Suryanarayanan, Arun (2009-05). Film Cooling, Heat Transfer and Aerodynamic Measurements in a Three Stage Research Gas Turbine. Doctoral Dissertation. Thesis uri icon

abstract

  • The existing 3-stage turbine research facility at the Turbomachinery Performance and Flow Research Laboratory (TPFL), Texas A and M University, is re-designed and newly installed to enable coolant gas injection on the first stage rotor platform to study the effects of rotation on film cooling and heat transfer. Pressure and temperature sensitive paint techniques are used to measure film cooling effectiveness and heat transfer on the rotor platform respectively. Experiments are conducted at three turbine rotational speeds namely, 2400rpm, 2550rpm and 3000rpm. Interstage aerodynamic measurements with miniature five hole probes are also acquired at these speeds. The aerodynamic data characterizes the flow along the first stage rotor exit, second stage stator exit and second stage rotor exit. For each rotor speed, film cooling effectiveness is determined on the first stage rotor platform for upstream stator-rotor gap ejection, downstream discrete hole ejection and a combination of upstream gap and downstream hole ejection. Upstream coolant ejection experiments are conducted for coolant to mainstream mass flow ratios of MFR=0.5%, 1.0%, 1.5% and 2.0% and downstream discrete hole injection tests corresponding to average hole blowing ratios of M = 0.5, 0.75, 1.0, 1.25, 1.5, 1.75 and 2.0 for each turbine speed. To provide a complete picture of hub cooling under rotating conditions, experiments with simultaneous injection of coolant gas through upstream and downstream injection are conducted for an of MFR=1% and Mholes=0.75, 1.0 and 1.25 for the three turbine speeds. Heat transfer coefficients are determined on the rotor platform for similar upstream and downstream coolant injection. Rotation is found to significantly affect the distribution of coolant on the platform. The measured effectiveness magnitudes are lower than that obtained with numerical simulations. Coolant streams from both upstream and downstream injection orient themselves towards the blade suction side. Passage vortex cuts-off the coolant film for the lower MFR for upstream injection. As the MFR increases, the passage vortex effects are diminished. Effectiveness was maximum when Mholes was closer to one as the coolant ejection velocity is approximately equal to the mainstream relative velocity for this blowing ratio. Heat transfer coefficient and film cooling effectiveness increase with increasing rotational speed for upstream rotor stator gap injection while for downstream hole injection the maximum effectiveness and heat transfer coefficients occur at the reference speed of 2550rpm.
  • The existing 3-stage turbine research facility at the Turbomachinery Performance and Flow
    Research Laboratory (TPFL), Texas A and M University, is re-designed and newly installed to enable coolant
    gas injection on the first stage rotor platform to study the effects of rotation on film cooling and heat
    transfer. Pressure and temperature sensitive paint techniques are used to measure film cooling
    effectiveness and heat transfer on the rotor platform respectively. Experiments are conducted at three
    turbine rotational speeds namely, 2400rpm, 2550rpm and 3000rpm. Interstage aerodynamic measurements
    with miniature five hole probes are also acquired at these speeds. The aerodynamic data characterizes the
    flow along the first stage rotor exit, second stage stator exit and second stage rotor exit. For each rotor
    speed, film cooling effectiveness is determined on the first stage rotor platform for upstream stator-rotor
    gap ejection, downstream discrete hole ejection and a combination of upstream gap and downstream hole
    ejection. Upstream coolant ejection experiments are conducted for coolant to mainstream mass flow ratios
    of MFR=0.5%, 1.0%, 1.5% and 2.0% and downstream discrete hole injection tests corresponding to
    average hole blowing ratios of M = 0.5, 0.75, 1.0, 1.25, 1.5, 1.75 and 2.0 for each turbine speed. To
    provide a complete picture of hub cooling under rotating conditions, experiments with simultaneous
    injection of coolant gas through upstream and downstream injection are conducted for an of MFR=1% and
    Mholes=0.75, 1.0 and 1.25 for the three turbine speeds. Heat transfer coefficients are determined on the
    rotor platform for similar upstream and downstream coolant injection. Rotation is found to significantly
    affect the distribution of coolant on the platform. The measured effectiveness magnitudes are lower than that obtained with numerical simulations. Coolant streams from both upstream and downstream injection
    orient themselves towards the blade suction side. Passage vortex cuts-off the coolant film for the lower
    MFR for upstream injection. As the MFR increases, the passage vortex effects are diminished.
    Effectiveness was maximum when Mholes was closer to one as the coolant ejection velocity is
    approximately equal to the mainstream relative velocity for this blowing ratio. Heat transfer coefficient
    and film cooling effectiveness increase with increasing rotational speed for upstream rotor stator gap
    injection while for downstream hole injection the maximum effectiveness and heat transfer coefficients
    occur at the reference speed of 2550rpm.

publication date

  • May 2009