Model validation for a transient ECS failure case in a business jet mock-up

One of the goals of the CleanSky2 Airframe project is the maturation of model based certification methods, replacing cost intensive and sometimes even impossible tests with simulations. One such impossible test scenario is the hazard assessment in case of an ECS failure in a business jet, leading to a continuous decrease of cabin temperature by conduction to the exterior environment and thus to a potentially hazardous condition for passengers and crew. Such failures have been tested on the Business Jet Cabin Demonstrator in the Fraunhofer Flight Test Facility. With the test data, a model based on the zonal approach is validated. Zonal modelling subdivides the indoor environment into typically 100-1000 zones, thus providing a local resolution of airflow and temperature distribution while still being numerically fast enough to simulate transient profiles. As the study focusses hazard conditions, subject testing is not considered possible while modelling allows for a judgement on the risk level.