Turbomachinery Aerodynamics and Heat Transfer

The research is both experimental and numerical and can be related to the different, more permanent test rigs that are re-equipped depending on the type of research performed. Aerodynamic turbine performance and stator-rotor cavity purge studies evolves around the rotating test turbine in the HPT laboratory. Cavity acoustics in the versatile transonic wind tunnel VM100. Film cooling investigations in the transonic annular sector cascade and conjugate heat transfer in rocket nozzle cooling channels at the MERiT facility.

More about the different test rigs and their capabilities can be seen . The research performed in the research group is applied, often in collaboration with European companies and other universities and spans from TRL 1 to 5, typically. Program funded as well as commissioned research are performed.

There are complex fluid phenomena involved in the stator-rotor cavity flow and its interaction with the annulus flow, driven by the potential fields in the main annulus and pumping in the cavity, unsteady in nature and that may couple to acoustic phenomena. The purge flows in gas turbines are vital to protect the turbine discs from hot gas ingestion that eventually lead to turbine failure. The research is oriented towards developing the cavity and seal designs based on high quality test data at engine representative conditions that serves to validate and develop correlations and computational codes, and to gain experience to support the science.

Acoustic resonance in cavities in aero engines is a current and major concern due to the detrimental effect the unsteady loads have on the nearby components in the engine. An example is the bleed system resonance in the intermediate compressor duct that may cause failure to the low-pressure compressor. So-called Rossiter resonance may occur due to an interaction between the radiating cavity acoustic resonance frequency and any dominant boundary layer vortex frequency from passing over the cavity.The research aim is to systematically experimentally quantify the coupled resonance occurring due to interaction between vortex oscillations from the boundary layer/shear layer flow passing over a cavity and the acoustic cavity. This targeted to provide validation data for in-house acoustic codes at industry in order to strengthen design prediction capabilities.

Protecting hot gas turbine parts like the first nozzle guide vane (NGV) by cooling is essential for enginge functionality and to prevent material failure. The research is focused on the external film cooling of NGVs and mostly the aerodynamic implications it has on component performance. Studies on reduced vane count and cooling row superposition are conducted, in engine realistic velocities.

Quantitative information on the heat transfer characteristics for nickel-alloy steels under influence of hydrocarbon fuels at high pressure and temperature, as for the cooling of rocket nozzles, is to a high degree unavailable in the open literature. The research aims, for different relevant nickel-alloys and typical channel geometries, hydrocarbon fuels and operating conditions to experimentally determine the heat transfer coefficient (HTC), degree of coking and corrosion in the cooling channel, pressure loss as a function of supplied heat load, wall temperature, Reynolds number, fuel composition and pressure level.