Spatial Arrangement Dependance of Cooling Performance of an Integrated Impingement and Pin Fin Cooling Configuration

Abstract

Experimental and numerical studies were conducted for the development of the integrated impingement and pin-fin cooling configuration. In the development, the spatial arrangements of impingement hole, pin-fin and film cooling (discharge) hole were the main concern. The temperature measurement was performed for different test pieces with various spatial arrangements to clarify the cooling effectiveness variation with the arrangement and the other cooling parameters. Experiments were conducted with 673K hot gas flow and room temperature cooling air. The Reynolds number of gas side flow was 380000 and cooling air Reynolds number was 5000–30000. Test plate surface temperatures were measured using an infrared camera. The cooling effectiveness obtained from the experiment for one specimen was different from that for a specimen that had the same pin density but a different spatial arrangement. So it was confirmed that an arrangement of hole and pin, as well as pin density, was an important parameter. CFD analysis was also conducted to make clear how spatial arrangement affected internal heat transfer characteristics. Pressure losses were also evaluated for each specimen, and total thermal performance was compared. A basic configuration with one pin at the center of a unit area showed the most superior total thermal performance.

Extensive Studies on Internal and External Heat Transfer Characteristics of Integrated Impingement Cooling Structures for HP Turbines

“…The mainstream velocity was 9.5 m/s for all test cases. The mainstream Reynolds number based on test plate length L was then 3.8×10 , which matched the Reynolds number in the study of Nakamata et al [8]. No attempt was made to measure the inlet velocity profile close to the target plate.…”

“…Model Structure Figure 5 depicts the two types of the acrylic-resin test models, named STAG and STAG2, respectively. Each of the test models featured almost the same cooling structure as the test piece employed by Nakamata et al [8]. The test models consisted of three parts, i.e., impingement plate with impingement holes, target plate with film holes and pins.…”

“…Nakamata et al [8] conducted extensive studies on the cooling performance of so-called quasi-transpiration cooling devices having different inside cooling structures, which were designed according to the concept of the integrated impingement cooling. They found out that the arrangements of impingement holes and film cooling holes mutually staggered with respect to pins provided better cooling performance than other non-staggered arrangements.…”

Heat Transfer Enhancement for Turbine Blade Internal Cooling

“…An early model of double wall cooling is shown in Figure 8 [78]. Nakamata et al [79] confirmed the use of pins within the impingement cavity of a double wall design enhances heat transfer compared to the baseline case of simple impingement onto the target surface. This conclusion was extended to high density ratio tests for a leading edge, double wall geometry (cylindrical leading edge model) [80].…”

Advances in gas turbine blade cooling technology

“…Examples of the overall cooling effectiveness and the film cooling are shown in Fig. 8 by Nakamata et al [4]. The challenges of this micro cooling include hole plugging, wall strength, film cooling, manufacturing, and cost.…”