This investigation explores the instability of the thermal characteristics of the rotary blade coupling (RBC) in real time four wheel drive (4WD) vehicles. The test rig is designed to make the key dimensionless parameters closely approach the operating conditions of a real vehicle. The range of parameters of the test rig is similar to that of a 4WD vehicle. A pattern of unstable Taylor vortices flow is found in the coupling of rotating blades. The flow pattern causes a wavy temperature distribution. A locally high operating temperature may cause material degradation, shortening the life of the rotary blade coupling. The local temperatur ratios were obtained in the gap between the inner and outer coupled of test section. A full-plane thermal imager also measured the overall temperature distributions on the rotary blade coupling and the rear differential. The mechanism of the influence of Taylor vortices was detailed by examining local thermal characteristics. One of the main goals of this study was to summarize the experimental results by fitting to equations for the temperature distribution ratio in real-time 4WD vehicles. The main findings are as follows: The temperature increases with the rotational speed. While rotating speed fixed at 1200 and 1600 rpm in the bottom zone and over 400 rpm in the top zone, an important Taylor vortex in fluid mechanics was found in this investigation. The experimental test rotation was performed above the critical Taylor number. Taylor vortices generate a wavy temperature distribution, raising the heat transfer problem, and inducing some regions of locally high temperature, eventually damaging the material, reducing the efficiency of the 4WD vehicle. The study also measures the full-plane temperature distribution to validate the related experimental data. The experimental data are reliable. Empirical correlations for local temperature distribution ratios in the considered ranges of real parameters are proposed. The correlations are useful for designing an RBC in a 4WD vehicle.
Unsteady thermal characteristics of a rotary blade coupling in a real-time four-wheel-drive vehicle
Unstetige thermische Charakteristiken von Drehflügelkupplungen in einem allradgetriebenen Echtzeit-Fahrzeug
International Journal of Vehicle Design ; 36 , 4 ; 365-384
2004
20 Seiten, 11 Bilder, 3 Tabellen, 16 Quellen
Article (Journal)
English
Unsteady thermal characteristics of a rotary blade coupling in a real-time four-wheel-drive vehicle
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