Transient temperature fields of turbulent mixed convection in an aircraft cabin caused by a local heat source

Abstract

The impact of a localized, transient head load on the temperature fields in aircraft cabin air flows was investigated in the Do 728 test bed of the German Aerospace Center. Surface and fluid temperatures were analyzed using more than 340 local sensors as well as a grid of polystyrene spheres, which was imaged by an infrared camera. To simulate the impact of the real passengers, thermal passenger dummies were used. The spatial spreading of the heat released by the local source could be characterized for the state of the art mixing ventilation system (MV – mixing ventilation) and a novel ventilation system (CCDV – ceiling based cabin displacement ventilation), which provides fresh air at low momentum through the cabin ceiling. As expected, CCDV provides lower cabin temperatures due to its higher heat removal efficiency. While MV tends to accumulate the heat released by the local source in the passenger zone, warm air is able to ascend to the ceiling more easy at CCDV due to the lower inertia forces. The different amount of inertia forces in the flow between MV and CCDV has a measureable impact on the temporal behavior of the resulting flow patterns during operation of the heat source, which is well reflected in the fluctuations of the temperature elevations.