Purge flow and interface gap geometry influence on the aero-thermal performance of a rotor blade cascade

• Published in: The International journal of heat and fluid flow 2013-12, Vol.44, p.563-575
• Main Authors: Barigozzi, Giovanna, Franchini, Giuseppe, Perdichizzi, Antonio, Maritano, Massimiliano, Abram, Roberto
• Format: Article
• Language: English
• Subjects: Adiabatic effectiveness; Applied sciences; Blowing; Cascades; Energy; Energy. Thermal use of fuels; Engines and turbines; Equipments for energy generation and conversion: thermal, electrical, mechanical energy, etc; Exact sciences and technology; Film cooling; Fluid dynamics; Fundamental areas of phenomenology (including applications); Instrumentation for fluid dynamics; Physics; Platforms; Purge flow; Rotor blades; Rotors; Seals; Secondary flows; Three dimensional; Wind tunnels
• ISSN: 0142-727X; 1879-2278
• DOI: 10.1016/j.ijheatfluidflow.2013.08.012

•Stator–rotor gap geometry influence has been documented aerodynamically and thermally.•Loss and film cooling effectiveness progressively increase with rising MFR.•A gap width increase marginally affects losses and film cooling effectiveness.•A radial misalignment allows a better distribution of coolant in the tangential direction.•Coolant injection angle is an important parameter, influencing aero and thermal performance. This paper is focused on the influence of the geometry of an interface seal gap on the aerodynamic and thermal performance of a rotor blade cascade. Tests are performed in a seven-blade cascade of a gas turbine high-pressure subsonic rotor at low Mach number (Ma2is=0.3). To simulate some of the effects of rotation on the seal flow exiting the gap on a linear cascade environment, a number of fins are installed inside the slot, providing the coolant flow with an injection angle in the tangential direction. Tests are carried out at variable blowing conditions and different gap widths. Moreover, the influence of a radial misalignment between stator and rotor platforms is also investigated for variable injection conditions. The 3D flow field is surveyed by traversing a 5-hole miniaturized pressure probe in a downstream plane. Secondary flows velocities, loss coefficient and vorticity distributions are presented for the most relevant test conditions. Film cooling effectiveness distributions on the platform are obtained by Thermochromic Liquid Crystals technique. Results show that engine purge flow injection conditions have to be reproduced in the wind tunnel as close as possible, in order to get the correct blade aero-thermal performance.