1. Clues for Improvements in I. C. Engine Design
P M V Subbarao
Professor
Mechanical Engineering Department
Future Direction for Better Performance !!!

2. Clues for Improvement- reduce heat loss
Heat losses caused by high engine turbulence level
Need high turbulence to
Wrinkle flame (premixed charge, gasoline)
Disperse fuel droplets (nonpremixed charge, Diesel)
"Inverse-engineer" engine for low-turbulenc
Gasoline - electrically-induced flame wrinkling?
Diesel - electrostatic dispersion of fuel in chamber?

3. Clues for Improvement - reduce throttling loss
Premixed-charge IC engines frequently operated at lower than maximum torque output (throttled conditions)
Throttling adjusts torque output of engines by reducing intake density through decrease in pressure ( P = rRT)
Throttling losses substantial at part load

4. Clues for Improvement for improvements : Reduce Friction Losses
Programmable intake/exhaust valve timing
Electrical/hydraulic valve actuation
Choose open/close timing to optimize power, emissions, efficiency - can eliminate throttling loss

5. The Art of Down Sizing an Engine

6. Clues for Improvement for improvements : Down Sizing

9. Clues for Improvement : Reduce NOx
Homogeneous ignition engine - controlled knocking
Burn much leaner mixtures - higher efficiency, lower Nox
Need to abandon traditional combustion control strategy

10. Ideas - improved lean-limit operation
Recent experiments & modelling suggest lean-limit rough operation is a chaotic process
Feedback via exhaust gas residual
Could optimize spark timing on a cycle-to-cycle basis
Need to infer state of gas & predict burn time for next cycle - need in-cylinder sensors

12. Fuel Savings due to down sizing + +

13. Conclusions
IC engines are the non-ideal form of vehicle propulsion, except for all the other forms
Despite over 100 years of evolution, IC engines are far from optimized
Any new idea must consider many factors, e.g.
Where significant gains can & cannot be made
Cost
Resistance of suppliers & consumers to change
Easiest near-term change: natural-gas vehicles for fleet & commuters
Longer-term solutions mostly require improved (cheaper)
Sensors (especially in-cylinder temperature, pressure)
Actuators (especially intake valves)

14. Development of Power Plant for A Vehicle
P M V Subbarao
Professor
Mechanical Engineering Department
Matching the horse to the Cart …..

15. TRACTIVE FORCE REQUIREMENTS
Vehicles require thrust forces, generated at the tires, to initiate and maintain motion.
These forces are usually referred to as tractive forces or the tractive force requirement.
If the required tractive force (F) is broken into various components.

16. Major Force Components Demanding Trctive Force
Resistance
Tractive effort
Vehicle acceleration
Braking
Stopping distance

17. Resistance Force : Ra
The major components of the resisting forces to motion are comprised of :
Aerodynamic loads (Faero)
Acceleration forces (Faccel = ma & I forces)
Gradeability requirements (Fgrade)
Chassis losses (Froll resist ).

18. Aerodynamic Force : Flow Past A Bluff Body
Composed of:
Turbulent air flow around vehicle body (85%)
Friction of air over vehicle body (12%)
Vehicle component resistance, from radiators and air vents (3%)

19. Aerodynamic Resistance on Vehicle
Dynamic Pressure:
Drag Force:
Aero Power