Upstream wake effect on flow and heat transfer characteristics at an endwall of first-stage blade of a gas turbine

Choi, Seok Min; Park, Jun Su; Chung, Hyo-Sang; Park, Sehjin; Cho, Hyung Hee

doi:10.1016/j.expthermflusci.2017.03.030

Cited by 21 publications

(4 citation statements)

References 34 publications

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“…13(e) is the reduction of endwall HTC near the suction side. It is contradictory to the knowledge obtained in experiments of linear cascade with moving bars (Park et al, 2014;Choi et al, 2017) where endwall heat transfer demonstrates high HTC in the SS and hub endwall corner because of the influence of passage vortex. Since there are no direct corresponding experiment data available to validate our simulation, we referred a similar computation case of the E 3 HP turbine stage by El-Gabry (2010), who validated their computation method through indirect comparison with other available test data.…”

Section: Sscontrasting

confidence: 94%

“…Similar models of stator/rotor ratio of 1:2 are used by in Simone et al (2012) and Wang et al (2017) which is equivalent to reduce half the wake passing frequency. However, Park et al (2014) and Choi et al (2017) revealed that the time-averaged HTC on endwall surface is directly connected with the Strouhal number which is proportional to the wake bar moving frequency.…”

Section: Introductionmentioning

confidence: 99%

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Unsteady Effects of Upstream Nozzle Wakes on Hub-Endwall Flow and Heat Transfer of an HPT Rotor

Chen

Dai

2020

JAFM

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Nozzle wakes have significant effects on the heat transfer on the rotor blade and endwall surfaces. Numerical studies have been carried out in a subsonic high pressure turbine stage to investigate the rotor's secondary flow field and endwall heat transfer. Both steady and unsteady RANS analyses were accomplished for the multiple blade rows using mixing-plane and domain-scaling techniques respectively. Special attention was focused on the particular nozzle wake structure of secondary passage vortex near the hub endwall and its effects on the endwall heat transfer characteristics. Unsteady solution indicates that the passage vortex near the rotor hub is transported toward the midspan due to the blade interaction and rotation effects. In the front passage region, the time-averaged result yields higher heat transfer up to 20% than a steady one, and the transient fluctuation amplitude reaches 40% of mean values along the passage vortex moving path. In the rear passage region, the difference between steady and unsteady solutions is negligible. Current study reveals that the major difference of wake effects between an actual turbine and a linear cascade with moving bars comes from the movement of the vortical endwall passage vortex in the incoming flow.

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Section: Sscontrasting

confidence: 94%

Section: Introductionmentioning

confidence: 99%

Unsteady Effects of Upstream Nozzle Wakes on Hub-Endwall Flow and Heat Transfer of an HPT Rotor

Chen

Dai

2020

JAFM

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“…11(a)). In the experimental work by Choi et al (2017), they also found that sharper inlet velocity profile generated lower overall heat transfer coefficients on the endwall. In addition to the reduced heat transfer levels by the inlet skew, the heat transfer patterns along the pressure side of the passage are changed by the inlet skew as well, especially for the case of r=0.61.…”

Section: Figure 9: Instantaneous and Time-averaged Pressure On Endwal...mentioning

confidence: 92%

Steady and unsteady RANS simulations of heat transfer on a turbine vane endwall with inlet boundary layer skew

Yang

Feng

Simon

2019

European Conference on Turbomachinery Fluid Dynamics and Hermodynamics

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In this study, steady Reynolds-averaged Navier-Stokes (RANS) and unsteady RANS (URANS) simulations in a turbine vane cascade are performed to study the effects of inlet boundary layer skew on flowfields in the vane passage and heat transfer over the endwall surfaces. The inlet skew simulates the relative movement between rotor platform and stator endwall in a turbine stage. The transverse motion of a moving wall, which is placed parallel to and upstream of the vane endwall, generates the inlet skew. An engine-like velocity profile yields a cascade inlet Reynolds number of 3.46×10 5 . A parametric study is conducted for two moving wall-to-freestream velocity ratios (r) of 0.61 and 0.76, representing the actual operation of an engine. In addition, steady and time-averaged results are compared to address the difference of predictions in heat transfer from the steady and unsteady simulations. The results show that the effects of unsteadiness due to inherent unsteadiness in the flow and inlet skew passage on the pressures over the endwall surface is negligible. However, the unsteadiness plays an important role in determining endwall heat transfer patterns. The inlet boundary layer skew modifies the development and migration of horseshoe vortex and passage vortex, resulting in local variation of heat transfer over most endwall surfaces. Lower heat transfer coefficients are found near the suction side beyond the passage throat, but overall heat transfer levels almost remain the same on the endwall in the presence of inlet skew.

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“…Their results showed that film cooling was affected by the passage vortex (PV), thus improving the cooling performance of the endwall, close to the SS. Choi et al [6] carried out experimental and numerical research on an endwall with a first-stage blade in a turbine cascade. They found that the heat transfer of the endwall corresponded to the distribution of secondary flows.…”

Section: Introductionmentioning

confidence: 99%

Numerical Study of Endwall Modification with Micro-Scale Ribs in a Turbine Cascade

Liu,

Song,

et al. 2023

Applied Sciences

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A novel modification method, the ‘micro-scale’ rib, is proposed to expand cooling coverage for turbine endwalls. However, the introduction of the rib will inevitably affect the flow in the near-wall region. Therefore, the variation in the flow pattern for the traditional model of secondary flow needs further exploration. In this paper, to gain a clearer understanding of the micro-scale rib, the original endwall and three types of ribbed endwalls were adopted to numerically present the detailed flow, film cooling, and heat transfer information for the endwall surface and phantom cooling on the suction side (SS) of the blade. The Ansys code CFX was utilized to solve the 3D Reynolds-averaged Navier–Stokes (RANS) equations, and the SST k-ω was selected as the turbulence model after the verification. The results show that the rib-like vortex changed the flow of the coolant and had various impacts on the cooling characteristics. Although the cooling performance of the ribbed endwall improved, it also had a negative impact on heat transfer in most cases. Compared with the original, the vertical rib cases provided optimal film cooling, with increases of 26.9% and 17.4% for rib spacing values of 8 mm and 10 mm, respectively, with little difference in heat transfer (less than 1%). In addition, the horizontal rib cases presented the worse performance for both film cooling and heat transfer, which indicates that the rib layout should consider a mainstream flow direction for future designs.

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Upstream wake effect on flow and heat transfer characteristics at an endwall of first-stage blade of a gas turbine

Cited by 21 publications

References 34 publications

Unsteady Effects of Upstream Nozzle Wakes on Hub-Endwall Flow and Heat Transfer of an HPT Rotor

Unsteady Effects of Upstream Nozzle Wakes on Hub-Endwall Flow and Heat Transfer of an HPT Rotor

Steady and unsteady RANS simulations of heat transfer on a turbine vane endwall with inlet boundary layer skew

Numerical Study of Endwall Modification with Micro-Scale Ribs in a Turbine Cascade

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