Download - Gte1.06 - Engine Turbine
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ENGINE GAS TURBINE 1ALD 20203
UNIKL MIATEngine Turbine
BY MUHAMAD SYAZWAN MAT GHANI
2OVERVIEW• OPERATION & CHARACTERISTICS OF DIFFERENT TURBINE
BLADE TYPES• BLADE TO DISK ATTACHMENT• NOZZLE GUIDE VANES• CAUSES & EFFECTS OF TURBINE BLADE STRESS & CREEP
3TURBINE SECTION• TO EXTRACT ENERGY AFTER FUEL & AIR ARE BURNED• TRANSFORM
• TURBINE ABSORBS APPROXIMATELY 60% - 80% OF TOTAL PRESSURE ENERGY FROM HOT GASES
• CONSISTS OF 4 BASIC ELEMENTSCASESTATORSHROUDROTOR
A PORTION OF KINETIC ENERGY
(HOT GASES)
MECHANICAL ENERGYINTO
ACCESSORIES
COMPRESSORRUN
4TURBINE ELEMENT
5TURBINE CASE• TO ENCLOSE TURBINE ROTOS & STATOR• HAS FLANGES ON BOTH SIDE TO PROVIDE A MEANS OF
ATTACHING THE TURBINE
6TURBINE ROTOR• CONSISTS OF:
• TURBINE DISK IS THE ANCHORING COMPONENT FOR TURBINE BLADES (EITHER BOLTED OR WELDED TO MAIN SHAFT)
• CENTRIFUGAL FORCE ACTING ON TURBINE BLADE WILL MAKE IT GROW OR CREEPING
• FIR TREE SLOTS IS MOST COMMONLY USE FOR ATTACHING TURBINE BLADES
TURBINE ROTOR / WHEEL TURBINE SHAFT
• ROTOR IS DYNAMICALLY BALANCED & TURBINE BLADES ARE MOMENT WEIGHED
• SHAFT ROTATES WITH BEARING THAT ARE LUBRICATED BY OIL
7TURBINE ROTOR
8TURBINE BLADES• AIRFOIL SHAPED DESIGNED TO EXTRACT MAXIMUM
AMOUNT OF ENERGY FROM FLOW OF HOT GASES• MADE OF STEEL FORGED or NICKEL ALLOY• FIT LOOSELY FOR EXPAND TO FIT TIGHTLY AT NORMAL
OPERATING TEMPERATURE• COMMONLY USE • BLADE CAN BE OPEN or SHROUDED AT TIP• BLADES ARE CLASSIFIED:
FIR TREE SLOT ATTACHMENT
IMPULSE BLADE
REACTION TURBINE BLADE
IMPULSE-REACTION TURBINE BLADE
9TURBINE BLADES
LOOSE FIT FIR TREE WITH OPEN END / TIP
10TURBINE BLADES
LOOSE FIT FIR TREE WITH SHROUDED END / TIP
11TURBINE BLADES – IMPULSE BLADES• IMPULSE BLADE
BLADES ONLY CHANGE THE DIRECTION OF AIRFLOW COMING FROM TURBINE NOZZLE WITH NO CHANGE OF GAS PRESSURE OR VELOCITY
TURBINE WHEEL:
IMPULSE FORCE ON TURBINE BLADES PUSHES TURBINE WHEEL TO ROTATE
ABSORBS THE FORCE REQUIRED TO CHANGE THE DIRECTION OF
AIRFLOW
ROTARY MOTION
CONVERT TO
12TURBINE BLADES – IMPULSE BLADES
13TURBINE BLADES – IMPULSE BLADES
14TURBINE BLADES – REACTION BLADES• REACTION BLADES
PRODUCE TURNING FORCE BASED ON AERODYNAMIC ACTION
THE TURBINE BLADES FORM A SERIES OF CONVERGENT DUCT
TURBINE BLADES ROTATE DUE TO REACTION OF AIRFLOW ACTING ON ITS AIRFOIL SHAPE
GAS VELOCITY
PRESSURE
RESULTS IN CREATING A COMPONENT OF LIFT THAT ROTATES TURBINE WHEEL
15TURBINE BLADES – REACTION BLADES
1. Turbine nozzle in a reaction turbine direct exhaust gas flow to strike turbine blades at positive angle of attack
2. Convergent shape between the turbine blades increases its gas velocity & decreases its pressure
16IMPULSE & REACTION TURBINE
17TURBINE BLADES - IMPULSE-REACTION• IMPULSE-REACTION BLADES
MOST MODERN AIRCRAFT USES THIS TYPE OF TURBINE BLADE
ADVANTAGE : WORKLOAD ALONG THE BLADE IS EVENLY DISTRIBUTED
BLADE ROOT BLADE TIPTHIS DESIGN CREATES UNIFORM VELOCITY & PRESSURE
DROP ACROSS THE ENTIRE BLADE LENGTH
IMPULSE SECTION
REACTION SECTION
18TURBINE BLADES - IMPULSE-REACTION
IMPULSE-REACTION TURBINE BLADES
19STAGGER ANGLE• TURBINE BLADE HAS STAGGER ANGLE (GREATER AT TIP
COMPARE TO ROOT)• REASON FOR TWIST
• RESULTS CERTAIN CHANGES IN VELOCITY, PRESSURE & TEMPERATURE OCCUR THROUGH TURBINE (FIG. PG.20)
• AS AIRFLOW LEAVES TURBINE BLADE, THE RESPECTIVE VELOCITY & PRESSURE ARE EQUAL BETWEEN BLADE TIP & ROOT
MAKE GAS FLOW FROM COMBUSTION SYSTEM DO EQUAL WORK AT ALL POSITIONS ALONG
THE LENGTH OF BLADE
TO ENSURE THE FLOW ENTERS EXHAUST SYSTEM WITH A UNIFORM AXIAL VELOCITY
20STAGGER ANGLE
A TYPICAL TURBINE BLADE SHOWING TWISTED CONTOUR
21STAGGER ANGLE
GAS FLOW PATTERN THROUGH NOZZLE & BLADE
22BLADE TO DISC ATTACHMENT• THE METHOD OF ATTACHING TURBINE BLADES TO TURBINE
DISC IS OF CONSIDERABLE IMPORTANCE, SINCE STRESS IN THE DISC AROUND THE FIXING OR IN BLADE ROOT HAS AN IMPORTANT BEARING ON THE LIMITING RIM SPEED
• THE BLADES ON EARLY WHITTLE ENGINE WERE ATTACHED BY THE DE LAVAL BULB ROOT FIXING
• THE BLADE IS FREE IN SERRATIONS WHEN TURBINE IS STATIONARY & STIFFENED IN ROOT BY CENTRIFUGAL LOAD
BUT THIS DESIGN WAS SOON SUPERSEEDED BY
THE “FIR TREE” – COMMONLY USED NOW
THEY ARE THEN LOCKED IN PLACE WITH RIVETS OR
METAL TABS.
INVOLVES VERY ACCURATE MACHINING TO ENSURE THAT THE LOADING IS SHARED BY
ALL THE SERRATIONS
23BLADE TO DISC ATTACHMENT
VARIOUS METHODS OF ATTACHING BLADES TO TURBINE DISCS
24TURBINE STATOR/NOZZLE GUIDE VANES• REFERRED TO TURBINE NOZZLE / TURBINE GUIDE
VANES / NOZZLE DIAPHRAGM• LOCATED DIRECTLY AFT OF COMBUSTION SECTION &
FORWARD OF TURBINE WHEEL
• PURPOSE
• FORMS A NUMBER OF CONVERGING NOZZLE THAT CONVERT SOME OF EXHAUST GASES PRESSURE TO VELOCITY ENERGY
EXPOSED TO HIGH TEMPERATURE IN A GAS TURBINE ENGINE
COLLECT HIGH ENERGY AIRFLOW FROM COMBUSTORS & DIRECT THE FLOW TO STRIKE THE TURBINE ROTOR AT APPROPRIATE ANGLE
25TURBINE STATOR/NOZZLE GUIDE VANES
26SHROUD• TURBINE NOZZLE ASSEMBLY CONSISTS OF AN INNER &
OUTER SHROUD THAT RETAINS & SURROUND THE NOZZLE VANE
• THE NOZZLE VANES MUST BE CONSTRUCTED LOOSELY TO ALLOW FOR THERMAL EXPANSION
• OUTER SHROUD IS CUT INTO SEGMENTS TO ALLOW FOR EXPANSION
• WITHOUT ALLOWING FOR THERMAL EXPANSION, THE HIGH ENGINE TEMPERATURE WILL CAUSE SEVERE DISTORTION OR WARPING
27TURBINE NOZZLE / TURBINE STATOR
28TURBINE NOZZLE / TURBINE STATOR
29CAUSES & EFFECTS OF STRESS & CREEP• TURBINE SECTION
AREA THAT SUBJECT TO GREAT DEAL OF HEAT & STRESSCRACKING IS MOST COMMON TYPE OF DAMAGE
FOLLOWED BY EROSIONTO CARRIED OUT THE INSPECTION OF THE COMPLETE
TURBINE SECTION; IT IS BEST TO INSPECT TURBINE NOZZLE VANE, TURBINE DISK & TURBINE BLADE SEPARATELY
30CAUSES & EFFECTS OF STRESS & CREEP
HOTTEST GASES PASS THROUGH THE FIRST TURBINE NOZZLE VANE
NORMALLY SMALL CRACK ARE FREQUENTLY FOUND (CHECK LIMITATION)
CERTAIN TURBINE NOZZLE VANE ARE CRACKING BY HIGH SPEED GASES CAUSING BOWING & WARPING
THIS BOWED & WARPAGE IS MEASURED ON THE TRAILING EDGE BY USING FLAT PLATE FIXTURE & THICKNESS GAUGE (CHECK LIMITATION)
TURBINE NOZZLE VANE
31CAUSES & EFFECTS OF STRESS & CREEP
INSPECTED BY USING STRONG INSPECTION LIGHT & MAGNIFYING GLASS
ANY CRACK ON TURBINE DISK CAUSES REJECTION & REPLACEMENT
SLIGHT PITTING EXIST CAN BE BLENDED BY STONING & POLISHING
TURBINE DISK
32CAUSES & EFFECTS OF STRESS & CREEP
• POTENTIAL TO CATASTROPHIC ENGINE FAILURE• CRACKING ARE NOT PERMITTED ON TURBINE BLADE• STRESS RUPTURE CRACKS TO BE CARRIED OUT ON
LEADING & TRAILING EDGE INCLUDE EXCESSIVE TEMPERATURE OR CENTRIFUGAL LOADING
• TURBINE BLADE ARE PRONE TO BLADE CREEP (HIGH TEMPERATURE) & CENTRIFUGAL LOADING DURING EACH CYCLE (SLIGHTLY LONGER)
• BLADE CREEP CAN BE DIVIDEDINTO 3 STAGES :
TURBINE BLADE
PRIMARY
SECONDARY
TERTIARY
33CAUSES & EFFECTS OF STRESS & CREEPPRIMARY CREEP
OCCURS DURING FIRST RUN WHEN NEW BLADES EXPERIENCE OPERATIONAL STRESS FOR THE FIRST TIME
SECONDARY CREEP OCCURS SLOWLY DURING MANY HOURS OF OPERATION
TERTIARY CREEP OCCURS AT AN ACCELERATED RATE AFTER A PERIOD OF
SECONDARY CREEP DUE TO ATTRIBUTION OF HOT START, OVER TEMPERATURE, OPERATION AT HIGH POWER SETTING CONTINUOUSLY & BLADE EROSION
34CAUSES & EFFECTS OF STRESS & CREEP• TURBINE BLADE & VANE ALSO MUST BE CHECKED FOR
UNTWIST WHICH RESULTING DECREASE BLADE EFFICIENCY & DETERIORATION
• OTHER INSPECTION FOR TURBINE BLADE ARE CURLING OF BLADE TIP, CRACKING & BREAKING BLADE TIP
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THANK YOU FOR YOUR ATTENTION
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