The Secondary Flow in a Cascade of Airfoils in a Nonuniform Stream

Squire, H. B.; Winter, K. G.

doi:10.2514/8.1925

Cited by 139 publications

(27 citation statements)

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“…• Designs with low Amplification Factor (AF Marsh ) have relatively low SKE and therefore exhibit only weak sensitivity to inlet conditions. • The variations in SKE can be captured using a simple model based on the inviscid vorticity calculation of Marsh (1976) and the streamfunction approach of Squire and Winter (1951). A similar approach could be used to perform sensitivity assessments in the preliminary stage of design, and could be readily extended to engine-realistic boundary conditions.…”

Section: Discussionmentioning

confidence: 99%

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The sensitivity of turbine cascade endwall loss to inlet boundary layer thickness

Coull

Clark

Vázquez

2019

J. Glob. Power Propuls. Soc.

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The development of hub and casing boundary layers through a turbomachine is difficult to predict, giving rise to uncertainty in the boundary conditions experienced by each blade row. Previous studies in turbine cascades disagree on the sensitivity of endwall loss to such inlet conditions. This paper explores the problem computationally, by examining a large number of turbine cascades and varying the inlet boundary layer thickness. It is demonstrated that the sensitivity of endwall loss to inlet conditions is design dependent, and determined by the component of endwall loss associated with the secondary flow. This Secondary-Flow-Induced loss is characterised by a vorticity factor based on classical secondary flow theory. Designs that produce high levels of secondary vorticity tend to generate more loss and are more sensitive to inlet conditions. This sensitivity is largely driven by the dissipation of Secondary Kinetic Energy (SKE): thickening the inlet boundary layer causes the secondary vorticity at the cascade exit to be more dispersed within the passage, resulting in larger secondary flow structures with higher SKE. The effects are captured using a simple streamfunction model based on classical secondary flow theory, which has potential for preliminary design and sensitivity assessment.

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Section: Discussionmentioning

confidence: 99%

“…The secondary velocities associated with the predicted vorticity field of the Marsh model are calculated via a streamfunction ψ (Squire and Winter, 1951), such that:…”

Section: Secondary Flow Velocities and Skementioning

confidence: 99%

The sensitivity of turbine cascade endwall loss to inlet boundary layer thickness

Coull

Clark

Vázquez

2019

J. Glob. Power Propuls. Soc.

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“…The secondary flow in a blade row can be defined as any flow, which is not in the direction of the primary or streamwise flow. The classical theories of secondary flow, as developed by Squire & Winter (1951), Hawthorne (1955) and Smith (1955) described the mechanism of the streamwise vorticity formation at blade row exit. Until now, several physical models have been developed to describe the secondary flow vortices in turbine cascade (e.g.…”

Section: Secondary Flow Interactionmentioning

confidence: 99%

Unsteady Flows in Turbines

Qi¹,

Zou²

2012

Noise Control, Reduction and Cancellation Solutions in Engineering

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“…Further, s-nce the particulate trajectories depend on the motion of fluid surrounding them, it is impossible to predict the particulate trajectories without first understanding the three-dimensional nature of the secondary flows in the blade passages and the wake. Although many analyses have been performed in efforts to understand the behaviro of particulate-free secondary flow [3,5,5,6,7], a precise mathematical description of the fluid motion still remains elusive.…”

Section: Introductionmentioning

confidence: 99%

“…The theoretical studies of secondary flows in References [4,5,6,12,13] have been confined to situations where incompressible fluid is deflected through a bend of constant curvature (i.e., an arc of circle) and constant cross section. While these theoretical investigations have considered both stationary and rotnting passages, many are still, limited by simplifying assumptions, not only with respect to the behavior of tIe fluid flow, but also to the geometry of the cascade.…”

Section: Introductionmentioning

confidence: 99%

Measurements of Secondary Flows Within a Cascade of Curved Blades and in the Wake of the Cascade

Lasser

Rouleau

1983

Volume 1: Turbomachinery

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A laser-Doppler anemometer was used to measure the three-dimensional velocity field within a typical turbine blade cascade. The blades had a 12.7 cm chord, a turning angle of 104.8°, and a shape conforming to the camber line of a commercial turboexpander. The cascade was operated at a Reynolds number of 1.25×105. Strong secondary velocities, ranging up to 35 percent of the primary flow velocity, were found, resulting from the development of counter-rotating vortices within the blade passages. Large midspan velocity defects in the primary flow were coincident with these high secondary flows. The secondary flow persisted throughout the near wake region.

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The Secondary Flow in a Cascade of Airfoils in a Nonuniform Stream

Cited by 139 publications

References 0 publications

The sensitivity of turbine cascade endwall loss to inlet boundary layer thickness

The sensitivity of turbine cascade endwall loss to inlet boundary layer thickness

Unsteady Flows in Turbines

Measurements of Secondary Flows Within a Cascade of Curved Blades and in the Wake of the Cascade

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