Generation of Abrasive Water Jets

1998 ◽  
pp. 20-76 ◽  
Author(s):  
Andreas W. Momber ◽  
Radovan Kovacevic
Keyword(s):  
Water Jets

scholarly journals Thermoelectric Generation with Impinging Nano-Jets

Energies ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 492
Author(s):  
Fatih Selimefendigil ◽  
Hakan F. Oztop ◽  
Mikhail A. Sheremet
Keyword(s):  
Fluid Dynamics ◽  
Power Generation ◽  
Computational Fluid Dynamics ◽  
Reynolds Number ◽  
Conversion Efficiency ◽  
Reynolds Numbers ◽  
Thermoelectric Generation ◽  
Volume Fractions ◽  
Water Jets ◽  
Conversion Efficiencies

In this study, thermoelectric generation with impinging hot and cold nanofluid jets is considered with computational fluid dynamics by using the finite element method. Highly conductive CNT particles are used in the water jets. Impacts of the Reynolds number of nanojet stream combinations (between (Re1, Re2) = (250, 250) to (1000, 1000)), horizontal distance of the jet inlet from the thermoelectric device (between (r1, r2) = (−0.25, −0.25) to (1.5, 1.5)), impinging jet inlet to target surfaces (between w2 and 4w2) and solid nanoparticle volume fraction (between 0 and 2%) on the interface temperature variations, thermoelectric output power generation and conversion efficiencies are numerically assessed. Higher powers and efficiencies are achieved when the jet stream Reynolds numbers and nanoparticle volume fractions are increased. Generated power and efficiency enhancements 81.5% and 23.8% when lowest and highest Reynolds number combinations are compared. However, the power enhancement with nanojets using highly conductive CNT particles is 14% at the highest solid volume fractions as compared to pure water jet. Impacts of horizontal location of jet inlets affect the power generation and conversion efficiency and 43% variation in the generated power is achieved. Lower values of distances between the jet inlets to the target surface resulted in higher power generation while an optimum value for the highest efficiency is obtained at location zh = 2.5ws. There is 18% enhancement in the conversion efficiency when distances at zh = ws and zh = 2.5ws are compared. Finally, polynomial type regression models are obtained for estimation of generated power and conversion efficiencies for water-jets and nanojets considering various values of jet Reynolds numbers. Accurate predictions are obtained with this modeling approach and it is helpful in assisting the high fidelity computational fluid dynamics simulations results.

Anomalous reduction in thrust/reaction of water jets issuing from microapertures

2007 ◽  
Vol 19 (5) ◽  
pp. 053102 ◽  
Author(s):  
Tomiichi Hasegawa ◽  
Hiroshi Watanabe ◽  
Takashi Sato ◽  
Tohru Watanabe ◽  
Masanao Takahashi ◽  
...  
Keyword(s):  
Water Jets

Effect of Tank Size and Geometry on the Flow Induced by Circular Bubble Plumes and Water Jets

2008 ◽  
Vol 134 (6) ◽  
pp. 833-842 ◽  
Author(s):  
Iran E. Lima Neto ◽  
David Z. Zhu ◽  
Nallamuthu Rajaratnam
Keyword(s):  
Water Jets ◽  
Bubble Plumes

Three-Dimensional Numerical Study of Impinging Water Jets in Runout Table Cooling Processes

2008 ◽  
Vol 39 (4) ◽  
pp. 593-602 ◽  
Author(s):  
Myung Jong Cho ◽  
Brian G. Thomas ◽  
Pil Jong Lee
Keyword(s):  
Numerical Study ◽  
Three Dimensional ◽  
Water Jets ◽  
Runout Table

Boiling Heat Transfer Characteristics of Rotary Hollow Cylinders with In-Line and Staggered Multiple Arrays of Water Jets

2021 ◽  
Author(s):  
Mohammad Jahedi ◽  
Bahram Moshfegh
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Stagnation Point ◽  
Surface Heat Flux ◽  
Surface Heat ◽  
Maximum Heat ◽  
Water Jets ◽  
Maximum Heat Flux ◽  
Inner Surface ◽  
Hollow Cylinders

Abstract Transient heat transfer studies of quenching rotary hollow cylinders with in-line and staggered multiple arrays of jets have been carried out experimentally. The study involves three hollow cylinders (Do/d = 12 to 24) with rotation speed 10 to 50 rpm, quenched by subcooled water jets (ΔTsub=50-80 K) with jet flow rate 2.7 to 10.9 L/min. The increase in area-averaged and maximum heat flux over quenching surface (Af) has been observed in the studied multiple arrays with constant Qtotal compared to previous studies. Investigation of radial temperature distribution at stagnation point of jet reveals that the footprint of configuration of 4-row array is highlighted in radial distances near the outer surface and vanishes further down toward the inner surface. The influence of the main quenching parameters on local average surface heat flux at stagnation point is addressed in all the boiling regimes where the result indicates jet flow rate provides strongest effect in all the boiling regimes. Effectiveness of magnitude of maximum heat flux in the boiling curve for the studied parameters is reported. The result of spatial and temporal heat flux by radial conduction in the solid presents projection depth of cyclic variation of surface heat flux in the radial axis as it disappears near inner surface of hollow cylinder. In addition, correlations are proposed for area-averaged Nusselt number as well as average and maximum local heat flux at stagnation point of jet for the in-line and staggered multiple arrays.

scholarly journals Low‐frequency acoustic emissions by impacting transient cylindrical water jets in fresh and salt water

1993 ◽  
Vol 94 (3) ◽  
pp. 1891-1891
Author(s):  
Ali R. Kolaini ◽  
Ronald A. Roy ◽  
David L. Gardner
Keyword(s):  
Salt Water ◽  
Acoustic Emissions ◽  
Low Frequency ◽  
Water Jets

Drag Force Reduction and VIV Suppression of Circular Cylinders Using Radial Water Jets

2003 ◽  
Author(s):  
Kjetil B. Skaugset ◽  
Carl M. Larsen
Keyword(s):  
Drag Force ◽  
Volume Flow Rate ◽  
Ocean Current ◽  
Cylinder Surface ◽  
Cylinder Wall ◽  
Local Pressure ◽  
Ambient Flow ◽  
Water Jets ◽  
Operational Life ◽  
Viv Suppression

Deep-water oilfield developments demand accurate predictions of vortex induced vibrations (VIV) of risers and free span pipelines subjected to ocean current. In order to prolong operational life of such structures, VIV suppression devices such as helical strakes or shrouds are often employed. Such devices will, however, imply certain disadvantages such as drag amplification and increased operational costs. Therefore the quest for effective suppression devices with a minimum of such drawbacks is still ongoing. The present paper presents a novel approach for VIV suppression based on radial water jets from prescribed patterns of circular openings in the cylinder wall. Jet flow will introduce a disturbance that will change VIV amplitudes. The alternation of the flow pattern must be understood to have both 2-dimensional (2-D) and 3-D effects. 2-D effects will influence the local pressure on the cylinder surface by altering the separation point as well as creating a general disturbance to the flow, while the 3-D effects involve changes in correlation of the vortex shedding process along the span of the cylinder. Results will be presented from experiments in a towing tank testing four 2m long spring supported cylinders with diameter 0.1m and three different patterns of radial water jets. One cylinder has three straight rows of holes at angular positions 0° and ±120° with respect to the ambient flow. The second has two straight rows of holes at positions ±120° with respect to the ambient flow, while the last has one straight line of holes blowing directly upstream. Since the first can be said to consist of the two latter, comparing them to each other gives valuable information in order to understand the physics of the first. The volume flow rate and reduced velocity have been varied in the tests. Oscillation amplitudes, frequencies, added mass and drag force coefficients are presented and compared to a smooth cylinder.

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