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A computational investigation is carried out to study the flow and heat transfer from a row of circular jets impinging on a concave surface. The computational domain simulates the impingement cooling zone of a gas turbine nozzle guide vane. The parameters which are varied in the study include jet Reynolds number (Re d =5000 to 54000), inter-jet distance to jet diameter ratio (c/d = 3.33 and 4.67) and target plate distance to jet diameter ratio (h/d=1, 3 and 4). The flow field, predicted with K-turbulence model (using Fluent 6.2), is characterized with the presence of a pair of counter rotating vortices, an upwash fountain flow and entrainment. The local pressure coefficient and Nusselt number variations along the concave plate are presented and these values are found to under predict the some available experimental data by about 12%.

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Flow and heat transfer characteristics for single and multiple rows of circular jets impinging on a concave surface are investigated experimentally. The dimensions of the concave target plate, impingement tube, orifice diameter, intra jet spacing are so selected that the present system represents a scaled-up (30:1) model for the leading edge of a typical gas turbine nozzle guide vane. The target plate is kept at a distance of one orifice diameter from the impingement tube, whilst the ratio of inter-jet distance to jet diameter is maintained at a value of 5.4. The parameters which are varied in the study include jet Reynolds number (Red = 2847–19300) and number of rows (nR = 1 and 5).The local dimensionless pressure and Nusselt number variations along the concave plate are presented at these parameters. A performance number named Thermo Hydrodynamic Performance Ratio (THPR) is introduced to evaluate different configurations on the basis of a combined pressure drop and heat transfer. Usage of multiple jets appears to offer much better THPR than that of single jet or single row of jets, for a chosen plenum condition.