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DESIGN, ANALYSIS AND LIFE ESTIMATION OF A FIRST STAGE ROTOR BLADE USING NICKEL BASED
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This article is presented by:
A.K.Matta1a
L.Narayana

DESIGN, ANALYSIS AND LIFE ESTIMATION OF A FIRST STAGE ROTOR BLADE USING NICKEL BASED SUPER ALLOY(CMSX4)


ABSTRACT-In a combined cycle gas turbine (CCGT) plant, high-temperature heat is input to the power plant, usually from burning of fuel,which is converted to electricity as one of the outputs.In continuous operation turbine blades are prone to high cycle fatigue failures.These failures are essentially due to resonance that occur at blade critical speed dry startup and shut down condition and in certain cases due to excursion of machine near an operating speed which is close to one of resonances.From the above criteria the failure of a First Stage rotor blade leads to callastropic effects . The material of the blade is considered as CMSX4 which is Nickel based super Alloy (Al2o3,TiN and AIN) .Mathematical calculations using inlet and outlet triangles and S.N diagram approach were carried out. From the paper, it can be concluded that for the continous operation of a CMSX4 rotor blade, power capacity of plant increases.

INTRODUTION
In a thermal power plant water is the working medium. High pressure steam requires strong, bulky components. High temperatures require expensive alloys made from nickel or cobalt, rather than inexpensive steel. These alloys limit practical steam temperatures to 655 C while the lower temperature of a steam plant is fixed by the boiling point of water. With these limits, a steam plant has a fixed upper efficiency of 35 to 42%.
An open circuit gas turbine cycle has a compressor, a combustor and a turbine. For gas turbines the amount of metal that must withstand the high temperatures and pressures is small, and lower quantities of expensive materials can be used. In this type of cycle, the input temperature to the turbine, is relatively high (900 to 1,400 C). The output temperature of the flue gas is also high (450 to 650 C). This is therefore high enough to provide heat for a second cycle which uses steam as the working fluid; (a Rankine cycle).
In a combined cycle power plant, the heat of the gas turbine's exhaust is used to generate steam by passing it through a heat recovery steam generator (HRSG) with a live steam temperature between 420 and 580 C. The condenser of the Rankine cycle is usually cooled by water from a lake, river, sea or cooling towers. This temperature can be as low as 15 C
In an automotive powerplant, an Otto, Diesel, Atkinson or similar engine would provide one part of the cycle and the waste heat would power a Rankine cyclesteam or Stirling engine, which could either power ancillaries (such as the alternator) or be connected to the crankshaft by a turbo compounding system.
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