In this paper working of Quasi-turbines is discussed. It is a rotary combustion engine generating rotary motion through the combustion of the fuel, unlike the piston which convert reciprocating motion. These devices directly generate the rotary motion avoiding sine wave crank shaft conversion. This paper reveals a high efficiency, low emissions combustion process called Photo Detonation which is superior to thermal ignition process like Spark Ignition, Compression Ignition ,Homogeneous Charge Compression Ignition.

The main principle behind this Quasi-turbine is to generate rotary motion through the combustion of fuel in the four combustion chambers only in one revolution involving the general four strokes Suction, Compression, Expansion and Exhaust. Complex set of valves and camshafts which use substantial amount of power, valve inertia ,intake depressurization and detonation are the major problems associated with the reciprocating piston engines. Though these problems can be solved by Wankel Rotary Combustion, the problems of low efficiency, poor combustion, high emissions, starting trouble made this ineffective. So these Quasi-turbines can overcome both the problems of piston and Wankel engines.

The Quasi-turbine consists of four combustion chambers associated with carriages, are semi-spherical in shape and inturn are sealed perfectly from each other. In all the combustion chambers all the four events occur per each revolution. The expansion stroke in each CC makes the Quasi-turbine to rotate. Each carriage is connected to the shaft. In this combustion namely photo-detonation, the combustion is initiated by a short strong pressure pulse.

Since there is no necessity to convert reciprocating motion to rotary motion there will be no mechanical losses. As high compression ratios can be maintained we can have high thermal efficiencies and low SFC s. Here dead times and reallocating times are totally absent. As the surface/volume ratio is very high Detonation is extremely low. It can generate high powers even at lower RPM s. Cooling can be easily provided. Combustion is very clean. Unburnt HC s and CO s are extremely less. As the residence of N2 in CC is reduced Nox emissions are reduced a lot.