Submerged gas jet in liquid cross flow: Modeling and flow structures analysis

2021 ◽  
Vol 242 ◽  
pp. 110128
Author(s):  
Ping Dong ◽  
Kai Wang ◽  
Dong Cheng ◽  
Bingju Lu
Keyword(s):  
Cross Flow ◽  
Gas Jet ◽  
Flow Structures ◽  
Flow Modeling

Direct Numerical Simulation of Single and Multiple Square Jets in Cross-Flow

2011 ◽  
Vol 133 (3) ◽  
Author(s):  
Y. Yao ◽  
M. Maidi
Keyword(s):  
Cross Flow ◽  
Vortex Pair ◽  
Flow Structures ◽  
Computational Domain ◽  
Freestream Velocity ◽  
Adjacent Edge ◽  
Vortex Pairs ◽  
Jet In Cross Flow ◽  
Edge Distance ◽  
Square Jets

Direct numerical simulations (DNSs) have been carried out for single and multiple square jets issuing normally into a cross-flow, with the primary aim of studying the flow structures and interaction mechanisms associated with the jet in cross-flow (JICF) problems. The single JICF configuration follows a similar study previously done by Sau et al. (2004, Phys. Rev. E, 69, p. 066302) and the multiple JICF configurations are arranged side-by-side in the spanwise direction with a jet-to-jet adjacent edge distance (H) for the twin-jet case and an additional third jet downstream along the centerline with a jet-to-jet adjacent edge distance (L) for the triple-jet case. Simulations are performed for two twin-jet cases with H=1D,2D, respectively, and for one triple-jet case with H=1D, L=2D, where D is the jet exit width. Flow conditions similar to Sau et al. are considered, i.e., the jet to the cross-flow velocity ratio R=2.5 and the Reynolds number 225, based on the freestream velocity and the jet exit width. For the single jet in cross-flow, the vortical structures from our DNS are in good qualitative agreement with the findings of Sau et al. For the side-by-side twin-jet configuration, results have shown that the merging process of the two initially separated counter-rotating vortex pairs (CRVPs) from each jet hole exit is strongly dependent on the jet-to-jet adjacent edge distance H with earlier merging observed for the case H=1D. Downstream, the flow is dominated by a larger CRVP structure, accompanied by a smaller inner vortex pair. The inner vortex pair is found not to survive in the far-field as it rapidly dissipates before exiting the computational domain. These observations are in good agreement with the experimental findings in the literature. Simulations of the triple-jet in cross-flow case have shown some complicated jet-jet and jet-cross-flow interactions with three vortex pairs observed downstream, significantly different from that seen in the twin-jet cases. The evidence of these flow structures and interaction characteristics could provide a valuable reference database for future in-depth flow physics studies of laboratory experimental and numerical investigations.

scholarly journals Experimental investigation and modelling of the gas jet in liquid cross flow

2019 ◽  
Vol 384 ◽  
pp. 012122
Author(s):  
Ping Dong ◽  
Shaofeng Gong ◽  
Bingju Lu ◽  
Dong Cheng
Keyword(s):  
Experimental Investigation ◽  
Cross Flow ◽  
Gas Jet

scholarly journals Vortex-Induced Vibration Analysis (VIVA) Based on Hydrodynamic Databases

2011 ◽  
Author(s):  
Haining Zheng ◽  
Rachel Price ◽  
Yahya Modarres-Sadeghi ◽  
George S. Triantafyllou ◽  
Michael S. Triantafyllou
Keyword(s):  
First Principles ◽  
Standing Waves ◽  
Cross Flow ◽  
Program Theory ◽  
Flow Modeling ◽  
Considerable Effort ◽  
Sheared Flow ◽  
Complex Modes ◽  
Flow Oscillations ◽  
Lock In

We outline the procedures used by program VIVA, developed over the last sixteen years to estimate the cross-flow vibration of marine risers in arbitrary currents. The program theory is based on a combination of first principles, extensive hydrodynamic databases, as well as modifications introduced through comparison against experimental and field data. The program was built from the start to handle standing as well as traveling waves, or arbitrary combinations of traveling and standing waves, through the use of complex modes. Considerable effort was expended to develop a hydrodynamic methodology that is suitable for short and long risers and cables, and which provides results in agreement with recent observed mechanisms. In particular, we outline changes to take into account: • the influence of in-line as well as cross-flow oscillations; • the influence of the Reynolds number; • the effect of high force harmonics; • modeling of lock-in in a sheared flow; • modeling of staked sections. The methodology is illustrated through several examples where predictions are compared with field and experimental data.

scholarly journals Experimental and Computational Study of the Unsteady Flow in a 1.5 Stage Axial Turbine With Emphasis on the Secondary Flow in the Second Stator

1998 ◽  
Author(s):  
Ralf E. Walraevens ◽  
Heinz E. Gallus ◽  
Alexander R. Jung ◽  
Jürgen F. Mayer ◽  
Heinz Stetter
Keyword(s):  
Unsteady Flow ◽  
Secondary Flow ◽  
Computational Study ◽  
Three Dimensional ◽  
Cross Flow ◽  
Axial Flow ◽  
Time Dependent ◽  
Flow Structures ◽  
Mean Flow ◽  
Dependent Flow

A study of the unsteady flow in an axial flow turbine stage with a second stator blade row is presented. The low aspect ratio blades give way to a highly three-dimensional flow which is dominated by secondary flow structures. Detailed steady and unsteady measurements throughout the machine and unsteady flow simulations which include all blade rows have been carried out. The presented results focus on the second stator flow. Secondary flow structures and their origins are identified and tracked on their way through the passage. The results of the time-dependent secondary velocity vectors as well as flow angles and Mach number distributions as perturbation from the time-mean flow field are shown in cross-flow sections and azimuthal cuts throughout the domain of the second stator. At each location the experimental and numerical results are compared and discussed. A good overall agreement in the time-dependent flow behaviour as well as in the secondary flow structures is stated.

Experimental Study of the Stability of a High-Speed Gas Jet Under the Influence of Liquid Cross-Flow

2007 ◽  
Author(s):  
Chris Weiland ◽  
Jon Yagla ◽  
Pavlos Vlachos
Keyword(s):  
Mach Number ◽  
Free Boundary ◽  
Boundary Conditions ◽  
High Speed ◽  
Cross Flow ◽  
Upper And Lower Bounds ◽  
Gas Jet ◽  
Mode Shapes ◽  
Free Boundary Conditions ◽  
The Stability

This paper reports on the interfacial character and deflection of a high-speed gas jet transverse to an aqueous cross-flow as a function of cross-flow speed and gas jet Mach number. Several gas exit velocities were tested including subsonic cases up to supersonic cases at cross-flow velocities from 0.3 m/s to 0.7 m/s. For the subsonic cases, it was found that the stability and resistance of the gas jet to deflect in the presence of cross-flow were increased with the jet Mach number. However, the Mach 1.6 jet was more stable than the Mach 1.9 jet, suggesting that there exists upper and lower bounds for jet stability which are Mach number dependent. Unstable gas jets were shown to pinch-off, meaning the interface of the gas jet in a plane parallel to the ejector exit collapsed to almost a point and an independent bubble rose to the free surface. The stagnation side gas/liquid interfaces were analyzed using the Proper Orthogonal Decomposition (POD) method to better understand the fundamental mode shapes contained in the interface waveforms. It was found that the subsonic jets shared many of the same characteristics in their first, second, and third mode shapes. The supersonic jets differed from the subsonic mode shapes. Interestingly, the mode shapes for the subsonic cases compared well to those of a beam in transverse vibration with sliding-free boundary conditions. The supersonic cases compared relatively well to pinned-free boundary conditions, owing to the more columnar nature of the gas jet as it exited the ejector.

Investigation of Large-Scale Structures Behind a Single Tube (Finned and Foamed Tube) Using Two-Point Correlations

2014 ◽  
Author(s):  
Iman Ashtiani Abdi ◽  
Morteza Khashehchi ◽  
Kamel Hooman
Keyword(s):  
Reynolds Number ◽  
Large Scale ◽  
Cross Flow ◽  
Reynolds Numbers ◽  
Finned Tube ◽  
Flow Structures ◽  
Analysis Tool ◽  
Standard Case ◽  
Statistical Analysis Tool ◽  
Point Correlation

Flow structures downstream of a finned-tube are compared to those of an identical pipe; with the same diameter and length, covered with a foam layer. The standard case of cross-flow over a bare tube, i.e. no surface extension, is also tested as a benchmark. Experiments are conducted in a wind tunnel at Reynolds numbers of 4000 and 16000. Particle image velocimetry (PIV) was used for flow visualization on two different perpendicular planes. To characterize the size of the flow structures downstream of the tube, for each of the aforementioned case, two-point correlation, as a statistical analysis tool, has been used. It has been observed that by decreasing the Reynolds number, the flow structures are further stretched in streamwise direction for both bare and finned-tube cases. This is, however, more pronounced with the former. Interestingly, with a foam-wrapped tube the sizes of the flow structures are found to be independent of the Reynolds number. Finally, the structure sizes are smaller in the case of the foam-wrapped tube compared to those of finned-tube.

scholarly journals Flow Structures of Submerged Gas Jet in Liquid Currents

2021 ◽  
Vol 299 ◽  
pp. 03011
Author(s):  
Ping Dong ◽  
Dong Cheng ◽  
Huixiang Jing ◽  
Guanghua Li ◽  
Bingju Lu ◽  
...  
Keyword(s):  
High Speed ◽  
Video Camera ◽  
Gas Jet ◽  
Flow Structures ◽  
Experimental Setup ◽  
High Speed Video ◽  
Gas Jets ◽  
High Speed Video Camera ◽  
Pod Analysis ◽  
Proper Orthogonal

The flow structure of the submerged gas jet in liquid currents is important to engineering applications. In the present study, the development of a submerged gas jet subjected to liquid current is experimentally investigated to evaluate the effects of the current on the underwater gas jet evolution. A full-scale experimental setup is designed for submerged gas jet release and dispersion in the liquid currents with different velocities. The flow structures of the gas jet are captured by shadow photography combined with a high speed video camera. The experimental images are processed to extract the parameters and perform Proper Orthogonal Decomposition (POD) analysis to reveal the characteristics of different modes standing for different flow structures. It turns out that the flow structures of the gas jets submerged in liquid currents with different velocities are affected by the liquid currents and gas jet pulsation, and the analysis will provide credible assessment and opportunity to take prompt response to control potential accidents caused by the submerged gas jet release in liquid current.

Experimental Flow Visualization Study in a Trapezoidal Duct With Impingement Jets and Cross Flow Near the Leading Edge

2010 ◽  
Author(s):  
Haiyong Liu ◽  
Songling Liu ◽  
Hongfu Qiang ◽  
Cunliang Liu
Keyword(s):  
Film Cooling ◽  
Cross Flow ◽  
Side Wall ◽  
Leading Edge ◽  
Flow Fields ◽  
Flow Structures ◽  
Internal Cooling ◽  
Design And Optimization ◽  
Target Wall ◽  
Cooling Hole

An enlarged model of trapezoidal duct in leading-edge with impingement jets, swirl, cross flow and effusion was built up. Experiments were performed to measure flow fields in the confined passage and exit holes on one of its side walls. A row of staggered circular impingement holes were arranged on the opposite side wall. Cross flow and effusion flow was induced in the channel by the outflow of exit hole and film cooling hole, which were oriented on one end wall and bottom wall of the passage. Detailed flow structures were measured for two impingement angles of 35° and 45° with 6 combinations of out flow ratios. Results showed that the small jets impinged the target wall effectively while the large jets contributed to inducing and impelling a strong counter-clockwise vortex in the upper part of the passage. Cross flow had significant effect on the flow structures in the passage and exit holes. It deflected the jets, enhanced swirl and deteriorated side exit conditions. Impingement angle also had important influence on flow fields and its effect revealed more evidently with cross flow. Within the present test conditions, the mass flow rates and outflow positions of film cooling holes had no distinct effect on the main flow structures. These data were helpful for the design and optimization of internal cooling structures in gas turbine airfoils.

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