Project sponsored by the Austrian Science Foundation FWF 

Project Start: 1995; Project End: 1998

Project Applicants / Contact: Dr. Jakob Woisetschläger, Prof. Dr. Herbert Jericha

Objective: In this project the possible use of underexpanded jets for turbine blade cooling shall be investigated experimentally. Underexpanded jets have a strong tendency to bend towards curved surfaces, so that these films have a high potential even for turbine blade leading edge film cooling. The experiments will be performed at the turbomachinery blade cascade test rig of the institute to see whether this effect results in an improvement in turbine blade film cooling efficiency.

• (MPEG 340KB) Underexpanded cooling jet under operation in a subsonic cascade flow . In this Schlieren visualisation you see a cooling film being ejected slightly below the stagnation point in the turbine blades leading edge area. The main flow is from the right at M=0.6, the pressure in the cooling slot is then increased from zero pressure until supercritical condition, with respect to the total pressure in the main flow. When the pressure ratio reaches the supercritical condition, the cooling film fully attaches to the leading edge surface.
• Visualization of the underexpanded cooling film at the turbine blade leading edge under the influence of superimposed pressure wakes (MPEG 90 KB). In this high speed Schlieren visualiziation (1000 frames per second) the cooling film around the leading edge area is seen, with a subsonic (M=0.6) main flow from below and periodic pressure wakes (20% pressure rise in the main flow) from the lower right (This recording was turned for 90 degree clockwise compared to the previous one).

1. Woisetschläger, J., Jericha, H., Sanz, W., Pirker, H.-P., Seyr, A., Ruckenbauer, T., 1997, "Experimental Investigation of Transonic Wall-Jet Film Cooling in a Linear Cascade", Proc. 2nd European Conference on Turbomachinery - Fluid Dynamics and Thermodynamics, Antwerpen, pp 447-451
2. Woisetschläger, J., Jericha, H., Sanz, W., Gollner, F., 1995, "Optical Investigation of Transonic Wall-Jet Film Cooling", ASME Paper 95-CT-26, ASME Cogen-Turbo Power Conference, Vienna
3. Woisetschläger, J., Pretzler, G., Jericha, H., Mayrhofer, N., Pirker, H.P., "Heterodyne differential interferometry for blade cascade flow investigations", Exp.Fluids, Vol.24, pp 102-109
4. Gehrer, A., Woisetschläger, J., Jericha, H., 1997, "Blade Film Cooling by Underexpanded Transonic Jet Layers", ASME Turbo Expo ´97, June 2-5, Orlando, Florida, paper 97-GT-246
5. Moser, S., Jericha, H., Woisetschläger, Gehrer, A., Reinalter, R., 1998, "Innovative Cooling System for Turbine Blade Cooling", ASME Turbo Expo '98, Stockholm, accepted

Schedule and connection between projects (JPEG 125 kB)