Cavity Flows

Cavity Flows
Author: Blaine Raphael Parkin
Publisher:
Total Pages: 166
Release: 1975
Genre: Science
ISBN:

Three-dimensional Flow in Cavity at Yaw

Three-dimensional Flow in Cavity at Yaw
Author: Alex Povitsky
Publisher:
Total Pages: 26
Release: 2001
Genre:
ISBN:

This study is motivated by three-dimensional flows about protrusions and cavities with an arbitrary angle between the external flow and rigid elements. The novel type of a "building block" cavity flow is proposed where the cavity lid moves along its diagonal (Case A). The proposed case is taken as a typical representative of essentially three-dimensional highly separated vortical flows having simple single-block rectangular geometry of computational domain. Computational results are compared to the previous studies where the lid moves parallel to the cavity side walls (Case B). These 3-D lid-driven cavity flows are studied by numerical modeling using second-order upwind schemes for convective terms. The volume and plane integrals of primary and transversal momentum are introduced to compare cases in a quantitative way. For the laminar flow in the cubic cavity, the integral momentum of the secondary flow (which is perpendicular to the lid direction) is about an order of magnitude larger than that in Case B. In Case A, the number of secondary vortices substantially depends on the Re number. The secondary vortices in the central part of the cavity in Case A distinguishes it from Case B, where only corner secondary vortices appear. For a rectangular 3-D 3: 1 : 1 cavity the integral momentum of the secondary flow in Case A is an order of magnitude larger than that in the benchmark cases. The flow field in Case A includes a curvilinear separation line and non-symmetrical vortices which are discussed in the paper. The estimated Goertler number is approximately 4.5 times larger in Case A than that in Case B for the same Re number. This indicates that in Case A the flow becomes unsteady for smaller Re numbers than in Case B. For developed turbulent flow in the cubic cavity, the yaw effect on amplifcation of secondary flow is as strong as that for the laminar flow despite the more complex vortical flow pattern in benchmark case B.

Cellular Flows

Cellular Flows
Author: Vladimir Shtern
Publisher: Cambridge University Press
Total Pages: 589
Release: 2018-02-08
Genre: Technology & Engineering
ISBN: 1108311210

A cell, whose spatial extent is small compared with a surrounding flow, can develop inside a vortex. Such cells, often referred to as vortex breakdown bubbles, provide stable and clean flame in combustion chambers; they also reduce the lift force of delta wings. This book analyzes cells in slow and fast, one- and two-fluid flows and describes the mechanisms of cell generation: (a) minimal energy dissipation, (b) competing forces, (c) jet entrainment, and (d) swirl decay. The book explains the vortex breakdown appearance, discusses its features, and indicates means of its control. Written in acceptable, non-math-heavy format, it stands to be a useful learning tool for engineers working with combustion chambers, chemical and biological reactors, and delta-wing designs.

Mach 0.6 to 3.0 Flows Over Rectangular Cavities

Mach 0.6 to 3.0 Flows Over Rectangular Cavities
Author: Louis G. Kaufman
Publisher:
Total Pages: 288
Release: 1983
Genre: Aeroacoustics
ISBN:

Internal weapons carriage in high performance aircraft is often adversely affected by the severe aeroacoustic environment produced with the weapons bay doors open. To obtain a better understanding of this fluid dynamic problem, basic static and oscillatory pressure data were obtained for Mach 0.6 to 3.0 flows over shallow rectangular cavities in a generic flat plate model. Cavity length to depth ratios were varied from approximately 5 to 10. Static pressure data characteristic of both open and closed cavity flows were obtained. An improved Rossiter method is presented that satisfactorily predicts the possible frequency modes within the cavity. Highest fluctuating pressure occurs on the aft bulkhead, peaking near Mach 1.5 for the conditions tested. Aeroacoustic levels are substantially reduced by installing suppression fences (spoilers) at subsonic and low supersonic conditions. Acoustic levels generally drop rapidly above Mach 1.5. (Author).

Numerical Method for Steady-state Cavity Flows

Numerical Method for Steady-state Cavity Flows
Author: Stanford University. Department of Civil Engineering
Publisher:
Total Pages: 136
Release: 1972
Genre:
ISBN:

The objective of the work was to develop a numerical method for steady-state cavity flows to provide systematic correction of an initial, assumed free streamline position. The method is based on an inviscid, irrotational and incompressible flowfield, uses a numerical finite-difference representation with the fluid velocities as dependent variables, and obtains a solution by successive-overrelaxation. It has been implemented for two-dimensional fully cavitating flow past a vertical plate in a channel. Typical results and the computer program listing and output are given. (Author).