Partition Alignment in Three Dimensional Unstructured Mesh Multi-Physics Modelling

AbstractHigh-order discretization techniques offer the potential to significantly reduce the computational costs necessary to obtain accurate predictions when compared to lower-order methods. However, efficient and universally-applicable high-order discretizations remain somewhat illusive, especially for more arbitrary unstructured meshes and for incompressible/low-speed flows. A novel, high-order, central essentially non-oscillatory (CENO), cell-centered, finite-volume scheme is proposed for the solution of the conservation equations of viscous, incompressible flows on three-dimensional unstructured meshes. Similar to finite element methods, coordinate transformations are used to maintain the scheme’s order of accuracy even when dealing with arbitrarily-shaped cells having non-planar faces. The proposed scheme is applied to the pseudo-compressibility formulation of the steady and unsteady Navier-Stokes equations and the resulting discretized equations are solved with a parallel implicit Newton-Krylov algorithm. For unsteady flows, a dual-time stepping approach is adopted and the resulting temporal derivatives are discretized using the family of high-order backward difference formulas (BDF). The proposed finite-volume scheme for fully unstructured mesh is demonstrated to provide both fast and accurate solutions for steady and unsteady viscous flows.

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Effects of Bleed Rate and Endwall Location on the Aerodynamic Behavior of a Circular Hole Bleed Off-Take

Journal of Turbomachinery ◽

10.1115/1.2752191 ◽

2006 ◽

Vol 129 (4) ◽

pp. 645-658 ◽

Cited By ~ 15

Author(s):

B. A. Leishman ◽

N. A. Cumpsty ◽

J. D. Denton

Keyword(s):

Circular Hole ◽

Unstructured Mesh ◽

Three Dimensional ◽

Air Pressure ◽

Suction Surface ◽

Primary Flow ◽

Jet Engine ◽

Blade Passage ◽

Pressure Surface ◽

Flow Through

In a jet engine bleed off-takes on the hub and casing endwalls, part way through the compressor, supply high-pressure air for cooling, sealing, de-icing, and aircraft cabin air applications; bleed also assists compressor operation at part-speed conditions. Two separate issues are of interest: the bleed off-take air pressure and the interaction of the bleed off-take with the primary flow through the blade passage. In this paper, the aerodynamic behavior is presented for a circular-hole bleed off-take at three endwall locations within a stationary cascade blade passage: at midpassage; near the blade pressure surface; and near the blade suction surface. Results from low-speed cascade experiments are complemented by three-dimensional numerical calculations using an unstructured mesh-based solver, in which the blade passage and bleed off-take geometry are fully modeled. The bleed off-take location and the magnitude of bleed rate influence the off-take air pressure and the interaction with the primary passage flow. For optimum design at zero and low bleed rates, off-takes near the blade pressure surface give the highest bleed air pressures and minimum loss in the blade passage. For minimum blade passage loss at higher bleed rates, however, it is necessary to take bleed near the blade suction surface. The paper discusses the causes for this pattern of behavior.

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