variable geometry turbocharger

this presentation tells about the variable geometry turbocharger, their design and comparison with simple turbocharger

1. Variable G eometry Turbocharger MALAVIYA NATIONAL INSTITUTE OF TECHNOLOGY , JAIPUR 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 D esigned 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: Turbine Compressor Common axle Sub assemblies 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 S tarting 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

11. 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

12. Designing of the VGT Three parts Electronic control unit Compressor designing Turbine designing

13. 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

14. Compressor design Flow coefficient Circumferential M ach number Isentropic work coefficient

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

16. 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.

17. 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  

18. Thank you