Effect of Squealer Tip on Rotor Heat Transfer and Efficiency

Ameri, Ali; Steinthorsson, Erlendur; Rigby, David L.

doi:10.1115/1.2841786

Cited by 159 publications

(60 citation statements)

References 14 publications

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“…Numerical methods have been widely used to study the thermal performance of film cooling in high-pressure turbines, e.g., Ameri [21] and Yang et al [22]. Computational fluid dynamics (CFD) tools were found to be able to produce good predictions of the thermal performance of the tip leakage flow in a number of studies, both at subsonic conditions (e.g., Zhou et al [9]) and at transonic conditions (e.g., Zhang et al [18]).…”

Section: Numerical Methods and Validationmentioning

confidence: 99%

Thermal Performance of Transonic Cooled Tips in a Turbine Cascade

Zhou

2015

Journal of Propulsion and Power

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Transonic high-pressure turbines are promising candidates for future aircraft engines. Recent studies in transonic turbine cascades showed that shock waves appeared over the uncooled flat tip, which affects its heat transfer. However, the effects of coolant injection on the thermal performance of transonic cooled tips are not clear. The current study aims to understand the thermal performance of a cooled flat tip and a cooled cavity tip in a transonic turbine cascade. The effects of tip film cooling are studied at five coolant pressure ratios (which are the stagnation pressure ratios of the coolant inlet and the cascade inlet) from 0.8 to 1.2. The flow physics over the tip, the heat transfer coefficient, the film-cooling effectiveness, and the heat flux of the tip are investigated. The effects of relative endwall motion are considered.= thermal conductivity of the air, W∕m · K Ma = Mach number P = static pressure, Pa P 0 = stagnation pressure, Pa Q = overall heat flux, W q = local heat flux per unit area, W∕m 2 K Re = Reynolds number; ρVC∕μ T = temperature, K T aw;c = adiabatic wall temperature (ratio of stagnation temperature of coolant to main flow is 0.6), K T g;1 = hot-gas recovery temperature (total temperature at coolant inlet is same as inlet flow), K T w = wall temperature, K T 0 = stagnation temperature, K U = velocity of endwall, m∕s V = velocity, m∕s V x;1 = axial velocity at cascade inlet, m∕s x = coordinate in axial direction y = coordinate in tangential direction η = cooling effectiveness; T aw;c − T aw;1 ∕T c − T aw;1 μ = dynamic viscosity, Pa · s ρ = density, kg∕m 3 σ = contraction coefficient (unblocked height at the vena contracta/tip gap τ) φ = flow coefficient; V x;1 ∕U Subscripts c = coolant 1 = cascade inlet freestream 2 = cascade exit (45%C x downstream of cascade)

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Section: Numerical Methods and Validationmentioning

confidence: 99%

Thermal Performance of Transonic Cooled Tips in a Turbine Cascade

Zhou

2015

Journal of Propulsion and Power

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“…CFD tools are known to be able to produce good predictions of the aerothermal performance of the tip-leakage flow: e.g., Schabowski and Hodson [2] and Ameri et al [5]. Furthermore, CFD results can provide insight into the physics of the tip-leakage flow.…”

Section: Methodsmentioning

confidence: 99%

“…There are some studies showed that the cavity tip provides very small aerodynamic benefits or even no benefit over a flat tip. For example, based on numerical simulations of a rotor at a rotational speed of 8450 rpm, Ameri et al [5] found a reduction in the tip-leakage mass flow by using a cavity tip instead of a flat tip, but no change in the efficiency was obtained.…”

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confidence: 99%

Squealer Geometry Effects on Aerothermal Performance of Tip-Leakage Flow of Cavity Tips

Zhou

Hodson

2012

Journal of Propulsion and Power

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In a high-pressure turbine, the tip-leakage flow reduces the efficiency of the turbine and results in high metal temperatures on the blade tip. Quite a few studies showed that cavity tips produced lower loss than a flat tip. Also, cavity tips are widely used in industrial gas turbines. This paper focuses on cavity-tip geometries. Both experimental and numerical methods are used to study the aerothermal performance of the tip-leakage flow of cavity tips. The effects of the squealer height and thickness are investigated. The current research aims to understand the change of the flow physics and its impact on the loss mechanism and heat transfer as the squealer geometry changes. The flow pattern over the tip, the tip-leakage loss, and the heat transfer of the tip are investigated. Reducing the squealer thickness reduces the tip-leakage loss. The squealer height has a complex effect on the tip-leakage loss. Reducing the thickness of the squealers reduces the average heat transfer coefficient and the heat load of the tip. Increasing the height of the squealer also reduces the heat transfer coefficient of the tip. However, due to the increase in the surface area of the tip, the increase of the squealer height increases the heat load of the tip.

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“…Ameri et al [18] numerically studied the flow and heat transfer on the squealer tip which had a 2% and 3% cavity recess. Ameri et al [19,20] numerically investigated the effect of tip clearance and casing (shroud) recess on heat transfer and stage efficiency for different recess depths.…”

Section: Introductionmentioning

confidence: 99%

Influence of Different Rim Widths and Blowing Ratios on Film Cooling Characteristics for a Blade Tip

Wang

Sundén

Zeng³

et al. 2012

Journal of Heat Transfer

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Three-dimensional simulations of the squealer tip on the GE-E 3 blade with eight film cooling holes were carried out. The effect of the rim width and the blowing ratio on the blade tip flow and cooling performance were revealed. Numerical simulations were performed to predict the leakage flow and the tip heat transfer with the k-e model. For the squealer tip, the depth of the cavity is fixed but the rim width varies to form a wide cavity, which can decrease the coolant momentum and the tip leakage flow velocity. This cavity contributes to the improvement of the cooling effect in the tip zone. To investigate the influence on the tip heat transfer by the rim width, numerical simulations were performed as a two-part study: (1) unequal rim width study on the pressure side and the suction side and (2) equal rim width study with rim widths of 0.58%, 1.16%, and 1.74% of the axial chord (0.5 mm, 1 mm, and 1.5 mm, respectively) on both the pressure side rim and the suction side rim. With different rim widths, the effect of different global blowing ratios, i.e., M ¼ 0.5, 1.0 and 1.5, was investigated. It is found that the total heat transfer rate is increasing and the heat transfer rates on the rim surface (RS) rapidly ascend with increasing rim width.

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Effect of Squealer Tip on Rotor Heat Transfer and Efficiency

Cited by 159 publications

References 14 publications

Thermal Performance of Transonic Cooled Tips in a Turbine Cascade

Thermal Performance of Transonic Cooled Tips in a Turbine Cascade

Squealer Geometry Effects on Aerothermal Performance of Tip-Leakage Flow of Cavity Tips

Influence of Different Rim Widths and Blowing Ratios on Film Cooling Characteristics for a Blade Tip

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