scholarly journals Effects of area-ratio on the near-field flow characteristics and deflection of circular inclined coaxial jets

2014 ◽  
Vol 54 ◽  
pp. 225-236 ◽  
Author(s):  
T.H. New ◽  
E. Tsioli
Keyword(s):  
Near Field ◽  
Flow Characteristics ◽  
Area Ratio ◽  
Coaxial Jets

scholarly journals Coaxial Circular Jets—A Review

Fluids ◽  
2021 ◽  
Vol 6 (4) ◽  
pp. 147
Author(s):  
René van Hout ◽  
Sudharson Murugan ◽  
Abhijit Mitra ◽  
Beni Cukurel
Keyword(s):  
Flow Field ◽  
Near Field ◽  
Mixing Layer ◽  
Flow Characteristics ◽  
Fine Tuning ◽  
Nozzle Geometry ◽  
Jet Flows ◽  
Coaxial Jets ◽  
Static Pressure Distribution ◽  
Circular Jets

This review article focuses on the near-field flow characteristics of coaxial circular jets that, despite their common usage in combustion processes, are still not well understood. In particular, changes in outer to inner jet velocity ratios, ru, absolute jet exit velocities and the nozzle dimensions and geometry have a profound effect on the near-field flow that is characterized by shear as well as wake instabilities. This review starts by presenting the set of equations governing the flow field and, in particular, the importance of the Reynolds stress distributions on the static pressure distribution is emphasized. Next, the literature that has led to the current stage of knowledge on coaxial jet flows is presented. Based on this literature review, several regions in the near-field (based on ru) are identified in which the inner mixing layer is either governed by shear or wake instabilities. The latter become dominant when ru≈1. For coaxial jets issued into a quiescent surrounding, shear instabilities of the annular (outer) jet are always present and ultimately govern the flow field in the far-field. We briefly discuss the effect of nozzle geometry by comparing the flow field in studies that used a blockage disk to those that employed thick inner nozzle lip thickness. Similarities and differences are discussed. While impinging coaxial jets have not been investigated much, we argue in this review that the rich flow dynamics in the near-field of the coaxial jet might be put to an advantage in fine-tuning coaxial jets impinging onto surfaces for specific heat and mass transfer applications. Several open questions are discussed at the end of this review.

scholarly journals Analysis of a Converging, Annular, Isothermal Melt Blowing Jet Using Computational Fluid Dynamics

2005 ◽  
Vol os-14 (3) ◽  
pp. 1558925005os-14
Author(s):  
Eric M. Moore ◽  
Dimitrios V. Papavassiliou ◽  
Robert L. Shambaugh
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Kinetic Energy ◽  
Near Field ◽  
Flow Characteristics ◽  
Sectional Area ◽  
Melt Blowing ◽  
Mean Velocity ◽  
Cross Sectional ◽  
Computational Fluid Dynamics Cfd

An unconventional melt blowing die was analyzed using computational fluid dynamics (CFD). This die has an annular configuration wherein the jet inlet is tapered (the cross-sectional area decreases) as the air approaches the die face. It was found that the flow characteristics of this die are different from conventional slot and annular dies. In particular, for the tapered die the near-field normalized turbulent kinetic energy was found to be lower at shallow die angles. Also, it was found that the peak mean velocity behavior was intermediate between that of conventional annular and slot dies. The centerline turbulence profiles were found to be qualitatively similar to those of annular dies; quantitatively, higher values were present for tapered dies.

Shear Instabilities in the near Field of Coaxial Jets

1998 ◽  
Vol 10 (9) ◽  
pp. S2-S2 ◽  
Author(s):  
E. Villermaux ◽  
H. Rehab ◽  
E. J. Hopfinger
Keyword(s):  
Near Field ◽  
Coaxial Jets ◽  
Shear Instabilities

Near Field Flow Characteristics of the Bjork-Shiley Monostrut Valve in a Modified Single Shot Valve Chamber

ASAIO Journal ◽  
2005 ◽  
Vol 51 (2) ◽  
pp. 133-138 ◽  
Author(s):  
Keefe B. Manning ◽  
T Michael Przybysz ◽  
Arnold A. Fontaine ◽  
John M. Tarbell ◽  
Steven Deutsch
Keyword(s):  
Near Field ◽  
Flow Characteristics ◽  
Single Shot

Study and Investigation on the Mach of Impeller Outlet and Diffuser Inlet in Stamping and Welding Centrifugal Pump

2012 ◽  
Vol 229-231 ◽  
pp. 2454-2458
Author(s):  
Jian Jun Gan ◽  
Jie Gang Mou ◽  
Shui Hua Zheng ◽  
Bo Zhu
Keyword(s):  
Centrifugal Pump ◽  
Experimental Research ◽  
Static Pressure ◽  
Flow Characteristics ◽  
Internal Flow ◽  
Area Ratio ◽  
Cfd Simulations ◽  
Impeller Outlet ◽  
And Performance

Based on CFD simulations and experimental research, this paper studied the mach of impeller outlet and diffuser inlet in stamping and welding centrifugal pump. The influence of area ratio Y of impeller outlet to diffuser inlet on pump internal flow characteristics and performance was studied. Five different area ratio pump models were analyzed. The results indicate that as the area ratio Y= F3/F2 increase, the velocity of fluid in diffuser inlet decreases continuously, the average static pressure of diffuser outlet increases, and the head and efficiency of the pump are risen. When the area ratio increases from Y=1.48 to Y=3.49, the head increases about 3.0% and the efficiency about 2.0%.

The Flow Dynamics of an Air-Driven Hydraulic Pump

2015 ◽  
Author(s):  
Yan Shi ◽  
Tiecheng Wu ◽  
Andrew R. Plummer ◽  
Maolin Cai
Keyword(s):  
Volume Flow Rate ◽  
Flow Characteristics ◽  
Area Ratio ◽  
Air Pressure ◽  
Hydraulic Systems ◽  
Hydraulic Pump ◽  
Oil Flow ◽  
System Input ◽  
Output Characteristics ◽  
Set Up

Air-driven hydraulic pumps are widely used to pump high-pressure oil for small hydraulic systems, where it is uneconomic to set up a conventional hydraulic power pack. To obtain good performance of a small hydraulic system, input air flow and output oil flow characteristics of the air-driven hydraulic pump should be properly understood. In this paper, based on a mathematical model which has been experimentally verified, the model of an air-driven hydraulic pump is proposed. Using the software MATLAB/Simulink for simulation, the dynamic characteristics of the pumps are obtained. To set a foundation for the optimization of the pump, the influence of key parameters on the output characteristics of the pump was studied. Through analysis, it can be obtained that, firstly, with an increase in the input air pressure, output oil pressure and area ratio, the ratio of output to input volume flow rate decrease approximately linearly. Moreover, when the output oil pressure was fixed, an energy-saving method to enhance the output oil flow is to enlarge the area ratio of the pump. Furthermore, the output oil flow can be increased rapidly through increasing the input air pressure, but that may result in an increase in compressed air consumption. This research is of use in the performance and design optimization of air-driven hydraulic pumps.

Acoustic and Flow Characteristics of Cold High-speed Coaxial Jets

AIAA Journal ◽  
1979 ◽  
Vol 17 (2) ◽  
pp. 153-159 ◽  
Author(s):  
M. R. Bassiouni ◽  
D. S. Dosanjh
Keyword(s):  
High Speed ◽  
Flow Characteristics ◽  
Coaxial Jets

scholarly journals Experimental Study of Mean Flow Characteristics in the Near Field of Wedge-Shaped Swirling Jets

2020 ◽  
Vol 5 (10) ◽  
pp. 1199-1203
Author(s):  
Md. Mosharrof Hossain ◽  
Muhammed Hasnain Kabir Nayeem ◽  
Dr. Md Abu Taher Ali
Keyword(s):  
Flow Field ◽  
Near Field ◽  
Flow Characteristics ◽  
Velocity Profiles ◽  
Mean Flow ◽  
Mean Velocity ◽  
Potential Core ◽  
Swirling Jets ◽  
The Mean ◽  
Sinusoidal Flow

In this investigation experiment was carried out in 80 mm diameter swirling pipe jet, where swirl was generated by attaching wedge-shaped helixes in the pipe. All measurements were taken at Re 5.3e4. In the plain pipe jet the potential core was found to exist up to x/D=5 but in the swirling jet there was no existence of potential core. The mean velocity profiles were found to be influenced by the presence of wedge-shaped helixes in the pipe. The velocity profiles indicated the presence of sinusoidal flow field in the radial direction existed only in the near field of the jet. This flow field died out after x/D=3 and the existence of jet flow diminished after x/D=5.

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