Jet Stability: A Computational Survey

2009 ◽  
pp. 179-199 ◽  
Author(s):  
Rony Keppens ◽  
Zakaria Meliani ◽  
Hubert Baty ◽  
Bart van der Holst
Keyword(s):  
Jet Stability

scholarly journals Stability of a Viscous Liquid Jet in a Coaxial Twisting Compressible Airflow

Processes ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 918
Author(s):  
Li-Mei Guo ◽  
Ming Lü ◽  
Zhi Ning
Keyword(s):  
Viscous Liquid ◽  
Axial Velocity ◽  
Liquid Velocity ◽  
Velocity Ratio ◽  
Dominant Mode ◽  
Liquid Jet ◽  
Axisymmetric Mode ◽  
Jet Instability ◽  
Jet Stability ◽  
Jet Breakup

Based on the linear stability analysis, a mathematical model for the stability of a viscous liquid jet in a coaxial twisting compressible airflow has been developed. It takes into account the twist and compressibility of the surrounding airflow, the viscosity of the liquid jet, and the cavitation bubbles within the liquid jet. Then, the effects of aerodynamics caused by the gas–liquid velocity difference on the jet stability are analyzed. The results show that under the airflow ejecting effect, the jet instability decreases first and then increases with the increase of the airflow axial velocity. When the gas–liquid velocity ratio A = 1, the jet is the most stable. When the gas–liquid velocity ratio A > 2, this is meaningful for the jet breakup compared with A = 0 (no air axial velocity). When the surrounding airflow swirls, the airflow rotation strength E will change the jet dominant mode. E has a stabilizing effect on the liquid jet under the axisymmetric mode, while E is conducive to jet instability under the asymmetry mode. The maximum disturbance growth rate of the liquid jet also decreases first and then increases with the increase of E. The liquid jet is the most stable when E = 0.65, and the jet starts to become more easier to breakup when E = 0.8425 compared with E = 0 (no swirling air). When the surrounding airflow twists (air moves in both axial and circumferential directions), given the axial velocity to change the circumferential velocity of the surrounding airflow, it is not conducive to the jet breakup, regardless of the axisymmetric disturbance or asymmetry disturbance.

scholarly journals Jet stability and wall impingement flow field in a thermal striping experiment

2017 ◽  
Vol 115 ◽  
pp. 1125-1136 ◽  
Author(s):  
S. Lomperski ◽  
A. Obabko ◽  
E. Merzari ◽  
P. Fischer ◽  
W.D. Pointer
Keyword(s):  
Flow Field ◽  
Jet Stability ◽  
Wall Impingement ◽  
Thermal Striping

Controls for Plasma Spraying Based on Plasma Jet Stability Analysis

1998 ◽  
Author(s):  
L. Beall ◽  
Z. Duan ◽  
J. Schein ◽  
J. Heberlein ◽  
M. Stachowicz ◽  
...  
Keyword(s):  
Process Control ◽  
Plasma Spraying ◽  
High Speed ◽  
Small Degree ◽  
Negative Effects ◽  
Microphone Signal ◽  
Jet Length ◽  
Jet Stability ◽  
Control Scheme ◽  
Coating Characteristics

Abstract Despite the fact that plasma spraying has been a widely used technology over the past three decades, industries using this technology still need higher quality products. Presently, only a small degree of process control is used in most plasma spraying systems. Improved process control should lead to more consistent results and higher quality products. We discuss a relatively simple control scheme consisting of a microphone as a primary sensor and a fuzzy logic look-up model indicating the condition of the anode. Selected frequency peaks in the power spectrum of the microphone signal are analyzed online, and the results are correlated with an average jet length obtained from a series of high speed images. The jet length, in turn, is correlated with coating characteristics. A simple feedback control system is proposed which will counteract the negative effects of an eroded anode on coating quality.

scholarly journals Jet Mode Recognition of Electrohydrodynamic Direct-Writing Based on Micro/Nano Current

Micromachines ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 128
Author(s):  
Guoyi Kang ◽  
Gaofeng Zheng ◽  
Yanping Chen ◽  
Jiaxin Jiang ◽  
Huatan Chen ◽  
...  
Keyword(s):  
Taylor Cone ◽  
Direct Writing ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Peak Current ◽  
Loop Control ◽  
Jet Stability ◽  
Mode Recognition ◽  
Patterned Structures ◽  
Current Characteristics

The online recognition of jet mode is important for the accurate control and further application of electrohydrodynamic direct-writing (EDW) technology. An EDW system with a current detection module is built for jet mode recognition. The current of the EDW jet is measured to recognize the jet mode when printing patterned structures. Then, a data processing program with a digital Kaiser low-pass filter is developed in MATLAB, via which the noise of the current signal is reduced. The features of EDW current, including the current fluctuation and the peak current intervals, are studied to recognize different jet modes. The current characteristics of three jet modes are investigated: droplet ejection mode, Taylor cone ejection mode, and retractive ejection mode. The Taylor cone ejection mode has the smallest coefficient of variation of peak current. This work provides a good way of designing the optimized control algorithm and of realizing the closed-loop control system, which contributes to enhancing the jet stability and accelerating the application of EDW technology.

Jet Stability and the Generation of Superluminal and Stationary Components

2001 ◽  
Vol 549 (2) ◽  
pp. L183-L186 ◽  
Author(s):  
Iván Agudo ◽  
José-Luis Gómez ◽  
José-María Martí ◽  
José-María Ibáñez ◽  
Alan P. Marscher ◽  
...  
Keyword(s):  
Jet Stability

scholarly journals Influence of a liquid-filled compartment structure on the incoming shaped charge jet stability

2020 ◽  
Author(s):  
X.D. Zu ◽  
Z.X. Huang ◽  
Z.W. Guan ◽  
X.C. Yin ◽  
Y.M. Zheng
Keyword(s):  
Shaped Charge ◽  
Jet Stability ◽  
Shaped Charge Jet

scholarly journals Chitosan & Conductive PANI/Chitosan Composite Nanofibers - Evaluation of Antibacterial Properties

2019 ◽  
Vol 4 (1) ◽  
pp. 6-20 ◽  
Author(s):  
Panagiota Moutsatsou ◽  
Karen Coopman ◽  
Stella Georgiadou
Keyword(s):  
Chronic Wounds ◽  
Antibacterial Properties ◽  
Wound Dressings ◽  
Bacterial Strains ◽  
Healthcare Applications ◽  
E Coli ◽  
Jet Stability ◽  
Electrospun Membranes ◽  
New Treatments ◽  
Chitosan Composite

Background: Within the healthcare industry, including the care of chronic wounds, the challenge of antimicrobial resistance continues to grow. As such, there is a need to develop new treatments that can reduce the bioburden in wounds. Objective: The present study is focused on the development of polyaniline (PANI) / chitosan (CH) nanofibrous electrospun membranes and evaluates their antibacterial properties. Methods: To this end, experimental design was used to determine the electrospinning windows of both pure chitosan and PANI/CH blends of different ratios (1:3, 3:5, 1:1). The effect of key environmental and process parameters (relative humidity and applied voltage) was determined, as well as the effect of the PANI/CH ratio in the blend and the molecular interactions between PANI and chitosan that led to jet stability. Results: The nanofibrous mats were evaluated regarding their morphology and antibacterial effect against model gram positive and gram negative bacterial strains, namely B. subtilis and E. coli. High PANI content mats show increased bactericidal activity against both bacterial strains. Conclusion: The blend fibre membranes combine the materials’ respective properties, namely electrical conductivity, biocompatibility and antibacterial activity. This study suggests that electrospun PANI/CH membranes are promising candidates for healthcare applications, such as wound dressings.

An Analytical and Empirical Basis for the Design of Turbulence Amplifiers: Part I: Analysis and Experimental Confirmation

1973 ◽  
Vol 95 (2) ◽  
pp. 133-140
Author(s):  
A. C. Bell
Keyword(s):  
Flow Characteristics ◽  
Design Procedure ◽  
Rational Basis ◽  
Operating Characteristics ◽  
Empirical Relationships ◽  
Stability And Control ◽  
Jet Stability ◽  
Rational Procedure ◽  
Pressure Part ◽  
And Control

The design of turbulence amplifiers is given a rational basis by identifying the critical parameter groups necessary to completely specify the performance of a given element, deriving by analysis or experiment the relationships between these nondimensional parameter groups, and developing a rational procedure for obtaining a quantitative dimensioned set of operating characteristics from these relationships. Part I of this paper outlines the problem, identifies the required relations, and presents analyses confirmed by data. These analyses develop relationships for tube pressure-flow characteristics, jet attenuation, and recovered pressure. Part II presents empirical relationships specifying jet stability and control characteristics, and develops a design procedure with an example.

Sign in / Sign up

Export Citation Format

Share Document