scholarly journals Development of Phased Twin Flip-Flop Jets

1994 ◽  
Vol 116 (3) ◽  
pp. 263-268 ◽  
Author(s):  
G. Raman ◽  
E. J. Rice
Keyword(s):  
High Velocity ◽  
Jet Flow ◽  
Flip Flop ◽  
Practical Applications ◽  
Oscillating Jet ◽  
Two Jets ◽  
Phase Differences ◽  
Moving Parts

The flip-flop nozzle is a device that can produce an oscillating jet flow without any moving parts. There is now a renewed interest in such nozzles due to their potential for use as excitation devices in practical applications. An experiment aimed at developing twin flip-flop jets that operate at prescribed frequencies and phase differences was performed. The phasing was achieved using two different nozzle interconnection schemes. In one configuration the two jets flapped in-phase and in another they flapped out-of-phase with respect to each other. In either configuration the frequencies of oscillation of both jets were equal. When one of the jets was run at a constant high velocity and the velocity of the second jet was increased gradually, the higher velocity jet determined the frequency of oscillation of both jets. The two flip-flop jet configurations described in this paper could be used to excite a primary jet flow in either an anti-symmetric (sinuous) or a symmetric (varicose) mode.

scholarly journals On the Application of Fourier Decomposition Parameters

1993 ◽  
Vol 134 ◽  
pp. 157-158
Author(s):  
J. O. Petersen
Keyword(s):  
Fourier Analysis ◽  
Light Curves ◽  
Amplitude Ratios ◽  
Fourier Decomposition ◽  
Practical Applications ◽  
Convincing Argument ◽  
Lee Form ◽  
Modern Form ◽  
Made In ◽  
Phase Differences

The application of Fourier decomposition parameters has revolutionized important areas of investigations of Cepheid type variables since the introduction of Fourier analysis in its modern form by Simon and Lee (1981).In the literature several different representations of the results of Fourier analysis have been utilized. In view of the growing interest for applications of Fourier decomposition it is important to use and publish Fourier data in an optimal way. Most studies until now have used amplitude ratios and phase differences derived from traditional light curves giving the light variation in magnitudes, following the original recipe of Simon and Lee (1981). However, Stellingwerf and Donohoe (1986) advocated the use of phases rather than phase differences. Recently, Buchler et al. (1990) argued that the standard Simon & Lee form contains all relevant physics, and suggested analysis of flux-values rather than of magnitudes, because this removes the distorting effects of constant, false light. Thus there are many choices to be made in practical applications of Fourier analysis, and there is at present no convincing argument for preferring one specific representation.

ICONE23-1467 Behavior of Entrainment Droplet formed by High Velocity Air Jet Flow in Stagnant Water

2015 ◽  
Vol 2015.23 (0) ◽  
pp. _ICONE23-1-_ICONE23-1
Author(s):  
Masaaki Akabane ◽  
Sachiyo Horiki ◽  
Masahiro Osakabe ◽  
Yasuo Koizumi ◽  
Akihiro Uchibori ◽  
...  
Keyword(s):  
High Velocity ◽  
Jet Flow ◽  
Stagnant Water ◽  
Air Jet

The Cooling Impact of a Pair of Opposed Unsteady Confined Impinging Air Jets

2005 ◽  
Author(s):  
Victor Chiriac ◽  
Jorge L. Rosales
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Unsteady Flow ◽  
Jet Flow ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Air Jets ◽  
Laminar Jets ◽  
Vortex Patterns ◽  
Two Jets

A numerical investigation was performed at two Reynolds numbers to analyze the flow-field and heat transfer characteristics for a pair of laminar jets impinging on opposite walls in a channel. The present study is a continuation of the authors’ earlier work [1] in which the jets flowing out normal to the top channel wall produce a large stagnant bubble between the two jets which greatly reduce the heat transfer removal from the lower wall. In this case, the lower Reynolds number jet flow of 300 produces a symmetric, steady flow hydrodynamic pattern with the jets being deflected laterally. By further increasing the Reynolds number to 750, a complex asymmetric and highly unsteady flow develops between the two jets due to the opposite jet flow interaction. The convective heat transfer coefficients and the unsteady flow development between the jets are studied for each case. The flow unsteadiness is also characterized by analyzing the stagnation point displacement on the channel walls. The complex vortex patterns resulting from the jet interaction at the higher Reynolds number is investigated and its impact on the chip/microelectronics component cooling is thoroughly documented.   This paper was also originally published as part of the Proceedings of the ASME 2005 Heat Transfer Summer Conference.

A Pneumatically Actuated Icing Detector for Stationary Operation

1958 ◽  
Vol 39 (11) ◽  
pp. 565-568
Author(s):  
R. C. Goettelman ◽  
I. G. Poppoff
Keyword(s):  
Pressure Drop ◽  
High Velocity ◽  
Mechanical Failure ◽  
Venturi Tube ◽  
Ice Formation ◽  
Quantitative Measurements ◽  
Air Stream ◽  
Air System ◽  
Stationary Operation ◽  
Moving Parts

An icing detector which operates on a pressurized air system and utilizes the pressure drop produced across a Venturi tube as an indication of icing conditions is described in this paper. Since the rate of ice formation on a surface is a function of the configuration of the surface, this detector has the unique advantage of being adaptable to conform with the shape of any structure on which it is mounted. Previously developed icing detectors require either a high velocity air stream, as in aircraft operation, or moving parts subject to possible mechanical failure during severe icing conditions. A pneumatically actuated icing detector designed specifically for stationary operation would be capable of icing measurements without either of these restrictions. Preliminary experiments indicate that this technique is feasible and capable of furnishing quantitative measurements of icing severity.

Numerical study on mean flow field of turbulent dual offset jet

2021 ◽  
pp. 095440622110007
Author(s):  
Tanmoy Mondal ◽  
Shantanu Pramanik
Keyword(s):  
Flow Field ◽  
Numerical Study ◽  
Jet Flow ◽  
Separation Distance ◽  
Bottom Wall ◽  
Mean Flow ◽  
Reattachment Point ◽  
The Mean ◽  
Two Jets ◽  
Offset Jet

A numerical investigation on the mean flow and turbulence characteristics of dual offset jet for various separation distances between the two jets with a fixed offset height of the lower jet from the bottom wall is reported in this study. The numerical simulations have been performed by solving the Reynolds-averaged Navier-Stokes equations (RANS) with two-equation standard [Formula: see text] turbulence model. The Reynolds number based on the jet width and the inlet turbulence intensity are considered as 15,000 and 5%, respectively. The computational results for the mean flow reveal that after issuing from the nozzles, the adjacent shear layers of the offset jets meet together at the merging point and then the merged jets reattaches on the bottom wall at the reattachment point before they combine together at the combined point forming a single jet flow. In the far downstream, the flow field behaves like a classical single wall jet flow. The self-similarity of mean flow field is achieved at far down stream of combined point. An increase in separation distance between the two jets [Formula: see text] results in a decrease in magnitude of the streamwise maximum velocity of the combined jet but with same rate of decay. The converging region of the jets has depicted considerable growth of turbulence as the jet centrelines bend towards the merging point. According to the mean flow results, the distances of the reattachment point and the combined point from the nozzle exit gradually increase with the progressive increase in separation distance between the two jets within the range d/ w = 3–8.

Investigation of Samples From the High-Velocity Water Jet Driven Micro/Nano Particle Collider

2009 ◽  
Author(s):  
Libor M. Hlava´cˇ ◽  
Irena M. Hlava´cˇova´ ◽  
Jaroslav Vasˇek ◽  
Petr Jandacˇka ◽  
Jirˇi´ Zegzulka ◽  
...  
Keyword(s):  
High Velocity ◽  
Water Jet ◽  
Nano Particle ◽  
Material Particle ◽  
Practical Applications ◽  
Mineral Particles ◽  
Mixing Chamber ◽  
Particle Preparation ◽  
Moving Particle ◽  
Further Development

The power of the high-velocity waterjets has been utilized for intentional disintegration of material particles, namely minerals. Firstly, the garnet particles were tested and studied being used usually as the most common abrasive additives for waterjets improving their cutting abilities. Later on, other mineral particles have been investigated because there are some practical applications of them. Primarily, the product generated inside the mixing chamber and the focusing tube has been studied. Subsequently, the special colliding chamber has been designed and produced enabling the collision of the two opposite moving waterjets containing material particles. This device was named “Water Jet Driven Particle Collider”, shortly WJDPC. The product created in the collision of the opposite moving particle containing waterjets has particle sizes covering partially both the nano-scale and the micro-scale. The investigation of parameters influencing the amount of particles with sizes in respective dimension scales is the topic of the contribution. Some samples of special materials were studied and tested. The discussion of the results of the computational modeling of the suction process and its influence on the final product is included. All results are discussed regarding their application in practice and further development of special routings for material particle preparation.

PSEUDO AND HIGH VELOCITY PSEUDO SAWs

2000 ◽  
Vol 10 (04) ◽  
pp. 1069-1109 ◽  
Author(s):  
MAURICIO PEREIRA DA CUNHA
Keyword(s):  
Surface Waves ◽  
High Velocity ◽  
Acoustic Waves ◽  
Power Flow ◽  
Numerical Solutions ◽  
Sagittal Plane ◽  
Surface Acoustic Waves ◽  
Crystal Symmetry ◽  
Flow Angle ◽  
Practical Applications

This article discusses the characteristics of pseudo surface waves (PSAWs) and high velocity pseudo surface waves (HVPSAWs). The fundamental properties of these waves, the matrix method formulation, the different solution types due to crystal symmetry, early experiments on HVPSAWs, and practical applications of pseudo surface acoustic waves serve as an introduction. The solutions to the pseudo modes are discussed by analyzing the boundary condition function for several orientations. The relation between the radiating partial modes and the sagittal plane bulk slowness reveals new characteristics of the different symmetry types of HVPSAW, and helps classify and understand the pseudo modes. The acoustoelectric Poynting vector is used along different crystal symmetry orientations to reveal and discuss the pseudo SAW characteristics: penetration depth, declination of the power vector, and an estimation of power flow angle. Experimental data and numerical solutions of HVPSAW and PSAW along selected planes and orientations are discussed. This article concludes with a brief analysis of layered structures on different symmetry type substrates and a discussion of the layered pseudo surface wave properties.

Swirl-Enhanced Internal Cooling of Turbine Airfoils: Part II—90 Degree Flow Entry

2011 ◽  
Author(s):  
Del Segura ◽  
Sumanta Acharya
Keyword(s):  
Heat Transfer ◽  
Channel Flow ◽  
High Velocity ◽  
Flow Direction ◽  
Jet Flow ◽  
Main Channel ◽  
Positive Pressure ◽  
Slot Channel ◽  
Lower Velocity ◽  
Flow Through

Heat transfer measurements and analysis have been performed on a uniquely designed multi-channel passage consisting of a slot shaped channel with a 3:1 aspect ratio with coolant-feed tubes located adjacent to the main slot shaped channel. Small round jets connect the outer feed passages to the main channels at a 15 degree angle relative to the main channel flow direction and at a position tangent to the floor/roof of the main channel. Flow entering the multi-channel passages is directed into the main channel through orifices that reduce the pressure in the main channel, thereby enabling positive pressure differences between the feed and the main channel and allowing high velocity flow through the jets. The flow enters the main channel via a 90-degree turn through the orifice. The resulting flow through the side jets and main channel causes high shear flow along the roof and floor of the channel where the jet flow enters the main channel, swirl motion as the high velocity side jet flow enters the main channel flow at an angle relative to the main flow direction, and high turbulence regions as the lower velocity main channel flow tumbles when coming in contact with the high velocity jets issuing from the side channels. The heat transfer characteristics were compared to the slot channel with a 90 degree inlet with no additional heat transfer enhancements. Four different jet configurations are presented along with three different orifice diameters. While a single channel passage with flow exiting freely is not a design typically found in a turbine airfoil, the benefits of this unique concept can be a basis for further studies with geometries more typical of a production airfoil. The results yield average normalized Nusselt numbers enhancement for the entire main channel as high as 10.7, when compared to a smooth slot channel without heat transfer enhancements. Pressure losses, mainly due to the orifices, were high but the overall performance shows significant improvements when compared to other heat transfer enhancement methods in turbine airfoil mid-span regions.

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