Mhetras, Shantanu (2006-08). Experimental study of gas turbine blade film cooling and internal turbulated heat transfer at large Reynolds numbers. Doctoral Dissertation. Thesis uri icon

abstract

  • Film cooling effectiveness on a gas turbine blade tip on the near tip pressure side and on the squealer cavity floor is investigated. Optimal arrangement of film cooling holes, effect of a full squealer and a cutback squealer, varying blowing ratios and squealer cavity depth are also examined on film cooling effectiveness. The film-cooling effectiveness distributions are measured on the blade tip, near tip pressure side and the inner pressure and suction side rim walls using a Pressure Sensitive Paint (PSP) technique. A blowing ratio of 1.0 is found to give best results on the pressure side whereas the other tip surfaces give best results for blowing ratios of 2. Film cooling effectiveness tests are also performed on the span of a fully-cooled high pressure turbine blade in a 5 bladed linear cascade using the PSP technique. Film cooling effectiveness over the entire blade region is determined from full coverage film cooling, showerhead cooling and from each individual row with and without an upstream wake. The effect of superposition of film cooling effectiveness from each individual row is then compared with full coverage film cooling. Results show that an upstream wake can result in lower film cooling effectiveness on the blade. Effectiveness magnitudes from superposition of effectiveness data from individual rows are comparable with that from full coverage film cooling. Internal heat transfer measurements are also performed in a high aspect ratio channel and from jet array impingement on a turbulated target wall at large Reynolds numbers. For the channel, three dimple and one discrete rib configurations are tested on one of the wide walls for Reynolds numbers up to 1.3 million. The presence of a turbulated wall and its effect on heat transfer enhancement against a smooth surface is investigated. Heat transfer enhancement is found to decrease at high Re with the discrete rib configurations providing the best enhancement but highest pressure losses. Experiments to investigate heat transfer and pressure loss from jet array impingement are also performed on the target wall at Reynolds numbers up to 450,000. The heat transfer from a turbulated target wall and two jet plates is investigated. A target wall with short pins provides the best heat transfer with the dimpled target wall giving the lowest heat transfer among the three geometries studied.
  • Film cooling effectiveness on a gas turbine blade tip on the near tip pressure side and on the
    squealer cavity floor is investigated. Optimal arrangement of film cooling holes, effect of a full
    squealer and a cutback squealer, varying blowing ratios and squealer cavity depth are also
    examined on film cooling effectiveness. The film-cooling effectiveness distributions are
    measured on the blade tip, near tip pressure side and the inner pressure and suction side rim
    walls using a Pressure Sensitive Paint (PSP) technique. A blowing ratio of 1.0 is found to give
    best results on the pressure side whereas the other tip surfaces give best results for blowing ratios
    of 2. Film cooling effectiveness tests are also performed on the span of a fully-cooled high
    pressure turbine blade in a 5 bladed linear cascade using the PSP technique. Film cooling
    effectiveness over the entire blade region is determined from full coverage film cooling,
    showerhead cooling and from each individual row with and without an upstream wake. The
    effect of superposition of film cooling effectiveness from each individual row is then compared
    with full coverage film cooling. Results show that an upstream wake can result in lower film
    cooling effectiveness on the blade. Effectiveness magnitudes from superposition of effectiveness
    data from individual rows are comparable with that from full coverage film cooling.
    Internal heat transfer measurements are also performed in a high aspect ratio channel and
    from jet array impingement on a turbulated target wall at large Reynolds numbers. For the
    channel, three dimple and one discrete rib configurations are tested on one of the wide walls for
    Reynolds numbers up to 1.3 million. The presence of a turbulated wall and its effect on heat
    transfer enhancement against a smooth surface is investigated. Heat transfer enhancement is
    found to decrease at high Re with the discrete rib configurations providing the best enhancement
    but highest pressure losses. Experiments to investigate heat transfer and pressure loss from jet array impingement are also performed on the target wall at Reynolds numbers up to 450,000.
    The heat transfer from a turbulated target wall and two jet plates is investigated. A target wall
    with short pins provides the best heat transfer with the dimpled target wall giving the lowest heat
    transfer among the three geometries studied.

publication date

  • August 2006