due to various factors that have a more significant influence on the microscale and extrapolation errors. In conclusion, the multiscale analyses provide unique insights into the complex flow dynamics in the sealing gap of rotary shaft seals. This presents clear evidence of the active dynamic lubrication and sealing mechanism. Additionally, the model presents various possibilities for extension and application to other tribological problems.
Open Access
Using multiphase conjugate heat transfer analyses to predict the contact temperature of rotary shaft seals
(2024) Hannss, Jacqueline; Grün, Jeremias; Olbrich, Christoph; Feldmeth, Simon; Bauer, Frank
Rotary shaft seals are used to seal shaft passages and prevent the exchange of fluids. The performance and service life of rotary shaft seals is strongly dependent on the temperature in the contact area between the sealing edge and the rotating shaft. Multiphase conjugate heat-transfer analyses covering different assembly scenarios, for example additional bearings or different shaft geometries, were performed in the software Ansys CFX 2021 R2. A model for predicting the maximum temperature in the sealing contact and for determining the heat dissipation from the sealing contact to the surrounding geometry was developed. This model provides the ability to predict the influence of the design of the surrounding sealing system on the contact temperature. Thus, the surrounding geometry of rotary shaft seals can be optimally designed to reduce the contact temperature between the sealing ring and the shaft as much as possible in order to achieve a longer service life.