Due to increasing demands on the efficiency of diesel engines, turbochargers are subjected to higher temperatures. In consequence rotor speed and temperature gradients in transient operations are more severe and therefore thermal and centrifugal stresses increase.
To determine the life cycle of turbochargers more precisely, the exact knowledge of the transient temperature distribution in the turbine wheel is essential.
The high temperature differences in turbochargers between turbine and compressor lead to heat transfer from the turbine in the direction of the bearing housing. A more precise solution was achieved by calculating the fluid at the beginning of the examined cooling down process by temporary solving all equations. The results of this approach met the transient and steady state measurements very well, and the transient thermal behavior of the solid body could be reproduced accurately.
On the other hand, already in 2006 gas temperatures up to 1050°C were reached in gasoline fired engines. Because of the higher turbine inlet temperatures, thermomechanical fatigue came more into focus. In the last years several studies related to thermomechanical fatigue in turbochargers were published. Based on the numerically predicted and validated temperature field in the turbine wheel, stress calculations were performed and zones of high thermal stress were identified in the turbine wheel. It is shown, that the magnitude of the thermal stress in these zones can be in the same range as the magnitude of the centrifugal stress alone, which means that the thermally induced stress cannot be neglected in the design process of a radial turbine wheel.
https://www.syuancn.com/aftermarket-komatsu-turbine-wheel-ktr130-product/
Reference
Ayed, A. H., Kemper, M., Kusterer, K., Tadesse, H., Wirsum, M., Tebbenhoff, O., 2013, „Numerical and experimental investigations of the transient thermal behaviour of a steam bypass valve at steam temperatures beyond 700 °C“, ASME Turbo Expo GT2013-95289, San Antonio, USA
R., Dornhöfer, W., Hatz, A., Eiser, J., Böhme, S., Adam, F., Unselt, S., Cerulla, M., Zimmer, K., Friedemann, W., Uhl, „Der neue R4 2,0l 4V TFSI-Motor im Audi A3“, 11. Aufladetechnische Konferenz, Dresden, 2006
Post time: Mar-13-2022