Quasiturbine> Type> Combustion


Let forget about comparing Quasiturbine with other engines.
Ignore also advanced detonation combustion mode.
Just considerer the Quasiturbine burning fuel the conventional way.

Quasiturbine Combustion Type

March 2003 - MIT study

Improving gasoline and diesel engines is the way to go! Hydrogen car is no environmental panacea. The hydrogen fuel-cell vehicle will not be better in terms of total energy use and greenhouse gas emissions by 2020. If we need to curb greenhouse gases, improving mainstream gasoline and diesel engines is the way to go. These results come from an assessment of a variety of engines and fuel technologies forecasting no real 'breakthroughs'
(The Quasiturbine having been excluded from the study).

Free Green House Gas Internal Combustion Engine: Hydrocarbons contain only Carbon and Hydrogen which are separated by heat, and recombine with air's oxygen to make water and CO2. People are complaining of bad combustion when engine is making black carbon particles though the exhaust, but this may be good new for GHG? In fact, a way to have a GHG pollution free combustion engine (with somewhat less total power) is to burn only the hydrogen from the hydrocarbon fuel, and recover the <burnt> Carbon (...not dropping it in fine particles in the environment). This is in some way what fuelcell (reformer) are attempting to do, by <burning> only the hydrogen. Modern diesel engine captures carbon particle in after treatment filers - where burning it does not bring any energy, worse is producing pure CO2! So, not burning the carbon from the hydrocarbon fuel would be a way equivalent or better than the CO2 sequestration. The carbon in the fossil fuel would then only play the role of a hydrogen storage chemical bound, a simple way to go around hydrogen storage.

How it works

In the Quasiturbine engine, the four strokes of a typical cycle de Beau de Rochas (Otto cycle) are arranged sequentially around a near oval, unlike the reciprocating motion of a piston engine. In the basic single rotor Quasiturbine engine, an oval housing surrounds a four-sided articulated rotor which turns and moves within the housing. The sides of the rotor seal against the sides of the housing, and the corners of the rotor seal against the inner periphery, dividing it into four chambers. As the rotor turns, its motion and the shape of the housing cause each side of the housing to get closer and farther from the rotor, compressing and expanding the chambers similarly to the "strokes" in a reciprocating engine.

combustion cycle

Intake (aqua),
Compression (fuchsia),
Combustion (red),
Exhaust (black).

A spark plug is located
at the top (green)

On the diagram, the cycle starts and ends when a blade is near vertical or near horizontal. Intake occurs when the chamber volume increases until the blade get vertical, compression follows. A benefit of this geometry is that the ports can be angularly moved to get optimum performance.

Continuous 32 Strokes!

The Quasiturbine makes 32 engine strokes every 2 revolutions, which makes it a very compact and light engine. Because it has no dead time, the gas flows quasi-continuously at intake and at exhaust for high performance. Furthermore, during the 4 strokes process, the gas flows almost unidirectional through the engine, without flow reciprocating or reversal of direction, for a better and efficient overall dynamic performance.

Engine Exhaust Heat Recovery:
By placing a hot Quasiturbine into or around an engine exhaust pipe, and injecting pressurized hot water (steam keep in the liquid state for better heat transfer), some heat can be recovered into mechanical energy. Stirling and short steam circuit Quasiturbine could do similarly!

Primary Pressure Source

In an internal combustion engine, part of the internal pressure is due to heat, but an even more important part of this pressure comes from state change and molecular dissociation (a vapor occupied in the order of 600 times the volume of the liquid phase, and molecular dissociation gives an extra contribution to partial pressure). If you burn fuel in open air, this pressure is released in turbulent motion and is transformed into heat in the flame, which heat has to be harvested back into mechanical energy. Because fuel internal pressure has an higher quality than heat energy, it is best suitable to use quality fuels in an internal combustion engine (extracting pressure energy), and to use a Stirling as a complementary machine to recover exhaust heat losses. For the same reason, the Stirling heat engine principle apply well to primary heat source like solar, wood stove, co-generation... However, making heat specifically for a Stirling engine from a quality liquid or gaseous fuel is generally not a good idea, because of the down grading of a valuable potential fuel pressure. Of course, there are exceptions...


Combustion in rotary engine has been well demonstrated over the years by the Wankel engine, which offers far from an optimum combustion chamber condition. Because there is no central shaft, the Quasiturbine combustion chamber can be cut deep and quite volumetric for optimum combustion. Because the Quasiturbine has no dead time, the ports can be moved angularly at design to make the 4 engine strokes of different duration, without excessive port overlap, since the intake and exhaust ports are at the opposite of the chamber and to get out in the exhaust, any intaken mixture would have to go across the whole chamber. Moving the port angularly could allow for example for some in-situ post combustion treatment, or intake could be spread through several intake cavities on a wider angular area...

Since the Quasiturbine has no dead time, when a combustion stroke reaches the end, the following combustion stroke is ready to fire. Consequently, by making a small cavity in the stator housing, a flame transfer can be made to assure a continuous combustion, just like in the airplane gas turbine! A sparkplug is needed to start the process, but since it is not later needed, and because the Quasiturbine has no oil pan, the Quasiturbine can be fully submersible, with a propeller inserted in its central area, and make this way a highly performing boat outboard engine...

The Quasiturbine is most adapted for asymmetric compression ratio as the Atkinson cycle, which is designed to provide efficiency at the expense of power. The Atkinson cycle allows the intake, compression, power, and exhaust strokes of the Four-stroke cycle to occur in a single turn of the crankshaft. Owing to the linkage, the expansion ratio is greater than the compression ratio, leading to greater efficiency than with engines using the alternative Beau de Rocha (Otto) cycle. The Atkinson cycle may also refer to a four strokes engine in which the intake is held open longer than normal to allow a reverse flow into the intake manifold. This reduces the effective compression ratio and when combined with an increased stroke and/or reduced combustion chamber volume allows the expansion ratio to exceed the compression ratio while retaining a normal compression pressure.

Quasiturbine can also accommodate a turbo, even with forced induction (supercharging) known as Miller cycle. The Miller cycle is a combustion process which reduces the power lost in an engine due to the energy needed to compress the charge during the compression stroke, so leading to greater efficiency. The supercharger typically will need to be of the positive displacement kind (due to its ability to produce boost at relatively low RPM - A Quasiturbine in compressor mode will do!) otherwise low-rpm torque will suffer. The key is that the compression stroke actually starts, only when the intake chamber has pushed out some "extra" charge, say 20 to 30% of the overall motion. In other words the compression stroke is only 70 to 80% as long as the physical motion. The engine gets all the compression for 70% of the work.

Quasiturbine Simplicity

The center of the Quasiturbine is empty and can receive the differential and the accessory (generator, gearbox...) shaft on which the hooks are attached. The contour housing seals and the lateral seals are drawer type and completely jointives and continuous. Cooling can be air or liquid, or both. Housing looking alike the Wankel is fine. The Quasiturbine center allows for a cooling air flow as there is no oil pan.

The average torque is only about 30 % lower than the peak torque, which imposes little on the construction robustness. It does not need any flywheel for most application, which is a serious handicap to accelerations and to the total engine weight. It has no cumbersome oil pan and can rotate in all orientations. It has no energy consuming internal engine accessories (like the cam shafts which take substantial power). It has good homo-kinetic geometry not imposing any violent accelerations and stops to the engine components, and does not generate vibration. Because it does split large piston combustion in smaller one, it does reduce the noise by a factor of 20.

No engine is easy to make. However, the Quasiturbine engines contain no gears and few moving parts. For instance, because intake and exhaust are openings cut into the walls of the rotor housing, there are no valves or valve trains. This simplicity and compact size allows for savings in construction costs. Because its center of mass is immobile during rotation, the Quasiturbine tends to have very little or no vibrations. It has high torque at low rpm, and is hydrogen combustion compatible.

Potential Applications

The Quasiturbine high power-to-weight ratio makes it exceptionally suitable for aircraft and light mobile or recreational vehicle, and its no-vibration attributes make it suitable for use as example: powered parachutes, chainsaws and hand tools... Later, the Quasiturbine could be a general replacement engine.

Engine Exhaust Heat Recovery:
By placing a hot Quasiturbine into or around an engine exhaust pipe, and injecting pressurized hot water (steam keep in the liquid state for better heat transfer), some heat can be recovered into mechanical energy. Stirling and short steam circuit Quasiturbine could do similarly!

More Technical

Quasiturbine compared to piston engine

Quasiturbine for vehicles