Numerical Simulation of Icing Clouds in the NASA Glenn Icing Research Tunnel

Abstract

The objective of this study was to develop and employ a numerical simulation strategy for predicting the liquid water content (LWC) at the test-section plane of the NASA Glenn Icing Research Tunnel (IRT) as well as to characterize the icing cloud uniformity as a function of tunnel speed, droplet size, etc. The droplets were injected with a polydisperse distribution and based on previous computational airflow results, which included the spray-bar wakes, the air jets, and the heat-exchanger flow. To simulate the effects of turbulent diffusion behavior of water droplets in the IRT, a continuous-random-walk methodology was employed, which corrects for nonhomogeneous turbulence. To first understand the cloud dynamics emanating from isolated nozzles, experiments and simulations were conducted with only four injectors spraying in the IRT. The simulations showed good representation of the width and position (though not necessarily the shape) of the individual spray clouds at the test-section plane. Next, droplets issued by the baseline group of spray nozzles were simulated in order to determine the test-section LWC distributions which in turn were used to compare with experiments. The simulations indicated the importance of including turbulent diffusion, and that increased tunnel speed and droplet size tended to reduce overall uniformity, which was generally consistent with experimental results.