Flow characteristics due to jet impact at low swirl intensity
School of Engineering
In this paper, an incompressible turbulent air jet which impacts on a flat plate is investigated, both experimentally and numerically. The aim is to study the sensitivity of wall shear stresses and the pressure distribution, at the impacting surface, in both non-swirling and low swirl intensities that do not induce vortex breakdown. A three-channel hotwire anemometer system is used to measure threedimensional time-mean velocity components and turbulent intensities at the nozzle exit plane. Pressure measurements are carried out via flush-mounted pressure taps on the impacting surface. The Reynolds-Averaged Navier Stokes (RANS) approach with RNG k-ε model is used for numerical simulations, with the methodology validated against an experimental data set. The investigations are performed for non-swirling (S=0) and low swirling (S=0.09) cases in the near-field (H=2D) at Re=35,000. Results show the impingement pressure is sensitive to even low values of swirl whereby it reduces at the stagnation point, but the surface static pressure increases at the outer parts of the impacting region. The wall shear stresses are also found to reduce at the surface at low swirl.