The document discusses variable geometry turbochargers (VGTs), which adjust the aspect ratio of the turbocharger to optimize engine performance across varying conditions. It covers the history, working principles, benefits, and design considerations of VGTs, including the role of the electronic control unit in managing nozzle angles. The conclusion highlights the VGT's ability to enhance intake air mass flow, reduce pumping losses, and improve overall engine efficiency.

1. MALAVIYA NATIONAL INSTITUTE OF
TECHNOLOGY , JAIPUR
Variable Geometry Turbocharger
Submitted by
RISHABH MISHRA
2011UME1540
M3

2. Content
 Introduction
 Turbocharging
 History
 Problems with simple turbocharging
Working of VGT
 Benefits
 Designing of VGT
 Summary and Conclusion
 References
Common questions

3. Introduction
 Variable-geometry turbochargers (VGTs) also known as variable nozzle
turbines/VNTs), are a family of turbochargers
 Designed to allow the effective aspect ratio (A:R) of the turbo to be altered as
conditions change
 It produces variations in the flow of inlet air mass by geometry change of inlet
conditions of turbine blades according to requirement.

4. Turbocharger
A turbocharger consist of four parts:
a) Turbine
b) Compressor
c) Common axle
d) Sub assemblies
e) Air cooler
WORKING
 The turbine inlet receives exhaust gases from the engine exhaust manifold
causing the turbine wheel to rotate
 This rotation drives the compressor, compressing ambient air
 After it delivers it to the air intake manifold of the engine at higher pressure,
 resulting in a greater amount of the air and fuel entering the cylinder

5. History
 1927: Swiss engineer Alfred Buchi is granted the first Patent for exhaust driven
Turbo-Supercharging or Turbocharger.
 1952: Garrett (Honeywell) & Schwitzer (BorgWarner) begin Turbocharger production
for Caterpillar & Mack Truck.
 1962: First Passenger Car Turbo application, General Motors Corvair is introduced,
followed by 1963 Oldsmobile Jetfire Turbo-Rocket V8.
 1979: Beginning of Downsized Turbo Era with Ford Mustang 2.3-liter, 4 cylinder engine,
Chrysler & GM also Compete with Turbo Models.
 1980: BorgWarner and IHI Japan form 50/50 Joint Venture, Warner-Ishi.
MHI of Japan begins development for US.
 1997: BorgWarner purchases majority shares of AG Kühnle, Kopp &
Kausch from Penske Corporation.
 1999: Kuhlman Corporation, parent of Schwitzer is purchasedby BorgWarner and
becomes part of BorgWarner Turbo Systems.
 2008: Bosch-Mahle & Continental Turbo Systems Begin Development.

6. Problems with simple Turbochargers
 Difference in the optimum aspect ratio of nozzle at different
running conditions
 Low boost at slow running conditions
 Choking at high speed
 Variation in the inlet air mass according to engine performance
 Starting lag

7. Turbocharger configuration

8. Turbocharger integration
 Linking of engine performance with turbocharger performance

9. Variable geometry turbocharger
 In variable geometry turbocharger the variation in inlet air mass is
brought by compressor speed
 Changes is done on the turbine
 Nozzle angle is changed by stator vane, operated by ECU unit of
vehicle
 For low speed, the vane is brought in closed position so that
boosting can be done by compressor
 At high speed ,the vane comes at open condition allowing most of
the exhaust to impact on the blades ,and the pressure decreases of
exhaust gases and choking is avoided

10. Working of VGT
 Low speed run condition
Engine running parameters is taken by
ECU as input and send direction to vane
to close
 High speed run condition

12. Benefits
 No throttling loss of the waste gate valve
 Higher air–fuel ratio and higher peak torque at low engine speeds
 Improved vehicle accelerations without the need to resort to turbines with high
pumping loss at high engine speeds
 Potential for lower engine ΔP (the difference between exhaust manifold and
intake manifold pressures)
 Control over engine ΔP that can be used to drive EGR flow in diesel engines with
high pressure loop (HPL) EGR systems
 A better ability to cover a wider region of low BSFC in the engine speed–load
domain
 Ability to provide engine braking
 Ability to raise exhaust temperature for after treatment system management

13. Designing of the VGT
Three parts
a) Electronic control unit
b) Compressor designing
c) Turbine designing

14. Electronic control unit
 The opening of the guide vanes is commanded by the electronic
control unit (ECU) of the car
 Aspects of engine performance that ECU consider for the varying
the nozzle angle
1) the instant and quantity of injected fuel
2) the opening and closing of the intake and exhaust valves
3) pressures, temperatures, flow rates
Mass flow rate is given by

15. Compressor design
Flow coefficient Circumferential Mach number Isentropic work coefficient

16. Turbine design
Parameters:
 Pressure ratio
 Corrected mass flow rate
 Isentropic efficiency
 Corrected speed
 VNT positions

17. Conclusion
 An VGT is designed to position the nozzle to attain the optimum air mass flow inside
the engine and improving the break specific fuel consumption.
 An VGT, under low running speed, provides closing of vane blades to allow more
impact of exhaust gases on it improving intake air mass..
 Designing of the compressor and turbine include the study of there design parameter
on the maps which allow us to decide standards for the components.
 Pumping losses , pressure energy loss, engine noise and heat energy loss is recovered
by VGT. These problems commonly occur on vehicle with conventional turbocharging
system or in case of no turbocharging.
 If there occurs VGT failure, the system will revert to normal turbocharging operation.
Normally the ECU unit will turn on the light in case of any fault.

18. References
 K. Segawa, A. Iwakami, S. Yamaguchi, H. Tange, K. Kimachi, Improvement of turbine
performance for small size variable geometry system Turbo charger, IHI Corporation,
Japan,2010.
 Rabih Omran, Rafic Younes, and Jean-Claude Champoussin, Optimal Control of a Variable
Geometry Turbocharged Diesel Engine Using Neural Networks: Applications on the ETC
Test Cycle, Lebanese University. Nov. 27, 2008.
 Daniel Cristian Dinescu, Mohand Tazerout, mean value modelling of a variable nozzle
turbocharger (VNT), U.P.B. Sci. Bull., 2010.
 Zhang Yang Jun, Chen Tao, Zhuge Weil, Zhang Shu Yong & XU Jian Zhong, An integrated
turbocharger design approach to improve engine Performance, Technological Sciences,
January 2010
 Tao Chen, Weilin Zhuge, Xinqian Zheng, Yangjun Zhang, turbocharger design for a 1.8 litre
turbocharged gasoline Engine using an integrated method, ASME, June 2009