American Journal of Aerospace Engineering 2015; 2(1-1): 31-37 Published online October 07, 2014 (http://www.sciencepublishinggroup.com/j/ajae) doi: 10.11648/j.ajae.s.2015020101.13 Design of mini wind tunnel based on coanda effect Yassen El-Sayed Yassen, Ahmed Sharaf Abdelhamed Mechanical Power Engineering, Faculty of Engineering, Port Said University, Port Said, Egypt Email address: y_yassen70 @yahoo.com (Y. El-S. Yassen), sh_ahmed99@yahoo.com (A. S. Abdelhamed) To cite this article: Yassen El-Sayed Yassen, Ahmed Sharaf Abdelhamed. Design of Mini Wind Tunnel Based on Coanda Effect. American Journal of Aerospace Engineering. Special Issue: Hands-on Learning Technique for Multidisciplinary Engineering Education. Vol. 2, No. 1-1, 2015, pp. 31-37. doi: 10.11648/j.ajae.s.2015020101.13 Abstract: An experimental investigation and CFD treatment were employed to design mini-wind tunnel based on Coanda effect for model tests and basic research. The inlet source flow is efficiently creating smooth steady airflow with acceptable noise, achieving the possibility of placing the test target closer to the source of flow with reasonable estimates of turbulence intensity. The design aims at achieving flow uniformity in the working section midplane, preventing separation in the contraction and minimizing the boundary–layer thickness. Intensive measurements after construction demonstrate the significance of the design process and validate the CFD predictions. The results are represented in graphic form to indicate the aspects of the contraction ratio. The numerical and experimental results show the uniformity of velocity distribution inside the working section. Tracing of separation and backflow is crucial allowing a variety of realistic demonstrations to be performed. The numerical solution provides a powerful tool to demonstrate the rate of boundary–layer growth inside the working section and validate against the empirical correlations with insignificant wall–friction drag. Assessment study to address large–scale wind tunnel based on coanda effect would be considered. Keywords: Separation, CFD, Coanda Effect, Mini–Wind–Tunnel, Boundary–Layer Growth 1. Introduction A conventional wind-tunnel design is a complex field involving many fluid mechanics and engineering aspects. The first attempt in providing some guidelines for the complete design of low-speed wind tunnels was that due to [1]. However, recent experimental studies of flow through individual components of a wind tunnel [2–4] have led to increase understanding and design philosophy for most of the components of wind tunnel. More theoretical and experimental investigations have been written about this topic and e.g. [5–8] are useful references when designing and constructing conventional low-speed wind-tunnels. Typically, the air is moved through conventional tunnel using a fan or blower. The airflow created by the fan entering the tunnel is itself highly turbulent due to the fan blade's motion. The air moving through the tunnel needs to be relatively turbulence-free [9]. Therefore, the overall length of the tunnel increases to smooth out the turbulent airflow before reaching the subject of the testing. This design is less than ideal for a wind tunnel but it is still the prevalent design. In the present study, both of computational treatment based on RNG turbulence model and experimental measurements are implemented to design an unconventional wind-tunnel (mini-wind tunnel) based on Coanda effect for model tests and laboratory teaching purpose. The inlet source flow is efficiently creating smooth steady airflow with acceptable noise, achieving the possibility of placing the test target closer to the source of flow with reasonable estimates of turbulence intensity. The design aims at achieving the flow uniformity in the working section midplane, without separation in the contraction and minimizing the boundary–layer thickness at entrance to the working section. Calibration of the proposed mini wind tunnel after construction is carried out. The boundary–layer growth inside the working section is determined using the empirical correlations and validated against the numerical results. Wall–friction drag is estimated. Both of CFD predictions and experimental results are validated against the uniformity of velocity distribution inside the working section. Also, tracing of separation and backflow through the tunnel is carried out for different values of contraction ratios. The overall length of mini wind tunnel is 160 cm with contraction ratio of 2.82 and the cross–sectional area of test section is 19×19 cm 2 with length 50 cm.