Development of Turbulent Quantities Inside an Axial Turbine Vane

Abstract

The paper presents experimental and numerical investigations of the three components of turbulent kinetic energy and its development upstream and downstream of the first vane of 1.5 stage axial flow turbine. The experimental data has been recorded using a miniature hot wire probe, equipped with three 9µm platinized tungsten wires, allowing the determination of the kinetic energy in all three spatial directions. By means of turbulent grids, a total of three different inlet turbulence levels, varying from 0.4 to 4.5%, was created. Extensive field traverses up- and downstream of the first stator have been conducted, covering more than one stator pitch and including both the free stream and the wake. For one inlet condition, a total of three axial positions between the stator and the rotor have been measured to evaluate the development of the composition of the turbulence. The type of turbulence is visualized by making use of the barycentric color map. Detailed investigations of all three fluctuation components reveal that, depending on the anisotropy level and the distribution of energy along the three spatial directions at the stator’s inlet, the velocity gradients within the first stator either promote a production or destruction of turbulent kinetic energy. As a consequence, the distribution of turbulent energy along the three spatial directions is at the stator’s outlet almost identical for the three configurations. Finally, the measurements with focus on the turbulence composition are compared to unsteady CFD simulations using, the, in industrial application, most commonly applied k-w turbulence model. In addition, an Explicit Algebraic Reynolds Stress Model (EARSM) is also applied and compared to numerical and experimental data. However, the paper is focused on the interpretation of the experimental data.