Session: 04-02-02: Advances in Aerodynamics & Novel Aerospace Propulsion Systems

Paper Number: 70504

Start Time: Tuesday, 10:25 AM

70504 - Development of a Novel 4-Stroke Spark Ignition Opposed Piston Engine of a Novel 4-Stroke Spark Ignition Opposed Piston Engine of a Novel 4 Stroke Spark Ignition Opposed Piston Engine 

The objective of this project was to develop a low-cost, 4-stroke gasoline-powered OP engine, joining two internal combustion engines from an alternative engine with side valves on the block, removing the heads. The union of these two engine blocks enabled the construction of an opposite piston engine (OPE) with two crankshafts. In this new engine, the combustion chamber is confined to the space inside the cylinder between the piston heads and the chamber between the valves. The pistons move on the cylinder shaft in opposite directions, a typical feature of opposite piston engines. 

It will be shown that it is feasible to build one engine from a different one already in use, reducing the manufacturing and development costs. In addition, higher power can be obtained with better specific fuel consumption and less vibration.

In the past, opposing piston engines were successfully used in almost all civil and military fields, where they set records of low consumption and high specific power, which still remain so many years later, despite the undeniable progress in this field [1]. However, two major obstacles were encountered: the first related to the restrictions imposed on the emissions of internal combustion engines (2 stroke opposing piston engines significantly exceed the legal limits in force, which led, for some time, to a minor interest in its development [2]), while the second is conditioned by the current economic crisis and the times of austerity imposed by the international situation (creating difficulties in investment on research of this type of engines). 

The development of this type of engine should preferably focus on a lightweight and compact one to be used in some aeronautical applications to replace boxer engines that dominate the market up to 8 kW of power (which would imply a two-stroke engine). However, emissions caused the choice to fall on an engine with a 4-stroke cycle over a 2-stroke one, although this would make it heavier and less compact than would be desirable for an aeronautical application. Nevertheless, during World War II, the majority of the piston engines were of 4-stroke [3], and in terms of specific power, were reached values still difficult today to match. This choice also allows for compatibility with widely reported gaseous effluent treatment systems.

The engine performance parameters, such as: rotational speed, torque, fuel consumption and emissions, were measured on an Eddy currents dynamometer. With the collected data, power, specific consumption and overall efficiency were calculated, allowing to conclude that the motor with the opposed-piston configuration is less expensive and is more powerful.

[1] Brójo F., Santos A., Gregório, J. (2010, June 30 - July 2). Computational Analysis of the Scavenging of a two-stroke Opposed Piston Diesel Engine. Proceddings of the world Congresss on Engineering 2010 Vol II, WCE 2010, (London, United Kingdom): 1448-1453.

[2] Pirault J-P., Flint M. (2009). Opposed Piston Engines: Evolution, Use, and Future Applications, Warrendale: SAE International.

[3] Fernandes A. (2008). Compendium of Alternative Engines, Military and Technical Training Center, Portugal: Portuguese Air Force, Ministry of National Defense.

Presenting Author: Francisco Brojo University of Beira Interior

Authors:

Alexandre Nunes C-MAST
Francisco Brojo University of Beira Interior