- Paul Pieringer, Arno Gehrer and Wolfgang Sanz, 2001,
"Calculation of the Stator-Rotor Interaction of a Transonic Turbine Stage using an Innovative Unsteady Flow Solver"
(ABSTRACT + PICTURE)
- Gehrer, A. , 2001,
"Simulation of Secondary Flow Development Downstream of a Transonic Turbine Cascade using an Iimplicit TVD Upwind Scheme"
(ABSTRACT + PICTURE)
- Erhard, J., Gehrer, A. , 2000,
"Design and Construction of a Transonic Test-Turbine Facility"
(ABSTRACT)
- Gehrer A., Lang H. , Mayrhofer N. , Woisetschläger J., 2000,
"Numerical and Experimental Investigation of Trailing Edge Vortex Shedding Downstream of a Linear Turbine Cascade "
(ABSTRACT & MPEG-MOVIES !!)
- Gehrer, A., 2000, "Berechnung der Druckverteilung in Radialgleitlagern"
(DOWNLOAD)
- Gehrer, A., Jericha, H., 1999,
"External heat transfer predictions in a highly-loaded
transonic linear turbine guide vane cascade using an upwind
biased Navier-Stokes solver"
(ABSTRACT + PICTURE)
- Gehrer, A., 1999, "Entwicklung eines 3D-Navier-Stokes Codes zur numerischen Berechnung der Turbomaschinenströmung"
(DOWNLOAD)
- Gehrer, A. , 1999, "Code specifications for detailed analysis of cooling flow"
- Gehrer, A., Jericha, H., 1998,
"External heat transfer predictions in a highly-loaded
transonic linear turbine guide vane cascade using an upwind biased Navier-Stokes solver"
(DOWNLOAD)
- Sanz, W., Gehrer, A., Woisetschläger, J., Forstner, M., Artner, W., Jericha, H., 1998
"Numerical and Experimental Investigation of the Wake Flow Downstream of a Linear Turbine Cascade"
(ABSTRACT)
- S.Moser, H.Jericha, J.Woisetschläger, A.Gehrer, W.Reinalter, 1998
"The Influence of Pressure Pulses to an Innovative Turbine Blade Film Cooling System "
- Woisetschläger, J., Mayrhofer, N., Forstner, M., Gehrer, A., Reinalter, W., 1998,
"Velocity measurements in transonic turbomachinery blade cascade flow"
- Gehrer A., Paßrucker H., Jericha H., Lang J., 1997,
"Blade design and Grid-generation for Computational Fluid Dynamics (CFD)
with Bézier-curves and Bézier-surfaces"
(ABSTRACT)
- Gehrer, A., Woisetschläger, J., Jericha, H., 1997,
"Blade Film Cooling by Underexpanded Transonic Jet Layers"
(ABSTRACT)
- Gehrer A., Zettl E., Pöschl R., Jericha H., Pachler, 1996,
"Teilchen bzw. Tröpfchenbahnen bei der Expansion von staubbeladenen bzw. feuchten Gasen in Radiallaufrädern"
- Gehrer, A., Paßrucker, H., 1996,
"Mitteilung zu Forschungsprojekt S6801:
Profilentwurf u. Schaufelkonstruktion von Turbomaschinen mit einer Schnittstelle zur
Rechennetzgenerierung für numerische Strömungsberechnungen "
(DOWNLOAD)
- Gehrer, A., 1996, "Mitteilung zu Forschungsprojekt S6801: Entwicklung eines Programmes zur
Berechnung der Turbomaschinenströmung, inklusive Überschall, Reibung und Turbulenz"
(DOWNLOAD)
- Gehrer, A., 1996, "Mitteilung zu Forschungsprojekt S6801:
Testfälle für die numerische Strömungsberechnung"
(DOWNLOAD)
- Gehrer, A., 1996, "Mitteilung zu Forschungsprojekt S6801: Visualisierung von numerischen Ergebnissen und Meßdaten"
(DOWNLOAD)
- Gehrer, A., 1996, "Mitteilung zu Forschungsprojekt S6801: Erstellung eines Rotor-Dynamik Simulationsprogrammes"
(DOWNLOAD)
- Gehrer, A., 1996, "Mitteilung zu Forschungsprojekt S6801: Erstellung eines Wärmeleitungsprogrammes"
(DOWNLOAD)
- Pöschl, R., Gehrer, A., Jericha, H., 1996, "Mitteilung zu Forschungsprojekt S6807: Auslegung, Konstruktion und Errichtung eines Erosionsprüfstandes"
- Zettl, E., Gehrer, A., Jericha, H., 1996, "Industrieprojekt: Numerische Untersuchungen einer Strömung mit sehr hoher Staubbeladung in einer Düse"
- Sanz, W., Gehrer, A.,Paßrucker, H. 1995, "An Implicit TVD Upwind Relaxation Scheme for the Unsteady 2D-Euler-Equations"
(ABSTRACT)
- Sanz W., Gehrer A., Paßrucker H., Jericha H., 1995, "Entwicklung von Turbomaschinenbeschaufelungen höchsten Wirkungsgrades"
- Gehrer, A., "Numerische Berechnung der Turbomaschinenströmung mit Hilfe eines TVD - Upwind Verfahrens"
(DOWNLOAD)
- Paul Pieringer, Arno Gehrer and Wolfgang Sanz, 2001,
"Calculation of the Stator-Rotor Interaction of a Transonic Turbine Stage using an Innovative Unsteady Flow Solver",
Proc. of the 4th European Conference on Turbomachinery, Firenze, Italy, Paper No. ATI-CST-087/01 (2001)
- ABSTRACT:
The computational investigation of the unsteady inviscid two-dimensional flow through a transonic
turbine stage is presented using an innovative method for solving the Euler equations.
The upwind discretisation of the conservative flow equations is very time- consuming due
to multiple matrix manipulations.
Therefore an unsteady flow solver using the characteristic form of the flow equations
is suggested resulting in simpler discretisation schemes, more obvious stability limits
and an enormous reduction of computer time. The conservative property of the scheme is
only slightly worse compared to a conservative solver.
This innovative flow solver is used to investigate the inviscid flow through a transonic
turbine stage where the shock waves emanating from the stator blade trailing edge are the
source of strong potential flow interactions. During the blade passing period the shock
waves hit the rotor blades at different locations. The shock waves are reflected causing
pressure waves moving back and forth influencing the flow at stator and rotor blades.
Finally, the time-averaged unsteady results are compared with a steady analysis using
circumferentially averaged values at the stator-rotor interface.
Applying non-reflective boundary conditions at the interface leads to a very good agreement
between steady and averaged unsteady results, whereas the "conventional" boundary condition
treatment results in large deviations.
Instantaneous pressure contours
- Gehrer, A. , 2001,
"Simulation of Secondary Flow Development Downstream of a Transonic Turbine Cascade using an Iimplicit TVD Upwind Scheme",
Proc. of the 4th European Conference on Turbomachinery, Firenze, Italy, Paper No. ATI-CST-057/01 (2001)
- ABSTRACT:
A three-dimensional, viscous, compressible flow solver for turbomachinery blade-row
analysis has been used to investigate secondary flow features downstream of a transonic
turbine cascade. The Navier-Stokes code solves the Reynolds-averaged Navier-Stokes
equations with one-equation (Spalart and Allmaras, 1994) turbulence closure by means
of a fully-implicit time-marching finite-volume method.
A series of computations were carried out for a transonic/supersonic turbine cascade
thus permitting an in-depth study into the mechanisms of secondary flow formation and
secondary losses at high Mach numbers.
This 3D cascade-flow was experimentally investigated extensively as described by
Bassi and Perdichizzi (1987) and Perdichizzi (1990) providing detailed experimental
data over a wide range of Mach numbers in several axial planes downstream of the
trailing edge. It was found that secondary losses and secondary flow deviation,
which are fairly constant in incompressible flows with similar geometries underwent
a significant reduction in the compressible flow range. Special emphasis is put on
discussing the accuracy and reliability of the flow solver by comparing computational
and experimental results.
wall stream lines & secondary stream traces in an axial plane downstream of the trailing edge
(click on a picture to enlarge)
- DOWNLOAD : slides, presented at the conference
PDF (4 MB)
- Erhard, J., Gehrer, A. , 2000,
"Design and Construction of a Transonic Test-Turbine Facility",
ASME TURBO EXPO 2000, Munich, paper 2000-GT-0480 (2000)
- ABSTRACT:
This paper describes the design concept and construction of a
continuous operating cold flow transonic test turbine facility,
which is a unique combination of a 2 MW axial test turbine and a
direct coupled brake compressor. To cover the losses additional
air is provided through a separate electrically driven compressor
station and fed into the turbine inlet casing via special mixer
inserts which are also fed by the hot compressed air from the brake
compressor. The main test rig dimensions and its capabilities are
outlined.
A brief description of the design process with step by step advanced
technology design methods is presented from the first ideas up to the
latest plant expansion for special testing conditions where two industrial
transonic turbine stages will be tested. The aerodynamic and structural
design of our transonic single turbine stage (TTM-Stage) is described in
detail and the results of the respective flow simulations are presented.
- Gehrer A., Lang H. , Mayrhofer N. , Woisetschläger J., 2000,
"Numerical and Experimental Investigation of Trailing Edge Vortex Shedding Downstream of a Linear Turbine Cascade " ,
ASME TURBO EXPO 2000, Munich, paper 2000-GT-0434 (2000)
- ABSTRACT:
In this study the evolution of the unsteady trailing edge vortex street
downstream of a linear turbine cascade is experimentally and computationally
investigated. In a transonic cascade test stand Laser Doppler velocimeter
(LDV) measurements are done in several axial planes downstream of the blade
trailing edge. In addition, direct detection of density changes near the
trailing edge provide information about the frequency of a vortex shedding
cycle.
A two-dimensional upwind-biased Navier-Stokes solver has then been used to
perform a series of steady and unsteady cascade simulations, allowing an
in-depth study into the mechanisms of the trailing edge vortex shedding.
The numerical results are compared with the experimental data to test the
quality of the numerical simulations.
- Gehrer, A., 2000,
"Berechnung der Druckverteilung in Radialgleitlagern",
Internal Publication (Vortrag am ITTM, 21.01.2000)
- Gehrer, A., Jericha, H., 1999,
"External heat transfer predictions in a highly-loaded
transonic linear turbine guide vane cascade using an upwind
biased Navier-Stokes solver",
published as ASME - Paper 98-GT-238 and in the ASME Journal of Turbomachinery, Vol. 121, pp. 525-531
- ABSTRACT:
External heat transfer predictions are performed for a two-dimensional
turbine blade cascade. The Reynolds-averaged Navier-Stokes equations
with algebraic (Arnone and Pacciani, 1996), one-equation (Spalart and
Allmaras, 1994) and two-equation (low-Re k-e,
Biswas and Fukuyama, 1994) turbulence closures are solved with a
fully-implicit time-marching finite volume method. Comparisons with
measurements (Arts et al., 1990, 1994) for a highly-loaded transonic
turbine nozzle guide vane cascade show good agreement in some cases,
but also reveal problems with transition prediction and turbulence
modelling. Special attention has been focused on the low-Re
k-e model concerning the influence of the
inlet boundary condition for the e-equation
and problems in the stagnation point region.
- Gehrer, A., 1999
"Entwicklung eines 3D-Navier-Stokes Codes zur numerischen Berechnung der Turbomaschinenströmung"
Dissertation an der Fakultät für Maschinenbau der TU Graz
- ABSTRACT
Subject of this work is the development of a Navier-Stokes solver for computing the three-dimensional,
compressible, viscous and turbulent flow in thermal turbomachines. In the present
work, a time-stepping algorithm, based on a cell-centred finite volume concept is introduced.
The convective (Euler) parts are discretized either using a third-order-accurate, TVD-upwind scheme
or a by applying a central difference method, coupled with a non-linear artificial dissipation model.
In order to construct the numerical viscous flux vector at the cell interfaces, it is necessary to
evaluate first-order derivatives of the dependant variables, which is done in a central-differencing
manner, using Green's theorem.
The governing equations are discretized in time using the Euler implicit method leading to a set of
non-linear finite difference equations which is solved using a Newton procedure. Alternatively the
explicit four stage Runge-Kutta time-stepping scheme is adopted.
In stationary simulations convergence is optimised by using a local time step based on a local
stability criterion. Furthermore, a Multi-Grid procedure is used to accelerate convergence to a steady
state.
The turbulent stresses are calculated using the Boussinesq assumption, which relates the turbulent
stress tensor with the mean strain-rate tensor by an eddy viscosity. The eddy viscosity is modelled
using either an algebraic turbulence model, a one-equation turbulence model or a low-Reynolds-number
k-e model.
In order to discretize the flow region, moving body-fitted Multi-Block grids, which are generated
with an algebraic method, based on Bézier curves and/or a numerical technique, are introduced.
The code is tested on simple benchmark problems (Laval-nozzle, shock-tube, Hobson's blade profile,
vibrating cascade of flat-plates, laminar flat-plate boundary layer) where analytical solutions are
available. The performance of the implemented time-stepping schemes is investigated by computing
the unsteady vortex shedding past a cascade of cylinders.
Several turbulent flow problems (turbulent flat-plate boundary layer, transonic airfoil flows, the
wake flow downstream of a linear turbine cascade, external heat transfer predictions in a highly-loaded
transonic linear turbine guide vane cascade, secondary flow effects in a transonic cascade)
are considered to validate the present solver.
Finally 3D computations, which were carried out during the design of the institute's transonic test
turbine and simulations of underexpanded transonic jet layers, applied to gas turbine blade film
cooling are presented.
- Gehrer, A. , 1999,
"Code specifications for detailed analysis of cooling flow"
, Report on the DITTUS Project, Subtask 1.2 "ANALYTICAL TOOLS SPECIFICATIONS (AERO AND HEAT TRANSFER)", Activity 1.2.2
- Gehrer, A., Jericha, H., 1998,
"External heat transfer predictions in a highly-loaded
transonic linear turbine guide vane cascade using an upwind biased Navier-Stokes solver"
,
ERCOFTAC SEMINAR and WORKSHOP on Turbomachinery Flow Prediction VI, 5th - 8th Jannuary '98,
Contribution to Testcase H1, Nozzle cascade heat transfer
- Sanz, W., Gehrer, A., Woisetschläger, J., Forstner, M., Artner, W., Jericha, H., 1998
"Numerical and Experimental Investigation of the Wake Flow Downstream of a Linear Turbine Cascade"
, ASME-Paper 98-GT-246
-
ABSTRACT:
In turbomachinery the wake flow together with the inherent unsteadiness caused
by interaction between stator and rotor has a significant impact on efficiency
and performance. The prediction of the wake flow depends largely on the turbulence
modeling. Therefore in this study the evolution of a viscous wake downstream of a
linear turbine cascade is experimentally and computationally investigated. In a
transonic cascade test stand Laser Doppler Velocimeter (LDV) measurements of
velocity and turbulent kinetic energy are done in several axial planes downstream
of the blade trailing edge. Two different turbulence models are then incorporated
into a two-dimensional Navier-Stokes solver to calculate the turbulent wake flow
and the results are compared with the experimental data to test the quality of
the turbulence models. The large discrepancies between measurement and calculation
are assumed to be caused by the periodic vortex shedding from the blunt trailing
edge which is not taken into account by the turbulence models. But further research
is needed to resolve this issue.
- Woisetschläger, J., Mayrhofer, N., Forstner, M., Gehrer, A., Reinalter, W., 1998,
"Velocity measurements in transonic turbomachinery blade cascade flow"
- Gehrer A., Paßrucker H., Jericha H., Lang J., 1997
"Blade design and Grid-generation for Computational Fluid Dynamics (CFD)
with Bézier-curves and Bézier-surfaces"
,
European Conference - Antwerpen March ’97, Paper No. 54
-
ABSTRACT:
This study presents systematic methodologies, based on the use of Bézier-curves and
Bézier-surfaces, for the design of turbine blading and for the generation of CFD-grids,
being directly derived from the design data. Two methods for generating two-dimensional
blade profiles represented by Bézier-curves are introduced. First a design process,
using inlet flow angle, outlet flow angle, axial length, chord length, blade pitch and
thickness distribution as input, and secondly, a procedure for representing blade
geometry defined by a series of points in space, are presented. With regards to flow
optimisation, the generation of 2d-grid types (H-type grid, HO-type grid) for CFD,
where orthogonal blade adapted grid lines appear as parameter lines of special
Bézier-patches, is demonstrated. Finally, applications for 3d-bade design and 3d-grid
generation are discussed.
- Gehrer, A., Woisetschläger, J., Jericha, H., 1997
"Blade Film Cooling by Underexpanded Transonic Jet Layers"
, ASME Paper 97-GT-246
-
ABSTRACT:
The evolution of increasing turbine inlet temperature has led to the necessity
of full-coverage film cooling for the first turbine vane and blade. A new approach
using high speed wall jets for blade cooling has been proposed by the authors.
In this paper a 2-D upwind-biased Navier-Stokes code is used to calculate the
aerodynamic behaviour of these surface coolant jets in a linear cascade. Special
emphasis is put on the investigation of the coolant flow around the leading edge.
Various numerical results concerning the leading edge flow are presented in detail,
showing a strong tendency of these jets to bend towards convex surfaces. Finally,
Schlieren pictures taken at the Institute’s transonic cascade on a 140mm chord
length blade are presented for comparison.
- Gehrer, A., Paßrucker, H., 1996
"Mitteilung zu Forschungsprojekt S6801:
Profilentwurf u. Schaufelkonstruktion von Turbomaschinen mit einer Schnittstelle zur
Rechennetzgenerierung für numerische Strömungsberechnungen "
,
Wissenschaftlicher Arbeitsbericht 1995-1996 des Institutes für Thermische Turbomaschinen und Maschinendynamik, Tu-Graz
- Gehrer, A., 1996
"Mitteilung zu Forschungsprojekt S6801: Entwicklung eines Programmes zur
Berechnung der Turbomaschinenströmung, inklusive Überschall, Reibung und Turbulenz"
,
Wissenschaftlicher Arbeitsbericht 1995-1996 des Institutes für Thermische Turbomaschinen und Maschinendynamik, Tu-Graz
- Gehrer, A., 1996
"Mitteilung zu Forschungsprojekt S6801:
Testfälle für die numerische Strömungsberechnung"
,
Wissenschaftlicher Arbeitsbericht 1995-1996 des Institutes für Thermische Turbomaschinen und Maschinendynamik, Tu-Graz
- Gehrer, A., 1996
"Mitteilung zu Forschungsprojekt S6801: Visualisierung von numerischen Ergebnissen und Meßdaten"
,
Wissenschaftlicher Arbeitsbericht 1995-1996 des Institutes für Thermische Turbomaschinen und Maschinendynamik, Tu-Graz
- Gehrer, A., 1996
"Mitteilung zu Forschungsprojekt S6801: Erstellung eines Rotor-Dynamik Simulationsprogrammes"
,
Wissenschaftlicher Arbeitsbericht 1995-1996 des Institutes für Thermische Turbomaschinen und Maschinendynamik, Tu-Graz
- Gehrer, A., 1996
"Mitteilung zu Forschungsprojekt S6801: Erstellung eines Wärmeleitungsprogrammes"
,
Wissenschaftlicher Arbeitsbericht 1995-1996 des Institutes für Thermische Turbomaschinen und Maschinendynamik, Tu-Graz
- Pöschl, R., Gehrer, A., Jericha, H., 1996,
"Mitteilung zu Forschungsprojekt S6807: Auslegung, Konstruktion und Errichtung eines Erosionsprüfstandes"
,
Wissenschaftlicher Arbeitsbericht 1995-1996 des Institutes für Thermische Turbomaschinen und Maschinendynamik, Tu-Graz
- Zettl, E., Gehrer, A., Jericha, H., 1996,
"Industrieprojekt: Numerische Untersuchungen einer Strömung mit sehr hoher Staubbeladung in einer Düse"
,
Wissenschaftlicher Arbeitsbericht 1995-1996 des Institutes für Thermische Turbomaschinen und Maschinendynamik, Tu-Graz
- Sanz, W., Gehrer, A.,Paßrucker, H. 1995
"An Implicit TVD Upwind Relaxation Scheme for the Unsteady 2D-Euler-Equations"
,
ASME Paper 95-CTP-71
-
ABSTRACT:
This study presents a finite-difference, implicit, TVD (Total Variation Diminishing) upwind scheme
based on Roe's approximate Riemann solver for calculating the flow in transonic cascades.
In the present solver, the relaxation is performed with a line Gauß-Seidel technique. To obtain
time-accurate solutions at each time level, inner iterations, so-called Newton iterations, are introduced.
A comparison of this modern scheme is presented with an explicit scheme and an explicit four-stage
Runge-Kutta scheme with regard to obtainable accuracy, maximal CFL number and convergence characteristics.
Finally, the computed results concerning the VKI-1 blade profile are discussed and some experimental data,
to be regarded as initial operation of the institutes cascade test stand, are presented for visual comparison
of the respective flow field.
- Gehrer, A., 1994
"Numerische Berechnung der Turbomaschinenströmung mit Hilfe eines TVD - Upwind Verfahrens"
Diploma Thesis, Institut für Thermische Turbomaschinen und Maschinendynamik, Tu-Graz
Page created 25.02.00 by Arno Gehrer, last update 17:59 03.03.00
,
MOVIES
& ABSTRACS)
MPEG-Movie: Velocity 
MPEG-Movie: Vorticity 
MPEG-Movie: Turbulent Kinetic Energy