Particle Flow Simulation for Large Diameter Squat Silos Eccentric Discharge

2011 ◽  
Vol 99-100 ◽  
pp. 1106-1112
Author(s):  
Fang Yuan ◽  
Cheng Ying Dong ◽  
Yao Hui Song ◽  
Song Song Zhang
Keyword(s):  
Lateral Pressure ◽  
Large Diameter ◽  
Pressure Coefficient ◽  
Side Wall ◽  
Operating Conditions ◽  
Particle Flow ◽  
Scale Model ◽  
Maximum Pressure ◽  
Centrifuge Model Test ◽  
Eccentric Distance

The scale model of squat silo in large diameter was established with Particle Flow Code (PFC3D) in this paper. This scale model uses the centrifuge model test principle for reference and provides the field of gravity in the calculation of archetypal squat silo. When the silo filled with granules reaches static equilibrium state, record the static lateral pressure measurement values of its each column measured wall, followed by eccentric discharge simulation in different operating conditions, while monitoring the changes of Measured walls in five different directions during discharging granules, in order to analyze the influence of eccentric discharge on the lateral pressure of large diameter squat silos wall. Thus the following conclusion can be obtained: （1）Overpressure coefficient is close extensive between eccentric distance and far extensive between physical reference of storing material.（2）Under the same condition, the overpressure coefficient of same side wall will be minished with the increasing of discharge port.（3）For the same silo model, maximum pressure coefficient is related with eccentric distance, discharge port size and the position with the wall measured, and its value is greater than the calculated value of standard, because the overpressure coefficient calculation formula is only related with silo diameter and eccentric distance, and this is worth further discussion.

Influence of Side-Pressure Coefficient on Deformation of Tunnel Surrounding Rock and Bolt Axial Force

2015 ◽  
Vol 741 ◽  
pp. 138-142 ◽  
Author(s):  
Feng Hai Ma ◽  
Yan Wang ◽  
Zhi Bin Wang
Keyword(s):  
Axial Force ◽  
Lateral Pressure ◽  
Pressure Coefficient ◽  
Side Wall ◽  
Horizontal Displacement ◽  
Internal Force ◽  
Surrounding Rock ◽  
Lateral Pressure Coefficient ◽  
Finite Element Software ◽  
Side Pressure

Internal force and deformation of surrounding rock and supporting structure of the nonlinear research is the use of finite element software ADINA by ideal elastic-plastic constitutive model.Results show that the lateral pressure coefficient increased from 0 to 1, and even decrease sharply arch sedimentation of surrounding rock, side wall horizontal displacement towards the hole along the radial direction development gradually reduced to 0 and reverse to the hole, when the lateral pressure coefficient is less than 0.5, bolt axial force biggest change is not obvious, when lambda increases gradually, the largest bolt axial force significantly increased.

scholarly journals Numerical Investigation of Unsteady Interaction between Rim Seal Flow and Upstream Vane

2019 ◽  
Vol 37 (1) ◽  
pp. 129-136
Author(s):  
Fan Yang ◽  
Li Zhou ◽  
Zhanxue Wang
Keyword(s):  
Lateral Pressure ◽  
Pressure Coefficient ◽  
Interaction Mechanism ◽  
Suction Side ◽  
Maximum Pressure ◽  
Turbine Stator ◽  
Passage Vortex ◽  
Coefficient Increase ◽  
Unsteady Interaction ◽  
Blockage Effect

To investigate unsteady interaction mechanism between the rim seal flow in turbine stator-rotor cavity and main flow, detailed unsteady numerical simulations of the flow field and unsteady characteristic of the vane were conducted under different rim seal mass flow rate. The results show the blockage effect resulting from the egress flow leads to the pressure to increase and static entropy to reduce on the latter half of suction side near the hub. From the case without a cavity to RI=1.7%, at 5% span, the maximum pressure coefficient increase on the suction side reaches 6%. Moreover, the blockage effect causes the velocity to decrease at vane exit. Furthermore, the rim seal flow results in the decrease in lateral pressure gradient, causing the strength of hub passage vortex and hub trailing shedding vortex to reduce. Without rim seal flow, the ingress flow contributes to decreasing unsteady fluctuation from the hub to 10% span. When there is rim seal flow, unsteady fluctuation continues to reduce due to coupling effects of the egress flow from the ingress and the egress flow form the cavity inlet.

Numerical evaluation of the side wall effect on the flow around a hydrofoil

2014 ◽  
Vol 31 (3) ◽  
pp. 501-509 ◽  
Author(s):  
Min He ◽  
Lingli Yuan ◽  
Lingjiu Zhou ◽  
Jing Yang ◽  
Zhengwei Wang
Keyword(s):  
Flow Field ◽  
Turbulence Model ◽  
Lift Coefficient ◽  
Pressure Coefficient ◽  
Three Dimensional ◽  
Side Wall ◽  
Wall Effect ◽  
Scale Model ◽  
Content Type ◽  
Rng Turbulence Model

Purpose – Studies of the three-dimensional flow characteristics during hydrofoil cavitation have shown that the side walls strongly affect the flow field around the hydrofoil. The purpose of this paper is to analyze the side wall effect for three-dimensional non-cavitating flows around a hydrofoil. Design/methodology/approach – A three-dimensional non-cavitating flow field around a hydrofoil is analyzed for different attack angles using the RNG turbulence model and large eddy simulations (LES). The effect of the hydrofoil span was analyzed using LES simulations for various spans. Findings – The lift coefficient, drag coefficient and pressure coefficient on the suction side are compared with experimental values. The results from the LES model (Smagorinsky-Lilly subgrid-scale model) agree better with the experimental data than those from the RNG turbulence model. Originality/value – This paper shows that the flow around the hydrofoil has significant three-dimensional characteristics due to the side wall. For wide hydrofoils, the wall vortex region becomes essentially stable, and the width of the span has little effect on the middle region.

Validation of mathematical model of electrothermal calculation of DC catenary on the basis of scale model

2018 ◽  
Vol 77 (4) ◽  
pp. 222-229 ◽  
Author(s):  
A. V. Paranin ◽  
A. B. Batrashov
Keyword(s):  
Mathematical Model ◽  
Operating Conditions ◽  
Scale Model ◽  
Contact Network ◽  
Scaled Model ◽  
Cross Sectional ◽  
Current Collection ◽  
Topological Features ◽  
Study Results ◽  
Real Physical Process

The article compares the results of calculation of the finite element simulation of current and temperature distribution in the scale model of the DC catenary with the data of laboratory tests. Researches were carried on various versions of the structural design of catenary model, reflecting the topological features of the wire connection, characteristic of the DC contact network. The proportions of the cross-sectional area of the scaled model wires are comparable to each other with the corresponding values for real DC catenary. The article deals with the operating conditions of the catenary model in the modes of transit and current collection. When studying the operation of the scale catenary model in the transit mode, the effect of the structural elements on the current distribution and heating of the wires was obtained. Within the framework of the scale model, theoretical assumptions about the current overload of the supporting cable near the middle anchoring have been confirmed. In the current collection mode, the experimental dependences of the current in the transverse wires of the scale model are obtained from the coordinate of the current collection point. Using the model it was experimentally confirmed that in the section of the contact wire with local wear, not only the temperature rise occurs but also the current redistribution due to the smaller cross section. Thus, the current share in other longitudinal wires of the scale model increases and their temperature rises. Scale and mathematical models are constructed with allowance for laboratory clamps and supporting elements that participate in the removal of heat from the investigated wires. Obtained study results of the scale model allow to draw a conclusion about the adequacy of the mathematical model and its correspondence to the real physical process. These conclusions indicate the possibility of applying mathematical model for calculating real catenary, taking into account the uneven contact wear wire and the armature of the contact network.

scholarly journals Numerical Study on Damage Zones Induced by Excavation and Ventilation in a High-Temperature Tunnel at Depth

Energies ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4773
Author(s):  
Jianyu Li ◽  
Hong Li ◽  
Zheming Zhu ◽  
Ye Tao ◽  
Chun’an Tang
Keyword(s):  
High Temperature ◽  
Lateral Pressure ◽  
Numerical Study ◽  
Pressure Coefficient ◽  
Fracture Morphology ◽  
In Situ Stress ◽  
Surrounding Rock ◽  
Geothermal System ◽  
Mechanical Coupling ◽  
Lateral Pressure Coefficient

Geothermal power is being regarded as depending on techniques derived from hydrocarbon production in worldwide current strategy. However, it has artificially been developed far less than its natural potentials due to technical restrictions. This paper introduces the Enhanced Geothermal System based on Excavation (EGS-E), which is an innovative scheme of geothermal energy extraction. Then, based on cohesion-weakening-friction-strengthening model (CWFS) and literature investigation of granite test at high temperature, the initiation, propagation of excavation damaged zones (EDZs) under unloading and the EDZs scale in EGS-E closed to hydrostatic pressure state is studied. Finally, we have a discussion about the further evolution of surrounding rock stress and EDZs during ventilation is studied by thermal-mechanical coupling. The results show that the influence of high temperature damage on the mechanical parameters of granite should be considered; Lateral pressure coefficient affects the fracture morphology and scale of tunnel surrounding rock, and EDZs area is larger when the lateral pressure coefficient is 1.0 or 1.2; Ventilation of high temperature and high in-situ stress tunnel have a significant effect on the EDZs scale; Additional tensile stress is generated in the shallow of tunnel surrounding rock, and the compressive stress concentration transfers to the deep. EDZs experiences three expansion stages of slow, rapid and deceleration with cooling time, and the thermal insulation layer prolongs the slow growth stage.

An Approximate THD Theory for Journal Bearings

1990 ◽  
Vol 112 (2) ◽  
pp. 224-229 ◽  
Author(s):  
G. Gupta ◽  
C. R. Hammond ◽  
A. Z. Szeri
Keyword(s):  
Journal Bearing ◽  
Load Capacity ◽  
Pressure Coefficient ◽  
Journal Bearings ◽  
Maximum Pressure ◽  
Substantial Agreement ◽  
Interactive Mode ◽  
Lubricant Flow ◽  
Bearing Load ◽  
Sophisticated Model

The aim of this paper is to make available to the industrial designer results of the thermohydrodynamic theory of journal bearings, by providing a simplified, yet accurate model of journal bearing lubrication that can be implemented on a personal computer and be used in an interactive mode. The simplified THD theory we propose consists of two coupled ordinary differential equations for pressure and energy and an algebraic equation for viscosity, which are to be solved iteratively. Bearing load capacity, maximum bearing temperature, maximum pressure, coefficient of friction and lubricant flow rate calculated from this simplified theory compare well with results from a more sophisticated model. We also make comparisons with experimental data on full journal bearings, demonstrating substantial agreement between experiment and simplified theory.

scholarly journals Influence of Pile Diameter and Aspect Ratio on the Lateral Response of Monopiles in Sand with Different Relative Densties

2021 ◽  
Vol 9 (6) ◽  
pp. 618
Author(s):  
Huan Wang ◽  
Lizhong Wang ◽  
Yi Hong ◽  
Amin Askarinejad ◽  
Ben He ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
Large Diameter ◽  
Pressure Coefficient ◽  
Offshore Wind ◽  
Fe Model ◽  
Soil Pressure ◽  
Pile Diameter ◽  
Centrifuge Tests ◽  
Aspect Ratios ◽  
Wide Range

The large-diameter monopiles are the most preferred foundation used in offshore wind farms. However, the influence of pile diameter and aspect ratio on the lateral bearing behavior of monopiles in sand with different relative densities has not been systematically studied. This study presents a series of well-calibrated finite-element (FE) analyses using an advanced state dependent constitutive model. The FE model was first validated against the centrifuge tests on the large-diameter monopiles. Parametric studies were performed on rigid piles with different diameters (D = 4–10 m) and aspect ratios (L/D = 3–7.5) under a wide range of loading heights (e = 5–100 m) in sands with different relative densities (Dr = 40%, 65%, 80%). The API and PISA p-y models were systematically compared and evaluated against the FE simulation results. The numerical results revealed a rigid rotation failure mechanism of the rigid pile, which is independent of pile diameter and aspect ratio. The computed soil pressure coefficient (K = p/Dσ′v) of different diameter piles at same rotation is a function of z/L (z is depth) rather than z/D. The force–moment diagrams at different deflections were quantified in sands of different relative density. Based on the observed pile–soil interaction mechanism, a simple design model was proposed to calculate the combined capacity of rigid piles.

Large eddy simulation study of turbulent flow around smooth and rough domes

2013 ◽  
Vol 227 (12) ◽  
pp. 2686-2700 ◽  
Author(s):  
N Kharoua ◽  
L Khezzar
Keyword(s):  
Large Eddy Simulation ◽  
Turbulent Flow ◽  
Flow Behavior ◽  
Pressure Coefficient ◽  
Horseshoe Vortex ◽  
Scale Model ◽  
Stream Velocity ◽  
Mean Velocity ◽  
Eddy Simulation ◽  
Large Eddy

Large eddy simulation of turbulent flow around smooth and rough hemispherical domes was conducted. The roughness of the rough dome was generated by a special approach using quadrilateral solid blocks placed alternately on the dome surface. It was shown that this approach is capable of generating the roughness effect with a relative success. The subgrid-scale model based on the transport of the subgrid turbulent kinetic energy was used to account for the small scales effect not resolved by large eddy simulation. The turbulent flow was simulated at a subcritical Reynolds number based on the approach free stream velocity, air properties, and dome diameter of 1.4 × 105. Profiles of mean pressure coefficient, mean velocity, and its root mean square were predicted with good accuracy. The comparison between the two domes showed different flow behavior around them. A flattened horseshoe vortex was observed to develop around the rough dome at larger distance compared with the smooth dome. The separation phenomenon occurs before the apex of the rough dome while for the smooth dome it is shifted forward. The turbulence-affected region in the wake was larger for the rough dome.

Experimental Study on the Behavior of a Swimming Pool Onboard a Large Passenger Ship

2009 ◽  
Vol 46 (01) ◽  
pp. 27-33
Author(s):  
Pekka Ruponen ◽  
Jerzy Matusiak ◽  
Janne Luukkonen ◽  
Mikko Ilus
Keyword(s):  
Large Scale ◽  
Hydraulic Cylinder ◽  
Operating Conditions ◽  
Swimming Pool ◽  
Scale Model ◽  
Longitudinal Motion ◽  
Sea State ◽  
Passenger Ship ◽  
Large Scale Model ◽  
Computer Controlled

The water in a swimming pool on the top deck of a large passenger ship can be excited to a resonant motion, even in a moderate sea state. The motion of the water in the pool is mainly caused by longitudinal acceleration, resulting from the ship's pitch and surge motions. At resonance, there can be high waves in the pool and splashing of water. In this study the behavior of the Solarium Pool of the Freedom of the Seas was examined in various sea states and operating conditions. The motions of the pool were calculated on the basis of a linear seakeeping method, and the behavior of the water in the pool was studied with experimental model tests. A large-scale model of the pool was constructed and fitted to a purpose-built test bench that could be axially moved by a computer-controlled hydraulic cylinder. Water elevation in the pool was measured, and all tests were video recorded. Different modifications of the pool were tested to improve the behavior of the pool. A strong correlation between the longitudinal motion and the behavior of the water in the pool was found.

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