Inertial supercharging effect

The inertial supercharging effect is the increase of volumetric efficiency in the cylinder of an engine.[1]

Background

The internal combustion engine is the most common engine found in mechanical devices across the world.  The engine is powered by an air/gasoline mixture and the physics principles of heat and pressure.

Overview

Inertial supercharging effect is the result of incoming fuel/air charge developing momentum greater than intake stroke would generate alone. It is achieved by the careful design of the shape of the piston head, the valves and cam profile/valve timing which creates a vacuum that pulls more exhaust gases (and some of the intake gasses) out of the engine. This is immediately followed by a reflected pressure wave timed to force the extra intake gasses back into the cylinder, thus achieving a greater mass of air/fuel mix in the combustion chamber than possible with conventional methods. Expansion chambers only work well at a narrow engine speed range which is why two stroke engines are referred to as having a "powerband". Since the early 1980s exhaust power valves have been developed which have the effect of altering the timing and/or volume of the expansion chamber, greatly improving the spread of power of high output two stroke engines.[2]

The idea behind this effect is that if more pressure is created within the cylinder, the faster the piston will be able to move.[1] The volumetric efficiency is maximized to increase the amount of air/fuel mixture in the cylinder during each cycle.[3] In turn, a greater air/fuel mixture in a cylinder will create a greater pressure therefore exerting a greater force on the piston.  This increased force on each individual piston increases the potential horsepower of the entire engine.[4] The timing of the opening and closing of the valves is essential to ensure the air in the cylinder is maximized to create the most power in each cycle.[5]

See also

• Exhaust pulse pressure charging
• Kadenacy effect
• Pressure wave supercharger
• Supercharger

References

1. "Inertia Supercharging Air Flow Optimization - Aircraft Engine Overhaul". www.victor-aviation.com. Retrieved 2019-03-25.
2. P.W Performance Aust.
3. Bohacz, Ray T. “Forced Induction .” Hemmings.com, May 2015, www.hemmings.com/magazine/hcc/2015/05/Forced-Induction/3748512.html.
4. Hu, Bo; Turner, James WG; Akehurst, Sam; Brace, Chris; Copeland, Colin (March 2017). "Observations on and potential trends for mechanically supercharging a downsized passenger car engine:a review". Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering. 231 (4): 435–456. doi:10.1177/0954407016636971. ISSN 0954-4070.
5. "Valve Timing Events and the Order of Importance". Engine Builder Magazine. 2016-04-15. Retrieved 2019-03-25.

1. “Timing Is Everything .” Magnaflux Inspection - Aircraft Engine Overhaul, Victor Aviation Services, www.victor-aviation.com/Inertia_Supercharging_AirFlow_Optimization.ph
2. Brain, Marshall, and Kristen Hall Geisler. “How Car Engines Work.” HowStuffWorks, 5 Apr. 2000, auto.howstuffworks.com/engine1.htm
3. P.W. Performance Exhaust
4. Bohacz, Ray T. “Forced Induction .” Hemmings.com, May 2015, www.hemmings.com/magazine/hcc/2015/05/Forced-Induction/3748512.html.
5. Hu, Bo, et al. “Observations on and Potential Trends for Mechanically Supercharging a Downsized Passenger Car Engine:a Review.” Journal of Research in Crime and Delinquency, 6 Apr. 2016, journals.sagepub.com/doi/full/10.1177/0954407016636971.
6. Kertes, Rick. “Valve Timing Events and the Order of Importance.” Engine Builder Magazine, 19 Apr. 2017, www.enginebuildermag.com/2016/04/valve-timing-events-and-the-order-of-importance/.