Gas turbine technology

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Gas turbine technology MTF 171
Tomas Grönstedt tomas.gronstedt_at_chalmers.se
Applied mechanics
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Why read the course ?

• Head of GE Europe about Scandinavia
• Large pool of talented people that we can tap
  on to become part of our organization. Medical
  area, power generation, aircraft engine,
  consumer finance
• As mechanical engineer, one should know how a
  jet engine works?
• Apply thermodynamics and fluid mechanics
• Fun?!
• Master thesis opportunities
• Previous work include modelingand diagnostics
  on PW100 engine JT9D, GT10C, Space launcher
  model, Cooled cooling in gas turbines, weight
  estimation, environmental modeling
• Aerospace is no longer composed of non-profit
  organizations
• GNP increased 3.8 between 1960-1990, revenue
  passenger miles 9.5
• 1990ies GNP 2.4 and RPM 5.7
• Air traffic growth triple over next 20 years.

Boeing is forecasting solid growth
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Lecture 1 - overview

• Course introduction
• History of the gas turbine
• Course content an overview
• Course evaluation process
• Revision of some elementary thermodynamics
• Gas turbine applications I
• Industrial gas turbines and aero derivatives
• Land and marine transport
• Aircraft propulsion

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History of the gas turbine

• 150 BC Hero, Aeolipile
• 1232 - Chinese began to use rockets as weapons
  (battle of Kai Keng)
• 1629 - Giovanni Branca developed a stamping mill

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History of the gas turbine

• 1687 - Sir Isaac Newtonannounces the three laws
  of motion
• Every object in a state of uniform motion tends
  to remain in that state of motion unless an
  external force is applied to it (Galileos
  concept of inertia)
• F ma
• For every action there is an equal and opposite
  reaction.

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History of the gas turbine

• 1872 - Dr. F. Stolze designed the first true gas
  turbine engine
• multistage axial compressor and turbine
  turbomachinery
• No net power output.
• Brayton cycle is loss sensitive! Specific work
  output w J/kg difference between two large
  numbers
• 1903 - Aegidius Elling of Norway built the first
  successful gas turbine
• both rotary compressors and turbines - the first
  gas turbine with excess power.

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The Elling turbine
The process was built as follows atmospheric air
enters through the compressor B, from which a
part of the compressed air is bled off at C,
constituting the net power output from the
engine. The rest of the compressed air passes to
the combustion chamber D, where fuel is injected,
E. The hot gases under pressure pass through a
water cooler F before it enters into the turbine
T. The steam produced in the cooler is mixed with
the combustion gases in front of the turbine. The
mixture of combustion gases and steam had a
temperature of about 400C.
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The Elling Turbine

• On the 27th June 1903 Elling wrote in his diary
• I think I have made the worlds first gas
  turbine which has given excess power

• In 1933 Elling propheticallywrote
• When I in 1882 started to work on the gas
  turbine it was for the sake of the aeronautics
  and I firmly believe that aeronautics is still
  waiting for the gas turbine

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History - characteristics

• High power to weight ratio
• Absence of reciprocating parts gt balance
  problems are few
• Lubricating oil consumption exceptionally low
• Reliability is high (at least it should be
  possible to make it high)
• Obvious application ?!

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History gas turbine

• Sir Frank Whittle, England patented a design for
  a gas turbine for jet propulsion.
• The specifications of the first jet engine were
  Airflow25 lb/s, Fuel Consumption 200 gal/hr or
  1300 lb/hr, Thrust 1000 lb, Specific Fuel
  consumption 1.3 lb/hr/lb
• Powered the Gloster E28/39 Britain on 15 May
  1941.

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History of the gas turbine

• In 1936
• Hans von Ohain (young Ph.D. student in Germany)
  developed and patented his own engine design.
• In 1939
• The aircraft company Ernst Heinkel Aircraft flew
  the first flight of a jet engine propelled
  aircraft, the HE178.

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Course overview

• History, revision of thermodynamics, introduction
  and applications. Ideal cycles. Industrial
  lecturer.
• Real cycles. Inclusion of component losses in
  preliminary design. Elementary nozzle and
  radial compressor theory. Hand out of Design
  task 1.
• Aircraft engines. Hand in of design task 1.
• Turbines. Elementary theory, performance and
  cooling. Centrifugal compressors 2. Hand out of
  Design task 2.
• Axial compressors. Tutorial using compEDU. Hand
  in of design task 2.
• Gas turbine performance 1 and combustion. Demo
  of research linear cascade. Hand out of Design
  task 3.
• Rya combined heat and power plant study visit.
  Hand in of design task 3.
• Written exam, 2007-03-10. Oral Exam, 2007-03-20
  (suggested date decided by you)

Thermodynamic design
of whole engine
Design turbine
blading
Simulate
flight
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Heritage from predecessors

• Goals 2003
• Course should provide different learning paths
• OH-material based on CRS nomenclature
• Build on Thermodynamics course MTF041, Boles,
  M.A., Cengel, Y.A. nomenclature
• Changes after 2003 course
• Hand out design tasks earlier
• Limit lectures to 3 hours
• Changes from 2004 course
• CompEDU support axial compressors, maintenance
  and overhaul
• Design task 3 excellent for learning chapter 8
  chapter 9 but time requiring gt this year it
  REPLACES chapter 8 and chapter 9.
• Changes from 2005 course
• "gas turbine for beginners...
• Study visit
• Learning goals and continuous course evaluation
• Changes from 2006 course
• Replace problem 2.3 with exam problem. MATLAB is
  a learning goal. Review of design task 2. Single
  light industrial lecturer.

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Continuous course evaluation

• 2 course representatives
• Compensation for effort
• Mail addresses stated on course home page
• Meeting 1
• Last years meeting protocol
• Planned changes are discussed
• Goals and structure of course is discussed
• Meeting 2
• Week 3-4.
• Feedback from group should be presented
• Present feedback on homepage
• Try to implement changes for the remaining part
  of the course
• Meeting 3
• Course survey handed out during week 7-8 (prior
  to third meeting)
• Student representatives compile the results
  (prior to third meeting)
• Evaluation meeting
• Discuss course evaluation and exam results
• Protocol by student representatives to be signed
  by program responsible and course responsible
• List of changes to be implemented until next
  year.

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Course PM

• Course Events
• Invited lecturer from Volvo Aero on Thursday
• 12th February - Henrik Ekstrand
• Study visit to Rya CHP plant (only mandatory
  event).
• Design tasks
• Either 10 bonus credits on exam
• Entry ticket to oral exam
• Literature Gas Turbine Theory, Cohen, Rogers,
  Saravanamuttoo
• First print 1951, focus on application. Still
  the best presentation of the field
• A considerable amount of sittfläsk is needed
  to excel in this course
• Book sections are broken down into Relevant,
  Important, Very important reading sections

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First law conservation of energy
Closed system (ideal gas turbine cycles)
Control volume. Fig. 4-10. (For instance, inlet,
compressor, burner, turbine, nozzle)
Flow work is performed.define h upv instead
of u
Gustav Zeuner 1859

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Basic concepts related to second law

• Reversible process process that can be reversed
  without leaving any trace on the surroundings
  (5.7 reversible and irreversible processes)
• Reservoir absorb finite amount of energy
  without changing temperature (5-2 thermal
  energy reservoirs)
• Heat engine receive heat from high-temp source
  and reject to low-temp. sink. Operate on cycle.
  Produce work

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The Carnot Principle

1. The efficiency of an irreversible heat engine is
   always less than the efficiency of a reversible
   one operating between the same two reservoirs.
2. The efficiencies of all reversible heat engines
   operating between the same two reservoirs are the
   same

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The Carnot Cycle

1. Hard to realize in practice
2. Standard against which real cycles can be compared

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Perfect gas and ideal gas
Ideal gas gt following equation of state holds
For an ideal gas experiment has shown (Joules
experiment, U is independent of v)
Enthalpy is defined
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Perfect gas and ideal gas
The specific heat at constant pressure is defined
Since the enthalpy for an ideal gas depends only
on T gt
Perfect gas gt temperature dependence is
neglected
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Combining the first and second laws
The first law
Only pressure-volume work (dw-Pdv) and for
reversible changes (dqrTds)
Using ideal gas law and assuming isentropic
process (ds0 as well as dudh - (PdvvdP) - by
definition of h)
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Industrial gas turbines

• Industrial gas turbines?
• Aircraft gas turbine is self-explanatory.
  Industrial the rest.
• Requirements for industrial gas turbines
• Long required life (100 000 hours between major
  overhaul)
• Size and weight not as critical as for aircraft
  gas turbine
• Kinetic energy leaving the turbine is wasted

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Marine and land transportation

• Gas turbine characteristics
• High power density
• High fuel consumption (for low pressure ratios
  and turbine inlet temperatures) compared to
  Diesel engine
• Poor part load performance
• Low noise and low maintenance
• Mainly successful in
• naval applications
• cruise ships
• M1 tank

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Marine and land transportation

• Example
• Max speed 36 knots, cruise 18 knots. Power
  requirement
• Thus, cruise power approx. 1/8 of max power
• Combined cycles were developed to avoid part load
  gas turbine inefficiency
• COSAG COmbined Steam And Gas
• CODOG COmbined Diesel Or Gas
• COGAG COmbined Gas And Gas

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Uses of combined configurations

• COSAG
• Only used on British military ships entering
  service between 1961 and 1973.
• CODOG
• Diesel has good cruise fuel economy, but bulkier
  and larger underwater noise. Small cruise Diesel
  and a large boost gas turbine is common.
• COGAG
• Frequent in destroyers (small, fast and lightly
  armored but heavily armed warship)
• The first large vessels to use COGAG was the
  Soviet "KASHIN" class in 1964 (design
  calculations appeared on 2003 exam)

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Naval ships

• Four LM2500 GE Marine Gas Turbines (105,000 shp
  in total) are used on the DDG-51 destroyer
• COGAG
• 31 knots (57 km/h)
• American navy has more than 600 engines of
  theLM2500 type

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The Millenium - why gas turbine propulsion ?

• Lower and easier maintenance
• Gain of volume and weight considerable (900 tons
  50 pax cabins 20 crew's cabins)
• Lower noise and vibrations level gt better
  comfort
• Reliable, one serious breakdown for 48,800 h.
  (10 years of commercial exploitation)
• A factor of 1000 less need for lubrication's oil!

Gas
Electricity
Steam
Electric power (propulsion other) by combined
cycle (COGES type) gas turbines and steam
turbines. Two main alternators (25 MW) are driven
by two gas turbines type LM2500. Each gas turbine
is equipped with a recuperative boiler which
produces the necessary steam to drive a steam
turbine (one for the 2 gas turbines) used to
drive 9MW alternator gt The thermal output is
then 43 instead of 39 with gas turbine only.
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The Millenium cruise ship
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Water jets

• Propulsive water jets range from small aluminum
  units handling powers up to a few hundred
  kilowatts to stainless steel units with ratings
  up to 50MW.
• As shown below they can be supplied with steering
  and reversing systems or as boosters giving ahead
  thrust only

• Water pump connected via drive shaft

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M1 tank part load performance

• Power plant AGT-1500 Turbine, 1500hp
• Performance   Maximum speed gt 70 km/h
• 1 efficiency at idle!!!!
• High power-to-weight ratio
• Use CODOG for extended range
• LV100-5 gas turbine engine for the M1A2. The new
  engine is lighter and smaller with rapid
  acceleration, quieter running and no visible
  exhaust.

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Aircraft propulsion

• Gas turbines are the dominating power plant for
  aircraft
• Piston engines restricted to niche market (light
  aircraft)
• Three major types of engines
• Turbojet (high speed flight)
• Turbofan (medium speed flight)
• Turboprop (low speed flight)

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Turboprop the PT6Pratt Whitney Canada
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Turbofan engine
Fan diameter 2.95 meters
Power A380 maiden flight
Thrust 338kN (Trent 977)
Civil turbofan (high bpr)
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Turbofan engine
RM12 engine powering the Swedish GRIPEN fighter
Military turbofan (low bpr)
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Learning goals

• Understand the steps in the slides on
  thermodynamics
• Check Cengel and Boles
• Check revision questions on next page
• Know several different fields of application for
  industrial gas turbines
• What is characteristic of a gas turbine engine
  when compared with outer power plants?
• Know the main types of aircraft gas turbine
  engines?
• Know which speed ranges that are suitable for the
  different cycles?

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Revision questions - thermodynamics

• Derive cpcvR. Hint use definitions of cp, cv, h
  and the ideal gas law.
• Complete the step
• Use cpcvR and
• Explain why the gas turbine cycle is very
  sensitive to losses