Performance of novel ventilation systems for passenger aircraft cabins with unsteady and unbalanced heat loads

Kurzfassung

We investigated the performance of five different ventilation scenarios in a passenger aircraft cabin with unsteady and unbalanced heat loads. The ventilation scenarios comprise mixing ventilation (MV), cabin displacement ventilation (CDV), ceiling based cabin displacement ventilation (CCDV) and two hybrid CCDV/CDV settings. To ensure a realistic test environment, we equipped the cabin of a grounded short-range aircraft (Dornier 728) with 70 thermal passenger dummies (TPDs) and more than 340 local temperature and velocity sensors. A grid of polystyrene spheres in combination with an infrared camera allowed for the acquisition of instantaneous temperature fields in the fluid. A local, unsteady heat load was realized using a specially developed cylindrical heat source at a nominal power of 200 W. At MV and CCDV, the released heat remained concentrated in the vicinity of the heat source and expands mainly to the rows adjacent to the source. At CDV, the released heat rises straight to the ceiling and leaves the cabin, having just a minimal impact on the mean cabin temperature. At the hybrid scenarios, a dispersion of the released heat over the next one to two adjacent rows was observed, resulting in a much more homogeneous temperature in the proximity of the heat source. To study the reaction to inhomogeneous thermal boundary conditions, we investigated the influence of dedicated load distributions in the cabin on the cabin air temperatures as compared to a fully occupied cabin. At CDV and the hybrid scenarios, the impact on the temperatures at chest level is located very strongly at the positions of the deactivated TPDs. For MV and CCDV, the localization is much less pronounced. Herewith, CDV shines out with the weakest imprint of the deactivated TPDs on the temperature field. Looking at the absolute temperature level in the passenger zone, we find the weakest impact of the heat load distribution for CDV, followed by MV and CCDV. The hybrid scenarios unveil the strongest temperature changes. On the other hand, the hybrid scenarios shined out with the most homogeneous temperatures in the passenger zone, while MV and CCDV, revealed the largest inhomogenities.