Study of jets from rectangular nozzles with square grooves

2011 ◽  
Vol 115 (1165) ◽  
pp. 187-196 ◽  
Author(s):  
P. Arun Kumar ◽  
S. B. Verma ◽  
S. Elangovan
Keyword(s):  
Major Axis ◽  
Minor Axis ◽  
Equivalent Diameter ◽  
Mean Velocity ◽  
Cross Sectional ◽  
Potential Core ◽  
Axis Direction ◽  
Square Configuration ◽  
Hotwire Anemometry ◽  
Axis Switching

AbstractAn experimental study has been carried out to understand jet flow development from plain and grooved rectangular nozzles of aspect ratio 2:1 using two-component hotwire anemometry. Grooves of square configuration (side 4mm) and length 5mm were introduced in the (i) minor-axis, (ii) major-axis and, (iii) in both minor- and major-axes directions. The equivalent diameter of the plain rectangular nozzle is 37·5mm. Studies were carried out for a nominal jet exit velocity of 20ms−1and for Reynolds number based on equivalent diameter of 54,000. The introduction of grooves in either plane does not show any influence on the potential-core length but results in faster jet-decay thereafter. It is observed that the grooves when introduced in minor-axis direction inhibit the jet growth in that plane while promoting the jet growth along major-axis plane and hence, delays the phenomena of axis-switching. However when introduced in major-axis direction, the grooves promote jet growth along major-axis plane while inhibiting jet-growth in minor-axis plane. Cross-sectional contours of mean-velocity suggest that the grooves modify the process of overall jet development significantly in the plane in which they are introduced relative to the plain jet and hence, significantly affect the axis-switching location in each case.

scholarly journals Numerical Study of the Velocity Decay of Offset Jet in a Narrow and Deep Pool

Water ◽  
2018 ◽  
Vol 11 (1) ◽  
pp. 59 ◽  
Author(s):  
Xin Li ◽  
Maolin Zhou ◽  
Jianmin Zhang ◽  
Weilin Xu
Keyword(s):  
Flow Field ◽  
Numerical Study ◽  
Expansion Ratio ◽  
Sudden Expansion ◽  
Mean Velocity ◽  
Cross Sectional ◽  
Potential Core ◽  
Early Region ◽  
Flow Development ◽  
Offset Jet

The present study examines the configuration of an offset jet issuing into a narrow and deep pool. The standard k-ε model with volume-of-fluid (VOF) method was used to simulate the offset jet for three exit offset ratios (OR = 1, 2 and 3), three expansion ratios (ER = 3, 4 and 4.8), and different jet exits (circular and rectangular). The results clearly show significant effects of the circumference of jet exits (Lexit) in the early region of flow development, and a fitted formula is presented to estimate the length of the potential core zone (LPC). Analysis of the flow field for OR = 1 showed that the decay of cross-sectional streamwise maximum mean velocity (Um) in the transition zone could be fitted by power law with the decay rate n decreased from 1.768 to 1.197 as the ER increased, while the decay of Um for OR = 2 or 3 was observed accurately estimated by linear fit. Analysis of the flow field of circular offset jet showed that Um for OR = 2 decayed fastest due to the fact that the main flow could be spread evenly in floor-normal direction. For circular jets, the offset ratio and expansion ratio do not affect the spread of streamwise velocity in the early region of flow development. It was also observed that the absence of sudden expansion of offset jet is analogous to that of a plane offset jet, and the flow pattern is different.

Flow field and acoustics characteristics of elliptical jet

2018 ◽  
Vol 90 (9) ◽  
pp. 1364-1371 ◽  
Author(s):  
S. Manigandan ◽  
Vijayaraja K.
Keyword(s):  
Flow Field ◽  
Large Scale ◽  
Rapid Change ◽  
Supersonic Jet ◽  
Major Axis ◽  
Minor Axis ◽  
Shock Cell ◽  
Potential Core ◽  
Content Type ◽  
Elliptical Jet

Purpose The purpose of this paper is to present the results of mixing promotion and screech frequency of controlled elliptical supersonic jet. Design/methodology/approach Flow field characteristics of low-aspect-ratio elliptical jets are examined at over-expanded, under-expanded and correctly expanded conditions. The tabs are placed at elliptical jet exit along the major and minor axes. Findings The results show that the mixing done by the minor axis is superior to the tabs along major axis. At all pressure ratios, the content of jet noise and the frequency are high for the tabs along the major axis because of increase in the amplitude of screech frequency. Further the tabs along minor axis show a dominance of large-scale vertical structures. In under-expanded conditions, the shock cell shows the rapid change because of the presence of tabs. The tabs along minor axis are making the shock weaker, hence no evidence of axis switching. Practical implications To achieve the greater performance of jet, the authors need to reduce the potential core length of the issuing jet. This can be achieved by implementing different types of tabs at the exit of the nozzle. Originality/value The present paper represents the flow of controlled jet using inverted triangular tabs. By achieving the controlled jet flow, the performance of propulsion systems can be improved. This can be used in systems such as combustion chamber, missile’s noise reduction and thrust vector control.

Fatigue Tests on Specimens Containing Skew Holes

1976 ◽  
Vol 18 (6) ◽  
pp. 287-291 ◽  
Author(s):  
I. Ficenec ◽  
G. Craggs ◽  
B. N. Cole
Keyword(s):  
Fatigue Life ◽  
Endurance Limit ◽  
Fatigue Crack Initiation ◽  
Major Axis ◽  
Fatigue Tests ◽  
Minor Axis ◽  
Skew Angle ◽  
Cross Sectional ◽  
Skew Angles ◽  
Fatigue Endurance

The fatigue life of uniaxial fatigue specimens containing a skew hole is investigated. Contrary to expectation, fatigue life and fatigue endurance limit show no discernible change for vertical skew angles up to 45 when stress is calculated using the gross cross-sectional area. The point of fatigue crack initiation moves from the tip of the minor axis of the ellipse towards the tip of the major axis as skew angle increases.

Geometric changes of the inferior vena cava in trauma patients subjected to volume resuscitation

Vascular ◽  
2014 ◽  
Vol 23 (5) ◽  
pp. 459-467 ◽  
Author(s):  
Samuel L Chen ◽  
Mayil S Krishnam ◽  
Thangavijayan Bosemani ◽  
Sumudu Dissayanake ◽  
Michael D Sgroi ◽  
...  
Keyword(s):  
Inferior Vena Cava ◽  
Renal Vein ◽  
Inferior Vena ◽  
Vena Cava ◽  
Major Axis ◽  
Minor Axis ◽  
Trauma Patients ◽  
Cross Sectional ◽  
Area And Perimeter ◽  
Left Anterior Oblique

ObjectiveDynamic changes in anatomic geometry of the inferior vena cava from changes in intravascular volume may cause passive stresses on inferior vena cava filters. In this study, we aim to quantify variability in inferior vena cava dimensions and anatomic orientation to determine how intravascular volume changes may impact complications of inferior vena cava filter placement, such as migration, tilting, perforation, and thrombosis.MethodsRetrospective computed tomography measurements of major axis, minor axis, and horizontal diameters of the inferior vena cava at 1 and 5 cm below the lowest renal vein in 58 adult trauma patients in pre-resuscitative (hypovolemic) and post-resuscitative (euvolemic) states were assessed in a blinded fashion by two independent readers. Inferior vena cava perimeter, area, and volume were calculated and correlated with caval orientation.ResultsMean volumes of the inferior vena cava segment on pre- and post-resuscitation scans were 9.0 cm3and 11.0 cm3, respectively, with mean percentage increase of 48.6% ( P < 0.001). At 1 cm and 5 cm below the lowest renal vein, the inferior vena cava expanded anisotropically, with the minor axis expanding by an average of 48.7% ( P < 0.001) and 30.0% ( P = 0.01), respectively, while the major axis changed by only 4.2% ( P = 0.11) and 6.6% ( P = 0.017), respectively. Cross-sectional area and perimeter at 1 cm below the lowest renal vein expanded by 61.6% ( P < 0.001) and 10.7% ( P < 0.01), respectively. At 5 cm below the lowest renal vein, the expansion of cross-sectional area and perimeter were 43.9% ( P < 0.01) and 10.7% ( P = 0.002), respectively. The major axis of the inferior vena cava was oriented in a left-anterior oblique position in all patients, averaging 20° from the horizontal plane. There was significant underestimation of inferior vena cava maximal diameter by horizontal measurement. In pre-resuscitation scans, at 1 cm and 5 cm below the lowest renal vein, the discrepancy between the horizontal and major axis diameter was 2.1 ± 1.2 mm ( P < 0.001) and 1.7 ± 1.0 mm ( P < 0.001), respectively, while post-resuscitation studies showed the same underestimation at 1 cm and 5 cm below the lowest renal vein to be 2.2 ± 1.2 mm ( P < 0.01) and 1.9 ± 1.0 mm ( P < 0.01), respectively.ConclusionsThere is significant anisotropic variability of infrarenal inferior vena cava geometry with significantly greater expansive and compressive forces in the minor axis. There can be significant volumetric changes in the inferior vena cava with associated perimeter changes but the major axis left-anterior oblique caval configuration is always maintained. These significant dynamic forces may impact inferior vena cava filter stability after implantation. The consistent major axis left-anterior oblique obliquity may lead to underestimation of the inferior vena cava diameter used in standard anteroposterior venography, which may influence initial filter selection.

The formation of elliptical wakes

1967 ◽  
Vol 27 (2) ◽  
pp. 353-360 ◽  
Author(s):  
Yung-Huang Kuo ◽  
Lionel V. Baldwin
Keyword(s):  
Strouhal Number ◽  
Cross Sections ◽  
Major Axis ◽  
Turbulent Energy ◽  
Minor Axis ◽  
The Body ◽  
Wake Flow ◽  
Mean Velocity ◽  
Elliptical Cross ◽  
Number Range

The wakes formed behind sharp-edged, bluff, elliptical bodies have elliptical cross-sections, but the major axis of the wake is aligned with the minor axis of the body. This effect was observed in both mean velocity and turbulent intensity data in wakes throughout the range of the experiment, from several body diameters to distances of 250 diameters downstream of the body. The turbulent energy in the wake flow near the body displayed a periodicity which was correlated using a Strouhal number. Over the Reynolds-number range from 8 × 103to 7 × 104, the Strouhal number depended only on the body eccentricity.

scholarly journals The Effect of wall on subsonic non-circular jets

2018 ◽  
Vol 6 (11) ◽  
Author(s):  
Bhatia Devansh Pradeep ◽  
Imanbir Singh ◽  
Sonam Eden Bhutia
Keyword(s):  
Surface Roughness ◽  
Major Axis ◽  
Minor Axis ◽  
Ambient Fluid ◽  
Potential Core ◽  
Jet Mixing ◽  
The Core ◽  
Mixing Characteristics ◽  
Circular Jets ◽  
Jet Axis

The present experimental study aims at characterizing the mixing characteristics of subsonic elliptic and rectangular orifice jets (Ve = 51 m/s) in the presence of wall of different surface roughness, namely smooth, fine and coarse, placed parallel to the jet axis at the edge of the orifice exit. The wall of length 120 cm of different surface roughness was oriented either parallel to the minor axis plane or major axis plane if the orifice. The wall had a strong effect on the mixing characteristics of elliptic and rectangular jets. The centerline velocity measurement showed that the potential core of elliptic and rectangular orifice jets was around 3De and 3.5De. For both jets, all the wall configurations retarded the mixing of jet with the ambient fluid only in the characteristic decay zone but not in the core and fully developed zones. The level of mixing retardation was found to be maximum when wall was placed parallel to the major axis plane of the jet. The effect of wall on jet mixing was intense for rectangular jet compared to elliptic jet.

Raised Object on a Planar Surface Stroked Across the Fingerpad: Responses of Cutaneous Mechanoreceptors to Shape and Orientation

1998 ◽  
Vol 80 (5) ◽  
pp. 2446-2466 ◽  
Author(s):  
R. H. Lamotte ◽  
R. M. Friedman ◽  
C. Lu ◽  
P. S. Khalsa ◽  
M. A. Srinivasan
Keyword(s):  
Horizontal Plane ◽  
Major Axis ◽  
Skin Surface ◽  
Minor Axis ◽  
Type I ◽  
Planar Surface ◽  
Cutaneous Mechanoreceptors ◽  
Cross Sectional ◽  
Orthogonal Axis ◽  
Object Shape

LaMotte, R. H., R. M. Friedman, C. Lu, P. S. Khalsa, and M. A. Srinivasan. Raised object on a planar surface stroked across the fingerpad: responses of cutaneous mechanoreceptors to shape and orientation. J. Neurophysiol. 80: 2446–2466, 1998. The representations of orientation and shape were studied in the responses of cutaneous mechanoreceptors to an isolated, raised object on a planar surface stroked across the fingerpad. The objects were the top portions of a sphere with a 5-mm radius, and two toroids each with a radius of 5 mm along one axis and differing radii of 1 or 3 mm along the orthogonal axis. The velocity and direction of stroking were fixed while the orientation of the object in the horizontal plane was varied. Each object was stroked along a series of laterally shifted, parallel, linear trajectories over the receptive fields of slowly adapting, type I (SA), and rapidly adapting, type I (RA) mechanoreceptive afferents innervating the fingerpad of the monkey. “Spatial event plots” (SEPs) of the occurrence of action potentials, as a function of the location of each object on the receptive field, were interpreted as the responses of a spatially distributed population of fibers. That portion of the plot evoked by the curved object (the SEPc) provided a representation of the shape and orientation of the two-dimensional outline of the object in the horizontal plane in contact with the skin. For both SAs and RAs, the major vector of the SEPc, obtained by a principal components analysis, was linearly related to the physical orientation of the major axis of each toroid. The spatial distribution of discharge rates [spatial rate surface profiles (SRSs), after plotting mean instantaneous frequency versus spatial locus within the SEPc] represented object shape in a third dimension, normal to the skin surface. The shape of the SA SRSs, well fitted by Gaussian equations, better represented object shape than that of the RA SRSs. A cross-sectional profile along the minor axis [spatial rate profile (SRP)] was approximately triangular for SAs. After normalization for differences in peak height, the falling slopes of the SA SRPs increased, and the base widths decreased with curvature of the object's minor axis. These curvature-related differences in slopes and widths were invariant with changes in object orientation. It is hypothesized that circularity in object shape is coded by the constancy of slopes of SA SRPs between peak and base and that the constancy of differences in the widths and falling slopes evoked by different raised objects encodes, respectively, the differences in their sizes and shapes regardless of differences in their orientation on the skin.

Analysis of Material Flow in Oval Upsetting Using Mild-Wedged Die

2016 ◽  
Vol 716 ◽  
pp. 379-388
Author(s):  
Takashi Nomura ◽  
Con Ngyuen ◽  
Kazuhiko Kitamura ◽  
Keiichi Matsunaga
Keyword(s):  
Process Design ◽  
Material Flow ◽  
Technical Information ◽  
Major Axis ◽  
Minor Axis ◽  
Nose Radius ◽  
Cross Sectional ◽  
Die Life ◽  
The Relationship ◽  
Forging Load

In multiple stages forging, an appropriate pre-form has reduced production cost, loss of material, and forging load, and it has also improved die life. However, it is difficult for beginner to make the process design of the pre-form because they have poor technical information. For example, experts have experimental knowledge how to form an oval cylinder by upsetting of a right cylinder with a mild-wedged die. This oval upsetting needs no container with oval hole. This paper investigates the oval upsetting with the relationship between the nose angle of the mild-wedged die and the shape of the product for assistance of the process design in forging. As the results, when the mild-wedged die having an appropriate angle and nose radius was applied to the upsetting, the oval cross-sectional ratio of the major axis to the minor axis achieved 1.45.

Experimental studies on rectangular jets with trapezoidal tabs

2013 ◽  
Vol 117 (1191) ◽  
pp. 505-517 ◽  
Author(s):  
A. Arokkiaswamy ◽  
S. B. Verma ◽  
S. Venkateswaran
Keyword(s):  
Flow Structure ◽  
Flow Direction ◽  
Experimental Studies ◽  
Major Axis ◽  
Minor Axis ◽  
Equivalent Diameter ◽  
Jet Mixing ◽  
Rectangular Nozzle ◽  
Flow Development ◽  
Jet Characteristics

Abstract An experimental investigation was carried out to study the flow development of a jet issuing from a 2:1 rectangular nozzle with mixing tabs using two-component hotwire anemometry. A pair of tabs of trapezoidal configuration (with 2% total blockage area) is placed on the minor-axis side of the rectangular nozzle and tested for two tab inclination angles of 135° and 45°, with respect to the flow direction. Tests were conducted for a nominal jet exit velocity of 20m/sec corresponding to a Reynolds number based on nozzle equivalent diameter of 5·013 × 104. Relative to the plain jet, the jet with tabs show significant reduction in jet-core length (by 67%) followed by a faster decay in jet centreline velocity (U/Ue ). This is also accompanied by a significant upstream shift in peak centreline turbulence intensity (u’/Ue ). The presence of tabs is observed to inhibit the jet growth along the minor-axis plane thereby introducing large distortion in the jet cross-sectional development that ultimately leads to jet-core bifurcation along its major-axis. While a mushroom-like flow structure develops behind the tab with 135° inclination, the flow structure behind a 45° inclined tab rather takes the shape of the tab itself. The former flow development is seen to enhance the jet growth more along the minor-axis while the latter improves the jet growth more along the major-axis plane. From application point of view, since both tab inclinations result in more or less similar jet characteristics, a 135° inclined tab would be preferable over a 45° inclined tab from the view of improved jet mixing.

Gender determination of caucasoid hair using image analysis

1993 ◽  
Vol 51 ◽  
pp. 216-217
Author(s):  
T.B. Ball ◽  
W.M. Hess
Keyword(s):  
Image Analysis ◽  
Cross Sections ◽  
Scalp Hair ◽  
The Body ◽  
Equivalent Diameter ◽  
Cross Sectional ◽  
Hair Samples ◽  
Length Width ◽  
Morphological Differences

It has been demonstrated that cross sections of bundles of hair can be effectively studied using image analysis. These studies can help to elucidate morphological differences of hair from one region of the body to another. The purpose of the present investigation was to use image analysis to determine whether morphological differences could be demonstrated between male and female human Caucasian terminal scalp hair.Hair samples were taken from the back of the head from 18 caucasoid males and 13 caucasoid females (Figs. 1-2). Bundles of 50 hairs were processed for cross-sectional examination and then analyzed using Prism Image Analysis software on a Macintosh llci computer. Twenty morphological parameters of size and shape were evaluated for each hair cross-section. The size parameters evaluated were area, convex area, perimeter, convex perimeter, length, breadth, fiber length, width, equivalent diameter, and inscribed radius. The shape parameters considered were formfactor, roundness, convexity, solidity, compactness, aspect ratio, elongation, curl, and fractal dimension.

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