Experimental Investigation of Secondary Flow Structure in a Blade Passage With and Without Leading Edge Fillets

Mahmood, Gazi I.; Acharya, Sumanta

doi:10.1115/1.2427075

Cited by 29 publications

(11 citation statements)

References 27 publications

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“…8(c) because of the additional film-jet momentum issued from the leading edge slots. As indicated in [18,26], the lower Yaw values of the endwall flows contribute to the weakening of the passage vortex. This is an additional advantage of the effects of the endwall film-cooling with the right configuration of the coolant slots or holes.…”

Section: Yaw Angle Deviation (δYaw)mentioning

confidence: 91%

“…The total pressure losses (P t,r -P t,x ) in the present cascade are obtained in a pitch-plane slightly downstream of the exit. The investigations of [3,17,26] indicate the reductions of adverse effects, size, and strength of the passage vortex system directly correspond to the decrease in C pt,loss at the cascade exit. Equation (3) excludes the pressure losses in the film-cooling slots and inlet boundary layer and is also used by [12,17,28,29].…”

Section: Total Pressure Loss Coefficient (C Ptloss )mentioning

confidence: 92%

“…Flow yaw angle near the endwall is responsible for the strong pitchwise crossflow [26,27] which then contributes to the development of the passage vortex system. The yaw angles relative to the axial direction in the blade passage increase in the endwall boundary layer as the streamlines of low velocity turn towards the suction side to balance the pitchwise pressure gradient with the opposing radial force [27].…”

Section: Yaw Angle Deviation (δYaw)mentioning

confidence: 99%

“…The secondary vortex structures result in entropy generation and increase the pressure losses along the blade passage [4,17,26]. The total pressure loss from the inlet to exit of the blade passage is a measure of the secondary flow losses and quantifies the aerodynamic performance of the passage.…”

Section: Total Pressure Loss Coefficient (C Ptloss )mentioning

confidence: 99%

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Effects of Upstream Endwall Film Cooling on a Vane Cascade Flowfield

Mahmood

Arnachellan

2018

Journal of Propulsion and Power

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The effects of film-cooling on the endwall region flow and aerodynamic losses are investigated experimentally as the film-flow is delivered from the slots in the endwall upstream of a linear vane cascade. Four slots inclined at 30° deliver the film-jet parallel to the main flow at four blowing ratios between 1.1 and 2.3 and at a temperature ratio of 1.0. The slots are employed in two configurations pitchwise-all four slots open (case-1) and two middle slots open (case-2). The inlet Reynolds number to the cascade is 2.0E+05. Measurements of the blade surface pressure, axial vorticities, yaw angles, and total pressure loss distributions along the cascade are reported with and without (Baseline) the film-cooling flow. The results show the film-flow changes the orientations, distributions,and strength of the endwall secondary flows and boundary layer. The case-1 of film-cooling provides more massflux and momentum than the case-2 affecting the passage vortex legs. The overall total pressure losses at the cascade exit are always lower for the film-cooling cases than for the Baseline. The overall losses are also lower at the low blowing ratios, but higher at the high blowing ratios for the film-cooling case-1 than for the case-2. NomenclatureC, C ax , P, S = true blade-chord, axial blade-chord, pitch, span C P,Blade = blade surface static pressure coefficient C pt,loss , C Pt,Loss = total pressure loss coefficient M = passage mass flow rate MFR, M in = mass fraction ratio, inlet blowing ratio P b,x = pressure on blade surface P s,r , P t,r = (static pressure, total pressure) at reference plane P t,x , P t,box = local total pressure at exit, total pressure in plenum box PS, SS, TE = pressure-side, suction-side, trailing edge Re = inlet Reynolds number based on actual-chord U = freestream velocity (X, Y, Z) = local Cartesian coordinates (X G , Y G , Z G ) = global Cartesian coordinates Lower Case u, v, w = velocity components along (X, Y, Z) s = blade surface coordinate Greek δ = boundary layer thickness Δ = change in related quantity ω = vorticity ρ = density

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Section: Yaw Angle Deviation (δYaw)mentioning

confidence: 91%

Section: Total Pressure Loss Coefficient (C Ptloss )mentioning

confidence: 92%

Section: Yaw Angle Deviation (δYaw)mentioning

confidence: 99%

Section: Total Pressure Loss Coefficient (C Ptloss )mentioning

confidence: 99%

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Effects of Upstream Endwall Film Cooling on a Vane Cascade Flowfield

Mahmood

Arnachellan

2018

Journal of Propulsion and Power

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“…Yan Shi et al [8] believe that the fillet on the turbine stage is extremely effective in inhibiting the flow separation near the leading edge of the rotor blade. The mechanism of the fillet structure to reduce loss lies in that it can reduce the intensity and size of horseshoe vortexes, thus delaying the development of passage vortices [9][10][11]. It can be seen that shaping at the junction between the blade root and endwall, whether it is leading edge or surrounding the entire blade root, is very important for the influence of passage.…”

Section: Introductionmentioning

confidence: 99%

Effects of Blade Fillet Structures on Flow Field and Surface Heat Transfer in a Large Meridional Expansion Turbine

2019

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This paper is a continuation of the previous work, aiming to explore the influence of fillet configurations on flow and heat transfer in a large meridional expansion turbine. The endwall of large meridional expansion turbine stator has a large expansion angle, which leads to early separation of the endwall boundary layer, resulting in excessive aerodynamic loss and local thermal load. In order to improve the flow state and reduce the local high thermal load, five typical fillet distribution rules are designed. The three-dimensional Reynolds-Averaged Navier-Stokes (RANS) solver for viscous turbulent flows was used to investigate the different fillet configurations of the second stage stator blades of a 1.5-stage turbine, and which fillet distribution is suitable for large meridional expansion turbines. The influence of fillet structures on the vortex system and loss characteristics was analyzed, and its impact on wall thermal load was studied in detail. The fillet structure mainly affects the formation of horseshoe vortexes at the leading edge of the blade so as to reduce the loss caused by horseshoe vortexes and passage vortexes. The fillet structure suitable for the large meridional expansion turbine was obtained through the research. Reasonable fillet structure distribution can not only improve the flow state but also reduce the high thermal load on the wall surface of the meridional expansion turbine. It has a positive engineering guiding value.

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An experimental study of the hydrodynamics and contaminant transport in a Y‐shaped confluence with flexible submerged vegetation

Tong

Liu

Yang

et al. 2022

Hydrological Processes

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Vegetation greatly affects the flow characteristics and contaminant transport in river confluences. In this study, the flow characteristics and contaminant transport in the non‐vegetated/vegetated Y‐shaped confluence were explored systematically through a series of experiments. A total of 10 scenarios were designed to answer the three main research questions: what is the difference between the flow characteristics and contaminant transport in (1) asymmetrical and Y‐shaped confluences; (2) non‐vegetated/vegetated Y‐shaped confluences; (3) vegetated Y‐shaped confluences with different confluence ratios? The experimental results revealed that vegetation remarkably changes the internal flow structure in Y‐shaped confluences. Briefly, the velocity profile can be divided into three vertical layers within the vegetated system, but it remains nearly constant in the non‐vegetated channel. Vegetation changes the circulation location and reduces the intensity of the secondary current, weakening the strength of contaminant mixing. However, the turbulent kinetic energy within the vegetated system is larger than that in the non‐vegetated case, and it peaks at the top of the vegetation canopy. Under different confluence ratio cases, the overall fluctuation of the longitudinal dispersion coefficients along the cross‐sections in the mainstream was similar but increasing the confluence ratio causes the circulation to appear to advance and enhances its intensity. In addition, the vegetation density (200 item/m2) in this study render the manning roughness coefficient at 0.068, which is larger than that under lower vegetation density cases. The outcomes from this study are helpful for both environmental and river management applications.

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Experimental Investigation of Secondary Flow Structure in a Blade Passage With and Without Leading Edge Fillets

Cited by 29 publications

References 27 publications

Effects of Upstream Endwall Film Cooling on a Vane Cascade Flowfield

Effects of Upstream Endwall Film Cooling on a Vane Cascade Flowfield

Effects of Blade Fillet Structures on Flow Field and Surface Heat Transfer in a Large Meridional Expansion Turbine

An experimental study of the hydrodynamics and contaminant transport in a Y‐shaped confluence with flexible submerged vegetation

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