“Design and analysis of turbo charger and
Extension of Turbo charging to
Two Wheelers”
ABSTRACT In these days of technological advancements in Automobile sector where mans penchant is to develop technologies that can improve the power and mileage of the vehicle TURBOCHARGER is one such exotic gadget. Any engine needs air for combustion of fuel and it is the Air-Fuel ratio the decides the performance of an engine. Hence supply of air is an important task. During high speed operation of any engine there is not enough time for air to be sucked in the cylinder by itself (by the creation of vacuum during suction stroke).Hence the volumetric efficiency goes on decreasing as engine picks up speed as a result of which only partial combustion takes place. To fulfill the deficiency of air supercharging and consequently turbo charging came into picture. A TURBO CHARGER is basically an exhaust gas driven air compressor which compresses the ambient air and sent this pre compressed (optionally Intercooled) air into the cylinder during suction stroke. It consists of two basic parts, the exhaust gas driven turbine and its housing, and the air compressor and its housing. The exhaust air from the engine spins the turbine and leaves while the compressor wheel, connected to the common shaft of turbine and compressor, compresses the ambient air and feeds it to the engine. Modern turbochargers are complex assemblies of various accessories attached to it like waste gate, blow off valves, oil and water plumbing, ECU with sensors, Pressure gauges etc. Since the turbine spins at exceptionally very high speeds of the order of 1-2 Lac rotations per minute it has to designed carefully taking various parameters into considerations. Also as it is continuously subjected to very high exhaust gas temperature of the order of 600-900 degree centigrade thermal strength also plays important role. Turbine of the turbocharger also has to resist the high pressure of the exhaust gas at elevated temperatures. Hence in our project we have incorporated the two major design considerations of turbine of Turbocharger: Structural Aspects. Thermal Aspects.
Modeling and Analysis of the turbine wheel of a turbocharger is presented in our project. For modeling we have used the real time modeling package ProEngineer WF 3.0 and for analysis we have used the prevalent FEM analysis package ANSYS 10. Our Analysis includes both Structural and Thermal Analysis of the turbine wheel. Special focus on the results part has been given in order to help designers. Various contour plots has been studied and presented so as to acquire proper idea about the deflections and stress distributions on the turbine blade. In case of thermal Analysis, Nodal temperatures and the distribution of the temperature across the turbine blade has been obtained and explained.
Another interesting part of our project is the “EXTENSION OF TURBOCHARGING TO TWO WHEELERS” We have presented the possibilities of turbo charging a two wheeler which has not been done yet in commercial vehicles till date. Turbo charging a two wheeler has many potential like power boost, Mileage improvement etc which can be achieved easily by installing a turbocharger. We have presented the advantages and limitations of this concept.
Name of the industry: Reverse Engineering And Product Development
INTRODUCTION TO TURBOCHARGERS A turbocharger, or turbo, is an air compressor used for forced-induction of an internal combustion engine. Like a supercharger, the purpose of a turbocharger is to increase the mass of air entering the engine to create more power. However, a turbocharger differs in that the compressor is powered by a turbine driven by the engine's own exhaust gases. Their total design, as in the other turbomachines, involves different types of analyses such as mechanical, thermal and acoustical. Engineers and researchers are still searching for ways to improve their designs while keeping the balance between the needs and costs.
Exhaust driven Turbochargers BACKGROUND AND MOTIVATION:
The first turbocharger was invented in the early twentieth century by the Swiss engineer Alfred Buchi who introduced a prototype to increase the power of a diesel engine. The idea of turbocharging at that time was very little accepted. However, in the last few decades, turbocharging has become essential part in almost all diesel engines, with the exception being
very small diesel engines. Their use in the petrol (gasoline) engines has also shown good boost for the power output.
Early Turbocharger
Turbocharger used in Diesel Engine
Turbocharger used in Aircraft Engine Since the earliest turbocharger prototypes, researchers have attempted to develop the design to be more reliable and economical for users. These studies were conducted on the output performance of the turbochargers with focus on the thermodynamics of the process. Although thermal analysis is an important part of the design process, thorough thermodynamic investigations of the turbochargers did not have a great attention at the early time.
WORKING PRINCIPLE:
A turbocharger, often called a turbo, is a small radial fan pump driven by the energy of the exhaust flow of an engine. A turbocharger consists of a turbine and a compressor on a shared shaft. The turbine inlet receives exhaust gases from the engine causing the turbine wheel to rotate. This rotation drives the compressor, compressing ambient air and delivering it to the air intake manifold of the engine at higher pressure, resulting in a greater mass of air entering each cylinder. In some instances, compressed air is routed through an intercooler before introduction to the intake manifold. The objective of a turbocharger is the same as a supercharger; to improve upon the size-to-output efficiency of an engine by solving one of its cardinal limitations. A naturally aspirated automobile engine uses only the downward stroke of a piston to create an area of low pressure in order to draw air into the cylinder through the intake valves. Because the pressure in the atmosphere is no more than 1 bar (approximately 14.7 psi), there ultimately will be a limit to the pressure difference across the intake valves and thus the amount of airflow entering the combustion chamber. This ability to fill the cylinder with air is its volumetric efficiency. Because the turbocharger increases the pressure at the point where air is entering the cylinder, a greater mass of air (oxygen) will be forced in as the inlet manifold pressure increases. The additional oxygen makes it possible to add more fuel, increasing the power and torque output of the engine. Because the pressure in the cylinder must not go too high to avoid detonation and physical damage, the intake pressure must be controlled by controlling the rotational speed of the turbocharger. The control function is performed by a wastegate, which routes some of the exhaust flow away from the exhaust turbine. This controls shaft speed and regulates air pressure in the intake manifold.
EXTENSION OF TURBOCHARGING TO COMMERCIAL TWO WHEELERS
The concept of Turbocharging is inevitably used in all four wheelers and bigger vehicles like busses, trucks etc, because of the following advantages, 1) Higher power 2) Lower fuel consumption. 3) Higher Power to weight ratio etc.
History of two wheelers turbocharging: The first example of a turbocharged bike is the 1978 Kawasaki Z1R TC. It used a Rayjay ATP turbo kit to build 2.3 Kg (5 lb) of boost, bringing power up from 90 HP to 105 HP. However, it was only marginally faster than the standard model. A US Kawasaki importer came up with the idea of modifying the Z1-R with a turbocharging kit as a solution to the Z1-R being a low selling bike. The 112 hp (84 kW) Kawasaki GPz750 Turbo was manufactured from 1983 to 1985. This motorcycle had little in common with the normally aspirated Kawasaki GPz750. Nearly every component was altered or strengthened for this GPz 750 Turbo to handle the 20 hp (15 kW) increase in power. 1982 Honda released the CX500T featuring a carefully developed turbo (as opposed to the Z1-R's bolt-on approach). It has a rotation speed of 200,000 rpm. The development of the CX500T was riddled with problems; due to being a V-twin engine the intake periods in the engine rotation are staggered leading to periods of high intake and long periods of no intake at all. Designing around these problems increased the price of the bike, and the performance still was not as good as the cheaper CB900 (a 16 valve in line four) During these years, Suzuki produced the XN85, a 650 cc in line four producing 85 bhp (63 kW), and Yamaha produced the Seca Turbo. Both had Carburettor fuel systems). Since the mid 1980s, no manufactures have produced turbocharged motorcycles making these bike a bit of a factory an educational experience; as of 2007 no factories offer turbocharged motorcycles (although the Suzuki B-King prototype featured a supercharged Hayabusa engine).
BIKE WITH A TURBOCHARGER We aim to extend the concept of turbocharging in commercial two wheelers aswell. As of now, This concept of supercharging (rarely turbocharging) is used in racing bikes with high capacity varying from 800-1400cc bikes. This concept if used in commercial two wheelers with proper modifications can yield higher power and mileage. A small compressor-Turbine assembly compatible with the emissions level from a two wheeler can be used. Here there are two important considerations, Firstly, If a gasoline injection engine is used (i.e, DTSI-Direct twin spark plug Injection as in Pulsar etc.) where fuel is injected through injector nozzle and only air is sucked in the cylinder during suction stroke of the piston. This air being inducted can be pressurized in order to increase the volumetric efficiency and allow complete combustion of fuel. Turbocharging will be easier and more effective.
DTSI ENGINE
FUEL INJECTOR
FUEL INJECTION :
As opposed to the carburetor, the fuel injection mechanism usually improves the engine startability, offers a brisker torque response to throttle changes and diagnostics features. It is possible to establish accurate closed-loop control of air-fuel ratio by using the fuel injection mechanism (as an actuator) and utilizing feedback information from an exhaust oxygen sensor (as a sensor). These two components require sophisticated manufacturing practices and therefore a closed-loop fuel injection system forms a costly proposition. It was discovered in late 1970s that accurate closed-loop control of air-fuel mixture encourages efficient destruction of exhaust pollutants in a three-way catalytic converters thereby enabling a gasoline engine to produce substantially low exhaust emission quantities as demanded by the emission standards worldwide. It is for this reason that microprocessor based fuel injection technology has been implemented widely in gasoline powered four-wheelers since early 1980s. In early 1990s, several global twowheeler OEMs also began downsizing and adapting the fuel injection technology for use in twowheelers; the most notable efforts have perhaps been those from Honda.
FUEL INJECTION TECHNOLOGY IN INDIA :
In India, all four wheelers since late 1990s feature microprocessor based closed-loop fuel injection technology in place of traditional carburetor to meet the Bharat emission standards imposed by the Government of India. Indian two-wheeler companies have been little sluggish in comparison, however since early 2000s, they too have initiated developing the fuel injection technology to meet the emission standards of the future (early 2010s) and for customer appeal of a high-end technology. The relatively late entry of fuel injection technology in Indian two-wheelers is mainly attributed to the higher cost sensitiveness of the Indian two-wheeler market in comparison with the Indian four-wheeler market. It is for these reasons, introductions of fuel-injected motorcycles such as Glamour FI, Pulsar 220 into Indian market are often considered as bold, aggressive moves. The often prohibitively higher cost that fuel-injection warrants limits the application to the 'premium' segment of the
motorcycle market, as is exemplified by the rather slow sales of the Glamour FI. However, the early fuel injected two-wheelers in India are not expected to implement the aforesaid closed-loop control of air-fuel ratio in view of the consequent cost implications. Rather they are likely to implement the less costly option of "open-loop" or feed-forward regulation of air-fuel ratio thereby avoiding usage of (costly) exhaust oxygen sensor. Automotive experts argue that such a scheme, in comparison with the aforesaid closed-loop scheme, is often significantly less effective in reducing exhaust pollutants. As a result, the early fuel injected Indian two-wheelers are not likely to be more environment-friendly than their carburetted counterparts. However, these fuel-injected two-wheelers are expected to outdo their carburetted counterparts in the areas of pickup, mileage, durability, dashboard diagnostics and the customer appeal of a high-end technology.
Pulsar 220 cc with Fuel injection system The main advantages of Fuel Injection are:
Increased power output for same capacity. Better low end torque. Lower fuel delivery & optimization of spark timing. Improved cold start, quick warm-up and excellent response to sudden acceleration. Lower emission levels. Self detection and communication of fuel system malfunctioning if any.
Secondly, If a carbureted engine is used then there are two possibilities of placing the turbocharger. It could be downstream or upstream of the carburetor. Turbocharging in this case is not that easy.
A CARBURETOR OF TWO WHEELER.
If the compressor is downstream of the carburetor then the charge contains both fuel and air, fuel droplets striking the compressor blades is not desirable. In the other case, where the compressor is upstream of the carburetor then the air could be pressurized and sent to the venturi of the carburetor. This could be used with proper modifications like air filters etc.
The following are the expected advantages of Turbocharging a Two Wheeler:
1) Higher power. 2) Considerably lower fuel consumptions. 3) Higher power to weight ratio. 4) As the flow rate of exhaust gas of a two wheeler is low hence smaller turbine and compressor can be used thus reducing weight of the turbocharger. 5) Also as the temperature of Exhaust gas is not that high (as compared to a four wheeler) Aluminum or steel can be used instead of costly Ni Alloys or composites. Hence Cost effective manufacturing can be done.
6) Since the exhaust gas is made to expand in the turbine the gas coming out from the turbine will be relatively coolers hence cooler ambient.
A Yamaha turbocharged bike
FUTURE SCOPES: The analyses dealt in this project are very useful in the design considerations of turbine wheel of a turbocharger. For further developments and for design of Compressor wheel and performance of turbine and compressor wheels
The following things are suggested:
1) Flow analysis of Compressor can be done using Computational Fluid
Dynamics (CFD)
techniques.
2) Compressor and Turbine wheel charts (Mapping charts) can be studied to obtain optimum design parameters like operating pressures, mass flow rate etc.
3) A proto type of the turbocharger could be fabricated by suitable processes and tested by properly installing it to a two wheeler. 4) Dynamic Vibration Analysis of a Turbocharger could also be carried out.
5) Also by extending the concept of Turbocharging to two wheelers better Power and Mileage levels can be developed. The same engine can produce much higher power just by using a turbocharger. This concept, if applied practically, would achieve better power and mileage levels. Even the cost and installation complexity can not impede its usage in bikes because of the power boost and mileage levels attained by using a Turbocharger.
