Numerical Simulation of Flow Characteristics in an Inclining Rotating Kiln with Continuous Feeding

2019 ◽  
Vol 17 (10) ◽  
Author(s):  
Xin Zheng ◽  
Baosheng Jin ◽  
Yong Zhang ◽  
Youwei Zhang ◽  
Chunlei Zhou
Keyword(s):  
Velocity Distribution ◽  
Influencing Factor ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Multiphase Model ◽  
Rotating Speed ◽  
Inclination Angles ◽  
Continuous Feeding ◽  
Rotary Kilns ◽  
The Impact

Abstract The granular behaviors in rotating kilns have been investigated using a three-dimensional CFD model based on Euler-Euler multiphase model and the kinetic theory of granular flow. The model is validated by comparing with published experiment data and existing theory. The continuous feeding progress and inclination angles are both taken into account in this work for thorough discussion. Typical regimes of solid motions and velocity distributions are shown in the simulation results. The results show that the impact caused by feeding process has an obvious influence on the velocity distribution of z axis, especially at the charging end of the kiln. A small inclination angle has a slight influence on the velocity distribution of z axis, and causes the thickness of the active region increasing with the increasing of axil distance. The rotating speed is the biggest influencing factor for the velocity distribution in the transverse plane. The result can help the development of three-dimensional models for rotary kilns and the improvement of kiln design and performance.

Numerical Investigation of Positive Displacement Rotary Lobe Pump With Twisted Rotors

2014 ◽  
Author(s):  
Xiaojun Jiang ◽  
Yi Li ◽  
Zhaohui He ◽  
Cui Baoling ◽  
Wenlong Dong
Keyword(s):  
Flow Structure ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Internal Flow ◽  
Dynamic Flow ◽  
Flow Fluctuation ◽  
Flow Field Characteristics ◽  
Lobe Pump ◽  
The Impact

The three-dimensional flow field characteristics are obtained by performing numerical simulation of flow in a lobe pump with twisted rotors. The relationship between the dynamic flow structure and the flow fluctuation is explored. Actually, the viscous incompressible Navier-Stokes equations are solved within an unsteady flow model. The dynamic mesh technique is applied to obtain the dynamic flow structure. By comparing the simulated results of straight rotor with those of twisted rotor, the effect of rotor shape on the flow fluctuation was revealed. Finally, the impact of the lobes number of rotors on flow pulsations is discussed. The results show that there is an intrinsic relationship between the flow fluctuation and the vortex in the lobe pump. The use of twisted rotors can effectively improve the internal flow characteristics of lobe pump and reduce flow fluctuation. With the increase of the number of lobes, the lobe pump output is more stable and capacity has been improved.

CFD Analysis of Composite Axial Water Turbine

2010 ◽  
Author(s):  
Jifeng Wang ◽  
Norbert Mu¨ller
Keyword(s):  
Design Method ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Cfd Analysis ◽  
Computational Investigation ◽  
Rotating Speed ◽  
Fundamental Understanding ◽  
Water Turbine ◽  
Water Turbines

This paper presents computational investigation of the flow in composite material axial water turbines using Finite Volume based commercial CFD package namely Fluent. Based on three dimensional numerical flow analysis and fluid-structure interaction, the flow characteristics of water turbines including nozzle, impeller and diffuser are predicted. Two particulare cases are studied and compared. The extract power of water turbine in different rotating speed and water inlet velocity are analyzed. The calculated results will provide a fundamental understanding of the impeller as water turbine, and this design method is used to shorten the design period and improve the water turbine’s performance.

Analysis of Internal Flow Field for Centrifugal Fan in Series

2012 ◽  
Vol 233 ◽  
pp. 96-99
Author(s):  
Ya Jun Fan ◽  
Zhang Xu ◽  
Ding Wensi
Keyword(s):  
Velocity Distribution ◽  
Total Pressure ◽  
Flow Characteristics ◽  
Internal Flow ◽  
Wind Pressure ◽  
Meridian Plane ◽  
Centrifugal Fan ◽  
Fan Performance ◽  
In Series ◽  
The Impact

Centrifugal fan in series with high wind pressure is the key facility of pneumatic transport equipment. To consider the impact of changed conditions on performance of centrifugal fan, internal flow of three-stage centrifugal fan at rated speed in different total pressure conditions is analyzed by CFD software FLUENT6.3 in this paper. Flow characteristics are obtained and the differences of total pressure and velocity distribution in each impeller are analyzed under different conditions, velocity distribution on the meridian plane and section of wind guide plates are compared. Finally, curves of P-Q and P-η at 4600 r/min are forecasted through the analysis of the data, which provide references for reducing impact that condition alteration on fan performance and improving the efficiency of the fan.

scholarly journals Supercritical flow at an abrupt drop: flow patterns and aeration

1998 ◽  
Vol 25 (5) ◽  
pp. 956-966 ◽  
Author(s):  
H Chanson ◽  
L Toombes
Keyword(s):  
Shock Waves ◽  
Open Channel ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Flow Patterns ◽  
Three Dimensional Flow ◽  
Supercritical Flow ◽  
Drop Flow ◽  
Supercritical Flows ◽  
The Impact

Stepped waterways and cascades are common features of storm waterways, at dam outlets, and in water treatment plants. At an abrupt drop, open channel flows are characterized by the presence of shock waves and a substantial flow aeration. There is, however, little information on the basic flow characteristics. The study presents new experimental data obtained in a 0.5-m-wide stepped flume with an unventilated nappe. The investigations describe the three-dimensional flow patterns, including shock waves, standing waves, and spray, downstream of the nappe impact. The characteristics of the flow patterns are similar to those observed with abrupt expansion supercritical flows. Downstream of the drop brink, substantial aeration takes place along the nappe interfaces and the flow downstream of the impact is deaerated.Key words: abrupt drop, supercritical flow, shock waves, flow patterns, cascade.

scholarly journals The Effect of Variable Air–Fuel Ratio on Thermal NOx Emissions and Numerical Flow Stability in Rotary Kilns Using Non-Premixed Combustion

Processes ◽  
2021 ◽  
Vol 9 (10) ◽  
pp. 1723
Author(s):  
Mohamed el Abbassi ◽  
Domenico Lahaye ◽  
Cornelis Vuik
Keyword(s):  
Wall Temperature ◽  
Diffusion Flames ◽  
Three Dimensional ◽  
Nox Emissions ◽  
Unstable Flow ◽  
Nox Formation ◽  
Fuel Ratio ◽  
Rotary Kilns ◽  
Thermal Nox ◽  
The Impact

One of the quickest ways to influence both the wall temperature and thermal NOx emissions in rotary kilns is to change the air–fuel ratio (AFR). The normalized counterpart of the AFR, the equivalence ratio, is usually associated with premixed flames and studies of its influence on diffusion flames are inconsistent, depending on the application. In this paper, the influence of the AFR is investigated numerically for rotary kilns by conducting steady-state simulations. We first conduct three-dimensional simulations where we encounter statistically unstable flow at high inflow conditions, which may be caused by vortex stretching. As vortex stretching vanishes in two-dimensional flow, the 2D simulations no longer encounter convergence problems. The impact of this simplification is shown to be acceptable for the thermal behaviour. It is shown that both the wall temperature and thermal NOx emissions peak at the fuel-rich and fuel-lean side of the stoichiometric AFR, respectively. If the AFR continues to increase, the wall temperature decreases significantly and thermal NOx emissions drop dramatically. The NOx validation, however, shows different results and indicates that the simulation model is simplified too much, as the measured NOx formation peaks at significantly fuel-lean conditions.

scholarly journals The impact of ambient pressure and tunnel inclination angle on the smoke transport in a subway tunnel

2021 ◽  
Author(s):  
Guang Chen
Keyword(s):  
Inclination Angle ◽  
Ambient Pressure ◽  
Three Dimensional ◽  
Concentration Field ◽  
Air Entrainment ◽  
Subway Tunnel ◽  
Environmental Pressures ◽  
Smoke Transport ◽  
Inclination Angles ◽  
The Impact

Abstract The subway tunnel will be built in the plateau where the pressure is relatively low, and the tunnel will tilt at a certain angle due to topographic factors. In order to investigate the smoke transport characteristics of moving subway trains caught fire under different ambient pressures and different tunnel inclination angles, three-dimensional full-scale calculation models of subway trains, two stations and one tunnel are established, and three different environmental pressures (50kPa, 75kPa, 100kPa) and three different tunnel inclination angles (− 1.5 °, 0 °, + 1.5 °) are simulated. The IDDES turbulence model based on kω-sst RANS combined with the overset grid technology is used to simulate the subway train movement and the detailed flow field. The velocity and temperature distribution characteristics and smoke concentration field are studied in detail. The soot density of smoke and temperature increases with reduced ambient pressure due to the weakening of air entrainment and the decreased air density and the influence of ambient pressure on smoke diffusion decreases with the increase of pressure. The longitudinal airflow induced by the stack effect under the negative inclination angle of the tunnel is helpful to prevent the flowing back of smoke.

scholarly journals Effects of Front Plate Geometry on Brush Seal in Highly Swirling Environments of Gas Turbine

Energies ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 7768
Author(s):  
Yuxin Liu ◽  
Benzhuang Yue ◽  
Xiaozhi Kong ◽  
Hua Chen ◽  
Huawei Lu
Keyword(s):  
Gas Turbine ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Swirl Flow ◽  
Seal Failure ◽  
Plane Front ◽  
Brush Seal ◽  
Front Plate ◽  
The Impact ◽  
Plate Geometry

Advanced brush seal technology has a significant impact on the performance and efficiency of gas turbine engines. However, in highly inlet swirling environments, the bristles of a brush seal tend to circumferentially slip, which may lead to aerodynamic instability and seal failure. In this paper, seven different front plate geometries were proposed to reduce the impact of high inlet swirl on the bristle pack, and a three-dimensional porous medium model was carried out to simulate the brush seal flow characteristics. Comparisons of a plane front plate with a relief cavity, plane front plate with axial drilled holes, anti-“L”-type plate and their relative improved configurations on the pressure and flow fields as well as the leakage behavior were conducted. The results show that the holed front plate can effectively regulate and control the upstream flow pattern of the bristle pack, inducing the swirl flow to move radially inward, which results in decreased circumferential velocity component. The anti-“L” plate with both axial holes and one radial hole was observed to have the best effect on reducing the swirl of those investigated. The swirl velocity upstream the bristle pack can decline 50% compared to the baseline model with plane front plate, and the circumferential aerodynamic forces on the bristles, which scale with the swirl dynamic head, are reduced by a factor of 4. This could increase the bristle stability dramatically. Moreover, the front plate geometry does not influence the leakage performance significantly, and the application of the axial hole on the front plate will increase the leakage slightly by around 3.5%.

scholarly journals The Use of Enhanced Nozzle Maps for Gas-Turbine Performance Modelling

2021 ◽  
Author(s):  
Aws A. Al-Akam ◽  
Theoklis Nikolaidis ◽  
David G. MacManus ◽  
Alvise Pellegrini
Keyword(s):  
Three Dimensional ◽  
Flow Characteristics ◽  
Engine Performance ◽  
Exhaust System ◽  
Limited Range ◽  
Performance Modelling ◽  
Essential Components ◽  
Wide Range ◽  
Aero Engine ◽  
The Impact

Abstract The use of a simulation tool to predict the aero-engine performance before committing to a final engine design has become one of the most cost-saving approaches in this field. However, most of these tools are based on low fidelity thermodynamic models, which are incapable of fully capturing the impact of three-dimensional flow characteristics. An aero-engine exhaust-system is one of the essential components that affect the engine performance. Currently, engine performance models tend to utilize simplified nozzle performance maps. These maps typically provide information over a very limited range of nozzle geometries, which may not apply to the wide range of architectures and designs of aeroengines. The current paper presents a methodology for the development of nozzle performance maps, which takes into account the aerodynamic and the geometric parameters of the nozzle design. The methodology is based on the reduced-order models. These models are integrated into a zero-dimensional engine performance code to improve the accuracy of its thrust calculation. The impact of the new thrust model on the overall engine performance and the operating point is analysed and discussed. The results showed that the implementation of the modified maps, which take into account the flow characteristics and the geometry of the nozzle, affects the thrust calculation. In a typical case of a turbofan operating at cruise conditions, the net thrust estimation with the modified nozzle maps showed a difference of 0.2%, compared with the simple nozzle maps. The new thrust calculation method has the advantage in capturing the multidimensional impact of the flow of the nozzle as compared with the conventional one. Furthermore, the implementation of the new method reduces the uncertainties introduced by a simplified nozzle model and, consequently, it can support the decision-making process in the design of the engine.

scholarly journals Three-dimensional numerical simulation of mud flow from a tailings dam failure across complex terrain

2019 ◽  
Author(s):  
Dayu Yu ◽  
Liyu Tang ◽  
Chongcheng Chen
Keyword(s):  
Stokes Equations ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Dam Break ◽  
Dam Failure ◽  
Tailings Dam ◽  
In Situ Investigation ◽  
Impact Area ◽  
The Impact ◽  
Mud Flow

Abstract. A tailings dam accident can cause serious ecological disaster and property loss. Simulation of a tailings dam accident in advance is useful for understanding the tailings flow characteristics and assessing the possible extension of the impact area. In this paper, a three-dimensional (3-D) computational fluid dynamics (CFD) approach was proposed for reasonably and quickly predicting the flow routing and impact area of mud flow from a dam failure across 3-D terrain. The Navier–Stokes equations and the Bingham-Papanastasiou rheology model were employed as the governing equations and the constitutive model, respectively, and solved numerically in the finite volume method (FVM) scheme. The volume of fluid (VOF) method was used to track the interface between the tailings and air. The accuracy of the CFD model and the chosen numerical algorithm were validated using an analytical solution of the channel flow problem and a laboratory experiment on the dam break problem reported in the literature. In each issue, the obtained results were very close to the analytical solutions or experimental values. The proposed approach was then applied to simulate two scenarios of tailings dam failures, one of which was the Feijão tailings dam that failed on 25 January 2019, and the simulated routing coincided well with the in situ investigation. Therefore, the proposed approach does well in simulating the flow phenomenon of tailings after a dam break, and the numerical results can be used for early warning of disasters and emergency response.

Numerical Simulation of Dynamic Flow Characteristics in a Centrifugal Water Pump Considering Shaft Torsional Vibration

2017 ◽  
Author(s):  
Shen Lv ◽  
Xiang-Yuan Zhang ◽  
Chen-Xing Jiang ◽  
Wan-You Li ◽  
Zhi-Jun Shuai ◽  
...  
Keyword(s):  
Flow Field ◽  
Torsional Vibration ◽  
Rotation Speed ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Water Pump ◽  
Centrifugal Pumps ◽  
Dynamic Flow ◽  
Rotating Speed ◽  
Speed Fluctuations

The complex three-dimensional turbulent flow field in a centrifugal water pump is numerically simulated considering torsional vibration of the shaft. The characteristic frequency and the frequency modulation phenomenon is investigated when the fluctuated-rotation-speed is considered. The results show that the amplitude of pressure fluctuation is bigger when the rotating-speed of shaft is unsteady, indicating that the speed fluctuations of impellers intensify the nonuniformity and instability of the whole flow field inside the pump. Besides, the Blade Passing Frequency (BPF) has obvious sidelobe frequency peaks when different frequency rate of speed appears. It can be concluded that sidelobes maybe come from the torsional vibration of the shaft. The main findings of this work can provide prediction of the pump performance and information for further optimal design of centrifugal pumps as well.

Sign in / Sign up

Export Citation Format

Share Document