PIV Measurements of the Cross-Flow Velocity Field Around a Turning Submarine Model (ONR Body-1). Part 1. Experimental Setup

2002 ◽  
Author(s):  
Thomas C. Fu ◽  
Paisan Atsavapranee ◽  
David E. Hess
Keyword(s):  
Velocity Field ◽  
Flow Velocity ◽  
Cross Flow ◽  
Experimental Setup ◽  
Piv Measurements ◽  
Flow Velocity Field ◽  
Cross Flow Velocity ◽  
The Cross

A Family of Hodograph Models for the Cross Flow Velocity Component of Three-Dimensional Turbulent Boundary Layers

1972 ◽  
Vol 94 (2) ◽  
pp. 321-329 ◽  
Author(s):  
J. R. Shanebrook ◽  
D. E. Hatch
Keyword(s):  
Flow Velocity ◽  
Boundary Layers ◽  
Velocity Component ◽  
Three Dimensional ◽  
Cross Flow ◽  
Turbulent Boundary Layers ◽  
Flow Profiles ◽  
Rectangular Channels ◽  
Cross Flow Velocity ◽  
The Cross

A family of hodograph models for the cross flow velocity component of three-dimensional, turbulent boundary layers is presented. The principal advantage of this family is its flexibility which allows a wide variety of possible shapes for the hodograph. An integral method based on this family is developed and applied to data obtained in curved, rectangular channels. For the cases treated, the method gives acceptable results for cross flow profiles with and without flow reversal. Suggestions for refining the method are given.

Mathematical and Physical Simulation of the Cross-Flow Velocity Pulsation Effect on the Flame Structure during the Diffusion Mode of Methane Combustion

2020 ◽  
pp. 65-84
Author(s):  
K.Yu. Arefyev ◽  
K.V. Fedotova ◽  
A.I. Krikunova ◽  
V.A. Panov
Keyword(s):  
Mathematical Model ◽  
Flow Velocity ◽  
Stokes Equations ◽  
Flame Structure ◽  
Cross Flow ◽  
Methane Combustion ◽  
Velocity Pulsation ◽  
Diffusion Mode ◽  
Cross Flow Velocity ◽  
The Cross

The paper presents the results of calculation and experimental studies of the diffusion combustion of methane in the air cross-flow. We developed a mathematical model for describing a diffusion air-methane flame, the model being based on solving a system of averaged Navier --- Stokes equations in an unsteady setting. To calculate the combustion processes, we used the flamelet models and eddy dissipation concept (EDC) model. The mathematical model was supplemented by a detailed kinetic mechanism consisting of 325 elementary reactions involving 53 substances. Furthermore, we carried out calculations and comparative analysis of the flame characteristics using various turbulence models: k − ε, k − ω SST and Transition SST. The study introduces a diagram of the experimental setup for physical modeling of methane combustion in the air cross-flow, and presents the results of the calculation and experimental study of the cross-flow velocity pulsation effect on the flame structure, as well as the efficiency of methane combustion in the diffusion mode. We obtained data on temperature and concentration fields at pulsation frequencies of 0--100 Hz. Findings of research show that for the case under consideration, stable combustion occurs at pulsation frequencies of 0--90 Hz. The maximum observed flame lift-off is 3.2 times the diameter of the burner nozzle

Critical Velocity of a Non-Linearly Supported Multi-Span Tube Bundle

2006 ◽  
Author(s):  
M. K. Au-Yang ◽  
J. A. Burgess
Keyword(s):  
Flow Velocity ◽  
Critical Velocity ◽  
Tube Bundle ◽  
Normal Modes ◽  
Cross Flow ◽  
Time History ◽  
Tube Bundles ◽  
Cross Flow Velocity ◽  
The Cross ◽  
The Time Domain

The phenomenon of fluid-elastic instability and the velocity at which a heat exchanger tube bundle becomes unstable, known as the critical velocity, was discovered and empirically determined based upon single-span, linearly supported tube bundles. In this idealized configuration, the normal modes are well separated in frequency with negligible cross-modal contribution to the critical velocity. As a result, a critical velocity can be defined and determined for each mode. In an industrial heat exchanger or steam generator, not only do the tube bundles have multiple spans, they are also supported in over-sized holes. The normal modes of a multi-span tube bundle are closely spaced in frequency, and the non-linear effect of the tube-support plate interaction further promotes cross-modal contribution to the tube responses. The net effect of cross-modal participation in the tube vibration is to delay the instability threshold. Tube bundles in industrial exchangers often have critical velocities far above what were determined in the laboratory based upon single-span, linearly supported tube bundles. In this paper, the authors attempt to solve this non-linear problem in the time domain, using a time history modal superposition method. Time history forcing functions are first obtained by inverse Fourier transform of the power spectral density function used in classical turbulence-induced vibration analyses. The fluid-structure coupling force, which is dependent on the cross-flow velocity, is linearly superimposed onto the turbulence forcing function. The tube responses are then computed by direct integration in the time domain. By gradually increasing the cross-flow velocity, a threshold value is obtained at which the tube response just starts to diverge. The value of the cross-flow velocity at which the tube response starts to diverge is defined as the critical velocity of this non-linearly supported, multi-span tube bundle.

PIV Measurements of the Cross-Flow Velocity Field in the Near Wake of a Generic Pickup Truck

2006 ◽  
Author(s):  
Bahram Khalighi
Keyword(s):  
Velocity Field ◽  
Symmetry Plane ◽  
Cross Flow ◽  
Velocity Data ◽  
Near Wake ◽  
Mean Velocity ◽  
Piv Measurements ◽  
Pickup Truck ◽  
The Mean ◽  
The Cross

The cross-flow field (flow in planes normal to the direction of motion) in the near wake of a generic pickup truck is investigated experimentally using Particle Image Velocimetry (PIV). The PIV measurements of the velocity field normal to the free-stream direction are carried out at four stream-wise locations behind the cab and the tailgate. The PIV data are processed to obtain the instantaneous velocity field, the mean and the turbulence properties of the flow. The instantaneous results in the near wake of the cab show various vortical structures. The mean velocity data shows that the flow moves from the sides toward the center of the bed near the tailgate. The velocity data in the near wake of the tailgate shows a pair of counter-rotating vortices that induces a downwash velocity field at the symmetry plane. This downwash promotes an attached flow behind the tailgate, thus generating a pressure recovery which leads to reductions in the total drag.

The shape of free jets of water under gravity

1976 ◽  
Vol 76 (4) ◽  
pp. 625-640 ◽  
Author(s):  
E. O. Tuck
Keyword(s):  
Free Surface ◽  
Aspect Ratio ◽  
Flow Velocity ◽  
Cross Section ◽  
Cross Sections ◽  
Cross Flow ◽  
Free Jets ◽  
Elliptic Cross ◽  
Cross Flow Velocity ◽  
The Cross

A study is made of the form taken by a slender jet of water whose only boundary is a free surface. The only forces acting are inertial and gravitational. Attention is paid to the cross-flow velocity components and to the development of the shape of the cross-section of the jet as it progresses. It is established that a jet with initially elliptic cross-sections can remain elliptical, and the variation in the aspect ratio along the jet is determined.

Sign in / Sign up

Export Citation Format

Share Document