scholarly journals Video: Visualization of Vortices formed by different Nozzle Geometries

2018 ◽  
Author(s):  
Paola Leon Guarneros ◽  
Carlos Echeverria ◽  
David Porta ◽  
Catalina Stern
Keyword(s):  
Nozzle Geometries ◽  
Video Visualization

Measurement of Biodiesel Blend and Conventional Diesel Spray Structure Using X-Ray Radiography

2009 ◽  
Vol 131 (6) ◽  
Author(s):  
A. L. Kastengren ◽  
C. F. Powell ◽  
K.-S. Im ◽  
Y.-J. Wang ◽  
J. Wang
Keyword(s):  
Cone Angle ◽  
Injection Pressure ◽  
Fuel Distribution ◽  
X Ray ◽  
Spray Structure ◽  
Quantitative Measurements ◽  
Biodiesel Blend ◽  
Temporal And Spatial ◽  
Nozzle Geometries ◽  
Fuel Effects

The near-nozzle structure of several nonevaporating biodiesel-blend sprays has been studied using X-ray radiography. Radiography allows quantitative measurements of the fuel distribution in sprays to be made with high temporal and spatial resolution. Measurements have been made at different values of injection pressure, ambient density, and with two different nozzle geometries to understand the influences of these parameters on the spray structure of the biodiesel blend. These measurements have been compared with corresponding measurements of Viscor, a diesel calibration fluid, to demonstrate the fuel effects on the spray structure. Generally, the biodiesel-blend spray has a similar structure to the spray of Viscor. For the nonhydroground nozzle used in this study, the biodiesel-blend spray has a slightly slower penetration into the ambient gas than the Viscor spray. The cone angle of the biodiesel-blend spray is generally smaller than that of the Viscor spray, indicating that the biodiesel-blend spray is denser than the Viscor spray. For the hydroground nozzle, both fuels produce sprays with initially wide cone angles that transition to narrow sprays during the steady-state portion of the injection event. These variations in cone angle with time occur later for the biodiesel-blend spray than for the Viscor spray, indicating that the dynamics of the injector needle as it opens are somewhat different for the two fuels.

Characterisation of supersonic gas jets for different nozzle geometries for laser-plasma acceleration experiments at SPARC_LAB

2022 ◽  
Vol 17 (01) ◽  
pp. C01049
Author(s):  
G. Costa ◽  
M.P. Anania ◽  
A. Biagioni ◽  
F.G. Bisesto ◽  
M. Del Franco ◽  
...  
Keyword(s):  
High Power ◽  
Plasma Channel ◽  
Laser Pulses ◽  
Industrial Applications ◽  
Point Of View ◽  
Theoretical Point ◽  
High Power Laser ◽  
Power Laser ◽  
Neutral Gas ◽  
Nozzle Geometries

Abstract Plasma-based technology promises a tremendous reduction in size of accelerators used for research, medical, and industrial applications, making it possible to develop tabletop machines accessible for a broader scientific community. The use of high-power laser pulses on gaseous targets is a promising method for the generation of accelerated electron beams at energies on the GeV scale, in extremely small sizes, typically millimetres. The gaseous target in question can be a collimated supersonic gasjet from a nozzle. In this work, a technique for optimising the so generated plasma channel is presented. In detail, a study on the influence of the nozzle throat shape in relation to the uniformity and density of the generated plasma profile is reported. These considerations are discussed first of all from a theoretical point of view, by means of a stationary one-dimensional mathematical model of the neutral gas, thus exploiting the possibility of comparing the properties of the output flow for different nozzle geometries. This is combined with an experimental approach using interferometric longitudinal density measurements of the plasma channel. The latter is generated by a high-power laser pulse focused on a helium gasjet, in the SPARC_LAB laboratories.

scholarly journals An investigation of the interaction between a travelling shock wave and a solid rocket motor nozzle

2021 ◽  
Author(s):  
Harmanjit Singh Chopra
Keyword(s):  
Shock Wave ◽  
Shock Tube ◽  
Reflected Shock Wave ◽  
Convergence Region ◽  
Rocket Motors ◽  
Additional Information ◽  
Reflected Shock ◽  
Solid Propellant Rocket ◽  
Computational Fluid Dynamics Cfd ◽  
Nozzle Geometries

A gasdynamic mechanism has been identified as a potential source of combustion instability in solid-propellant rocket motors (SRMs). This mechanism involves the reinforcement of a reflected shock wave in the nozzle convergence region of an SRM's exhaust nozzle. A shock tube apparatus was developed for the experimental component of this study. Various factors, such as the effect of different nozzle geometries and driven channel pressures, were examined. Also, a model of the shock tube was developed for computational fluid dynamics (CFD) simulations. These simulations were generated for comparison with the experimental results and to provide additional information regarding the nature of the flow behaviour. A gasdynamic mechanism has been identified as a potential source of combustion instability in solid-propellant rocket motors (SRMs). This mechanism involves the reinforcement of a reflected shock wave in the nozzle convergence region of an SRM's exhaust nozzle.A shock tube apparatus was developed for the experimental component of this study. Various factors, such as the effect of different nozzle geometries and driven channel pressures, were examined. Also, a model of the shock tube was developed for computational fluid dynamics (CFD) simulations. These simulations were generated for comparison with the experimental results and to provide additional information regarding the nature of the flow behaviour.Experimental and numerical pressure-time profiles confirm the appearance of transient radial wave activity following the initial incidence of the normal shock wave on the convergence region of the nozzle. The results establish that the strength of this activity is markedly dependent upon the nozzle convergence wall angle and the location within the shock tube

scholarly journals Effects of Nozzle Geometries on Thrust Performance Improvement of Micro-Multi-Nozzle-Array Thrusters

2009 ◽  
Vol 7 (ists26) ◽  
pp. Pb_77-Pb_82
Author(s):  
Fujimi SAWADA ◽  
Atsushi KOSHIYAMA ◽  
Shuji HAGIWARA ◽  
Hideyuki HORISAWA ◽  
Ikkoh FUNAKI
Keyword(s):  
Performance Improvement ◽  
Nozzle Geometries ◽  
Thrust Performance

Numerical Simulation on Flow Structure of a Steam-Jet Pump Influenced by Primary Nozzle Geometries

2011 ◽  
Vol 130-134 ◽  
pp. 1703-1707 ◽  
Author(s):  
Xiao Chun Dai ◽  
Jian Huo
Keyword(s):  
Fluid Dynamics ◽  
Flow Structure ◽  
Mixing Process ◽  
Nozzle Outlet ◽  
Jet Pump ◽  
Entrainment Ratio ◽  
Great Loss ◽  
Mixing Chamber ◽  
Throat Diameter ◽  
Nozzle Geometries

The aim of the paper is to reveal the flow structure and the mixing process of a steam-jet pump by using a computational fluid dynamics code FLUENT. Discusses the effect on a steam-jet pump’s entrainment ratio when the throat diameter of the primary nozzle as well as the outlet diameter of the primary nozzle is varied. Analyzes the position of shock wave which will bring the steam-jet pump’s performance a great loss. The performances of a steam-jet pump are studied by changing back pressures while the distance between primary nozzle outlet and mixing chamber inlet (DPM) is varied. The entrainment ratios of a steam-jet pump with different values of DPM and different back pressures are calculated.

An Attempt to Improve the Deposition Efficiency of AI2O3 Coating by HVOF Spraying

2000 ◽  
Author(s):  
Y. Shimizu ◽  
K. Sugiura ◽  
K. Sakaki ◽  
A. Devasanapathi
Keyword(s):  
Hardness Test ◽  
Deposition Efficiency ◽  
Nozzle Geometry ◽  
Hvof Spraying ◽  
Fuel Gas ◽  
Dense Microstructure ◽  
Alumina Particles ◽  
Coating Characteristics ◽  
Nozzle Geometries ◽  
Spraying Process

Abstract High Velocity Oxy-Fuel (HVOF) method using propylene as a fuel gas was employed to spray alumina particles. In order to improve the coating characteristics such as the deposition efficiency and the hardness, three HVOF gun nozzles of varying geometry were designed and tested experimentally. The spraying process was also simulated numerically for each of the nozzle geometries to understand their effectiveness in influencing the velocity and temperature of the sprayed particles. The coating was characterized using optical and scanning electron microscopy (SEM), micro-vickers hardness test and X-ray diffractometry (XRD). Results showed that with the use of a convergent and divergent type gun nozzle, similar to that of a Laval nozzle, the extent of melting of the alumina particles could be increased. This was exhibited by an increase in the deposition efficiency to the extent of 45%. However, the sharp changes in the convergent and divergent nozzle geometry, resulted in fusion and agglomeration of alumina particles leading to spitting during the spraying process. The results clearly showed that alumina coatings of excellent hardness in the range of 920-1290 HV, with a relatively dense microstructure could be obtained in HVOF method irrespective of the gun nozzle geometry, provided the spraying parameters are properly controlled.

scholarly journals Video Description Model Based on Temporal-Spatial and Channel Multi-Attention Mechanisms

2020 ◽  
Vol 10 (12) ◽  
pp. 4312 ◽  
Author(s):  
Jie Xu ◽  
Haoliang Wei ◽  
Linke Li ◽  
Qiuru Fu ◽  
Jinhong Guo
Keyword(s):  
Neural Network ◽  
Spatial Attention ◽  
Semantic Information ◽  
Attention Mechanism ◽  
Visual Features ◽  
Feature Maps ◽  
Global Features ◽  
Model Based ◽  
Video Description ◽  
Video Visualization

Video description plays an important role in the field of intelligent imaging technology. Attention perception mechanisms are extensively applied in video description models based on deep learning. Most existing models use a temporal-spatial attention mechanism to enhance the accuracy of models. Temporal attention mechanisms can obtain the global features of a video, whereas spatial attention mechanisms obtain local features. Nevertheless, because each channel of the convolutional neural network (CNN) feature maps has certain spatial semantic information, it is insufficient to merely divide the CNN features into regions and then apply a spatial attention mechanism. In this paper, we propose a temporal-spatial and channel attention mechanism that enables the model to take advantage of various video features and ensures the consistency of visual features between sentence descriptions to enhance the effect of the model. Meanwhile, in order to prove the effectiveness of the attention mechanism, this paper proposes a video visualization model based on the video description. Experimental results show that, our model has achieved good performance on the Microsoft Video Description (MSVD) dataset and a certain improvement on the Microsoft Research-Video to Text (MSR-VTT) dataset.

Nozzle Geometry Effect on Twin Jet Flow Characteristics

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Muthuram A ◽  
Thanigaiarasu S ◽  
Rakesh Divvela ◽  
Rathakrishnan Ethirajan
Keyword(s):  
Mach Number ◽  
Flow Characteristics ◽  
Nozzle Geometry ◽  
Ambient Atmosphere ◽  
Free Jets ◽  
Twin Jets ◽  
Equivalent Area ◽  
Nozzle Configuration ◽  
Jet Nozzle ◽  
Nozzle Geometries

AbstractEffect of nozzle geometries on the propagation of twin jet issuing from nozzles with circle-circle, circle-ellipse, circle-triangle, circle-square, circle-hexagon and circle-star geometrical combinations was investigated for Mach numbers 0.2, 0.4, 0.6 and 0.8. In all the cases, both jets in the twin jet had the same Mach number. All the twin jets of this study are free jets, discharged into stagnant ambient atmosphere. The result of the twin jets issuing from circle-circle nozzle is kept as the reference in this study. For all the twin jet nozzles, the inter nozzle spacing; the distance between the nozzle axes (S) was 20 mm and all the nozzles had an equivalent area of 78.5 mm2. Thus for all the cases of the present study, S/D ratio is 2. The results show that the mixing of the combined jet, after the merging point is strongly influenced by the combined effect of the nozzle geometry and jet Mach number. Among the six different twin jet nozzle configuration studied, circle-square combination is found to be the most superior mixing promoter.

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