The Experts below are selected from a list of 270 Experts worldwide ranked by ideXlab platform
Yong-sheng Hu - One of the best experts on this subject based on the ideXlab platform.
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NO emission numerical Simulation of a 1000MW Ultra Supercritical Dual Circle Tangential Boiler with different burner structure
World Automation Congress 2012, 2012Co-Authors: Yong-sheng HuAbstract:The combustion process of a 1000 MW ultra supercritical dual circle boiler was numerically studied with Realizable k-ε model. The influence of the boiler NO distribution was studied when burner Nozzle Air velocity and structure change, NO distribution was compared between the original and being improved structure. The numerical simulation results show as follows, two opposite oval rotary temperature and flow field are formed in the furnace during the combustion process, When shape and layout of the burner Nozzle are different, large change about NO distribution in the furnace. NO emissions change small in every conditions. Increasing the size of pollen tube Nozzle can reduce NO emissions, which is the best improvement programe and provide some theoretical basis for the burner design and operation.
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NO emission numerical Simulation of a 1000MW Ultra Supercritical Dual Circle Tangential Boiler with different burner structure
2012Co-Authors: Yong-sheng HuAbstract:The combustion process of a 1000 MW ultra supercritical dual circle boiler was numerically studied with Realizable k-e model. The influence of the boiler NO distribution was studied when burner Nozzle Air velocity and structure change, NO distribution was compared between the original and being improved structure. The numerical simulation results show as follows, two opposite oval rotary temperature and flow field are formed in the furnace during the combustion process, When shape and layout of the burner Nozzle are different, large change about NO distribution in the furnace. NO emissions change small in every conditions. Increasing the size of pollen tube Nozzle can reduce NO emissions, which is the best improvement programe and provide some theoretical basis for the burner design and operation.
Chen Huang - One of the best experts on this subject based on the ideXlab platform.
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Study of convective heat transfer load induced by Nozzle Air supply in large spaces with thermal stratification based on Block-Gebhart model
Sustainable Cities and Society, 2019Co-Authors: Yukun Xu, Xin Wang, Jingsi Ma, Chen HuangAbstract:Abstract The Block-Gebhart (B-G) model is proposed to predict the convective heat transfer load for the stratified Air-conditioning system using Nozzle Air supply. The scale-model experiments were carried out in an enthalpy difference laboratory in Shanghai. The theoretical solutions of convective heat transfer load calculated by the B-G model were experimentally verified. The results showed the feasibility and accuracy of the B-G model in calculating the convective heat transfer load for the stratified Air-conditioning system in large spaces. The key factors affecting the convective heat transfer load were analyzed. The nomogram of convective heat transfer load was made, which could be used to determine the relationship among the non-dimensional convective heat transfer load (ratio of convective heat transfer load to heat gain in non-Air-conditioned area), the heat intensity ratio (ratio of heat intensity in non-Air-conditioned area to heat intensity in Air-conditioned area), and the exhaust heat ratio (ratio of exhaust heat to heat gain in non-Air-conditioned area). Through this method, the convective heat transfer load can be effectively calculated in practical engineering applications, which provides the theoretical basis for the optimal design of Airflow distribution in large spaces.
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on the calculation of heat migration in thermally stratified environment of large space building with sidewall Nozzle Air supply
Building and Environment, 2019Co-Authors: Haidong Wang, Pengzhi Zhou, Xiaocen Tang, Chen HuangAbstract:Abstract Vertical thermal stratification is typical for partially conditioned large space building. Heat accumulation in the upper part of unoccupied zone will have significant effect on the cooling load of occupied zone. In order to accurately estimate this cooling load, calculation of the heat migration occurs in the thermally stratified environment is critical. Heat migration in this study refers to the amount of heat transferred from unoccupied zone to occupied zone (or between other adjacent zones). This paper discusses the method to calculate heat migration through convection and conduction in a large space building served by side wall Nozzle Air-supply system. In a scaled laboratory, three experiment cases with different exhaust Air flow ratio are investigated. CFD simulations of the same cases are performed. Vertical temperature distribution and detailed cooling load results of the whole system as well as those of occupied zone are validated against experiment result. A detailed analysis on the total heat migration and its components between different zones is conducted. Inter-zonal heat transfer coefficient Cb used in a zonal BLOCK model and heat conductivity across the intersection of zones is obtained by dividing the whole space into two and four zones vertically. It is found that both Cb and thermal conductivity value across the intersection is greater than expected and affected by the local turbulent intensity.
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Model for Indoor Air Vertical Temperature Distribution under Nozzle Air Supply System in Large Space Building
Procedia Engineering, 2017Co-Authors: Chen HuangAbstract:Abstract A model for indoor Air vertical temperature and inner wall temperature is presented under Nozzle Air supply system in a large space building. Through discussion of the key parameters such as floor temperature and regional heat transfer coefficient, the floor heat transfer correction equation and modifier formula of zone heat transfer coefficient is founded. Through the summer experiment under Nozzle Air supply system in a large space building, the indoor Air vertical temperature, inner wall temperature are tested and the modifier solving model is verified and promoted. The results show that the experiment data and the calculation results agreed well.
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Experimental study on the comparison of thermal environment between Nozzle Air supply and column Air supply in summer
Procedia Engineering, 2017Co-Authors: Chen Huang, Ling Yu, Shuai ChenAbstract:Abstract In this paper, the Air flow at the Nozzle side and the column side were set up in a large space. The thermal environment of the two Air supply modes were compared and analyzed by using the Air diffusion performance index (ADPI), the draft sensation blowing index and so on. The results show that the uniformity of indoor Air temperature and velocity of the column Air supply is better than the Nozzle; the percentage of dissatisfaction of the indoor average Air blowing is less than that of the Nozzle; The ADPI value of two Airflow pattern changes with the Air flow. The Nozzle Air supply shows a decreasing trend with the increase of Air flow. The ADPI of the column Air supply is higher than that of the Nozzle, and both of them are less than 80%. Results of this paper provide a reference for Airspace organization selection and the design of large space buildings.
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The Characters of the Nozzle’s Jet and Design Method of the Secondary Airflow-Relay Equipment in the Large-Space Building
Lecture Notes in Electrical Engineering, 2013Co-Authors: Chen HuangAbstract:When the Nozzle is used to form the stratified Air-conditioning system in the large-space and large-span building, the Nozzle Air supply does not meet the requirements of the Air-conditioning zone in the stratified Air-conditioning system because the Nozzle’s jet range is limited. To solve this problem, we have taken an actual large-space building as an example and adopted the secondary Airflow-relay equipment to relay the Nozzle’s Air supply. In this paper, basing on the results of the field experiments, we described the design method of the secondary Airflow-relay equipment, studied the characters of the Nozzle’s jet, and provided the size and fixed form of the secondary Airflow-relay equipment in the large-space and large-span building.
Cristian Picioreanu - One of the best experts on this subject based on the ideXlab platform.
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computational and experimental investigation of biofilm disruption dynamics induced by high velocity gas jet impingement
Mbio, 2020Co-Authors: Lledo Prades, Stefania Fabbri, Antonio David Dorado, Xavier Gamisans, Paul Stoodley, Cristian PicioreanuAbstract:ABSTRACT Experimental data showed that high-speed microsprays can effectively disrupt biofilms on their support substratum, producing a variety of dynamic reactions such as elongation, displacement, ripple formation, and fluidization. However, the mechanics underlying the impact of high-speed turbulent flows on biofilm structure is complex under such extreme conditions, since direct measurements of viscosity at these high shear rates are not possible using dynamic testing instruments. Here, we used computational fluid dynamics simulations to assess the complex fluid interactions of ripple patterning produced by high-speed turbulent Air jets impacting perpendicular to the surface of Streptococcus mutans biofilms, a dental pathogen causing caries, captured by high-speed imaging. The numerical model involved a two-phase flow of Air over a non-Newtonian biofilm, whose viscosity as a function of shear rate was estimated using the Herschel-Bulkley model. The simulation suggested that inertial, shear, and interfacial tension forces governed biofilm disruption by the Air jet. Additionally, the high shear rates generated by the jet impacts coupled with shear-thinning biofilm property resulted in rapid liquefaction (within milliseconds) of the biofilm, followed by surface instability and traveling waves from the impact site. Our findings suggest that rapid shear thinning under very high shear flows causes the biofilm to behave like a fluid and elasticity can be neglected. A parametric sensitivity study confirmed that both applied force intensity (i.e., high jet Nozzle Air velocity) and biofilm properties (i.e., low viscosity and low Air-biofilm surface tension and thickness) intensify biofilm disruption by generating large interfacial instabilities. IMPORTANCE Knowledge of mechanisms promoting disruption though mechanical forces is essential in optimizing biofilm control strategies which rely on fluid shear. Our results provide insight into how biofilm disruption dynamics is governed by applied forces and fluid properties, revealing a mechanism for ripple formation and fluid-biofilm mixing. These findings have important implications for the rational design of new biofilm cleaning strategies with fluid jets, such as determining optimal parameters (e.g., jet velocity and position) to remove the biofilm from a certain zone (e.g., in dental hygiene or debridement of surgical site infections) or using antimicrobial agents which could increase the interfacial area available for exchange, as well as causing internal mixing within the biofilm matrix, thus disrupting the localized microenvironment which is associated with antimicrobial tolerance. The developed model also has potential application in predicting drag and pressure drop caused by biofilms on bioreactor, pipeline, and ship hull surfaces.
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computational and experimental investigation of biofilm disruption dynamics induced by high velocity gas jet impingement
bioRxiv, 2019Co-Authors: Lledo Prades, Stefania Fabbri, Antonio David Dorado, Xavier Gamisans, Paul Stoodley, Cristian PicioreanuAbstract:Experimental data showed that high-speed micro-sprays can effectively disrupt biofilms on their support substratum, producing a variety of dynamic reactions such as elongation, displacement, ripples formation and fluidization. However, the mechanics underlying the impact of high-speed turbulent flows on biofilm structure is complex in such extreme conditions, since direct measurements of viscosity at these high shear rates are not possible using dynamic testing instruments. Here we used computational fluid dynamics simulations to assess the complex fluid interactions of ripple patterning produced by high-speed turbulent Air jets impacting perpendicular to the surface of Streptococcus mutans biofilms, a dental pathogen causing caries, captured by high speed imaging. The numerical model involved a two-phase flow of Air over a non-Newtonian biofilm, whose viscosity as a function of shear rate was estimated using the Herschel-Bulkley model. The simulation suggested that inertial, shear and interfacial tension forces governed biofilm disruption by the Air jet. Additionally, the high shear rates generated by the jet impacts coupled with shear-thinning biofilm property resulted in rapid liquefaction (within milliseconds) of the biofilm, followed by surface instability and travelling waves from the impact site. Our findings suggest that rapid shear-thinning in the biofilm reproduces dynamics under very high shear flows that elasticity can be neglected under these conditions, behaving the biofilm as a Newtonian fluid. A parametric sensitivity study confirmed that both applied force intensity (i.e. high jet-Nozzle Air velocity) and biofilm properties (i.e. low viscosity, low Air-biofilm surface tension and thickness) intensify biofilm disruption, by generating large interfacial instabilities.nnIMPORTANCEKnowledge of mechanisms promoting disruption though mechanical forces is essential in optimizing biofilm control strategies which rely on fluid shear. Our results provide insight into how biofilm disruption dynamics is governed by applied forces and fluid properties, revealing a mechanism for ripples formation and fluid-biofilm mixing. These findings have important implications for the rational design of new biofilms cleaning strategies with fluid jets, such as determining optimal parameters (e.g. jet velocity and position) to remove the biofilm from a certain zone (e.g. in dental hygiene or debridement of surgical site infections), or using antimicrobial agents which could increase the interfacial area available for exchange, as well as causing internal mixing within the biofilm matrix, thus disrupting the localized microenvironment which is associated with antimicrobial tolerance. The developed model also has potential application in predicting drag and pressure drop caused by biofilms on bioreactor, pipeline and ship hull surfaces.
Paul Stoodley - One of the best experts on this subject based on the ideXlab platform.
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computational and experimental investigation of biofilm disruption dynamics induced by high velocity gas jet impingement
Mbio, 2020Co-Authors: Lledo Prades, Stefania Fabbri, Antonio David Dorado, Xavier Gamisans, Paul Stoodley, Cristian PicioreanuAbstract:ABSTRACT Experimental data showed that high-speed microsprays can effectively disrupt biofilms on their support substratum, producing a variety of dynamic reactions such as elongation, displacement, ripple formation, and fluidization. However, the mechanics underlying the impact of high-speed turbulent flows on biofilm structure is complex under such extreme conditions, since direct measurements of viscosity at these high shear rates are not possible using dynamic testing instruments. Here, we used computational fluid dynamics simulations to assess the complex fluid interactions of ripple patterning produced by high-speed turbulent Air jets impacting perpendicular to the surface of Streptococcus mutans biofilms, a dental pathogen causing caries, captured by high-speed imaging. The numerical model involved a two-phase flow of Air over a non-Newtonian biofilm, whose viscosity as a function of shear rate was estimated using the Herschel-Bulkley model. The simulation suggested that inertial, shear, and interfacial tension forces governed biofilm disruption by the Air jet. Additionally, the high shear rates generated by the jet impacts coupled with shear-thinning biofilm property resulted in rapid liquefaction (within milliseconds) of the biofilm, followed by surface instability and traveling waves from the impact site. Our findings suggest that rapid shear thinning under very high shear flows causes the biofilm to behave like a fluid and elasticity can be neglected. A parametric sensitivity study confirmed that both applied force intensity (i.e., high jet Nozzle Air velocity) and biofilm properties (i.e., low viscosity and low Air-biofilm surface tension and thickness) intensify biofilm disruption by generating large interfacial instabilities. IMPORTANCE Knowledge of mechanisms promoting disruption though mechanical forces is essential in optimizing biofilm control strategies which rely on fluid shear. Our results provide insight into how biofilm disruption dynamics is governed by applied forces and fluid properties, revealing a mechanism for ripple formation and fluid-biofilm mixing. These findings have important implications for the rational design of new biofilm cleaning strategies with fluid jets, such as determining optimal parameters (e.g., jet velocity and position) to remove the biofilm from a certain zone (e.g., in dental hygiene or debridement of surgical site infections) or using antimicrobial agents which could increase the interfacial area available for exchange, as well as causing internal mixing within the biofilm matrix, thus disrupting the localized microenvironment which is associated with antimicrobial tolerance. The developed model also has potential application in predicting drag and pressure drop caused by biofilms on bioreactor, pipeline, and ship hull surfaces.
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computational and experimental investigation of biofilm disruption dynamics induced by high velocity gas jet impingement
bioRxiv, 2019Co-Authors: Lledo Prades, Stefania Fabbri, Antonio David Dorado, Xavier Gamisans, Paul Stoodley, Cristian PicioreanuAbstract:Experimental data showed that high-speed micro-sprays can effectively disrupt biofilms on their support substratum, producing a variety of dynamic reactions such as elongation, displacement, ripples formation and fluidization. However, the mechanics underlying the impact of high-speed turbulent flows on biofilm structure is complex in such extreme conditions, since direct measurements of viscosity at these high shear rates are not possible using dynamic testing instruments. Here we used computational fluid dynamics simulations to assess the complex fluid interactions of ripple patterning produced by high-speed turbulent Air jets impacting perpendicular to the surface of Streptococcus mutans biofilms, a dental pathogen causing caries, captured by high speed imaging. The numerical model involved a two-phase flow of Air over a non-Newtonian biofilm, whose viscosity as a function of shear rate was estimated using the Herschel-Bulkley model. The simulation suggested that inertial, shear and interfacial tension forces governed biofilm disruption by the Air jet. Additionally, the high shear rates generated by the jet impacts coupled with shear-thinning biofilm property resulted in rapid liquefaction (within milliseconds) of the biofilm, followed by surface instability and travelling waves from the impact site. Our findings suggest that rapid shear-thinning in the biofilm reproduces dynamics under very high shear flows that elasticity can be neglected under these conditions, behaving the biofilm as a Newtonian fluid. A parametric sensitivity study confirmed that both applied force intensity (i.e. high jet-Nozzle Air velocity) and biofilm properties (i.e. low viscosity, low Air-biofilm surface tension and thickness) intensify biofilm disruption, by generating large interfacial instabilities.nnIMPORTANCEKnowledge of mechanisms promoting disruption though mechanical forces is essential in optimizing biofilm control strategies which rely on fluid shear. Our results provide insight into how biofilm disruption dynamics is governed by applied forces and fluid properties, revealing a mechanism for ripples formation and fluid-biofilm mixing. These findings have important implications for the rational design of new biofilms cleaning strategies with fluid jets, such as determining optimal parameters (e.g. jet velocity and position) to remove the biofilm from a certain zone (e.g. in dental hygiene or debridement of surgical site infections), or using antimicrobial agents which could increase the interfacial area available for exchange, as well as causing internal mixing within the biofilm matrix, thus disrupting the localized microenvironment which is associated with antimicrobial tolerance. The developed model also has potential application in predicting drag and pressure drop caused by biofilms on bioreactor, pipeline and ship hull surfaces.
Mansour H. Mohamed - One of the best experts on this subject based on the ideXlab platform.
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Mechanics of a Single Nozzle Air-Jet Filling Insertion System: Part III: Yarn Insertion Through Tubes
Textile Research Journal, 2016Co-Authors: Mahmoud Salama, Sabit Adanur, Mansour H. MohamedAbstract:Yarn insertion through regular and slotted tubes (simulating the Air guide system on Air-jet looms) has been investigated. A theoretical analysis describing the yarn movement during insertion and the equation of motion is presented. The effects of the conditions behind the Nozzle on yarn insertion are shown in terms of the loop length and the speed of the feeding system. Experimental results of yam insertion using different conditions for the various parameters are discussed. Good agreement between experimental and theoretical results was found.
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Analysis of Yarn Motion in Single-Nozzle Air—jet Filling Insertion. Part I: Theoretical Models for Yarn Motion
Journal of The Textile Institute, 1992Co-Authors: Sabit Adanur, Mansour H. MohamedAbstract:Dynamic analysis of Air-jet filling insertion has been carried out both experimentally and theoretically for unsteady-state running conditions. In Part I of this series, analytical models for both loop- and drum-storage systems are developed to investigate the Air-jet filling-insertion process. The flight of the yarn in an Air jet is a complex dynamic problem, which is affected by many factors, such as Air velocity and yarn characteristics, as well as the yarn-storage and yarn-feeding systems. Theoretical analysis shows that the yarn velocity can be increased by increasing the Air/yarn frictional force and by decreasing the yarn tension. Numerical solutions for the equations of yarn motion are obtained
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Analysis of Yarn Motion in Single-Nozzle Air-jet Filling Insertion. Part II: Experimental Validation of the Theoretical Models and Statistical Analysis
Journal of The Textile Institute, 1992Co-Authors: Sabit Adanur, Mansour H. MohamedAbstract:The analytical models which were developed in Part I of this series are compared with experimental results. The models give good predictions of the insertion behavior and average yarn velocity considering the complexity of the yarn motion. Loop- and drum-storage systems are compared. A loop-storage system gives higher yarn velocities than a drum-storage system. However, there is better control on the yarn with drum storage than with loop storage. Since the filling insertion with an Air jet is not positively controlled, pick-to-pick variations occur. Statistical analysis of experimental data was therefore performed.
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Analysis of Air Flow in Air-Jet Filling Insertion
Textile Research Journal, 1991Co-Authors: Sabit Adanur, Mansour H. MohamedAbstract:A qualitative analysis of Air flow in Air-jet filling insertion is given. The Air flow in single Nozzle Air-jet insertion is unsteady and turbulent, and can be compressible or incompressible depending on the velocity. Dynamic Air velocity measurements showed that the Air velocity depends on two variables—distance and time. It increases with time (distance constant) and decreases with distance from the Nozzle.
