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Alexandros Terzis

Cette personne a quitté l’EPFL

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Publications associées (27)

Page 1 sur 2

Transient Liquid Crystal Thermography Using a Time Varying Surface Heat Flux

Peter Ott, Alexandros Terzis, Michele Gaffuri

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 ...

2021

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

Peter Ott, Bernhard Weigand, Alexandros Terzis

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 ...

Elsevier2015

Detailed heat transfer distributions of narrow impingement channels for cast-in turbine airfoils

Alexandros Terzis

Gas turbine operation at elevated temperatures ensures increased thermal efficiency and useful power output. However, the industrial tendency to push further firing temperatures is limited by the capabilities of the current turbine blade cooling technologi ...

2014

Effects of Swirl Velocities From Fan Assemblies Mounted on Lifting Surfaces

Alexandros Terzis, Charilaos Kazakos

The penetration of a jet of fluid into a traversal moving stream is a basic configuration of a wide range of engineering applications, such as film cooling and V/STOL aircrafts. This investigation examines experimentally the effect of blowing ratio of fans ...

2011

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

Peter Ott, Bernhard Weigand, Alexandros Terzis, Philip Peschke

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 ...

Iop Publishing Ltd2015

Influence of Thermocouple Thermal Inertia in Impingement Heat Transfer Experiments Using Transient Techniques

Peter Ott, Alexandros Terzis, Bernhard Weigand, Guillaume Wagner

A typical transient heat transfer experiment for an impingement cooling configuration requires usually a temperature step in the flow. A moving isotherm of the liquid crystal surface coating is then monitored using a video camera. However, for small imping ...

2012

Detailed Heat Transfer Distributions of Narrow Impingement Channels for Cast-In Turbine Airfoils

Peter Ott, Bernhard Weigand, Alexandros Terzis

The current capabilities of the foundry industry allow the production of integrally cast turbine airfoils. Impingement cooling effectiveness can be then further increased due to the manufacturing feasibility of narrow impingement cavities in a double-wall ...

American Society of Mechanical Engineers2014

A Comparative Study of the Local Heat Transfer Distributions Around Various Surface Mounted Obstacles

Robert Wyssmann, Peter Ott, Alexandros Terzis

In many engineering applications, heat transfer enhancement techniques are of vital importance in order to ensure reliable thermal designs of convective heat transfer applications. This study examines experimentally the heat transfer characteristics on the ...

Science Press2014

Evaluation of Heat Transfer Coefficients for an Impingement Cooling Cascade: Experimental Challenges and Preliminary Results

Peter Ott, Alexandros Terzis, Michele Gaffuri

In this paper, a modification of the widely used transient liquid crystal heat transfer measurement technique for impingement cooling is presented, in which a constant heat flux at the surface is used to drive the experiment, instead of a step change in th ...

2018

Effect of Stators on the Performance and the Thermal Capabilities of Small Axial Cooling Fans

Peter Ott, Alexandros Terzis

This investigation examines experimentally the effect of stators on the performance curves and the heat transfer capabilities of small axial cooling fans. The experimental data indicated that the results are highly affected by the flow conditions at the fa ...

2011

Detailed Heat Transfer Distributions of Narrow Impingement Channels with Varying Jet Diameter

Peter Ott, Bernhard Weigand, Alexandros Terzis

The development of integrally cast turbine airfoils allows the production of narrow impingement channels in a double-wall configuration, where the coolant is practically injected within the wall of the airfoil providing increased heat transfer capabilities ...

ASME2014

Heat Transfer and Performance Characteristics of Axial Cooling Fans with Downstream Guide Vanes

Peter Ott, Alexandros Terzis

This study examines experimentally the effect of stators on the performance and heat transfer characteristics of small axial cooling fans. A single fan impeller, followed by nine stator blades in the case of a complete stage, was used for all the experimen ...

2012

Experimental and Numerical Investigation of a Fully Confined Impingement Round Jet

Gabriel Charles Gnaegi, Peter Ott, Alexandros Terzis

The heat transfer characteristics of a fully confined impingement jet are experimentally and numerically evaluated. Full surface heat transfer coefficient distributions are obtained for the target and impingement plate of the model using the transient liqu ...

Pergamon-Elsevier Science Ltd2013

On the Effects of Coating Thickness in Transient Heat Transfer Experiments Using Thermochromic Liquid Crystals

Peter Ott, Alexandros Terzis

Transient heat transfer experiments typically employ thermochromic liquid crystals to temporally map surface temperatures. The desired heat transfer coefficient is then calculated from the solution of Fourier’s 1D transient heat conduction equation which i ...

Elsevier2016

On the Applicability of Oil and Dye Technique During the Design Phase and Operation of Experimental Rigs

Alexandros Terzis

In this paper, an oil and dye flow visualization technique applied in two different cases of experimental testing is described, namely a single fan in crossflow and the wake of a compressor cascade. In both cases, the mixture of paint was prepared using a ...

2011

Swirl Jets in Crossflow at Low Velocity Ratios

Charilaos Kazakos, Peter Ott, Alexandros Terzis

This investigation examines experimentally the behavior of swirled jets produced by axial flow fans blowing into a crossflow at low velocity ratios. The main difference with non-swirl cases is an asymmetry of the dominant kidney vortex and a slight distort ...

2012

Narrow Impingement Channels: Recent Advancements and Future Directions

Peter Ott, Alexandros Terzis, Michele Gaffuri

This paper summarizes the state-of-the-art related to the heat transfer characteristics of narrow impingement cooling channels, which can nowadays be integrated within the external wall of turbine airfoils. Particular emphasis is given to the experimental ...

European Turbomachinery Society2019

Heat Transfer Characteristics of High Crossflow Impingement Channels: Effect of Number of Holes

Peter Ott, Alexandros Terzis

In modern turbine airfoils, narrow impingement cooling channels can be formed in a double-wall configuration. In these wall-integrated cooling cavities, the generated crossflow is one of the most important design factors, and hence, the number of impingeme ...

Sage Publications Ltd2015

Thermocouple Thermal Inertia Effects on Impingement Heat Transfer Experiments Using the Transient Liquid Crystal Technique

Peter Ott, Alexandros Terzis, Bernhard Weigand

The transient liquid crystal technique is widely used for impingement heat transfer experiments. Additionally, due to the difficulty of producing pure temperature steps in the flow, many authors assumed the fluid temperature evolution as a series of step c ...

IOP Publishing2012

Detailed heat transfer distributions of narrow impingement channels for integrally cast turbine airfoils

Alexandros Terzis

EPFL2014