Clocking Effects of Inlet Nonuniformities in a Fully Cooled High-Pressure Vane: A Conjugate Heat Transfer Analysis

Abstract

A high-pressure vane (HPV) equipped with a realistic film-cooling configuration has been studied. The vane is characterized by the presence of multiple rows of fan-shaped holes along pressure and suction side, while the leading edge (LE) is protected by a showerhead system of cylindrical holes. Steady three-dimensional Reynolds-averaged Navier–Stokes simulations have been performed. A preliminary grid sensitivity analysis with uniform inlet flow has been used to quantify the effect of spatial discretization. Turbulence model has been assessed in comparison with available experimental data. The effects of the relative alignment between combustion chamber and HPVs are then investigated, considering realistic inflow conditions in terms of hot spot and swirl. The inlet profiles used are derived from the EU-funded project TATEF2. Two different clocking positions are considered: the first in which hot spot and swirl core are aligned with passage; and the second in which they are aligned with the LE. Comparisons between metal temperature distributions obtained from conjugate heat transfer (CHT) simulations are performed, evidencing the role of swirl in determining both the hot streak trajectory within the passage and the coolant redistribution. The LE aligned configuration is determined to be the most problematic in terms of thermal load, leading to increased average and local vane temperature peaks on both suction side and pressure side with respect to the passage-aligned case. A strong sensitivity to both injected coolant mass flow and heat removed by heat sink effect has also been highlighted for the showerhead cooling system.

The Effect of Hot Streaks on a High Pressure Turbine Vane Cascade with Showerhead Film Cooling

“…Conversely, the hot gas is able to impact directly on the stagnation point and penetrate in between the showerhead rows of the cooling holes. Nevertheless, the hot streak effects, which are somewhat mitigated in the front part of the vane due to film cooling, lead to a significant increase in surface temperature in the rear part of the vane, in agreement with [12]. It becomes evident from Figure 12 that the lower-rear part of the pressure side is exposed to hot flow, with no coolant coverage.…”

“…Errors in predicting the peak of the cooled hot streak were below 20%. Another upgrade in the study of film cooled high pressure vanes with non-uniform inlet conditions was proposed by Griffini et al [12]. They employed the conjugate heat transfer analysis to establish that the hot streak alignment with the leading edge makes average and local temperature peaks increase on both the suction and pressure side of the vane, with respect to the passage-aligned configuration.…”

Full annulus numerical study of hot streaks propagation in a hydrogen-rich syngas-fired heavy duty axial turbine

“…Later studies also highlight the need of combustion representative data with regard to the propagation of hot streaks, considering a combination of temperature non-uniformities and engine-realistic velocity at the turbine inlet. 14,15 Later CFD simulations 16,17 confirmed the additional secondary flow production due to hot streaks and the impact of that on the spanwise migration of hot fluid on the PS and SS of rotor blade. However, those are general trends and are quite dependent on specific conditions in different turbines.…”

“…Later studies also highlight the need of combustion representative data with regard to the propagation of hot streaks, considering a combination of temperature non-uniformities and engine-realistic velocity at the turbine inlet. 14,15…”

Numerical prediction of heat transfer characteristics on a turbine nozzle guide vane under various combustor exit hot‐streaks

“…Therefore, several DHS types can be obtained depending on the combustor geometry and flow conditions. In the literature, only a few studies focus on the influences of DHS combined with residual swirl generated by LBC [22][23][24][25][26][27][28] compared to the abundant studies on the combination of uniform or rounded hot-streak with a residual swirl. The studies of Andreini et al 22 and Koupper et al 23 within the framework of the European project FACTOR are interested in the influence of a swirled DHS on turbine vane aerothermal behavior.…”