ABSTRAKT

The present contribution gives an overview of the numerical work performed at the Von Kármán Institute in the framework of the European research program AITEB-2, concerning the numerical investigation of tip gap flows in linear turbomachinery cascades, representatives of high-pressure turbine rotor blade geometries. The primary goal of the project is the simulation of flow and heat transfer on four distinct blade tip geometries in 3D, including the entire internal cooling setup inside a blade, the validation of the results versus the experimental campaign of Hofer et al. [1] and evaluation of the geometries. The paper presents the computations performed on the first tip geometry (TG1 hereinafter) with recessed tip. The geometry and the numerical setup are described in detail, with emphasis on the grid generation and connection method between internal and external flows. Validation is introduced on the most delicate, zero cooling flow case, in which internal flow in the cooling channels is driven exclusively by pressure difference between pressure side tip region and tip gap. The comparison with experiments is performed for one exit Reynolds number (Re = 900,000), and two exit Mach numbers; M = 0.8 (HRLM) and M = 1.1 (HRHM). Flow visualization is performed and set against experimental oil flow visualization; the basic features of the flow topology are analyzed. Typical results of from heat transfer simulations are shown in both test cases.