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

Abstract

Stanton numbers, skin friction coefficients, aerodynamic losses, and Reynolds analogy behavior are numerically predicted for a turbine vane using the FLUENT commercial code with a k-e RNG model to show the effects of Mach number, mainstream turbulence level, and surface roughness. Test vane geometry, configuration, and flow conditions match ones from a practical application. Comparisons with experimental data on wake aerodynamic losses are made. Numerical and experimental results show that the magnitudes of integrated aerodynamics losses increase dramatically as the exit Mach number increases from 0.35 to 0.71. Downstream wakes are also widened as the mainstream turbulence intensity level, exit Mach number, or level of surface roughness increases. Deviations of numerically predicted 2 St=C f magnitudes from 2 St=C f ffi 1 on the vane suction and pressure sides are also presented for a variety of flow conditions.

Aerodynamic Losses in Turbines with and without Film Cooling, as Influenced by Mainstream Turbulence, Surface Roughness, Airfoil Shape, and Mach Number

“…For the present airfoil shape and configuration, numerical predictions by Zhang and Ligrani [39] show that flow separation regions (as well as associated form drag contributions) are about the same for all three airfoils, regardless of their k s /cx value (of either 0, 0.00069, or 0.00164). Numerical results also show that boundary layers are almost entirely turbulent along the entire length of all three tested airfoils.…”

“…The data of Zhang and Ligrani [8] show that magnitudes of Integrated Aerodynamic Losses change by much larger amounts as either the freestream Mach number or turbulence intensity are altered, when the airfoil is roughened (compared to smooth airfoil results). Other recent investigations are described by Zhang et al [37,38] and by Zhang and Ligrani [39,40].…”

“…Numerical results also show that boundary layers are almost entirely turbulent along the entire length of all three tested airfoils. From these numerical predictions, values of k + s just before the airfoil trailing edge for M e,∞ = 0.6, normalized by friction velocity and kinematic viscosity, are approximately 24.8 and 60.9 for the small-sized roughness and large-sized roughness, respectively [39].…”

“…With this approach, the local stagnation pressure loss is normalized by a quantity which does not vary with cascade exit location. Zhang et al [5,37,38], Jackson et al [54], Chappell et al [55], and Zhang and Ligrani [8,27,39,40] employ integrated aerodynamic loss IAL to quantify aerodynamic losses in turbine components. Dimensional magnitudes of Integrated Aerodynamic Loss, IAL, are determined by integrating profiles of (P oi − P oe ) with respect to y in the transverse flow direction across the wake for one single vane spacing, from −p/2 to p/2 [54].…”

“…section. Additional details on experimental apparatus and procedure details are provided by Zhang et al [37,38], and Zhang and Ligrani [27,39,40]. Wake profile data are presented for two different locations downstream the vane trailing edge, which illustrate the influences of varying freestream turbulence intensity level, surface roughness, and vane Mach number on local aerodynamic losses, Integrated…”