Numerical study on effects of chamber design and multi-inlet on storm geyser

Jiachun Liu; Shuangqing Zhang; Biao Huang; David Z. Zhu

doi:10.2166/wst.2021.061

Numerical study on effects of chamber design and multi-inlet on storm geyser

Water Science & Technology ◽

10.2166/wst.2021.061 ◽

2021 ◽

Vol 83 (6) ◽

pp. 1286-1299

Author(s):

Jiachun Liu ◽

Shuangqing Zhang ◽

Biao Huang ◽

David Z. Zhu

Keyword(s):

Peak Pressure ◽

Numerical Study ◽

Three Dimensional ◽

Mitigation Measures ◽

Maximum Pressure ◽

Rapid Urbanization ◽

Inflow Condition ◽

Entrapped Air ◽

Mitigation Methods ◽

Dynamics Models

Abstract Storm geysers increasingly occur in sewer systems under climate change and rapid urbanization. Mitigation measures are in great demand to avoid safety problems. In this study, three-dimensional computational fluid dynamics models of single-inlet and multi-inlet systems were established to investigate geysering induced by rapid filling and assess the effectiveness of potential mitigation methods. The modeling results suggest that increasing the capacity of the downstream pipe before the inflow front reaches the chamber can effectively reduce the maximum geyser pressure. The peak pressure can be significantly mitigated when the chamber size is designed with care and the drop height between the upstream and downstream pipes is reduced. A diversion deflector with air vents and an orifice plate at the riser top end can alleviate the maximum pressure by about 65% with about 75% of the entrapped air being released. The peak pressure during the geyser event in the multi-inlet model is less than that of a single-inlet model under the same total inflow condition, but more water can be released.

Download Full-text

Arc Behavior Numerical Analysis in GMAW Welding Deposition-Based Rapid Forming

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.488-489.285 ◽

2014 ◽

Vol 488-489 ◽

pp. 285-288

Author(s):

Feng Liang Yin ◽

Sheng Zhu ◽

Hong Wei Liu ◽

Lei Guo

Keyword(s):

Heat Flux ◽

Fluid Flow ◽

Weld Pool ◽

Numerical Study ◽

Three Dimensional ◽

Radial Distance ◽

Maximum Pressure ◽

Forming Process ◽

Arc Behavior ◽

Gmaw Welding

Metal fluid flow in weld pool would influence final quality of forming part in GMAW welding deposition-based rapid forming process. To numerical study fluid flow in weld pool, heat and force effects on weld pool surface must been made clear firstly. A three-dimensional numerical model has been built to study arc behavior in GMAW welding deposition-based rapid forming process. Solving the model, heat flux and pressure distributions on the cathode were derived. Calculated results show that heat flux from the arc to the cathode is related to arc temperature nearly above the cathode, and is not monotonous about radial distance within 2 mm distance away from arc axis. A maximum pressure with a value of 800 Pa happens at 1mm away from arc axis.

Download Full-text

Investigating the Effect of Utilizing New Induction Manifold Designs on the Combustion Characteristics and Emissions of a Direct Injection Diesel Engine

Journal of Energy Resources Technology ◽

10.1115/1.4041543 ◽

2018 ◽

Vol 140 (12) ◽

Cited By ~ 5

Author(s):

Mohamed A. Bassiony ◽

Abdellatif M. Sadiq ◽

Mohammed T. Gergawy ◽

Samer F. Ahmed ◽

Saud A. Ghani

Keyword(s):

Diesel Engine ◽

Peak Pressure ◽

Direct Injection ◽

Three Dimensional ◽

Engine Performance ◽

Combustion Characteristics ◽

Maximum Pressure ◽

Performance And Emissions ◽

Di Diesel Engine ◽

Dynamics Simulations

New induction manifold designs have been developed in this work to enhance the turbulence intensity and improve the mixing quality inside diesel engine cylinders. These new designs employ a spiral-helical shape with three different helical diameters (1D, 2D, 3D; where D is the inner diameter of the manifold) and three port outlet angles: 0 deg, 30 deg, and 60 deg. The new manifolds have been manufactured using three-dimensional printing technique. Computational fluid dynamics simulations have been conducted to estimate the turbulent kinetic energy (TKE) and the induction swirl generated by these new designs. The combustion characteristics that include the maximum pressure raise rate (dP/dθ) and the peak pressure inside the cylinder have been measured for a direct injection (DI) diesel engine utilizing these new manifold designs. In addition, engine performance and emissions have also been evaluated and compared with those of the normal manifold of the engine. It was found that the new manifolds with 1D helical diameter produce a high TKE and a reasonably strong induction swirl, while the ones with 2D and 3D generate lower TKEs and higher induction swirls than those of 1D. Therefore, dP/dθ and peak pressure were the highest with manifolds 1D, in particular manifold m (D, 30). Moreover, this manifold has provided the lowest fuel consumption with the engine load by about 28% reduction in comparison with the normal manifold. For engine emissions, m (D, 30) manifold has generated the lowest CO, SO2, and smoke emissions compared with the normal and other new manifolds as well, while the NO emission was the highest with this manifold.

Download Full-text

Numerical study on dynamic behavior of entrapped air in a partially filled pipe

Water Science & Technology ◽

10.2166/wst.2021.018 ◽

2021 ◽

Vol 83 (4) ◽

pp. 771-780

Author(s):

Hengliang Guo ◽

Ye Guo ◽

Biao Huang ◽

Jiachun Liu

Keyword(s):

Dynamic Behavior ◽

Peak Pressure ◽

Numerical Study ◽

Relative Length ◽

Time Duration ◽

Initial Water ◽

Pipe Length ◽

System Parameters ◽

Air Volume ◽

Entrapped Air

Abstract Rapid filling in horizontal partially filled pipes with entrapped air may result in extreme pressure transients. This study advanced the current understanding of dynamic behavior of entrapped air above tailwater (the initial water column with a free surface in a partially filled pipe) through rigid-column modeling and sensitivity analysis of system parameters. Water and air were considered as incompressible fluid and ideal gas, respectively, and the continuity and momentum equations for water and a thermodynamic equation for air were solved by using the fourth order Runge-Kutta method. The effects of system parameters were examined in detail, including tailwater depth, entrapped air volume, driving head, pipe friction, and relative length of entrapped air and pipe. The results indicate that the presence of tailwater can mitigate the peak pressure when with identical initial volumes of entrapped air, as it can be considered to reflect a certain amount of loss of the net driving head. However, the peak pressure can increase as much as about 45% for the cases with fixed pipe length, due to the reduction in the initial entrapped air volume. The rise time for the first peak pressure was closely related to pipe friction, whereas the oscillation period (defined as the time duration between the first and second peaks) was virtually irrelevant. The applicability of the rigid-column model was discussed, and a time scale relevant indicator was proposed. When the indicator is larger than 20, the relative difference between the peak pressure estimation and experimental measurements is generally below 5%.

Download Full-text

Comparison of an analytical and computational fluid-dynamics models of a commercial Ranque-Hilsch vortex tube operating with Air and Methane

CT&F - Ciencia Tecnología y Futuro ◽

10.29047/01225383.145 ◽

2019 ◽

Vol 9 (2) ◽

pp. 61-71

Author(s):

Luz Marlen Ahumada ◽

Antonio José Bula Silvera ◽

Kevin Andres Melendez Valencia ◽

Julio Medina Suarez

Keyword(s):

Analytical Model ◽

Vortex Tube ◽

Numerical Study ◽

Fluid Dynamic ◽

Three Dimensional ◽

Vortex Generator ◽

Preliminary Information ◽

Industrial Implementation ◽

Inlet Conditions ◽

Dynamics Models

This paper presents a comparison between the behavior predicted by a computational fluid-dynamic model (CFD) and an analytical model for a commercial vortex tube using air and methane as working fluids, in addition to a three-dimensional mesh for this purpose. The numerical simulation of the turbulent, compressible and high vorticity flow was carried out using RANS equations, the Realizable k-e turbulence model and STAR-CCM+ as software for the equations solution. The variables measured in this work were temperature, pressure and velocity at the exit nozzles of the vortex generator and the tube discharges, resulting in errors of less than 16% between CFD and the analytical model. This numerical study represents a first approximation of the vorticityphenomenon and has been developed in order to establish a prototype simulation model that provides, under certain inlet conditions to the process, preliminary information on the vortex tube industrial implementation for obtaining liquefied natural gas.

Download Full-text

Concrete wave barriers to mitigate ground vibrations induced by railway traffic: a three-dimensional numerical study

10.7764/rdlc.19.3.395-406 ◽

2020 ◽

Vol 19 (3) ◽

pp. 395-406

Author(s):

Jesús Fernández Ruiz ◽

◽

Luis Medina Rodríguez

Keyword(s):

Continuous Wave ◽

Numerical Study ◽

Three Dimensional ◽

Mitigation Measures ◽

3D Fem ◽

Technical Literature ◽

Fem Model ◽

Railway Line ◽

Railway Traffic ◽

Efficient Measure

Continuous wave barriers are mitigation measures to reduce vibrations induced by railway traffic which have been well studied in technical literature. Nevertheless, there are not many studies about discontinuous concrete wave barriers. By this reason, in this paper continuous and discontinuous concrete wave barriers are studied and compared. With this objective, two theoretical cases with discontinuous barriers have been analysed and the results have been compared with those from both continuous barriers and without barriers cases. The study has been carried out with a dynamic numerical 3D FEM model formulated in the space/time domain, which has previously been validated by authors on the Lisbon-Oporto (Portugal) railway line. The numerical results show the discontinuous barriers with a small separation between axles (less than twice the thickness of the continuous barrier) are an efficient measure in the reduction of vibrations, reaching values of insertion loss of up to 13 dB. So, these could be a very interesting alternative to continuous barriers, in order to conjugate a somewhat lower level of reduction of vibration at a considerable lower cost.

Download Full-text

Experimental and numerical study on the thrust of a water-retaining curtain

Journal of Hydroinformatics ◽

10.2166/hydro.2017.095 ◽

2017 ◽

Vol 20 (2) ◽

pp. 316-331 ◽

Cited By ~ 2

Author(s):

Wei He ◽

Jijian Lian ◽

Fang Liu ◽

Chao Ma ◽

Shunqi Pan

Keyword(s):

Pressure Difference ◽

Numerical Study ◽

Experimental Tests ◽

Maximum Pressure ◽

Arc Length ◽

Practical Application ◽

Force Analysis ◽

Height Ratio ◽

Maximum Value ◽

Inflow Condition

Abstract A water-retaining curtain (WRC) has become a useful facility in selective withdrawal and sedimentation control, but the force analysis of a curved curtain is still lacking. Based on flume experimental tests and numerical simulations, this paper analyzes the variation laws of pressure difference and thrust of WRC. The results show that under the uniform inflow condition, the distribution of pressure difference on the WRC is relatively even, and the maximum value is located at the upper part of the curtain. When arc length–height ratio increases, the location of maximum pressure difference gets lower. In addition, the variation law of thrust of WRC conforms to the classical resistance equation. The drag coefficient is found to fit a power function of the water-retaining ratio, a second-degree polynomial function of arc length–height ratio, and linear function of inclination ratio. The results also yield a simplified forecasting formula of thrust of WRC which is proposed and verified using flume simulations and a real reservoir model test. The newly developed formula systematically considers the water-retaining height, arc length and inclination degree, providing a rapid and accurate algorithm to predict the thrust, and lays a theoretical foundation for practical application.

Download Full-text

Numerical Study of Combustion in a Porous Medium With Liquid Fuel Injection

Volume 8: Heat Transfer and Thermal Engineering ◽

10.1115/imece2017-72483 ◽

2017 ◽

Cited By ~ 1

Author(s):

Arash Mohammadi ◽

Mona Benhari ◽

Mehrdad Nouri Khajavi

Keyword(s):

Porous Medium ◽

Free Volume ◽

Liquid Fuel ◽

Fuel Injection ◽

Soot Formation ◽

Numerical Study ◽

Three Dimensional ◽

Nitrogen Monoxide ◽

Maximum Pressure ◽

Fluid Temperature

Porous medium (PM) has potential advantage to enhance evaporation of droplets in liquid-fuel burners, low emissions and minimize instabilities of combustion. This paper represents the numerical study of liquid-fuel injection, evaporation, and combustion inside constant-volume chemically inert PM. It stabilizes lean combustion and decreases emissions. Three-dimensional numerical results were obtained based on a modified KIVA-3V code. Diesel fuel is directly injected into chamber for two cases, free volume and PM reactor. With high initial temperature, fast evaporation and self-ignited occur. The results for specified conditions were compared with experimental data in literature. Effects of injection on mixture formation was investigated. Distribution of diesel vapor, fluid and solid temperature of PM in a cutting plane, were shown. Diagram of diesel vapor, CO, NO, Soot, solid and fluid temperature versus time for different mass of injected fuel, were presented. Also, results of diesel vapor, pressure and temperature in free volume and PM reactor have compared. The results show considerable reduction in maximum pressure and temperature, carbon monoxide, nitrogen monoxide and soot formation in PM reactor in comparison with free volume.

Download Full-text