1. Performance of Turbocharged I.C. Engines
P M V Subbarao
Professor
Mechanical Engineering Department
Impact of Artificially Breathing ….

2. Capacity of Turbocharger

3. Turbine Sizing
The selection of the turbine size is a bit simpler than the sizing of the compressor.
Important to note that the turbine size effects boost threshold, turbolag and fuel consumption.
Boost threshold is the engine speed at which there is sufficient exhaust gas flow to generate positive (intake) manifold pressure, or boost.
Turbolag is the difference between the time of demand for an increase in power raised by the engine and the time of turbocharger started providing increased intake pressure, and hence increased power.
The selection is basically just a balancing act.
There are no complicated maps or processes used to select the turbine size.

4. Large Turbine
Larger turbines, conversely, allow much more airflow through the compressor and reduce back pressure.
Demands less enthalpy exhaust in manifold .
Leads to higher boost thresholds and larger turbo lag.

5. Small Turbine
Smaller turbines will provide lower boost thresholds and better turbo response.
Able to create limited airflow through the compressor.
Demands higher enthalpy exhaust in manifold.
Leads to lower turbine exit pressure.

6. Selection of Turbine Exducer bore
Higher Limit
Lower Limit

7. Geometrical Design of Casing for Turbine

8. Steps in Geometrical Design

9. Geometric Parameter : Casing for Turbine
The A/R ratio of the turbine is the ratio of the housing discharge area to the radius of the center of the discharge area to the center of the turbine blades

10. Guide for selecting a turbine A/R ratio
High Power Engine
Lower Boost Threshold

11. Performance Studies on Turbocharged Engine

12. The Breathing Effectiveness

13. Engine Power Rating

14. Engine Compactness

15. Engine Fuel Economy

16. Strange Thinking/Understanding for Future
Turbocharged modes were found to match or exceed the capabilities of typical larger bore normally aspirated engines found in passenger vehicles.
Case studies showed that A normally aspirated engine could be readily matched with the smaller turbocharged unit, with a 66% reduction in engine capacity.
It is possible to achieve 22% reduction in fuel consumption and CO2 emissions, including a reduction of 62% at idle conditions.

17. Advanced Turbo-charging Systems
Higher volumetric efficiency is achieved through increased IVC.
Go back to Era of Otto or Diesel.
Compression ratio has a great impact on fuel consumption of an engine.
Generally, the bigger the compression ratio is, the lower the fuel consumption can be reached.
Knock limit constrains the compression ratio increase of SI engines.
It is known to all that any effort resulting in intake air temperature decreasing will extend the knock limit.
Attainment of higher volumetric efficiency with lower Tivc is the theme of advanced turbo-charging methods.

18. Turbocharger with Intercooler

19. Scheme of the Advanced turbo-cooling system

20. Effect of Turbo-cooling