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Experimental investigations and numerical modeling with the objective to study the effects that surface discharge plasmas can provoke on aerodynamic flow situations, including high speed flows present in aero-engines, are undertaken at EPFL. The actuator’s potential to influence the flow under realistic flight and engine operating conditions, largely depends on its geometric configuration and the power supply. Initially, a long-life (more than 12 hours) surface discharge actuator was designed at EPFL and pr

Heat transfer measurements are required in a wide range of fields, for example to validate new cooling concepts in turbomachinery, to assess the performances of heat exchangers, and to provide data for numerical simulations. Thereby transient methods are o ...

This investigation centers on the effects of oscillating normal shocks in unsteady flow. Systematic measurements in a turbine model in an annular cascade preceded the detailed investigations. This setup was used to detect the phenomena which cause shock induced flutter. The phenomenon "oscillating shock" was then isolated and investigated in a 2-D nozzle. The objectives of the investigation were the Installation of a system for the excitation of periodic oscillations of a normal shock in a nozzle. Measureme

The stabilizing effect of grouping rotor blades in pairs has been assessed both, numerically and experimentally. The bending and torsion modes of a low aspect ratio high speed turbine cascade tested in the non-rotating test facility at EPFL (Ecole Polytech ...

The prediction of flutter and forced response at normal flow conditions has become a standard procedure during the design of compressor airfoils. But at severe off-design conditions, the flow field becomes very complex, especially during the surge blow-dow ...

Film cooling experiments are commonly performed with Pressure Sensitive Paint (PSP). The oxygen sensitive probe molecules allow for measurement of the adiabatic film cooling effectiveness by detecting the concentration of a tracer-gas with different oxygen content. This is made possible by the analogy between transport of heat and mass. The technique is particularly advantageous when the high density of a cold coolant in gas turbines is simulated by the injection of CO2 into air flow (iso-thermal experiment

Non-synchronous excitation under low volume operation is a major risk to the mechanical integrity of last stage moving blades (LSMBs) in low-pressure (LP) steam turbines. These vibrations are often induced by a rotating aerodynamic instability similar to rotating stall in compressors. Currently extensive validation of new blade designs is required to clarify whether they are subjected to the risk of not admissible blade vibration. Such tests are usually performed at the end of a blade development project. I

Detailed surface measurements of the thermal performance of a film cooling system have been performed on the endwall of a nozzle guide vane (NGV) mounted in a linear cascade facility at EPFL. An external cooling scheme including several rows of fan-shaped ...

Nonsynchronous excitation under low volume operation is a major risk to the mechanical integrity of last stage moving blades (LSMBs) in low-pressure (LP) steam turbines. These vibrations are often induced by a rotating aerodynamic instability similar to ro ...

The present study demonstrates an alternative approach for describing ﬂuid ﬂow characteristics very close to the wall, using locally resolved convective heat transfer experiments. Heat transfer coefﬁcients on the base surface and around a surface mounted v ...

The mean value of turbine entry temperature increased to improve efficiency and specific power. Due to the combustor characteristics, thermal and aero-dynamics non-uniformities can be individuated at the turbine inlet section. Then, a further increase in t ...

The diversification of power generation methods within existing power networks has increased the requirement for operational flexibility of plants employing steam turbines. This has led to the situation where steam turbines may operate at very low volume flow conditions for extended periods of time. Under operating conditions where the volume flow through the last stage moving blades (LSMBs) of a low-pressure (LP) steam turbine falls below a certain limit, energy is returned to the working fluid rather than

Integrally cast turbine airfoils with wall-integrated cooling cavities are greatly applicable in modern turbines providing enhanced heat exchange capabilities compared to conventional cooling passages. In such arrangements, narrow impingement channels can be formed where the generated crossflow is an important design parameter for the achievement of the desired cooling efficiency. In this study, a regulation of the generated crossflow for a narrow impingement channel consisting of a single row of five inlin

This paper demonstrates that the impact of nanosecond pulsed dielectric barrier discharge (ns-DBD) actuators on the structure of the boundary layer can be investigated using quantitative convective heat transfer measurements. For the experiments, the flow ...

Detailed surface measurements of the heat transfer coefficient and the film cooling effectiveness by application of the transient liquid crystal method were carried out on a heavily film cooled nozzle guide vane (NGV) in a linear cascade wind tunnel at the ...

The characterization of non-thermal homogeneous plasmas is possible using optical emission spectroscopy (OES), notably by estimating the reduced electric field. This method was applied to characterize streamers generated by a nanosecond pulsed surface diel ...

The applications of surface dielectric barrier discharge plasma actuators, (DBD), have known a considerable interest recently in the field of flow control. In general, such actuators consist of two electrodes separated by an insulation covering the lower e ...

Peter Ott

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Aero Engine Flow Control by Surface Discharge Plasma

Transient Liquid Crystal Thermography Using a Time Varying Surface Heat Flux

Oszillierender senkrechter Verdichtungsstoss in einer ebenen Düse

Experimental and Numerical Assessment of the Aeroelastic Stability of Blade Pair Packages

Aeroelasticity at Reversed Flow Conditions – Part 1: Numerical and Experimental Investigations of a Compressor Cascade with Controlled Vibration

Heat Transfer Measurements in a Turbine Cascade: Taking Advantage of the Thermal Bahaviour of a PSP Sensor

Unsteady Aerodynamics of Low-Pressure Steam Turbines Operating Under Low Volume Flow

Experimental and Numerical Study of the Thermal Performance of a Film Cooled Turbine Platform

Turbulent scale resolving modelling of rotating stall in low-pressure steam turbines operated under low volume flow conditions

Unsteady Aerodynamics of Low-Pressure Steam Turbines Operating Under Low Volume Flow

A method to visualise near wall fluid flow patterns using locally resolved convective heat transfer experiments

Investigation of High Pressure Turbine End-Wall Film Cooling Performances under Realistic Inlet Conditions

Aerodynamic Excitation of a Model Low-Pressure Steam Turbine Stage Under Low Volume Flow

Numerical and Experimental Investigation of the Aerodynamic Excitation of a Model Low-Pressure Steam Turbine Stage Operating Under Low Volume Flow

Numerical and Experimental Investigation of the Aerodynamic Excitation of a Model Low-Pressure Steam Turbine Stage Operating Under Low Volume Flow

Aerothermal Investigation of a Single Row Divergent Narrow Impingement Channel by Particle Image Velocimetry and Liquid Crystal Thermography

Impact of ns-DBD Plasma Actuation on the Boundary Layer Transition Using Convective Heat Transfer Measurements

Comparison of Numerical Investigations With Measured Heat Transfer Performance of a Film Cooled Turbine Vane

OES Characterization of Steamers in a Nanosecond Pulsed SBDB Using N2 and Ar Transitions

High Voltage Pulsed DBD Effects on the Aerodynamic Performances and on the Shock Buffet