Study on Advanced Internal Cooling Technologies for the Development of Next-Generation Small-Class Aircraft Engines

An innovative internal cooling structure named multislot cooling has been invented for high-pressure turbine (HPT) nozzles and blades. This cooling structure has been designed to be simple and inexpensive and to exhibit good cooling performance. In order to confirm the cooling performance of this structure, test pieces of dummy turbine nozzles were manufactured. Three geometric parameters (width of slots, overall height of cooling channel, and height of jet impingement) are associated with these test pieces. The cooling performance tests were conducted by using these test pieces for several Reynolds numbers of the mainstream hot gas $[2.2×105–3.4×105]$ and cooling airflow $[3×103–1×104]$⁠. Infrared images of the heated surfaces of the test pieces were captured for every Reynolds number in the tests, and then the distributions of the cooling effectiveness were obtained. Simultaneously, the pressure losses were measured. This paper describes the hot gas flow tests performed to confirm the effects of the geometric parameters on the cooling performance and pressure loss, and to obtain data of Nusselt number and pressure loss coefficient for the design of turbine nozzles in the future by applying this new cooling structure to next-generation small-class aircraft engines. Additionally a preliminary analysis of airfoil cooling was performed to evaluate both cooling performance of conventional impingement cooling and multislot cooling when applied to a HPT nozzle. As a result it was found that the multislot cooling is well applicable to cooling of HPT airfoils.