Abstract
Annular rotary engine" is a newly designed type of rotary engine that looks like a ring. This engine is able to use all types of current fuels and can be used in all fields which we need internal combustion engine.
Here, we have changed the cylinder to in a ring-shaped form and a rotary piston rotates inside the cylinder via ignition. First, intake air compresses by the piston and charges a divided combustion chamber. Last, the burned gases of the previous working cycle push the piston at the next working cycle. The first stroke is the same as two-stroke reciprocating engines and the second stroke is a little difference.
In this engine, because of efficient heat transfer and high thermal surface, maximum temperature and maximum pressure are less than the reciprocating engines; therefore, less work is produced. However, by providing the special conditions of generating the work, we can generate huge power, more fuel conversion efficiency, and higher mechanical efficiency as compared with reciprocating engines. The most important conditions are reducing friction area and the working cycle repetition at less than one period of perfect central shaft rotation. It means in this engine, we can use bigger ring while using more pistons for generating more power. When we use 2, 3, 4 ... pistons, working cycle will be complete at 1/2, 1/3, 1/4 … a period of central shaft perfect rotation. However working cycle is constant in all situations and will be same as the mentioned cycle.
Fewer emissions are the other important points in this engine. Distractive effect of KNOCK and undesirable effect of crevice volume to producing HC, is limited to zero because of constant rotation direction of the piston and increased relative linear velocity between piston and burned gases. Different working cycle leads this engine to decrease oil burning, absorption of the fuel vapor by the deposits on the walls. In addition it limits exit of unburned fuel during valve overlap. Thus all of them decrease producing HC strongly. Less NOX produced due to high thermal surface and unavailable advanced ignition (only retard is available) which makes less pressure and temperature.
Keywords: Rotary Engine, Efficiency, Power, Emission, prototype