A Numerical Methodology to Compute Temperatures of a Rotating Cardan Shaft

In this paper a new numerical methodology to compute component temperatures of a rotating cardan shaft is described. In general temperatures of the cardan shaft are mainly dominated by radiation from the exhaust gas system and air temperatures in the transmission tunnel and underbody. While driving the cardan shaft is rotating. This yields a uniform temperature distribution of the circumference of the shaft. However most simulation approaches for heat protection are nowadays steady-state computations. In these simulations the rotation of the cardan shaft is not considered. In particular next to the exhaust gas system the distribution of the temperatures of the cardan shaft is not uniform but shows hot temperatures due to radiation at the side facing the exhaust gas system and lower temperatures at the other side. This paper describes a new computational approach that is averaging the radiative and convective heat fluxes circumferentially over bands of the cardan shaft. This yield a uniform distribution of relevant heat fluxes at the circumference of the rotating shaft. Based on these modified heat fluxes the temperature of the cardan shaft is computed considering as well conduction. The approach is validated within a special test rig. Temperatures of a rotating cardan shaft are measured by optical sensors. The comparison of measured and computed temperatures in the test rig shows a very good agreement. Therefore the new methodology will be used in the near future in full vehicle computations in the Vehicle Thermal Management (VTM) at the Mercedes-Benz Car Group. This methodology will be implemented into the commercial software STAR-CCM+ based on the work performed and described in this paper in the near future.