The Effect of Initial Cross Flow on the Cooling Performance of a Narrow Impingement Channel

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Impingement channels are often used in turbine blade cooling configurations. This paper examines the heat transfer performance of a typical integrally cast impingement channel. Detailed heat transfer coefficient distributions on all heat transfer surfaces were obtained in a series of low temperature experiments carried out in a large-scale model of a turbine cooling system using liquid crystal techniques. All experiments were performed on a model of a 19-hole, low aspect ratio impingement channel. The effect of flow introduced at the inlet to the channel on the impingement heat transfer within the channel was investigated. A novel test technique has been applied to determine the effect of the initial cross flow on jet penetration. The experiments were performed at an engine representative Reynolds number of 20,000 and examined the effect of additional initial cross flow up to 10 percent of the total mass flow. It was shown that initial cross flow strongly influenced the heat transfer performance with just 10 percent initial cross flow able to reduce the mean target plate jet effectiveness by 57 percent.