scholarly journals Simplified Modelling of Inclined Turbulent Dense Jets

Fluids ◽  
2020 ◽  
Vol 5 (4) ◽  
pp. 204
Author(s):  
Ilias G. Papakonstantis ◽  
George C. Christodoulou
Keyword(s):  
Inclination Angle ◽  
Analytical Approximation ◽  
Maximum Height ◽  
Axial Distance ◽  
Fourth Degree ◽  
Polynomial Coefficients ◽  
Inclination Angles ◽  
Straightforward Computation ◽  
Good Agreement ◽  
Return Point

An analytical approximation to the entire centerline trajectory of inclined round dense jets in dimensionless form is proposed, in terms of a fourth degree polynomial. The coefficients of the polynomial for a certain inclination angle can be easily obtained if the position of the maximum height and the return point are known. Experimental data of the authors are used to determine these coefficients for six inclination angles between 35° and 75°. The resulting trajectories are then compared to data of other investigators and found to be in good agreement. The variation of the polynomial coefficients with inclination angle is also studied. The proposed analytical expression allows for a straightforward computation of the trajectory length for any inclination angle in the range studied. It is found that the longest trajectory occurs for the 60° angle. The relation between the computed length and the measured minimum (centerline) dilutions at the location of maximum height and at the return point is examined. Finally, the laws governing the variation of the minimum dilution with the axial distance from the source are explored and similarities with the laws of simple jets and plumes are discussed.

Saturation Boiling Critical Heat Flux of PF-5060 Dielectric Liquid on Microporous Copper Surfaces

2015 ◽  
Vol 137 (4) ◽  
Author(s):  
Mohamed S. El-Genk ◽  
Amir F. Ali
Keyword(s):  
Heat Flux ◽  
Critical Heat Flux ◽  
Inclination Angle ◽  
Nucleate Boiling ◽  
Dielectric Liquid ◽  
Copper Surfaces ◽  
Inclination Angles ◽  
Surface Inclination ◽  
Effect Of Surface ◽  
Good Agreement

Pool boiling experiments are performed to investigate potential enhancement of critical heat flux (CHF) of PF-5060 dielectric liquid on microporous copper (MPC) surfaces and the effect of surface inclination angle. The morphology and microstructure of the MPC surfaces change with thickness. The experiments tested seven 10 × 10 mm MPC surfaces with thicknesses from 80 to 230 μm at inclination angles of 0 deg (upward facing), 60 deg, 90 deg (vertical), 120 deg, 150 deg, 160 deg, 170 deg, and 180 deg (downward facing). CHF increases as the thickness of the surface increases and/or the inclination angle decreases. The values in the upward facing orientation are 36–59% higher than on smooth Cu. For all surfaces, CHF values in the downward facing orientation are approximately 28% of those in the upward facing orientation. A developed CHF correlation, similar to those of Zuber and Kutateladze, accounts for the effects of inclination angle and thickness of the MPC surfaces. It is in good agreement with experimental data to within ±8%. Still photographs of nucleate boiling on the MPC surfaces at different inclinations help the interpretation of the experimental results.

scholarly journals On the question of assesing the size of ice rubble pile in front of the obstacle

2020 ◽  
pp. 66-72
Author(s):  
К.Е. Сазонов ◽  
А.А. Симакина
Keyword(s):  
Inclination Angle ◽  
Ice Cover ◽  
Stability Loss ◽  
Maximum Height ◽  
Loss Of Stability ◽  
Factors Influencing ◽  
Inclination Angles ◽  
Vertical Walls ◽  
Main Factors ◽  
Rubble Pile

В работе рассматривается основные факторы, влияющие на высоту сформировавшегося ледяного нагромождения, при взаимодействии льда и наклонного сооружения. Представлены основные факторы, определяющие характер развития ледяного нагромождения перед препятствием. Рассмотрены механизмы разрушении ледяного покрова с нагромождением при контакте с сооружением с различными углами наклона. Для угла наклона, лежащего между двумя предельными случаями (горизонтальная и вертикальная стенка) проведена оценка максимальной высоты нагромождения, вызывающее разрушения ледяного покрова. Для описания процессов сдвига нагромождения по некоторой поверхности, включая поверхность сооружения рассмотрены модели сыпучих сред. Исследован механизм потери устойчивости ледяного нагромождения и процесс выноса части разрушенного льда за пределы сооружения. Показано, что одним основным из факторов, ограничивающих высоту нагромождения является потеря устойчивости. The paper examines the main factors influencing the height of an ice rubble pile rising as a result of interaction of ice and an inclined structure. One of the main factors determining the mechanism of destruction is the inclination angle of the structure. The mechanisms of ice destruction upon contact with structures with different inclination angles are considered. For the inclination angle laying between the two limiting cases (horizontal and vertical walls), the maximum height of the heap causing the destruction of the ice cover was estimated. Other factors influencing the height of the ice heap are considered. The models of free-flowing media are considered to describe the shear processes of a piling up along a certain surface, including the surface of the structure. The mechanism of stability loss of the ice rubble pile and the process of removing a part of the destroyed ice outside the structure are investigated. One of the main factors limiting the heap height is demonstrated to be the loss of stability.

scholarly journals Acoustic Emission Characteristics and Joint Nonlinear Mechanical Response of Rock Masses under Uniaxial Compression

Energies ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 200
Author(s):  
Zhongliang Feng ◽  
Xin Chen ◽  
Yu Fu ◽  
Shaoshuai Qing ◽  
Tongguan Xie
Keyword(s):  
Acoustic Emission ◽  
Uniaxial Compression ◽  
Inclination Angle ◽  
Failure Modes ◽  
Strain Curve ◽  
Particle Flow Code ◽  
Rock Masses ◽  
Physical Experiments ◽  
Inclination Angles ◽  
Joint Inclination

The joint arrangement in rock masses is the critical factor controlling the stability of rock structures in underground geotechnical engineering. In this study, the influence of the joint inclination angle on the mechanical behavior of jointed rock masses under uniaxial compression was investigated. Physical model laboratory experiments were conducted on jointed specimens with a single pre-existing flaw inclined at 0°, 30°, 45°, 60°, and 90° and on intact specimens. The acoustic emission (AE) signals were monitored during the loading process, which revealed that there is a correlation between the AE characteristics and the failure modes of the jointed specimens with different inclination angles. In addition, particle flow code (PFC) modeling was carried out to reproduce the phenomena observed in the physical experiments. According to the numerical results, the AE phenomenon was basically the same as that observed in the physical experiments. The response of the pre-existing joint mainly involved three stages: (I) the closing of the joint; (II) the strength mobilization of the joint; and (III) the reopening of the joint. Moreover, the response of the pre-existing joint was closely related to the joint’s inclination. As the joint inclination angle increased, the strength mobilization stage of the joint gradually shifted from the pre-peak stage of the stress–strain curve to the post-peak stage. In addition, the instantaneous drop in the average joint system aperture (aave) in the specimens with medium and high inclination angles corresponded to a rapid increase in the form of the pulse of the AE activity during the strength mobilization stage.

Theoretical Assessment of Compressibility Factor of Gases by Using Second Virial Coefficient

2018 ◽  
Vol 73 (2) ◽  
pp. 121-125
Author(s):  
Bahtiyar A. Mamedov ◽  
Elif Somuncu ◽  
Iskender M. Askerov
Keyword(s):  
Virial Coefficient ◽  
Second Virial Coefficient ◽  
Compressibility Factor ◽  
Analytical Approximation ◽  
Accurate Evaluation ◽  
Numerical Examples ◽  
Lennard Jones ◽  
Theoretical Assessment ◽  
Good Agreement

AbstractWe present a new analytical approximation for determining the compressibility factor of real gases at various temperature values. This algorithm is suitable for the accurate evaluation of the compressibility factor using the second virial coefficient with a Lennard–Jones (12-6) potential. Numerical examples are presented for the gases H2, N2, He, CO2, CH4 and air, and the results are compared with other studies in the literature. Our results showed good agreement with the data in the literature. The consistency of the results demonstrates the effectiveness of our analytical approximation for real gases.

An Experimental Examination of the 2D+T Approximation

2009 ◽  
Vol 53 (02) ◽  
pp. 59-67
Author(s):  
Mostafa Shakeri ◽  
Eric Maxeiner ◽  
Thomas Fu ◽  
James H. Duncan
Keyword(s):  
Froude Number ◽  
Longitudinal Wave ◽  
Contact Line ◽  
Three Dimensional ◽  
Maximum Height ◽  
Hull Form ◽  
Ship Model ◽  
Wave Maker ◽  
Acceleration Of Gravity ◽  
Good Agreement

Measurements of contact line height and longitudinal wave profiles from experiments with a three-dimensional naval ship model and experiments using a 2D+T wave maker with motions approximating the three-dimensional hull form are compared. The shape and maximum height of the contact line in the bow region are nearly the same in the two experiments, and the distance downstream along the hull over which the two measurements agree increases with increasing Froude number, Fn = Um/√gLm, where Um is the ship model speed, g is the acceleration of gravity, and Lm is the ship model waterline length. The comparison of the longitudinal wave profile (wave cut) data from the two experiments shows fairly good agreement for wavelengths and amplitudes at the highest Froude number and the measurement position closest to the hull.

Aerodynamic effects of bio-inspired corrugated wings on gliding and hovering performances

2020 ◽  
pp. 095440622091799
Author(s):  
Haibin Xuan ◽  
Jun Hu ◽  
Yong Yu ◽  
Jiaolong Zhang
Keyword(s):  
Inclination Angle ◽  
Fluid Dynamic ◽  
Angle Of Attack ◽  
Aerodynamic Forces ◽  
Limited Effect ◽  
Gliding Flight ◽  
Significant Difference ◽  
Inclination Angles ◽  
Underlying Mechanisms ◽  
Lift And Drag

Recently, numerous studies have been conducted to clarify the effects of corrugation wing on aerodynamic performances. The effects of the corrugation patterns and inclination angles were investigated using computational fluid dynamic method in gliding and hovering flight at Reynolds numbers of order 104. The instantaneous aerodynamic forces and the vorticity field around the wing models were provided to research the underlying mechanisms of aerodynamic effects of corrugated wing models. The findings can be concluded as follows: (1) the corrugation patterns have different effects on aerodynamic performance. The effect of noncamber corrugated wing is to decrease the lift and increase drag compared with a flat-plate when the angle of attack is less than 25° during gliding flight. The corrugated wing with a camber (corrug-2) after the valleys enhances the aerodynamic forces when angle of attack is higher than 35°. The valley inclination angle has limited effect on aerodynamic forces in gliding flight. (2) The lift forces of different corrugation patterns show significantly asymmetric during the upstroke and downstroke. The main reason leads to this phenomenon is the case that two sides of the corrugated wings are not symmetric around the pitching axis. The corrugated wing with only two valleys (corrug-1) changes the lift and drag very slightly. Corrug-2 produces larger peak during downstroke and smaller peak during upstroke. The increase in the inclination angle has limited effect on the aerodynamic forces. The possible reason for these small aerodynamic effects might be that the corrugated wings are smoothed by small vortices trapped in valleys. The main reason for the significant difference between plate and corrug-2 is that the recirculating vortices trapped in the saddle and hump reduce the pressure above the wing surface.

Effect of Fluke Inclination on Behavior of Drag Anchor in Uniform Clay Under Unidirectional and Combined Loading

2019 ◽  
Vol 141 (5) ◽  
Author(s):  
Xiaoni Wu ◽  
Yean Khow Chow ◽  
Chun Fai Leung
Keyword(s):  
Inclination Angle ◽  
Promising Method ◽  
Combined Loading ◽  
Embedment Depth ◽  
Practical Case ◽  
Depth Ratio ◽  
Envelope Method ◽  
Inclination Angles ◽  
Selection Of ◽  
Shape And Size

Prediction of trajectory of drag anchor is important for the design and selection of drag anchor. Prediction based on yield envelope characterizing the anchor behavior under combined loading provides a promising method. However, the existing application of the yield envelope method ignores the effect of the fluke inclination angle by assuming a horizontally placed anchor fluke. This study aims to investigate the behavior of inclined fluke, which is the practical case during installation. The effects of the fluke inclination angle and embedment depth ratio on the anchor behavior in uniform clay under unidirectional loading and combined loading are investigated. It is found that the effect of the fluke inclination angle on the unidirectional capacity factors is mainly for anchor with embedment depth ratio less than 3. This results in the large difference of the size of the yield envelopes for fluke with same smaller embedment depth ratio but different fluke inclination angle, while the effect is minor on the shape of the yield envelope for such cases. However, there is large difference in the shape and size of the shallow yield envelopes for fluke with different embedment depth ratios and inclination angles.

scholarly journals Bayesian hierarchical inference of asteroseismic inclination angles

2019 ◽  
Vol 488 (1) ◽  
pp. 572-589 ◽  
Author(s):  
James S Kuszlewicz ◽  
William J Chaplin ◽  
Thomas S H North ◽  
Will M Farr ◽  
Keaton J Bell ◽  
...  
Keyword(s):  
Inclination Angle ◽  
Angle Distribution ◽  
Data Set ◽  
Single Star ◽  
Bayesian Hierarchical ◽  
Hierarchical Method ◽  
Giant Stars ◽  
Inclination Angles ◽  
Red Giant Stars ◽  
Red Giant

Abstract The stellar inclination angle – the angle between the rotation axis of a star and our line of sight – provides valuable information in many different areas, from the characterization of the geometry of exoplanetary and eclipsing binary systems to the formation and evolution of those systems. We propose a method based on asteroseismology and a Bayesian hierarchical scheme for extracting the inclination angle of a single star. This hierarchical method therefore provides a means to both accurately and robustly extract inclination angles from red giant stars. We successfully apply this technique to an artificial data set with an underlying isotropic inclination angle distribution to verify the method. We also apply this technique to 123 red giant stars observed with Kepler. We also show the need for a selection function to account for possible population-level biases, which are not present in individual star-by-star cases, in order to extend the hierarchical method towards inferring underlying population inclination angle distributions.

scholarly journals An experimental study on the effect of tool geometry on tool wear and surface roughness in hard turning

2020 ◽  
Vol 12 (9) ◽  
pp. 168781402095988
Author(s):  
Pham Minh Duc ◽  
Le Hieu Giang ◽  
Mai Duc Dai ◽  
Do Tien Sy
Keyword(s):  
Surface Roughness ◽  
Tool Wear ◽  
Inclination Angle ◽  
Hard Turning ◽  
Rake Angle ◽  
Machining Process ◽  
Tool Geometry ◽  
Standard Tool ◽  
Inclination Angles ◽  
Mixed Ceramic

The main purpose of this study is to investigate the influence of tool geometry (cutting edge angle, rake angle, and inclination angle) and to optimize tool wear and surface roughness in hard turning of AISI 1055 (52HRC) hardened steel by using TiN coated mixed ceramic inserts. The results show that the inclination angle is the major factor affecting the tool wear and the surface roughness in hard turning. With the increase in negative rake and inclination angles, the tool wear decreases, and the surface roughness increases. However, the surface roughness will decrease when the inclination angle increases to overpass a certain limit. This is a new and significant point in the research of the hard turning process. From this result, the large negative inclination angle (λ = −10°) should be applied to reduce the surface roughness and the tool wear simultaneously. With the optimal cutting tool angles in the research, the hard machining process is improved remarkably with decreases of surface roughness and tool wear 8.3% and 41.3%, respectively in comparison with the standard tool angles. And the proposed tool-post design approach brings an effective method to change the tool insert angles using standard tool-holders to improve hard or other difficult-to-cut materials turning quality.

A Numerical Study on the Effect of Hole Inclination Angle With Imperfection on Film Cooling Effectiveness

2019 ◽  
Author(s):  
Taha Rezzag ◽  
Bassam A. Jubran
Keyword(s):  
Inclination Angle ◽  
Film Cooling ◽  
Numerical Study ◽  
Vortex Pair ◽  
Dimensionless Temperature ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Laser Percussion Drilling ◽  
Inclination Angles ◽  
Lift Off

Abstract The present study numerically evaluates the influence of hole inclination angle with a hole imperfection on film cooling performance. Here, the hole imperfection due to laser percussion drilling is modelled as a half torus. Three hole inclination angles were investigated: 35°, 45° and 55°. Furthermore, every case was evaluated at three blowing ratios: 0.45, 0.90 and 1.25. Each case is compared to a baseline case where the hole imperfection is absent. The results indicate that the hole inclination angle has a strong influence on the film effectiveness performance when a hole imperfection is present. Centerline effectiveness plots reveal a maximum effectiveness deterioration of 89% for a blowing ratio of 0.90 in the vicinity of the hole exit. Dimensionless temperature contours show that the jet produced in the presence of an imperfection is much more compact causing the counter rotating vortex pair to be closer to each other. This enhances the jet to lift off from the plate.

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