Experimental and computational investigation of Reynolds number effect on the longitudinal ventilation in large enclosure of twin inclined jets

An experimental and computational study is presented on ventilated large enclosure using two inclined and impinging jets. Computationally, k-ɛ standard with a wall function treatment “enhanced wall treatment” was used to simulate the flow inside the enclosure. Experimentally, Hot Wire Anemometry and tomography laser are applied to characterize the dynamic field. Measurements have been carried out at Reynolds numbers, Rej = (UjD)/ν (based on the nozzle hydraulic diameter D = 0.044 m, the injection velocity, Uj and the kinematic viscosity of air, ν) ranging from 2 × 103 to 8 × 103. The effect of Reynolds number on the flow field and on the installation efficiency for various pitch angles and enclosure heights has been investigated. The obtained results show that the Reynolds number affects various flow properties such as the velocity decay rate, the jet spreading rate and the turbulence intensity. Analysis proved that there exists a critical value of Reynolds number (Rejc). Under this value the induction coefficient, η = Qi/Qj (where Qi is the induced flow and Qj is the injected flow) increases with increasing Reynolds number. Beyond this value the jet reaches a convergence state. Results show also that the critical Reynolds number value decreases with increasing pitch angle of the jets.