EXPERIMENT 6 CASE STUDY OF JET ENGINE (ROLLS ROYCE GRIFFON)

AIMTo do a case study on a jet engine.

THEORYA jet engine is a reaction engine discharging a fast moving jet that generates thrust by jet propulsion in accordance with Newton's third law of motion.Highly compressed air and fuel are burnt in the combustion chamber. The energy generated is transferred to the exhaust gases. This change in momentum between inlet and exhaust gases provides the thrust.

The different types of jet engines are Turbojet Turboprop Turbofan Ramjet Scramjet

WORKING PRINCIPLE

Almost all jet engines work on the basis of Brayton's cycle.

ENGINE: ROLLS ROYCE GRIFFON

INTRODUCION

TheRolls-Royce Griffonis a British 37-litre(2,240cu in)capacity, 60-degreeV-12, liquid-cooledaero enginedesigned and built byRolls-Royce Limited. In line with company convention, the Griffon was named after abird of prey, in this case theGriffon Vulture.

Developments over its predecessor RR Merlin

One significant development was the incorporation of thecamshaftandmagnetodrives into the propellerreduction gearsat the front of the engine, rather than using a separate system of gears driven from the back end of thecrankshaft; this allowed the overall length of the engine to be reduced as well as making the drive train more reliable and efficient.

The Griffon was the first Rolls-Royce production aero engine to use a hollow crankshaft as the means of lubricating the main andbig end bearings, providing a more even distribution of oil to each bearing

GENERAL CHARACTERISTICS

Fuel System - Speed/Density type Fuel Injection (injected into eye of supercharger)

Weight - 2,000 lbs

Power - 2,450 HP

Performance parameters - 0.82 lbs/hp, 314 psi BMEP, 0.42 lbs fuel/hp/hr SFC

Octane fuel

Specific power: 0.91 hp/in3 (41.4 kW/L)

Compression ratio: 6:1

Power-to-weight ratio: 1.03 hp/lb (1.69 kW/kg)

COMPONENTS

Pistons: Machined from close forgings of Rolls-Royce 59 alloy (aluminum). The piston carries two compression rings and an oil scraper ring above the piston pin and another oil scraper ring below it. The oil ring groves are drilled to return oil to the crankcase. The fully floating piston pins of hardened steel are captured by spring wire circlips.

Cylinders : Twelve cylinders consisting of high-carbon steel, floatingwet liners[15]set in two, two-piece cylinder blocks of castaluminum alloyhaving separate heads and skirts.

Connecting rods : H-section machined nickel-steel forgings, each pair consisting of a plain and a forkedrod. The forked rod carries a nickel-steel bearing block which accommodates steel-backed lead-bronze-alloy bearing shells.

Crankshaft : One-piece, machined from anitrogen-hardenednickel-chromemolybdenumsteel forging.Statically and dynamically balanced. Seven main bearings and six throws. Internal oilway, with feed from both ends, used to distribute lubricants to main and big end bearings.

Crankcase : Two aluminum-alloy castings joined together on the horizontal centreline. The upper portion bears the wheelcase, cylinder blocks and part of the housing for theairscrew reduction gear; and carries the crankshaft main bearings.

Wheelcase : Aluminum-alloy casting fitted to rear of crankcase. Carries the supercharger; and houses drives to the supercharger, auxiliary gearbox coupling, engine speed indicator, airscrew constant-speed unit, intercooler pump and fuel pump, as well as the oil and coolant pumps in the lower half crankcase.

APPLICATIONS

In 1965, SFR Yugoslavia used Griffon engines as the main power unit for their first domestically producedself-propelled artillery system, the S65, but the system was withdrawn from service in the early 1980s, because of poor fuel economy. They formed an integral part of the Spitfire series.

The 1980Miss BudweiserUnlimited Hydroplanedominated the race circuit with a Rolls-Royce Griffon engine. It was the last of the competitive piston-engined boats, before turbo shaftpower plants took over.

In modern daytractor pulling, Griffon engines are also in use, a single or double, rated each at 3,500hp (2,600kW).

The Griffon engine continues to be used in restored Fireflies and later mark Spitfires worldwide. TheRoyal Air ForceBattle of Britain Memorial Flightis a notable current operator of the Griffon.

Griffon-enginedFairey Barracuda Preserved Rolls-Royce Griffon with cutaway sections.

Spitfire LF Mk IX,MH434with Griffon engine.

RESULTThus the jet engine and its applications were studied.