Exit combustor ow and thermal elds entering downstream stator vane passages in a gas turbine engine are highly nonuniform. These ow and thermal elds can signi cantly affect the development of the secondary ows in the turbine passages attributing to high platform heat transfer and large aerodynamic losses. An analysis is presented of the effects of both the temperature and velocity pro les on the secondary ows in the endwall region of a rst-stage stator vane geometry. These effects were assessed using the predicted ow eld results from computational uid dynamics (CFD) simulations. Prior to using the predictions, these CFD simulations were benchmarked against ow eld data measured in a large-scale, linear, turbine vane cascade. Good agreement occurred between the computational predictions and experimentally measured secondary ows. Analyses of the results for several different cases indicate the stagnation pressure gradient is a key parameter in determining the character of the secondary ows. Nomenclature= mass ow through passage n = coordinate normal to inviscid streamline P = pitch P 0 = total pressure p = static pressure q = velocity vector R = radius of curvature of an inviscid streamline R g = gas constant Re ex = Reynolds number, CU ex / m Re in = Reynolds number, CU in / m S = span of stator vane s = coordinate aligned with inviscid streamline T S = static temperature U = freestream velocity U, V , W = absolute velocity components u, v, w = secondary ow plane, transformed velocity components V n = normal velocity, ¡ u sin w ms + v cos w ms V S = streamwise velocity, u cos w ms + v sin w ms V z = spanwise velocity, w X, Y, Z = absolute, stationary coordinate system x = distance normal to the secondary ow plane Y S = pressure loss coef cient,Çm y = distance tangent to the secondary ow plane z = radial or spanwise distance z + = inner coordinates spanwise distance, z p (s w / q )/ m c = speci c heat ratio= boundary-layer thickness d th = thermal boundary-layer thickness e = dissipation m = viscosity q = density s w = wall shear stress w ms = midspan turning angle, tan ¡ 1 (v ms / u ms ) X s = streamwise vorticity, X x cos(w ms ) + X y sin(w ms ) X x = x vorticity, (@W / @Y ) ¡ (@V / @Z ) X y = y vorticity, (@U / @Z ) ¡ (@W / @X ) Subscripts av = mass averaged value ex = value at vane exit in = value at 0.7C upstream of vane mid = value at vane midspan wall = value at vane endwall

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Endwall secondary flows in gas turbines are complicated by highly non-uniform combustor exit profiles. Most experimental endwall studies do match turbine Reynolds numbers, but not Mach numbers, and assume constant temperature conditions with a simple turbulent boundary layer. This paper presents results for benchmarking of a CFD code with experimental data and the effects of inlet profiles at both low and high Mach number conditions under matched Reynolds number conditions. Detailed flowfield measurements were obtained in a large scale, linear turbine vane cascade and were used for CFD benchmarking. Analysis of the results for spanwise varying inlet profiles indicate that the stagnation pressure gradient is the key parameter in determining the character of the secondary flows in the first Stator vane passage. Temperature gradients applied at the inlet were distorted in relation to the secondary flows influencing heat transfer to the vane and the inlet thermal field for the next rotor stage. Comparisons of CFD simulations at engine operating Mach number and Reynolds number conditions to the low-speed wind tunnel simulations indicate that the secondary flow pattern develops similarly up to the location of the shock.

Exit combustor flow and thermal fields entering downstream stator vane passages in a gas turbine engine are highly nonuniform. These flow and thermal fields can significantly affect the development of the secondary flows in the turbine passages contributing to high platform heat transfer and large aerodynamic losses. The flow and thermal fields combine to give nonuniform total pressure profiles entering the turbine passage which, along with the airfoil geometry, dictate the secondary flow field. This paper presents an analysis of the effects of varying total pressure profiles in both the radial and combined radial and circumferential directions on the secondary flowfields in a first-stage stator vane. These inlet conditions used for the first vane simulations are based on the exit conditions predicted for a combustor. Prior to using the predictions, these CFD simulations were benchmarked against flowfield data measured in a large-scale, linear, turbine vane cascade. Good agreement occurred between the computational predictions and experimentally measured secondary flows. Analyses of the results for several different cases indicate variations in the secondary flow pattern from pitch to pitch, which attributes to the rationale as to why some airfoils quickly degrade while others remain intact over time.

Exit combustor flow and thermal fields entering downstream stator vane passages in a gas turbine engine are highly non-uniform. These flow and thermal fields can significantly affect the development of the secondary flows in the turbine passages contributing to high platform heat transfer and large aerodynamic losses. The flow and thermal fields combine to give non-uniform total pressure profiles entering the turbine passage which, along with the airfoil geometry, dictate the secondary flow field. This paper presents an analysis of the effects of varying total pressure profiles in both the radial and combined radial and circumferential directions on the secondary flow fields in a first stage stator vane. These inlet conditions used for the first vane simulations are based on the exit conditions predicted for a combustor. Prior to using the predictions, these CFD simulations were benchmarked against flow field data measured in a large-scale, linear, turbine vane cascade. Good agreement occurred between the computational predictions and experimentally measured secondary flows. Analyses of the results for several different cases indicate variations in the secondary flow pattern from pitch to pitch, which attributes to the rationale as to why some airfoils quickly degrade while others remain intact over time.