Direct Computations of Boundary Layers Distorted by Migrating Wakes in a Linear Compressor Cascade

Zaki, Tamer A.; Wissink, Jan G.; Durbin, Paul A.; Rodi, W.

doi:10.1007/s10494-009-9216-0

Cited by 40 publications

(31 citation statements)

References 20 publications

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“…This technique matches that used in the experimental investigation of this case [31]. However on the pressure side the irrotational curved stream introduces some difficulty in determining the boundary layer thickness, hence the approach used by Chen et al [34] is employed, such that δ = 1.936r| (r|du/dr|) max (12) with the edge velocity computed accordingly. For Case 8 the LES prediction of the edge velocity is in excellent agreement with the experimental data, as shown in Figure 4.…”

Section: Case 8 β = 40 •mentioning

confidence: 95%

“…The influence of freestream turbulence on transition on turbine blades has been investigated using LES [11], highlighting the need for reasonably posed inlet conditions. Simulations of a linear compressor cascade at a moderate Reynolds number was studied by Zaki et al [12] -the periodically passing wake caused the suction-side flow to separate and roll-up into discrete K-H vortices. On the pressure side the flow underwent a bypass transition due to the passing of the wake.…”

Section: Introductionmentioning

confidence: 99%

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Large Eddy Simulation of a Controlled Diffusion Compressor Cascade

McMullan

Page

2010

Flow Turbulence Combust

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In this research a Controlled Diffusion (CD) compressor cascade stator blade is simulated at a Reynolds number of ∼ 700, 000, based on inflow velocity and chord length, using Large Eddy Simulation (LES). A wide range of flow inlet angles are computed, including conditions near the design angle, and at high negative and positive incidence. At all inlet angles the surface pressure distributions are well-predicted by the LES. Near the design angle the computed suction side boundary layer thickness agrees well with experimental data, whilst the pressure side boundary layer is poorly predicted due to the inability of LES to capture natural boundary layer transition on the present grid. A good estimation of the loss is computed near the design angle, whilst at both high positive and negative incidences the loss is less well predicted owing to discrepancies between the computed and experimental boundary layer thickness. At incidences above the design angle a laminar separation bubble forms near the leading edge of the suction surface, which undergoes a transition to turbulence. Similar behaviour is noted on the pressure surface at negative incidence. At high negative incidence contra-rotating vortex pairs are found to form around the leading edge inThe authors would like to thank Rolls-Royce plc and the UK Technology Strategy Board for the funding this work under the CFMS Core Programme (TP/L3001H). The simulations in this study were performed on HECToR, the UK National Supercomputing Facility, under the UKAAC-2 Framework, EPSRC grant number EP/F005954/1. response to an unsteady stagnation line across the span of the blade. Such structures are not apparent in time-averaged statistical data due to their highly-transient nature.

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Section: Case 8 β = 40 •mentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

Large Eddy Simulation of a Controlled Diffusion Compressor Cascade

McMullan

Page

2010

Flow Turbulence Combust

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“…The Reynolds number based on the inflow velocity and the axial chord length is 138 500. This choice of non-dimensionalization and Reynolds number are the same as adopted in previous DNS studies (Zaki et al 2009(Zaki et al , 2010 and Floquet and transient growth analyses (Rocco et al 2015).…”

Section: Discretization and Convergencementioning

confidence: 99%

Transition induced by linear and nonlinear perturbation growth in flow past a compressor blade

et al. 2017

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Flow past a NACA 65 blade at chord-based Reynolds number 138 500 is studied using stability analysis, generalized (spatially weighted) transient growth analysis and direct numerical simulations (DNS). The mechanisms of transition on various sections of the blade observed in previous work by Zaki et al. (J. Fluid Mech., vol. 665, 2010, pp. 57-98) are examined, with a focus on the pressure side around the leading edge. In this region, the linearly most energetic perturbation has spanwise wavenumber 40π (five boundary-layer thicknesses) and is tilted against the mean shear to take advantage of the Orr mechanism. In a DNS, the nonlinear development of this optimal perturbation induces Λ structures, which are further stretched to hairpin vortices before breaking down to turbulence. At higher spanwise wavenumber, e.g. 120π, a free-stream optimal perturbation is obtained upstream of the leading edge, in the form of streamwise vortices. During its nonlinear evolution, this optimal perturbation tilts the mean shear and generates spanwise periodic high-and low-speed streaks. Then through a nonlinear lift-up mechanism, the low-speed streaks are lifted above the high-speed ones. This layout of streaks generates a mean shear with two inflectional points and activates secondary instabilities, namely inner and outer instabilities previously reported in the literature.

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“…With the enormous development in computer science, the large eddy simulation (LES) method has been used in compressor cascade flow simulation in recent years, utilizing a large amount of computer resources (Matsuura & Kato, 2007;McMullan & Page, 2011;Teramoto, 2005;Zaki, Wissink, Durbin, & Rodi, 2009). Modeling threedimensional corner separation requires the CFD code to be very robust.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of RANS turbulence models in simulating the corner separation of a high-speed compressor cascade

Zhang

2015

Engineering Applications of Computational Fluid Mechanics

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A typical high-speed compressor cascade flow is simulated using an eddy viscosity model and a Reynolds stress model. Based on comparisons with experimental results, the simulation accuracies of the two turbulence models are evaluated, and some recommendations are provided for further research. Inside the cascade flow passage, the simulation accuracies of both turbulence models decrease because of the corner effect. Downstream of the blade, the wake mixing influence, and thus the flow loss, is under-predicted by both turbulence models. Compared with the linear eddy viscosity model, the modification of the simulation accuracy with regard to endwall flow prediction using the Reynolds stress model is limited, which only occurs at a highly positive incidence angle. The corner separation strength and wake mixing influence predicted by the eddy viscosity model are surpassed by those of the Reynolds stress model. At a negative incidence angle, the simulation result of the Reynolds stress model is proved to be physically unreasonable according to the flow loss prediction.

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Direct Computations of Boundary Layers Distorted by Migrating Wakes in a Linear Compressor Cascade

Cited by 40 publications

References 20 publications

Large Eddy Simulation of a Controlled Diffusion Compressor Cascade

Large Eddy Simulation of a Controlled Diffusion Compressor Cascade

Transition induced by linear and nonlinear perturbation growth in flow past a compressor blade

Evaluation of RANS turbulence models in simulating the corner separation of a high-speed compressor cascade

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