Detailed airflow information around a building can be crucial for the design of naturally ventilated systems and for exhaust air dispersion practices in agricultural buildings like greenhouses and livestock buildings. Full-scale measurements are cost-intensive and difficult to achieve due to varied wind conditions. A common method to gain insight of flow field under different wind conditions is the numerical simulation by using computational fluid dynamics (CFD). Still, evaluation of a CFD models’ performance and validation of its predictions with high quality experimental data is necessary before the model is used in practice. In this research three types of common agricultural buildings, arched-type, pitched-type and flat-type roof, were examined by conducting experiments in a wind tunnel with controlled airflow conditions, in order to validate different 3D turbulence models for predicting airflow patterns. The focus of this work was the detailed description of the external airflow field over the varied roof geometries and especially the velocity distribution and turbulent kinetic energy in the wake of each building. Experimental measurements of velocity were performed with a Laser Doppler Anemometer (LDA) and were compared with 3D RANS turbulence models’ simulation results. A reasonable agreement was found between experimental and simulation results concerning the velocity and the turbulence kinetic energy with CFD models slightly underestimating these magnitudes. The k-ε series turbulence models and especially the standard k-ε, RNG k-ε and Realizable k-ε models presented good agreement concerning velocity contours; however, high prediction error occurred over the roof of the buildings compared to the average values.

The environmental control system (ECS) of a commercial airplane supplies air to the cabin in order to maintain a safe, comfortable, and healthy environment for passengers and crew members. Because about half of the air supplied to the cabin is outside air, atmosphere particles could deposit in the ECS before entering the cabin. This investigation developed a model to calculate the particle deposition rates in the ECS for different particle sizes on the basis of a set of empirical equations from the literature. The model was used to predict particle deposition in five types of commercial airplanes (a regional jet, Boeing 737-800, Airbus 319, Airbus 320, and MD-82). The predicted results were compared with data measured in-flight or during operation on the ground and agreed well with the measured data. Both the simulated and measured results showed that almost all the large particles (d_p ≥ 5.0 μm) and 75% of small particles (d_p = 0.3–5.0 μm) were deposited in the ECS. Most of the particle deposition occurred near the entrance to the ECS where the geometry was the most complex.

Commercial aircraft use environmental control systems (ECSs) to control the thermal environment in cabins and thus ensure passengers’ safety, health, and comfort. This study investigated the interaction between ECS operation and cabin thermal environment. Simplified models were developed for the thermodynamic processes of the key ECS components in a commercial software program, ANSYS Simplorer. A computational fluid dynamics (CFD) program, ANSYS Fluent, was employed to simulate the thermal environment in a cabin. Through the coupling of Simplorer and Fluent, a PID control method was applied to the aircraft ECS in Simplorer to achieve dynamic control of the temperature of the supply air to the cabin, which was used as a Fluent input. The calculated supply air temperature agreed with the corresponding experimental data obtained from an MD-82 aircraft on the ground. The coupled model was then used to simulate a complete flight for the purpose of studying the interaction between ECS operation and the cabin thermal environment. The results show that the PID controller in the ECS can maintain the cabin air temperature within ±0.6 K of the set point, with an acceptable air temperature distribution. The coupled models can be used for the design and analysis of the ECS and cabin thermal environment for commercial airplanes.