Experimental investigation and extended simulation of turbocharger non-adiabatic performance

Vom Fachbereich Maschinenbau der Universitt Hannover

zur Erlangung des akademischen Grades Doktor-Ingenieur

genehmigte Dissertation

von

MSc Eng. Sameh Shaaban geboren am 01.02.1970 in Kairo, gypten

2004

Stichworte fr die Dokumentation:

Turbolader, diabatisches Verhalten, Simulation, Radialverdichter, radiale Turbine

Key words:

Turbocharger, non-adiabatic performance, simulation, centrifugal compressor, radial

turbine, micro compressor.

1. Referent: Prof. Dr.-Ing. J. Seume

2. Referent: Prof. Dr.-Ing. H. Pucher

Tag der Promotion: 14.12.2004

i

Abstract

Turbocharging is nowadays considered the most commonly used method of engine

supercharging. One of the important factors affecting the turbocharger performance

is the heat transfer inside the turbocharger and from the turbocharger to the ambient.

Heat transfer takes place due to the high temperature gradient between the turbine

and the other components of the turbocharger as well as between the turbine and the

ambient. This heat transfer causes underestimation of the measured compressor

efficiency and overestimation of the turbine efficiency. This results in an inaccurate

estimation of the compressor power and the turbine power. Therefore, the measured

turbocharger performance maps are not accurate enough to simulate the

turbocharger performance in engine simulation programs. Furthermore, the

measured turbocharger performance maps provide the turbocharger performance for

very few operating points in comparison with the engine operating points.

The present research work aims at investigating the turbocharger non-adiabatic

performance. It also aims at extending the simulation of the turbocharger

performance down to very low turbocharger rotational speeds as well as compressor

operation in the fourth quadrant of the performance map. The turbocharger

performance simulation is based on physically meaningful models for the

aerodynamic performance of radial turbomachines. The aerodynamic performance of

micro radial compressors is also experimentally investigated.

Three different turbochargers are investigated in the present research work. The

experimental investigation is conducted using two different combustion chamber test

rigs. Models and correlations for the estimation of the amount of heat transfer

between the components of the turbocharger as well as between the turbine and the

ambient are developed. Empirical loss correlations are obtained for micro radial

compressors. Correlations for estimating the slip factor of radial compressors are

also presented. A program for predicting the actual performance of micro radial

compressors in low rotational speed operating range is introduced. A turbocharger

performance simulation program is also presented. This program is designed to

operate as a stand alone program or as two subroutines in the engine simulation

programs.

ii

Kurzfassung

Turboaufladung ist heutzutage die am hufigsten verwendete Methode fr die

Aufladung von Verbrennungsmotoren. Wrmebertragung innerhalb des Turboladers

und vom Turbolader an die Umgebung ist einer der wichtigen Faktoren, die das

Turboladerverhalten beeinflussen. Sie findet wegen des hohen

Temperaturgradienten zwischen der Turbine und den anderen

Turboladerbestandteilen sowie zwischen der Turbine und der Umgebung statt. Diese

Wrmebertragung fhrt zur Unterschtzung des Verdichterwirkungsgrades und

berschtzung des Turbinenwirkungsgrades. Die berechnete Verdichter- bzw.

Turbinenleistung mit Hilfe der gemessenen Kennfelder wird deswegen zu gro

geschtzt. Das bedeutet, dass die gemessenen Kennfelder nicht genau genug fr die

Simulation des Turboladerverhaltens in Motorsimulationsprogrammen sind.

Auerdem stellen die gemessenen Kennfelder das Turboladverhalten nur fr wenige

Betriebspunkte dar.

Ziel der vorliegenden Arbeit ist, das diabate Verhalten des Turboladers zu

untersuchen und die Simulation des Turboladers bis zu sehr niedrigen Drehzahlen zu

erweitern. Die Simulation des Verdichters deckt auch den Verdichterbetrieb im

vierten Quadranten des Kennfeldes ab. Die Erweiterung der Kennfelder basiert auf

physikalisch sinnvollen Modellen fr das aerodynamische Verhalten der

Radialturbomaschinen. Das aerodynamische Verhalten der Mikroradialverdichter

wird auch untersucht.

Drei Turbolader werden im Rahmen der vorliegenden Arbeit untersucht. Die

experimentelle Untersuchung wird mit zwei unterschiedlichen

Brennkammerprfstnden durchgefhrt. Modelle bzw. empirische Korrelationen fr

die Bestimmung der Wrmebertragung innerhalb des Turboladers und vom

Turbolader an die Umgebung werden entwickelt. Des Weiteren werden empirische

Korrelationen fr die Bestimmung der aerodynamischen Verluste und des

Minderleistungsfaktors erstellt. Ein Programm fr die Vorhersage des

Radialverdichterverhaltens im niedrigen Drehzahlbereich wird erstellt. Ein anderes

Programm fr die Erweiterung der gemessenen Kennfelder bis zu sehr niedrigen

Drehzahlen wird erarbeitet. Dieses Programm dient sowohl als Stand-Alone

Programm als auch als Subroutinen in Programmen zur Simulation des Motors.

iii

Acknowledgment

The present research work is developed during my work as research assistance in

the institute of turbomachinery (IfS), Hanover University. The research work was

supervised by Prof. Dr.-Ing. J. Seume.

I would like to express my thanks and gratitude to Prof. Dr.-Ing. J. Seume for the

continuous support, the helpful advice, and the valuable guidance throughout the

present research work.

I thank Prof. Dr.-Ing. M. Rautenberg for the discussions during the research work. I

also thank Prof. Dr.-Ing. H. Pucher and Prof. Dr.-Ing. J. Linnhoff for the support

during the development of the TC_2003 program. My thanks are also to Dr.-Ing. R.

Baar, VW-company, for the support.

I would like to express my thanks and gratitude to Prof. Dr.-Ing. H. Heikal and Prof.

Dr. Eng. A. Abdelhafiz for the continuous support during my study in Egypt. I would

also like to thank Prof. Dr.-Ing. A. Mobarak for the information and discussions during

his visit to Germany.

I thank all my colleagues in the institute of turbomachinery for the valuable

discussions. My thanks are also to the technical staff of the institute of

turbomachinery for the technical support during my research work.

Finally, I would like to express my special thanks to my family for the patience and

encouragement.

Hanover, December 2004

Sameh Shaaban

iv

Table of contents

v

Table of contents

Abstract .......................................................................................................................i

Kurzfassung...............................................................................................................ii

Acknowledgment......................................................................................................iii

Table of contents.......................................................................................................v

List of figures..........................................................................................................viii

List of tables ............................................................................................................xx

List of symbols .......................................................................................................xxi

1. INTRODUCTION.....................................................................................................1

1.1 Introduction .......................................................................................................1

1.2 Turbocharging...................................................................................................3

1.3 Mechanical design of the turbocharger .............................................................4

1.3.1 The radial compressor of the turbocharger.................................................4

1.3.2 The radial turbine of the turbocharger.........................................................5

1.3.3 Turbocharger bearing system.....................................................................6

1.4 Methods of controlling the turbocharger............................................................6

1.4.1 By-pass control ...........................................................................................7

1.4.2 Variable geometry control...........................................................................7

1.5 Turbocharger performance maps......................................................................8

1.5.1 Compressor performance map ...................................................................8

1.5.2 Turbine performance map ..........................................................................9

1.6 Adiabatic versus non-adiabatic turbocharger performance.............................11

1.7 Methods of turbocharger performance simulation...........................................13

1.8 Importance of the present