IC Engines

IC EnginesAssignment 1Himanshu RanjanB12084Mechanical Engineering

Gnome Engine

A rotary engine is essentially a standard Otto cycle engine, but instead of having a fixed cylinder block with rotating crankshaft as with a conventional radial engine, the crankshaft remains stationary and the entire cylinder block rotates around it. In the most common form, the crankshaft was fixed solidly to an aircraft frame, and the propeller simply bolted onto the front of the crankcase.It is a unique type of engine such that the intake valves are located within the pistons, this makes it different from Otto four stroke engine.This engine also follows four stroke cycle:-IntakeCompressionCombustionExhaust

Three key factors contributed to the rotary engines success are: -Smooth running: Rotaries delivered power very smoothly because (relative to the engine mounting point) there are no reciprocating parts, and the relatively large rotating mass of the cylinders acted as a flywheel.Weight advantage: Many conventional engines had to have heavy flywheels added to smooth out power impulses and reduce vibration. Rotary engines gained a substantial power-to-weight ratio advantage by having no need for an added flywheel.Improved cooling: When the engine runs the rotating cylinder block creates its own fast-moving cooling airflow, even with the aircraft at rest.

Steam Locomotive Engine

Asteam locomotiveis arailway locomotivethat produces itspulling powerthrough asteam engine. These locomotives are fuelled by burning combustible material, usually coal, wood or oil, to produce steam in aboiler.Steam engines powered most trains from the early 1800s to the 1950s. The engines varied in size and complexityIn a steam engine, the boiler (fuelled by wood, oil, or coal) continuously boils water in an enclosed chamber, creating high-pressure steam. This high pressure steam causes piston to move forward and backward.

Steam engines operates through four different phases:-

First stroke:- In this the steam from the boiler enters thesteam chestand is admitted to the front end of the cylinder by a valve slide (illustrated in blue). The high pressure steam presses the piston backward, driving the engine wheels around one half turn.

Exhaust:- At the end of the piston stroke, the valve shifts, allowing the remaining steam pressure to escape through the exhaust port underneath valve slide (in blue).

First strokeExhaustSecond stroke:- At the same time, the valve slide begins admitting high pressure steam to the back end of the cylinder. This presses the piston forward, pulling the engine wheels around another half turn.

Exhaust:- At the end of the second stroke, the steam is released from the rear portion of the cylinder.

Second strokeExhaustTwo Cylinder Stirling Engine

AStirling engineis aheat enginethat operates by cyclic compression and expansion of air or other gas (theworking fluid) at different temperatures, such that there is a net conversion ofheatenergy to mechanicalwork.Stirling engines feature a completely closed system in which the working gas is alternately heated and cooled by shifting the gas to different temperature locations within the system.In the two-cylinder Stirling, one cylinder is kept hot while the other is kept cool. In the shown figure, the lower-left cylinder is heated by burning fuel. The other cylinder is kept cool by air circulating through a heat sink (using cooling fins).The engine also has aregenerator, illustrated by the chamber containing the green hatch lines. It is constructed of material that readily conducts heat and has a high surface area, typically a mesh of closely spaced, thin metal plates. When hot gas is transferred to the cool cylinder, it is first driven through the regenerator, where a portion of the heat is deposited. When the cool gas is transferred back, this heat is reclaimed; thus the regenerator pre heats and pre cools the working gas, improving efficiency.

The Stirling cycle can be thought of as four different phases: expansion, transfer, contraction, and transfer.

Expansion:- Most of the gas in the system has just been driven into the hot cylinder. The gas heats and expands driving both pistons inward.Transfer:- The gas has expanded (about 3 times in this example). Most of the gas (about 2/3) is still located in the hot cylinder. Flywheel momentum carries the crankshaft the next 90 degrees, transferring the bulk of the gas to the cool cylinder.

ExpansionTransferContraction:- The majority of the expanded gas has shifted to the cool cylinder. It cools and contracts, drawing both pistons outward.

Transfer:- The contracted gas is still located in the cool cylinder. Flywheel momentum carries the crank another 90 degrees, transferring the gas to back to the hot cylinder to complete the cycle.

ContractionTransferThank You