دانلود رایگان مقاله مدلی برای پیش بینی خط سیر قطره آب در جریان گذشته ایرفویل

Abstract

A theoretical model is presented to predict water droplet trajectories in the flow past an airfoil. The model considers droplet deformation and includes a drag coefficient that accounts for the influence of flow acceleration. This is because, as seen from the reference frame of the droplet, the flow accelerates as the airfoil approaches, even if the airfoil moves at constant velocity. To validate the theoretical model, a series of experimental tests have been carried out in a rotating arm facility. Three parameters were changed in the experiments: 1) the size of the model airfoil (radius of curvature 0.103 m, 0.070 m, and 0.030 m), 2) its velocity (50 m/s, 60 m/s, 70 m/s, 80 m/s, and 90 m/s), and 3) the droplets' initial diameters (in the range from 550 μm to 1050 μm). Comparison between the results obtained using the theoretical model and those collected in the experimental tests (droplet tracking was carried out using a high speed imaging system) showed a good agreement. This suggests that, within the range of parameters that has been tested, the proposed theoretical model could be confidently used for trajectory prediction purposes.

5. Conclusions

A theoretical model has been presented that predicts droplet trajectory and deformation in the vicinity of an incoming airfoil. The model is of interest both to gain a better understanding of droplet trajectories in some flows of aeronautics interest, and to provide an alternate formulation to researchers that develop numerical flow solvers in the field of icing conditions simulations. The model has been tested and calibrated using a series of dedicated experimental tests in a rotating arm facility. The novelty of the study consists on the fact that it accounts for the actual flow acceleration profile that the droplet senses as the airfoil closes on it. This is in contrast to other more basic-physics oriented studies in which shock tube type acceleration profiles are considered. The conclusions that have been obtained are, basically, two.