Marc Gugau

BorgWarner (Germany)

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Harald Roclawski

University of Kaiserslautern

Martin Böhle

Rheinland-Pfälzische Technische Universität Kaiserslautern-Landau

Tom Heuer

BorgWarner (Germany)

Amir Rohi

Kirchhoff (Germany)

Ralf Christmann

BorgWarner (Germany)

Jan F. Suhrmann

Rolls-Royce (Germany)

Dieter Peitsch

Technische Universität Berlin

Sascha Weiske

BorgWarner (Germany)

K. Shoghi

BorgWarner (United Kingdom)

Alberto Tamm

Technical University of Darmstadt

Cooperative Institutions

BorgWarner (Germany)

University of Kaiserslautern

BorgWarner (Brazil)

Technical University of Darmstadt

Daimler (Germany)

Kirchhoff (Germany)

Deutsches Zentrum für Luft- und Raumfahrt e. V. (DLR)

RWTH Aachen University

Rolls-Royce (Germany)

Technische Universität Berlin

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Kugelgelagerte VTG-Turbolader für Ottomotoren

MTZ - Motortechnische Zeitschrift (2019)

Ralf Christmann Amir Rohi Sascha Weiske Marc Gugau

10.1007/s35146-019-0105-3

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Citations (1)

On the Design and Matching of Turbocharger Single Scroll Turbines for Pass Car Gasoline Engines

Journal of Engineering for Gas Turbines and Power (2014)

Marc Gugau Harald Roclawski

With emission legislation becoming more stringent within the next years, almost all future internal combustion gasoline engines need to reduce specific fuel consumption, most of them by using turbochargers. Additionally, car manufactures attach high importance to a good drivability, which usually is being quantified as a target torque already available at low engine speeds—reached in transient response operation as fast as possible. These engine requirements result in a challenging turbocharger compressor and turbine design task, since for both not one single operating point needs to be aerodynamically optimized but the components have to provide for the optimum overall compromise for maximum thermodynamic performance. The component design targets are closely related and actually controlled by the matching procedure that fits turbine and compressor to the engine. Inaccuracies in matching a turbine to the engine full load are largely due to the pulsating engine flow characteristic and arise from the necessity of arbitrary turbine map extrapolation toward low turbine blade speed ratios and the deficient estimation of turbine efficiency for low engine speed operating points. This paper addresses the above described standard problems, presenting a methodology that covers almost all aspects of thermodynamic turbine design based on a comparison of radial and mixed-flow turbines. Wheel geometry definition with respect to contrary design objectives is done using computational fluid dynamics (CFD), finite element analysis (FEA), and optimization software. Parametrical turbine models, composed of wheel, volute, and standard piping allow for fast map calculation similar to steady hot gas tests but covering the complete range of engine pulsating mass flow. These extended turbine maps are then used for a particular assessment of turbine power output under unsteady flow admission resulting in an improved steady-state matching quality. Additionally, the effect of various design parameters like either volute sizing or the choice of compressor to turbine diameter ratio on turbine blade speed ratio operating range as well as well as turbine inertia effect is analyzed. Finally, this method enables the designer to comparatively evaluate the ability of a turbine design to accelerate the turbocharger speed for transient engine response while still offering a map characteristic that keeps fuel consumption low at all engine speeds.

Operating point

10.1115/1.4027710

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Citations (9)

New Modular Test Rig for Unsteady Performance Assessment of Automotive Turbocharger Turbines

Volume 8: Microturbines, Turbochargers and Small Turbomachines; Steam Turbines (2017)

Paul Lyttek Harald Roclawski Martin Böhle Marc Gugau

Standard test rigs for basic research on turbochargers usually do not provide the capability of periodically changing, instantaneous process values, which are characteristic for the real application of these turbines. The challenge of testing the performance potential of turbocharger turbines under pulsating inflow conditions is mainly originated by the complex compatibility of two main issues that need to be implemented at a test facility: Firstly, a special device is required that reproducibly provides real engine-like exhaust gas pulsations with some variability representing different engine operating conditions. Secondly, appropriate real time measurement techniques for all significant transient values are required to measure both, instantaneous turbine inflow conditions and turbine power output. This paper presents a new developed test rig that enables a preferably high overlap between the above mentioned supply of approximately real engine exhaust gas conditions and the fundamental and scientifically based attempt of unsteady gas flow examinations.

Inflow

Jet engine

10.1115/gt2017-64218

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Citations (3)

Influence of Degree of Reaction on Turbine Performance for Pulsating Flow Conditions

Harald Roclawski Marc Gugau Florian Langecker Martin Böhle

This paper presents a study on the influence of the degree of reaction (DoR) on turbine performance under highly pulsating inflow. A reference test turbine wheel is designed and scaled to three different wheel diameters while an identical flow capacity of all three turbines is provided by adjusting the volute size. Hence, the three turbines differ by their DoR, inertia and efficiency characteristic. The investigation is done completely numerically using highly validated models. Naturally, the pulsating flow character of a 4-cylinder gasoline engine requires unsteady CFD. In addition steady-state turbine maps were calculated beforehand as a reference base. The results of the steady state calculation show that for the combination of the bigger turbine wheel with the smaller turbine volute the peak efficiency is smaller but is shifted towards higher pressure ratios respectively to lower blade speed ratios. This is fundamentally beneficial for turbines in automotive turbochargers for gasoline engines characterized by highly pulsating flow conditions, in particular at lower engine speeds. For the transient flow calculations with pulsating turbine inflow, the hysteresis loop and the turbine power generation was investigated. It is shown that the smallest volute compared to the biggest one causes a more contracted hysteresis loop combined with increased power output within one pulse cycle. In order to include the influence of moment of inertia, the turbines with varying DoR but same flow capacity were analytically compared with a 1D code simulating engine load step operation. Thus, the paper shows the effect of turbine DoR on both, steady-state turbine performance under pulsating inflow and the capability for optimum engine load step operation.

Volute

Inflow

10.1115/gt2014-25829

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Citations (11)

CFD Analysis of a Radial Turbine during Load Step Operation of an Automotive Turbocharger

Harald Roclawski Marc Gugau Martin Böhle

Source

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Citations (0)

On the Design and Matching of Turbocharger Turbines for Pass Car Gasoline Engines

Marc Gugau Harald Roclawski

With emission legislation becoming more stringent within the next years, almost all future internal combustion gasoline engines need to reduce specific fuel consumption, most of them by using turbochargers. Additionally, car manufactures attach high importance to a good drivability, which usually is being quantified as a target torque already available at low engine speeds that is fast reached in transient response operation. These engine requirements result in a challenging turbocharger compressor and turbine design task, since for both not one single operating point needs to be aerodynamically optimized but the components have to provide for the optimum overall compromise for maximum thermodynamic performance. The component design targets are closely related and actually controlled by the matching procedure that fits turbine and compressor to the engine. Inaccuracies in matching a turbine to the engine full load are largely due to the pulsating engine flow characteristic and arise from the necessity of arbitrary map extrapolation to low turbine blade speed ratios and the estimation of turbine efficiency for low engine speeds. This paper addresses the above described standard problems, presenting a methodology that covers almost all aspects of thermodynamic turbine design based on a comparison of radial and mixed flow turbines. Wheel geometry definition with respect to contrary design objectives is done using CFD, FEA and optimization software. Parametrical turbine models, composed of wheel, volute and standard piping allow for fast map calculation similar to steady hot gas tests but covering the complete range of engine pulsating mass flow. These extended turbine maps are then used for a particular assessment of turbine power output under unsteady flow admission resulting in an improved steady state matching quality. Additionally, the effect of various design parameters like either volute sizing or the choice of compressor to turbine diameter ratio on turbine blade speed ratio operating range as well as its inertia is analyzed. Finally, this method enables the designer to comparatively evaluate the ability of a turbine design to accelerate the turbocharger speed for transient engine response while still offering a map characteristic that keeps fuel consumption low at all engine speeds.

Operating point

10.1115/gt2012-68575

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Citations (3)

On the influence of thermal boundary conditions on the Thermo Mechanical Analysis of turbine housing of a turbocharger

Elsevier eBooks (2012)

Claus Oberste‐Brandenburg K. Shoghi Marc Gugau Felix Kruse

10.1533/9780857096135.2b.83

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Citations (7)

On the Effect of Volute Tongue Design on Radial Turbine Performance

Jan F. Suhrmann Dieter Peitsch Marc Gugau Tom Heuer

With an increasing need for gas turbines with rather low flow rates in many industrial applications, e.g. decentralized power generation, aircrafts or automotive turbochargers, the development of small size radial turbines becomes more and more important. A major step in the development of a radial turbine stage is the preliminary design, which is the definition of basic geometrical features and the calculation of general turbine flow parameters at the design point and within the operating range. These are mainly the rotational speed, the expansion ratio, the flow rate and in particular the expected turbine efficiency. In a radial turbine stage, the volute component delivers the flow to the rotor wheel and according to the geometrical form it defines major flow parameters like the mass flow parameter or the absolute rotor inlet flow angle. Amongst others, the way the flow enters the turbine wheel represents one of the most important loss generating factors. Thus, on the one hand an approach is necessary for the calculation of the optimum rotor inlet flow angle, in order to avoid dispensable losses due to secondary flow in the turbine wheel region. On the other hand, the volute tongue generates flow non-uniformity which has an effect on the overall circumferential averaged rotor inlet flow angle. Furthermore, the local flow pattern downstream of the volute tongue can generate suboptimal flow conditions for the turbine wheel. Hussain and Bhinder [1] measured the flow field at the outlet of a vaneless volute at different circumferential positions and detected a variation of the outlet angle of about Δα = 10°. The authors conclusion was, that the influence on the stage performance of flow non-uniformity generated by the volute could exceed the one of pressure losses through the volute. In this paper, the effect of different geometrical volute parameters on the flow condition especially at the turbine wheel inlet area is investigated. Experimental data of the influence of different volute tongue geometries on the flow field is difficult to generate. Hence, comprehensive numerical investigations are made using steady 3D-CFD calculations of the turbine volute as well as calculations of complete turbine stages including a turbine wheel geometry. Based on the numerical results, a design guideline is developed to estimate the influence of the geometric volute parameters on the flow and to raise the quality of the preliminary design process.

Volute

Specific speed

10.1115/gt2012-69525

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Citations (17)

VTG Turbochargers with Ball Bearings for Gasoline Engines

MTZ worldwide (2019)

Ralf Christmann Amir Rohi Sascha Weiske Marc Gugau

Ball (mathematics)

10.1007/s38313-019-0097-x

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Citations (0)

Validation and Development of Loss Models for Small Size Radial Turbines

Jan F. Suhrmann Dieter Peitsch Marc Gugau Tom Heuer Uwe Tomm

Today an increasing need for gas turbines with extremely low flow rates can be noticed in many industrial sectors, e.g. power generation, aircraft or automotive turbo chargers. For any application it is essential for the turbine to operate at best possible efficiency. It is known that for turbines the specific optimum achievable power output decreases with smaller size. A major contribution for this reduction in efficiency comes from the relative increase of aerodynamic losses in smaller turbine stages. In the early turbine design stage, easy and fast to use two-dimensional calculation codes are widely used. In order to produce qualitatively good results, all of these codes contain a diversity of loss models that more or less exactly describe physical effects which generate losses. It emerges to be a real problem that most of these empirical models were derived for rather large scale turbo machines and that they are not necessarily suitable for application to small turbines. In this paper many of the commonly known and well established loss models used for the preliminary design of radial turbines were collected, reviewed, and validated with respect to their applicability to small-size turbines, i.e. turbines of inlet diameter smaller than 40 mm. Comprehensive numerical investigations were performed and the results were used to check and verify the outcome of loss models. Based on the results, loss models have been improved. Furthermore, new correlations were developed in order to raise the quality of loss prediction especially for the design of small-size turbines. After receiving an optimum set of loss prediction models, all of them were implemented into a two-dimensional solver program for the analytical iterative solution of a complete turbine stage. Hence a powerful tool for preliminary radial turbine design has been created. This program enables the user to analytically evaluate the effects of changing key design properties on performance. These are amongst others the optimum rotor inlet flow angle according to the slip-factor definition, the value of flow deviation, and hence the optimum blade outlet angle for a minimum adverse flow-swirl at turbine outlet. Complementarily the turbine key performance indicators, e.g. pressure ratio, power output, rotational turbine speed, and mass flow can be calculated for optimum efficiency of a given turbine geometry. The paper presents the most important loss models implemented in the new code and weights their relative importance to the performance of small size radial turbines. The data acquisition was done using the new code itself as well as accompanying full 3D CFD calculations.

Turbo

Turbomachinery

10.1115/gt2010-22666

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Citations (70)