Non-Reacting and Combusting Flow Investigation of Bluff Bodies in Cross Flow

2006 ◽  
Author(s):  
Barry Kiel ◽  
Kyle Garwick ◽  
Amy Lynch ◽  
James Gord ◽  
Terrence Meyer
Keyword(s):  
Cross Flow ◽  
Bluff Bodies ◽  
Flow Investigation

scholarly journals Kill Line Model Cross Flow Inline Coupled Vortex-Induced Vibration

2017 ◽  
Author(s):  
Baiheng Wu ◽  
Jorlyn Le Garrec ◽  
Dixia Fan ◽  
Michael S. Triantafyllou
Keyword(s):  
Bluff Body ◽  
Oil And Gas ◽  
Cross Flow ◽  
The Body ◽  
Bluff Bodies ◽  
Structural Vibrations ◽  
Vortex Induced Vibrations ◽  
Series Of Experiments ◽  
Central Pipe ◽  
Semi Empirical

Currents and waves cause flow-structure interaction problems in systems installed in the ocean. Particularly for bluff bodies, vortices form in the body wake, which can cause strong structural vibrations (Vortex-Induced Vibrations, VIV). The magnitude and frequency content of VIV is determined by the shape, material properties, and size of the bluff body, and the nature and velocity of the oncoming flow. Riser systems are extensively used in the ocean to drill for oil wells, or produce oil and gas from the bottom of the ocean. Risers often consist of a central pipe, surrounded by several smaller cylinders, including the kill and choke lines. We present a series of experiments involving forced in-line and cross flow motions of short rigid sections of a riser containing 6 symmetrically arranged kill and choke lines. The experiments were carried out at the MIT Towing Tank. We present a systematic database of the hydrodynamic coefficients, consisting of the forces in phase with velocity and the added mass coefficients that are also suitable to be used with semi-empirical VIV predicting codes.

Assessment of Cooling Tower Discharge Recirculation and Dispersion Using CFD Techniques

2015 ◽  
Author(s):  
S. Pal ◽  
L. J. Peltier ◽  
A. Rizhakov ◽  
M. P. Kinzel ◽  
M. H. Elbert ◽  
...  
Keyword(s):  
Experimental Data ◽  
Cooling Tower ◽  
Cross Flow ◽  
Bluff Bodies ◽  
Cooling Towers ◽  
Design Strategies ◽  
Worst Case ◽  
Buoyant Jets ◽  
Design Values ◽  
High Reynolds

The performance of cooling towers, whether operating by themselves, or in close vicinity of other cooling towers can be adversely affected by the re-ingestion of the cooling tower discharge into the tower intakes. The recirculation of the discharge from a wet cooling tower raises the wet bulb temperature of the air entering a wet cooling tower. Current design strategies, often account for this discharge re-ingestion issue, through a conservative adjustment to the far field ambient wet bulb temperature to calculate the actual intake wet bulb temperature. Critical applications, such as those related to nuclear safety applications where there is concern about cooling tower performance, may require more accurate and comprehensive assessment of the recirculation and dispersion of cooling tower discharge. Gaussian plume models alone are of limited use when dealing with discharges in the vicinity of large structures. This paper discusses the use of a computational fluid dynamics approach to evaluate worst case discharge recirculation effects in cooling towers. The bounding design values of tower intake wet bulb temperature increase due to recirculation (ingestion of tower’s own discharge), and interference (ingestion of another interfering tower’s discharge), are calculated considering the various conditions of cooling tower operation, ambient temperature, humidity and wind conditions. The RANS CFD model used in the study is evaluated against published experimental data for flow over bluff bodies at high Reynolds numbers, and experimental data on buoyant jets in cross flow.

Experimental Study of Non-Premixed Flames of Liquefied Petroleum Gas and Air in Cross-Flow and the Effects of Fuel Properties on Flame Stability

2019 ◽  
Vol 0 (0) ◽  
Author(s):  
S. Muthu Kumaran ◽  
Vasudevan Raghavan
Keyword(s):  
Premixed Flames ◽  
Cross Flow ◽  
Operating Conditions ◽  
Fuel Properties ◽  
Jet Flows ◽  
Flame Stability ◽  
Bluff Bodies ◽  
Liquefied Petroleum Gas ◽  
Air Jet ◽  
The Stability

Abstract Stability of flames are affected by fuel properties, geometry of the burner and operating conditions. In this experimental work, first the characteristics of non-premixed flames of Liquefied Petroleum Gas (LPG) and air in cross-flow configuration, where air jet flows perpendicular to the fuel stream, are studied experimentally. Flame transition and stability regimes of non-premixed flames of LPG and air, in a cross-flow burner without and with obstacles, are determined by systematically varying the fuel and air flow rates. Obstacles such as backward facing step and cylindrical bluff bodies are considered. Subsequently, the effects of fuel properties on the stability of flames are analyzed, Flame stability regimes of natural gas (methane) and biogas (methane and carbon-dioxide), measured from a similar burner are available in literature. These have been compared with the stability of LPG flames in terms of power rating of the burner and global equivalence ratio (defined for non-premixed flames).

System Identification of Hydrokinetic Energy Harvester Using Flow Induced Oscillations

2018 ◽  
Author(s):  
Ralph Saxton ◽  
Soumyadip Patra ◽  
Nikolaos I. Xiros ◽  
Michael M. Bernitsas ◽  
Hai Sun
Keyword(s):  
Control System ◽  
Vortex Shedding ◽  
Cross Flow ◽  
Rigid Bodies ◽  
Data Series ◽  
Bluff Bodies ◽  
Hydrokinetic Energy ◽  
Dynamics And Control ◽  
Using Data ◽  
Set Up

Using data series obtained by experiments at the Marine Renewable Energy Laboratory of the University of Michigan, a Data-Driven Model is constructed for further investigation of the Process Dynamics and Control System Design and Configuration. This will enable advances in hydrokinetic energy harvesting using Vortex Induced Vibrations (VIV) and galloping, or more generally, Flow Induced Oscillations (FIO). Typically in such energy converters, one or more multiple bluff bodies, such as cylinders are suspended on springs in a water flow (currents, tides, rivers). In commonly encountered flows, oscillations are induced to the bluff rigid bodies due to vortex shedding in their wake, or due to lift instabilities in galloping, or both. These phenomena are dependent on stiffness, damping, mass ratio and the resulting vortex shedding frequency. The experiments in the cases investigated generated position signal recordings for one or two cylinders used as bluff bodies in FIO in a cross-flow. The position signals are used to set up a dynamic model. The model equation helps in gaining insight into the dynamics and underlying physics of the modeled FIO and can be used for Control System Tuning and Verification.

scholarly journals Flow investigation of cross-flow turbine using CFD method

2020 ◽  
Vol 1007 ◽  
pp. 012035
Author(s):  
Joshua Aditya Sardjono ◽  
Steven Darmawan ◽  
Harto Tanujaya
Keyword(s):  
Cross Flow ◽  
Flow Investigation ◽  
Cfd Method

INFLUENCE OF THE INLET SHAPE ON THE PERFORMANCE OF DOUBLE OFFSET TRANSITION S-DUCT WITH DIFFUSION

2008 ◽  
Vol 05 (01) ◽  
pp. 1-19 ◽  
Author(s):  
RAJESH KUMAR SINGH ◽  
SIDHNATH SINGH ◽  
V. SESHADRI
Keyword(s):  
Total Pressure ◽  
Free Stream ◽  
Flow Behavior ◽  
Flow Analysis ◽  
Cross Flow ◽  
Area Ratio ◽  
Stream Velocity ◽  
Crucial Component ◽  
Flow Investigation ◽  
Cross Flow Velocity

Transition S-shaped intake duct is a crucial component of dual engine used in modern combat aircrafts. Present flow investigation demonstrates the flow behavior of double offset transition S-duct for different inlet geometries having circular exit (ϕ = 72.5 mm) and uniform roughness. The inlet geometries namely rectangular, square, elliptical, oval, and semicircular have been analyzed for double offset transition S-duct having 300 mm centerline length and an area ratio of 2.0. Incompressible flow analysis carried out for free stream velocity at 30 m/s with RNG k–ε turbulence model has shown that the elliptical inlet shape gives the best performance whereas square inlet gives the worst performance in terms of longitudinal and cross-flow velocity distribution, pressure recovery, total pressure loss, distortion coefficient, and swirl coefficient at the exit of the duct.

scholarly journals Turbulent wake past a three-dimensional blunt body. Part 2. Experimental sensitivity analysis

2014 ◽  
Vol 752 ◽  
pp. 439-461 ◽  
Author(s):  
M. Grandemange ◽  
M. Gohlke ◽  
O. Cadot
Keyword(s):  
Three Dimensional ◽  
Cross Flow ◽  
Body Part ◽  
General Concept ◽  
Bluff Bodies ◽  
Vertical Control ◽  
Induced Drag ◽  
Natural Flow ◽  
Set Up ◽  
The Impact

AbstractThe sensitivity of the flow around three-dimensional blunt geometry is investigated experimentally at Reynolds number $\def \xmlpi #1{}\def \mathsfbi #1{\boldsymbol {\mathsf {#1}}}\let \le =\leqslant \let \leq =\leqslant \let \ge =\geqslant \let \geq =\geqslant \def \Pr {\mathit {Pr}}\def \Fr {\mathit {Fr}}\def \Rey {\mathit {Re}}9.2\times 10^4$. Vertical and horizontal control cylinders are used to disturb the natural flow which is the superposition of two reflectional symmetry breaking states (see Part 1 of this study, Grandemange, Gohlke & Cadot, J. Fluid Mech., vol. 722, 2013b, pp. 51–84). When the perturbation breaks the symmetry of the set-up, it can select one of the two asymmetric topologies so that a mean side force is found. When the reflectional symmetry is preserved, some positions of horizontal and vertical control cylinders alter the natural bi-stability of the flow which may result in drag reduction. In addition, it is found that the horizontal perturbation affects the lift force especially when the top and bottom mixing layers are disturbed. The ability of the disturbances to suppress the bi-stable behaviour is discussed and, introducing a formalism of induced drag, a quantification of the impact on the drag of the cross-flow forces observed for the natural bi-stable wake is suggested. Finally, a general concept for a control strategy of separated flows past three-dimensional bluff bodies can be drawn up from these analyses.

scholarly journals Numerical Study on the Influence of Mass and Stiffness Ratios on the Vortex Induced Motion of an Elastically Mounted Cylinder for Harnessing Power

Energies ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2580 ◽  
Author(s):  
Vidya Chandran ◽  
Sekar M. ◽  
Sheeja Janardhanan ◽  
Varun Menon
Keyword(s):  
Numerical Study ◽  
Cross Flow ◽  
Maximum Amplitude ◽  
Field Tests ◽  
Operating Conditions ◽  
Irrigation Canal ◽  
Bluff Bodies ◽  
Low Velocity ◽  
Useful Power ◽  
The Face

Harnessing the power of vortices shed in the wake of bluff bodies is indeed a boon to society in the face of fuel crisis. This fact serves as an impetus to develop a device called a hydro vortex power generator (HVPG), comprised of an elastically mounted cylinder that is free to oscillate in the cross-flow (CF) direction even in a low velocity flow field. The oscillatory motions in turn can be converted to useful power. This paper addresses the influence of system characteristics viz. stiffness ratio (k*) and mass ratio (m*) on the maximum response amplitude of the elastically mounted cylinder. Computational fluid dynamics (CFD) simulations have been used here to solve a two way fluid–structure interaction (FSI) problem for predicting the trend of variation of the non-dimensional amplitude Y/D with reduced velocity Ur through a series of simulations. Maximum amplitude motions have been attributed to the lowest value of m* with Ur = 8. However, the maximum lift forces correspond to Ur = 4, providing strong design inputs as well as indicating the best operating conditions. The numerical results have been compared with those of field tests in an irrigation canal and have shown reasonable agreement.

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