SCT INSTITUTE OFTECHNOLOGY DEPARTMENT OF AERONAUTICAL ENGINEERING final REVIEW of project “ENGINE SURGE DURING REHEAT ENGAGEMENT -A CASE STUDY” Carried out At HAL ENGINE DIVISION under the guidance Prof. NARAYANA SWAMY S Presented by GANESH R MANDIL SHARMA PRASHANTH C SHARATH J K

CONTENTS ABSTRACT AIM AND OBJECTIVES INTRODUCTION LITERATURE SURVEY ENGINE MK-811 ENGINE MODULES AFTERBURNER/REHEAT MAINFOLD SYSTEM A/B SYSTEM COMPONENTS SURGE SNAGS OCCURED IN ENGINE SNAGS DUE TO REHEAT CONCLUSION REFERENCES

ABSTRACT Jaguar is a low altitude fighter and trainer aircraft used by Indian Air Force (IAF), powered by ADOUR MK-811 engine. The license of engine manufacture are from RR/TM. The present TBO life for MK-811engine are 1200 hrs of service usage and withdraw for service related defects. The study of available data reveals that the major defects occurring in these engines are turbine gas temperature, surging, low thrust, reheat snags ,high NH etc.. The most probable cause and maximum number of withdrawals are identified to be due to reheat and surge. MK-811 engine repair schemes and analysis on components which are related to the reheat snag was analyzed. Based on the case study ,the various reasons for failure faced by the engines due to REHEAT and remedial measures are taken.

AIM OF THE PROJECT The main aim is to extract maximum thrust during reheat without any physical damage to the engine components. Engine components analysis was carried out which are related to the reheat snag. Study on afterburner. Components causing surge and possible solutions to avoid surge. To study the root cause for the engine surge during reheat engagement.

INTRODUCTION REHEAT Reheat or after burning is a method of augmenting a turbojet or turbo fan engine thrust, with a relatively small weight increase, an engine thrust can be doubled. fuel consumption is 3 to 8 times greater than engine dry running conditions. Therefore reheat is used for short duration to improve takeoff, climb, combat and for single engine landing. There are some problems which occurs due to reheat engagement like Surge, Vibrations, unusual noise and buzz.

INTRODUCTION ENGINE SURGE A compressor stall occurs when there is disruption to flow of air in the engine compressor. A compressor stall occurs when the pressure of air entering the engine drops below the pressure in the compressor. Then compressed air expands and travels towards the area of less pressure. this happens quit fast and can be explosive. Engine surge occurs when the compressor completely looses compression and the explosive effect is herd

Literature Survey The study on various aircraft engines showed that the surge occurs mainly during REHEAT. During reheat the components of the Reheat system also get affected. Failure of these components will lead to surge.

INTRODUCTION TO TURBO FAN ENGINE

TURBOFAN ENGINE Turbo fan Engines have basic components: Fan Compressor Combustor Turbine Nozzle As MK 811 is a turbofan engine, therefore we will discuss about Adour MK 811 and its Components.

ENGINE MK-811 A spool turbofan with reheat capability and operates at moderate temperatures and rotational speed. There are seven stages of compressor, 2LP & 5HP. A high pressure shaft is supported by a ball and roller bearing which carries bevel gear to drive the external high speed gear box . The reheat jet pipe and burner manifold forms a part of the propulsion unit assembly together with a variable area exhaust nozzle.

LEADING PARTICULARS Type Compressor Compression Ratio Turbine Combustion Chamber By-pass ratio Engine RPM Thrust (kg/SHP) Aircraft Weight Direction of rotation TBO MK-811 Axial flow turbofan engine 7 stage (2 LP & 5 HP) 11.8:1 2 stage (1 LP & 1 HP) Annular 0.75:1 N1 = 14,144 & N2 = 16,132 2549 kg (dry) & 3811 kg(wet) Jaguar 784kg (1728 lbs) Anti-clockwise viewed from rear 1200 hrs

ENGINE MODULES It has a total of 12 modules, each module can be individually replaced Module1 :Low Pressure compressor consisting of one stage titanium rotor blades(27 blades) then one stage aluminum stator blades then one stage aluminum rotor blades(32 blades).   Module 2: 2 stator vanes which are aluminum Module 3 is where bypass of air starts and It is a low bypass type of engine

Module 4 is the High pressure compressor which has 5 stage rotor and 4 stage stator. The rotor blades are titanium while the stator blades are made up of aluminum. Module5 is the High Pressure Nozzle Guide Vanes (HP NGV) Module 6 is the HP Turbine. It has 78 nemonic rotor blades Module 7 is low pressure NGV Module 8 is low pressure turbine Module 9 is the jet exhaust. This is where the air mixture happens Module 10 consists of gear box and many small accessories like LP pump, HP pump, AC generator, air starter Module 11 consists of oil tank (21 pins cap),fuel control unit, re-heat fuel control unit. Oil control unit has 3 filters oil filter, LP fuel filter, RH fuel filter. Module 12 is catalytic igniters which is fitted to the afterburner

AFTER BURNER(A/B) systems

REHEAT/Afterburner SYSTEMS Reheat or after burning is augmenting a turbojet or turbo fan engine thrust, with small increase in weight. The fuel consumption is about 3 to 8 times greater than engine dry running conditions. Reheat is used for short duration to improve takeoff, climb, combat and for single engine landing. For efficient combustion necessary to have more oxygen for complete combustion of fuel . 75% of oxygen is unburnt. Reheat fuel uses this unburnt oxygen plus oxygen by-pass air for combustion.

AFTERBURNER SYSTEM COMPONENTS Afterburner Fuel Filter Vapour Gutter Metering Unit Non-return Main Fuel Fill Valve A/B Speed Controlled Arming Switch Part Throttle Reheat Valve Nozzle Actuating Rams Afterburner/Reheat Fuel Control Unit

AFTERBURNER FUEL FILTER It presents particles of dirt and foreign matter from entering the afterburner system Fuel from LP passes through the filter element. Any contamination being deposited on the external surface of the filter the filtering capacity is 40 microns. Vapour Gutter Metering Unit The vapour gutters spray fuel into the gas stream. Non-return Main Fuel Fill Valve The catalyst non-return valve assembly is fitted on the underside of the diffuser casing. The non-return valve is a sliding piston type valve. The ferrule and filters assemble consists of a housing in which the catalyst fuel and air are mixed.

A/B Speed Controlled Arming Switch The speed switch is a hydraulically operate two position valve sensing engine speed. prevents afterburning selection below a specific engine speed. The afterburner speed controlled arming switch is fitted to reduce the possibility of engine surge during slam accelerations, direct into afterburning from low engine speed in non-afterburning throttle range. Part Throttle Reheat Valve To provide a separate catalyst fuel flow to the catalysts when part throttle afterburning is selected. To provide a by-pass flow across the augmenting valve when pump delivery pressures may be too low to open the augmenting valve.

Nozzle Actuating Rams The nozzle is a conventional type of unbalanced hydraulic ram using fuel as the hydraulic medium The Variable nozzles open to maintain pressure and to ensure reheat has no effect on engine Reheat Fuel Control Unit Fuel from low pressure system is fed to total flow control which uses P3 air high pressure.

Surge Surge is a complete breakdown in compression resulting in a reversal of flow & violent expulsion of previously compressed air out through the engine intake. In other terms, surging in a gas turbine means that the pressure at the delivery end of the compressor becomes very high as a result of reduced flow at the compressor outlet.

Causes of surge A surge from a turbofan engine is the result of instability of the engines operating cycle Compressor surge may be caused by engine deterioration Nozzle Actuating Rams are not opening timely Arming switch to control A/B Speed is not functioning

SYMPTOMS OF SURGE Surge is recognize by loud banging coming from the engine with engine instrument fluctuation. However 80% that air flow problems through the compressor are encountered. Tremendous vibration will be experienced due to flow reversal caused inside the engine. Visible flames from the inlet and from the tail pipe. Engine parameters fluctuation and EGT increase.

SNAGS OCCURRED IN ENGINE From the study some snags occurred in the engine are as follow Surge TET() Vibration Nozzle not opening NH() Unscheduled Reheat Unusual Noise Buzz

Adour MK-811 RTS Analysis 2007-2013

SNAGS DUE TO REHEAT Study shows that, There are some major and repeating snags in engine due to reheat Unscheduled reheat Surge Fuel leakage Unusual noise from gear box Acceleration time is more Flame after reheat shut off Surge during part throttle reheat PTR delay Nozzle Not Opening NH

The engines RTS during the year 2007 & 2008 are around 12. SNAGS IN 07 & 08 The engines RTS during the year 2007 & 2008 are around 12.

The engines RTS during 09,10,11are around 29. SNAGS IN 09,10& 11 The engines RTS during 09,10,11are around 29.

The engines RTS during the year 2012 & 2013 are around 7. SNAGS IN 12 & 13 The engines RTS during the year 2012 & 2013 are around 7.

CONCLUSION Engines are designed to obtain maximum thrust, range endurance and their own operational life. however without completion of their time between overhaul life engines are being withdrawn from service. The ADOUR MK 811 engines are assured for 1200 hours of service life, these hours are assured based on their actual service, flying conditions. Based on case study and analysis on components which are related to reheat snag on Adour MK 811 engines are, unscheduled reheat, nozzle malfunction, fuel leak from RHFCU, surge in PTR reheat, etc,. and the necessary remedial measures to be taken to over come the snags are discussed.

REFERENCES We have referred some books, documents and journals available at HAL engine division. -The Jet Engine by ROLLS-ROYCE TURBO MECCA -Aircraft Gas Turbine engine Technology by Irwin e Treager. -.

THANKYOU