scholarly journals INVESTIGATION OF GAS-DYNAMIC PROCESSES IN PIPELINE COMMUNICATIONS DURING THEIR TRENCHLESS RECONSTRUCTION WITH THE TECHNOLOGY "TRACTION PISTON"

2019 ◽  
pp. 43-53
Author(s):  
K. A. Poliarush
Keyword(s):  
Stokes Equations ◽  
Air Flow ◽  
Longitudinal Section ◽  
Cfd Modeling ◽  
Navier Stokes ◽  
Dynamic Processes ◽  
Ansys Fluent ◽  
Navier Stokes Equations ◽  
Software Complex ◽  
Gas Dynamic

The technology of the trenchless reconstruction of pipeline communications "Traction Piston", which consists in running a new polyethylene pipeline into a steel one worn by pigis described. At the same time, in order to maintain the necessary pressure in the cavity, the space between the new polyethylene pipeline and the worn steel one is sealed. A 3D modeling of the annulus and space behind the piston, where the complex turbulent flow of air flows, is carried out. A CFD modeling of gas-dynamic processes in the annulus and space behind the piston while laying a worn steel pipeline with a polyethylene pipeline in the ANSYS Fluent software system is performed. The mathematical model is based on the solution of the Navier-Stokes equations and the continuity of the flow closed by a two-parameter turbulence model of Launder-Sharma with the use of a wall function with corresponding initial and boundary conditions. A dynamic grid model was used to simulate the motion of the piston and the polyethylene pipeline. The type of adjustment of the dynamic grid parameters during the stroke of a new polyethylene pipeline into a defective steel one – Layering was chosen. The simulation results were visualized in the postprocessor of the software complex by constructing flow lines, velocity vectors, pressure fields on the contours and in the longitudinal section of the annulus and space behind the piston. The exact values of velocity, pressure at different points between the annulus and space behind the piston were determined. The structure of the air flow in the cavity and interstitial space is studied. The places of slowdown and acceleration of air flow, falling and increase of pressure are found. The loss of pressure in the annular space is determined.

The inlet flow structure of a conceptual open-nose supersonic drone

2021 ◽  
pp. 095441002098304
Author(s):  
Eiman B Saheby ◽  
Xing Shen ◽  
Anthony P Hays ◽  
Zhang Jun
Keyword(s):  
Flow Structure ◽  
Stokes Equations ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Computational Fluid Dynamic Simulation ◽  
Navier Stokes ◽  
Ansys Fluent ◽  
Navier Stokes Equations ◽  
Aerodynamic Efficiency ◽  
Performance Effects

This study describes the aerodynamic efficiency of a forebody–inlet configuration and computational investigation of a drone system, capable of sustainable supersonic cruising at Mach 1.60. Because the whole drone configuration is formed around the induction system and the design is highly interrelated to the flow structure of forebody and inlet efficiency, analysis of this section and understanding its flow pattern is necessary before any progress in design phases. The compression surface is designed analytically using oblique shock patterns, which results in a low drag forebody. To study the concept, two inlet–forebody geometries are considered for Computational Fluid Dynamic simulation using ANSYS Fluent code. The supersonic and subsonic performance, effects of angle of attack, sideslip, and duct geometries on the propulsive efficiency of the concept are studied by solving the three-dimensional Navier–Stokes equations in structured cell domains. Comparing the results with the available data from other sources indicates that the aerodynamic efficiency of the concept is acceptable at supersonic and transonic regimes.

scholarly journals PARALLEL COMPUTATIONS IN STUDIES OF DEPENDENCE OF GAS DYNAMIC PARAMETERS OF UPWARD SWIRLING FLOW OF GAS ON BLOWING VELOCITY

2016 ◽  
pp. 92-97
Author(s):  
R. E. Volkov ◽  
A. G. Obukhov
Keyword(s):  
Stokes Equations ◽  
Swirling Flow ◽  
Initial Conditions ◽  
Exact Analytical Solution ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Heat Conducting ◽  
Computational Domain ◽  
Navier Stokes Equations ◽  
Gas Dynamic

The rectangular parallelepiped explicit difference schemes for the numerical solution of the complete built system of Navier-Stokes equations. These solutions describe the three-dimensional flow of a compressible viscous heat-conducting gas in a rising swirling flows, provided the forces of gravity and Coriolis. This assumes constancy of the coefficient of viscosity and thermal conductivity. The initial conditions are the features that are the exact analytical solution of the complete Navier-Stokes equations. Propose specific boundary conditions under which the upward flow of gas is modeled by blowing through the square hole in the upper surface of the computational domain. A variant of parallelization algorithm for calculating gas dynamic and energy characteristics. The results of calculations of gasdynamic parameters dependency on the speed of the vertical blowing by the time the flow of a steady state flow.

Numerical Analysis of Streamlines in Kaplan Turbine with Different Distributor Fins Design

2020 ◽  
Vol 35 ◽  
pp. 46-54
Author(s):  
Daniele Twardowski ◽  
Diego Alves de Miranda
Keyword(s):  
Stokes Equations ◽  
Turbine Blades ◽  
Navier Stokes ◽  
Flow Profile ◽  
Ansys Fluent ◽  
Navier Stokes Equations ◽  
Kaplan Turbine ◽  
Current Lines ◽  
High Level ◽  
Volume Method

With each passing day companies are looking more and more in the initial phase of the project, to understand the phenomena arising, so that in the execution of the project there are no failures, much less when the project is in operation. For this, the numerical simulation has been shown an increasingly efficient tool to assist the engineers and designers of machines and equipment. The Kaplan turbine design requires a high level of engineering expertise combined with a high level of knowledge in fluid mechanics, as poor design of a diffuser fin can lead to disordered turbulent flow which, when mixed with a high pressure drop, can cavitate into turbine blades. The aim of this study is to evaluate different types of diffuser fin profiles in the inlet at Kaplan turbines. For this, numerical computer simulation was used with the aid of the Ansys Fluent software, in which simulations of water flow in a steady state occurred. The software works with the finite volume method for the discretization of the Navier-Stokes equations. The simulations have proved to be efficient in capturing current lines and pointing out the best flow profile in a project, avoiding more complex turbine blade problems.

scholarly journals Effect of Leading-Edge Bulges on Aerodynamic Characteristics of Bionic Wingsail

2021 ◽  
Author(s):  
Chen Li ◽  
Peiting Sun ◽  
Hongming Wang
Keyword(s):  
Stokes Equations ◽  
Lift Coefficient ◽  
Leading Edge ◽  
Aerodynamic Characteristics ◽  
Navier Stokes ◽  
Suction Surface ◽  
Ansys Fluent ◽  
Navier Stokes Equations ◽  
Extension Direction ◽  
Lift And Drag

The leading-edge bulges along the extension direction are designed on the marine wingsail. The height and the spanwise wavelength of the protuberances are 0.1c and 0.25c, respectively. At Reynolds number Re=5×105, the Reynolds Averaged Navier-Stokes equations are applied to the simulation of the wingsail with the bulges thanks to ANSYS Fluent finite-volume solver based on the SST K-ω models. The grid independence analysis is carried out with the lift and drag coefficients of the wingsail at AOA = 8° and AOA=20°. The results show that while the efficiency of the wingsail is reduced by devising the leading-edge bulges before stall, the bulges help to improve the lift coefficient of the wingsail when stalling. At AOA=22° under the action of the leading-edge tubercles, a convective vortex is formed on the suction surface of the modified wingsail, which reduces the flow loss. So the bulges of the wingsail can delay the stall.

scholarly journals INVESTIGATION HYPERBOLIC PARABOLOID SHELL IN THE WIND TUNNEL AND COMPARISON WITH NUMERICAL SIMULATIONS

2018 ◽  
Vol 64 ◽  
Author(s):  
V.V. Stojanov ◽  
S. Jgalli
Keyword(s):  
Numerical Simulation ◽  
Wind Tunnel ◽  
Stokes Equations ◽  
Navier Stokes ◽  
Wind Flow ◽  
Hyperbolic Paraboloid ◽  
Ansys Fluent ◽  
Navier Stokes Equations ◽  
Basic Model ◽  
The Impact

There are different ways to determine aerodynamic parameters, using analytical and experimental data for analyzing the behavior of structures when exposed to wind load. To date, the most developed is considered a numerical method for determining the characteristics of the above methods, based on the numerical solution of the Navier-Stokes equations. The accuracy of the results obtained using such a calculation method and obtaining the values of aerodynamic forces has increased due to the revision of mathematical models and the development of software complexes for the discretization of object bodies. This article gives an analytical overview of the results of research in the field of study the impact of wind loads on hypar (shell square in plan with the form of a hyperbolic paraboloid). The features of the investigated forms a discretization surface depending on pressure coefficients obtained in foreign literatures. Particular attention is paid to the numerical determination of aerodynamic coefficients on the surfaces of a hyperbolic paraboloid. The results were discussed and the nature of the distribution of coefficients depending on the angle of attack of the wind. Achieved analytical comparison computer modeling turbulent wind flows, based on solving the Reynolds equations arising from the use of averaging the Navier-Stokes equations. The basic model of turbulence such as: k-ε Standard Model; MMK; DBN; Shear-Stress Transport k-ω model; Transition k-kl-ω model. The possibility of choosing one or another model depending on the properties and characteristics of the wind flow is analyzed, for application in numerical simulation of wind flow around hyperbolic shells. The same was done, a comparative analysis of the results of physical testing in a wind tunnel with a numerical simulation in Ansys Fluent.

Modelling of hydrogen-air supersonic mixing and combustion in near-wall region

2021 ◽  
Vol 36 (2) ◽  
pp. 101-115
Author(s):  
Roman S. Solomatin ◽  
Ilya V. Semenov
Keyword(s):  
Turbulence Model ◽  
Stokes Equations ◽  
Air Flow ◽  
Flame Stabilization ◽  
Navier Stokes ◽  
Wall Region ◽  
Navier Stokes Equations ◽  
Supersonic Mixing ◽  
Ignition And Combustion ◽  
Near Wall

Abstract Turbulent mixing, ignition, and flame stabilization in the non-premixed supersonic hydrogen-air flow is numerically modelled in a near-wall region. Mixing algorithm based on the turbulence approach SARANS (Reynolds Averaged Navier–Stokes equations closed with Spalart–Allmaras turbulence model) with a diffusion model and a detailed kinetic model for hydrogen-air chemical reactions are employed. The system of governing equations that consists of basic conservation laws and the turbulence model equation is solved in a coupled manner with the LU–SGS–GMRES method. The model is applied to simulate the process of hydrogen injection into a M = 2.44 air flow with their subsequent mixing, ignition, and combustion in the Burrows– Kurkov chamber. The results are compared to available experimental and reference computational data. All calculations are carried out on the ‘MVS-10P’ JSCC RAS supercomputer cluster.

GENERALIZED GAS DYNAMIC EQUATIONS WITH MULTIPLE TRANSLATIONAL TEMPERATURES

2009 ◽  
Vol 23 (03) ◽  
pp. 237-240 ◽  
Author(s):  
KUN XU ◽  
ZHAOLI GUO
Keyword(s):  
Flow Regime ◽  
Stokes Equations ◽  
Dimensional Space ◽  
Natural Extension ◽  
Dynamic Equations ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Gas Dynamic ◽  
Continuum Flow ◽  
Gas Dynamic Equations

Based on a multiple stage BGK-type collision model and the Chapman–Enskog expansion, the corresponding macroscopic gas dynamics equations in three-dimensional space will be derived. The new gas dynamic equations have the same structure as the Navier–Stokes equations, but the stress strain relationship in the Navier–Stokes equations is replaced by an algebraic equation with temperature differences. In the continuum flow regime, the new gas dynamic equations automatically recover the standard Navier–Stokes equations. The current gas dynamic equations are natural extension of the Navier–Stokes equations to the near continuum flow regime and can be used for near continuum flow study.

Aerodynamic Simulation of the Air Flow beneath the High Speed Train

2012 ◽  
Vol 253-255 ◽  
pp. 2035-2040
Author(s):  
Ye Bo Liu ◽  
Zhi Ming Liu
Keyword(s):  
High Speed ◽  
Stokes Equations ◽  
Air Flow ◽  
Pressure Coefficient ◽  
Three Dimensional ◽  
Navier Stokes ◽  
High Speed Train ◽  
Navier Stokes Equations ◽  
Pressure Distributions ◽  
High Speed Trains

Numerical simulations were carried out to investigate the air flow and pressure distributions beneath high speed trains, based on the three-dimensional Reynolds-averaged Navier-Stokes equations with the SST k-ω two-equation turbulence model. The simulation scenarios were of the high speed train, the CRH2, running in the open air at four different speeds: 200km/h, 250km/h, 300km/h and 350km/h. The results show that, the highest area of pressure is located at the front underbody part of the train whist the pressure for rest of the train is relatively small. Increasing speed does not visibly increase the pressure coefficient, indicating that the pressure increases with the square of the operational speed.

scholarly journals ACCOUNTING INFLUENCE OF CENTRIFUGAL FORCE IN THE NUMERICAL MODELING OF RISING SWIRLED GAS FLOW

2015 ◽  
pp. 92-97
Author(s):  
S. P. Bautin ◽  
A. G. Obukhov
Keyword(s):  
Centrifugal Force ◽  
Gas Flow ◽  
Stokes Equations ◽  
Swirling Flow ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Heat Conducting ◽  
Navier Stokes Equations ◽  
Power Characteristics ◽  
Gas Dynamic

In work the consistent inclusion of centrifugal force in the numerical calculations of three-dimensional gas-dynamic characteristics of the unsteady flow of compressible viscous heat-conducting gas in an upward swirling flow caused by the vertical cold blowing. Provides detailed conversion of the complete system of Navier-Stokes equations associated with consistent view of the centrifugal force. Results of thermodynamic calculations and comparisons, speed and power characteristics of emerging upward swirling flows. There was a slight influence of the centrifugal force on the basic parameters of the gas-dynamic study of complex flows of gas.

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