Mach Number Effects on Turbine Blade Transition Length Prediction

Abstract

The effect of a Mach number correction on a model for predicting the length of transition was investigated. The transition length decreases as the turbulent spot production rate increases. Much of the data for predicting the spot production rate comes from low speed flow experiments. Recent data and analysis showed that the spot production rate is affected by Mach number. The degree of agreement between analysis and data for turbine blade heat transfer without film cooling is strongly dependent of accurately predicting the length of transition. Consequently, turbine blade heat transfer data sets were used to validate a transition length turbulence model. A method for modifying models for the length of transition to account for Mach number effects is presented. The modification was made to two transition length models. The modified models were incorporated into the two-dimensional Navier-Stokes code, RVCQ3D. Comparisons were made between predicted and measured midspan surface heat transfer for stator and rotor turbine blades. The results showed that accounting for Mach number effects significantly improved the agreement with the experimental data.

Effects of Reynolds and Mach numbers on the profile losses of a conventional low-pressure turbine rotor cascade with an increasing pitch-chord ratio

“…6b). At rst glance, this contradicts the results of Narasimha [12] or Boyle and Simon [13]. They observed a delay of the onset of transition and a reduction of the turbulent spot production rate for increasing Mach numbers.…”

Numerical Predictions of Stanton Numbers, Skin Friction Coefficients, Aerodynamic Losses, and Reynolds Analogy Behavior for a Transsonic Turbine Vane

“…The resulting measured airfoil loss characteristics and heat transfer data are in good agreement with analytical predictions using a modified version of the STAN5 parabolic prediction code [7]. Boyle and Simon [8] propose a transition-length model to account for the effects of Mach number in their numerical predictions of turbulent boundary layers on turbine airfoils. Comparisons are made with experimental data for both stator and rotor geometries for a range of turbulence intensities and Reynolds numbers.…”

Heat Transfer Measurements in a Compressible Flow Vane Cascade Showing the Influence of Reynolds Number, Mach Number, and Turbulence Level on Transition and Augmentation of Laminar Heat Transfer by Free-Stream Turbulence

“…On the suction surface, transition is predicted early and too rapidly by the Mayle [24] turbulence model. The model does not account for the effect of curvature as noted by Rinaldi et al [26], and Mach number [25] as noted by Boyle and Simon may also play a role. Additionally, the model can quickly shift between high and low spot productions as acceleration changes from adverse to favorable providing an unphysical drop off in heat transfer prediction.…”

“…Heat transfer measurements provide critical test cases in the grounding of heat transfer predictive methods. As noted by Boyle and Simon [25] heat transfer measurements are useful in assessing effects of turbulence on heat transfer augmentation, transition and even the location and extent of separation. The constant heat flux foil technique has been used in a significant number of studies to assess local heat transfer levels [7][8][9]17,18].…”

“…Mayle [24] discussed the influence of turbulence combined with favorable and adverse pressure gradient on spot production. Other factors which affect transition include Mach number effects [25] and effects of curvature [26].…”