Experimental Study of the Endwall Heat Transfer of a Transonic Nozzle Guide Vane With Upstream Jet Purge Cooling Part 2—Effect of Combustor-Nozzle Guide Vane Misalignment

Journal of Thermal Science and Engineering Applications

et al. 2022

In this paper, the endwall film cooling and vane pressure side surface phantom cooling performances of a first nozzle guide vane (NGV) with endwall contouring, similar to an industry gas turbine, were experimentally and numerically evaluated at simulated realistic gas turbine operating conditions (high inlet freestream turbulence level of 16 %, exit Mach number of 0.85, exit Reynolds number of 1.7 × 106). A novel numerical method for the predictions of adiabatic wall film cooling effectiveness was proposed, based on a double coolant temperature model. The credibility and accuracy of this numerical method were validated by comparing the predicted results with experimental data. Results indicate that the present numerical method can accurately predict endwall film cooling performance and vane surface phantom cooling performance for both the ideal low density ratio (DR=1.2) and the typical high density ratio (DR=2.0) conditions. The endwall film cooling effectiveness, vane surface phantom cooling effectiveness and secondary flow field were compared and analyzed for the axisymmetric convergent contoured endwall at three coolant injection angles (small injection angle of θ = 40°, design injection angle of θ = 50°, large injection angle of θ = 60°), two density ratios (low density ratio of DR=1.2, typical high density ratio of DR=2.0) and the design blowing ratio (BR=2.5), based on the commercial CFD solver ANSYS Fluent.

Turbine Vane Endwall Film Cooling and Pressure Side Phantom Cooling Performances With Upstream Coolant Flow at Various Injection Angles

Journal of Thermal Science and Engineering Applications

et al. 2022

Effects of Upstream Step Geometries on Endwall Film Cooling and Phantom Cooling Performances of a Transonic Turbine Vane

Journal of Thermal Science and Engineering Applications

et al. 2022

This paper presents a detailed experimental and numerical study on endwall film cooling and vane pressure side surface phantom cooling at simulated realistic gas turbine operating conditions (high inlet freestream turbulence level of 16%, exit Mach number of 0.85 and exit Reynolds number of 1.7×106). The experiment measurements were conducted at Virginia Tech's transonic blowdown wind tunnel for two configurations: baseline cascade (HR = 0 mm) and forward-facing step geometry (HR = -5 mm). The numerical predictions were performed by solving the steady-state Reynolds Averaged Navier Stokes (RANS) with Realizable k-e turbulence model. Based on a double coolant temperature model, a novel numerical method for the predictions of adiabatic wall film cooling effectiveness was proposed. The qualitative and quantitative comparisons between the numerical prediction results and experiment data are provided in this paper. The results indicate that this method can reliably predict endwall film cooling distributions and vane pressure side surface phantom cooling distributions, and significantly reduce (more than 50%) numerical prediction errors. The effects of upstream step geometries were numerically studied at the design flow conditions (BR = 2.5, DR=1.2), by quantizing the endwall film cooling effectiveness, vane pressure side surface phantom cooling effectiveness and total pressure loss coefficients (TPLC) for various upstream step heights: three forward-facing step heights (HR = −8, −5, −3 mm), a baseline cascade (HR = 0 mm), and four backward-facing step heights (HR = 3, 5, 6.78, 10 mm).

Uncertainty Quantification on the Cooling Performance of a Transonic Turbine Vane With Upstream Endwall Misalignment

Hao

Journal of Turbomachinery

et al. 2022

With increasing aerodynamic and thermal loads, film cooling has been a popular technology integrated into the design of the modern gas turbine vane endwall, especially for the first-stage vane endwall. A staggering amount of research has been completed to quantify the effect of operating conditions and cooling hole geometrical properties. However, most of these investigations did not address the influence of the manufacturing tolerances, assembly errors and operation degradations on the endwall misalignment. In this paper, uncertainty quantification (UQ) analysis was performed to quantify the impacts of upstream endwall misalignment uncertainties on the endwall film cooling performance and vane surface phantom cooling performance. The upstream endwall misalignment, step geometry with various step heights, commonly exists between the combustor exit and the first-stage vane endwall. Based on the non-intrusive polynomial chaos expansion (NIPC) and the uniform probability distribution assumption, the deviation (step height) uncertainties of the upstream endwall misalignment were quantified. To predict the endwall secondary flow and film cooling effectiveness in the transonic linear vane passage, the commercial CFD solver ANSYS FLUENT was used to numerically solve the three dimensional steady-state Reynolds-Averaged Navier-Stokes (RANS) equations. The robustness analysis of endwall film cooling performance and phantom cooling performance to the upstream endwall misalignment was conducted for three design upstream step heights (ΔH): a baseline configuration (ΔH = 0 mm), two misaligned configurations with forward step (ΔH = −5 mm) and backward step (ΔH = 5 mm), respectively.