Development of novel low-speed open jet wind tunnel equipped with plenum chamber for testing of aero-rotors

Conventional blower-type open-circuit open-jet wind tunnels use a blower, wide-angle diffuser, settling chamber, screens, honeycomb, contracting nozzle, test section, and exit diffuser to develop a uniform, plug shaped velocity profile, inside the test-section. In the current study, a hypothetical design of a low-cost and simple wind tunnel has been proposed to produce similar flow characteristics but by using fewer components viz. blower, inlet duct, plenum chamber, test section, and collector, which is the novelty of the current design. The basis of the hypothesis is to obtain fully developed flow at the exit of the duct, produce moving belt-type lid-driven cavity flow inside the plenum chamber, create a low-speed movable membrane at the boundary of the main jet, and cessation of free jet expansion to a significant amount inside test section. The new design is validated through numerical and experimental results as well as mathematical modelling. The values of the ratio of standard deviation and average of normalized velocity are found in the range of 10−2 for a 50% blockage cross-section. Curve fitting of velocity values with plug profile equation showed a close resemblance. Experiments are performed on Savonius rotor inside the modified tunnel and compared with classic results obtained with a conventional tunnel. The RMS error between both results is contained in the range of 10−1 to 10−2. All validations proved the aptness of the new innovative tunnel for low-speed testing. The presented wind tunnel design is the first of its kind and generates the flow with the desired characteristics.