Ricerc@Sapienza

We use DNS to analyze the cooling of a heated curved surface due to a cold subsonic impinging jet. The configuration resembles several industrial applications such as impingement cooling in gas turbine blade. The ratio between the distance from the nozzle (H) and the jet diameter (D) is equal to 5. The results in terms of velocity, turbulence and heat transfer are compared with a reference simulation with where a subsonic jet impingesing on a flat surface. The results allowed to assess the influence of the curvature on the velocity and Nusselt number distribution is assessed. Time averaged profiles were shown along two lines passing by through the stagnation point: A is aligned with the direction of concavity, B is perpendicular to A and the normal-to-the wall direction. In particular, we noticed that: a) for r/D<3 and along the A line, Nu value is greater than in the other cases along the (B line and flat plate)the reference case that have similar values ; b) the near wall velocity distribution is similar for A and B lines and wall velocity is always smaller when com-pared with a lower magnitude than the reference case; c) the second peak of Nu, that is generally present in impinging jets (here , that is more reduced to an inflection point due to the large H/D ratio),in this configura-tion, of the Nu number as well as the maximum value of the radial velocity are located further farther down-stream than the stagnation point when compared with the reference case.