Design and development of low-speed water tunnel

Abstract

The water tunnel is an essential exploratory office utilized for examining the hydrodynamic behavior of submerged bodies in the flow of water. Its use in checking the behavior over various structures and analyzing the boundary layer process (i.e. separation of flow, shedding of vortex etc.) makes it more useful over other counterpart facilities. The principle of operation of the water tunnel resembles the wind tunnel but in the wind tunnel, air is used as working fluid instead of water. Water tunnel has higher capacity for pumping of flow than wind tunnel. In water tunnel, visualization of flow is easier than wind tunnel due to higher viscosity of water and various kinds of techniques for visualization can be used. This paper discusses the design, fabrication, and analysis of low-speed water tunnel that was assembled as a part of this research. The water tunnel has dimensions of WHL 2×1.5×8 meters with a capacity of 2000 gallons and weight 500 kg without water. Material used for the tunnel is aluminum with a thickness of 3mm, which has suitable strength against hydrostatic forces. Aluminum is corrosion resistant in case of water. Various parts, their uses, and different changes that require to be made during their design are discussed. The test section dimensions were taken as WHL: 0.4 × 0.5 × 2 m with the flow velocity range of 0–0.5 m/sec. Contraction ratio of 5 is used and L/D ratio is taken as 1.16 for the contraction chamber. The pump used for water circulation is centrifugal type with specifications of 10 hp and 1100 GPM. The purpose of the water tunnel is to obtain uniform and steady speed of flow in the test section. This tunnel is well suited for Particle Image Velocimetry (PIV). The water tunnel developed will be utilized to conduct the low Reynolds number experimentation for different objects. The water tunnel can also be utilized for the purpose of education such as fluid mechanics lab activity to learn about different topics taught in the class.