scholarly journals Numerical Simulation of the Effects of the Helical Angle on the Decaying Swirl Flow of the Hole Cleaning Device

Processes ◽  
2019 ◽  
Vol 7 (2) ◽  
pp. 109 ◽  
Author(s):  
Jingyu Qu ◽  
Tie Yan ◽  
Xiaofeng Sun ◽  
Zijian Li ◽  
Wei Li
Keyword(s):  
Flow Direction ◽  
Tangential Velocity ◽  
Axial Flow ◽  
Critical Value ◽  
Swirl Flow ◽  
Swirl Number ◽  
Hole Cleaning ◽  
Helical Angle ◽  
Swirl Intensity ◽  
Cleaning Device

The application of the hole cleaning device in downhole is a new technology that can improve the problem of cuttings accumulation in the annulus and improve the hole cleaning effect of the wellbore during drilling. In this paper, the Reynolds Averaged Navier–Stokes model, together with the Realizable k-ε turbulence model, are used to perform transient simulations. The effects of rotational speed, blade shape, and helical angle on the initial swirl intensity and its decay behavior along the flow direction are studied. The swirl number, the initial swirl intensity, the decay rate, the tangential velocity distribution, and the variation of pressure are analyzed. The results indicate that the swirl number of the swirl flow exponentially decays along the flow direction. The straight blade and V-shaped blade have different swirl flow induction mechanisms. Under specific drilling parameters, the critical helical angle is determined for both types of blades. When the selection of the helical angle is close to the critical value, the swirl flow will be close to the axial flow, which is of little help in hole cleaning. Moreover, the rotation direction of swirl flow will change when the helical angle exceeds the critical value.

scholarly journals Decaying Swirl Flow and Particle Behavior through the Hole Cleaning Device for Horizontal Drilling of Fossil Fuel

Energies ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 336 ◽  
Author(s):  
Jingyu Qu ◽  
Tie Yan ◽  
Xiaofeng Sun ◽  
Zijian Li ◽  
Wei Li
Keyword(s):  
Fluid Model ◽  
Flow Direction ◽  
Tangential Velocity ◽  
Swirl Flow ◽  
Horizontal Drilling ◽  
Hole Cleaning ◽  
Particle Behavior ◽  
Swirl Intensity ◽  
Cleaning Device ◽  
Two Fluid Model

The hole cleaning device is a powerful application which can effectively slow down the deposition of cuttings during drilling. However, in this complicated swirl flow created by the device, the decay of the swirl flow and the particle behavior are not evident yet. In this paper, the decay of the swirl flow and the particle behavior in the swirl flow field are studied by the Eulerian–Eulerian two-fluid model (TFM) coupled with the kinetic theory of granular flows (KTGF), and sliding mesh (SM) technique for simulating the fluid flow. The results show that the swirl intensity decays exponentially along the flow direction under laminar flow conditions. The swirl flow has a longer acting distance at a higher rotational speed, which can effectively slow down the deposition of cutting particles. The initial swirl intensity of swirl flow induced by the blades increases significantly with the increase of blade height and the decrease of the blade angle. The tangential velocity of the cutting particles in the annulus is more significant near the central region, gradually decreases toward the wall in the radial direction, and rapidly decreases to 0 at the wall surface. The decay rate is negatively correlated with the initial swirl intensity. The results presented here may provide a useful reference for the design of the hole cleaning device.

Flow Fields in an Axial Flow Compressor During Four-Quadrant Operation

2013 ◽  
Author(s):  
Andrew Gill ◽  
Theodor W. von Backström ◽  
Thomas M. Harms ◽  
Dwain Dunn
Keyword(s):  
Flow Direction ◽  
Tangential Velocity ◽  
Axial Compressor ◽  
Axial Flow ◽  
Pressure Rise ◽  
Flow Fields ◽  
Time Dependent ◽  
Axial Flow Compressor ◽  
Compressor Rotor ◽  
Flow Compressor

It has been shown in previous investigations that when all combinations of both positive and negative direction of rotation and flow direction are allowed in operating a multistage axial flow compressor, the operating point may be in any of the four quadrants of the pressure rise versus flow characteristic. The present paper is the first discussion of the flow field of all possible modes of operation of an axial flow compressor. During the present study interstage time dependent hot film velocity measurements and five hole pneumatic probe measurements were combined with steady and time dependent CFD solutions to investigate the flow fields in the three-stage axial compressor. Results are presented in terms of mean-line velocity triangles, mean stream surface plots, mid-span radial velocity contours right through the compressor, rotor-downstream radial distributions of axial and tangential velocity, stator-downstream axial velocity contours and mid-span entropy contours through the compressor. Main flow features are pointed out and discussed. The study was instigated in an effort to understand possible accident scenarios in a three-shaft closed cycle nuclear powered helium gas turbine.

Performance Degradation and Flow Instability of Axial-Flow Fan Due to Upstream Obstacle

2020 ◽  
Vol 142 (9) ◽  
Author(s):  
Donghyuk Kang ◽  
Takeru Shinohara ◽  
Shinsaku Nakamura ◽  
Koichi Nishibe ◽  
Kotaro Sato ◽  
...  
Keyword(s):  
Pressure Loss ◽  
Flow Instability ◽  
Flow Direction ◽  
Axial Flow ◽  
Swirl Flow ◽  
Performance Degradation ◽  
Low Flow ◽  
Power Coefficient ◽  
Centrifugal Fan ◽  
Axial Fan

Abstract This paper elucidates the performance degradation and flow instability of an axial fan caused by the presence of disk-shaped obstacles upstream of the fan, such as wall surfaces. The increase in pressure loss and the decrease in shaft power coefficient due to inlet swirl flow, and the increase in pressure loss due to the outlet swirl flow, cause performance degradation. When the obstacle is closer to the fan, the strong swirl flow causes a negative pressure region between the fan and the obstacle, reversing the flow direction. This phenomenon is caused by the diffuser effect of the outward flow and the increase in pressure by acting as a multiblade centrifugal fan. At a low flow rate, a clockwise vortex is generated at the center of the obstacle and induces two counterclockwise rotating vortices. The vortices circumferentially separate the inward and outward flows along the fan's axis in a uniform manner, and their cores are circularly rotated by the clockwise vortex. These findings can contribute to the layout of fans under spatial restriction and suppression of flow instability due to obstacles.

Flow Fields in an Axial Flow Compressor During Four-Quadrant Operation

2013 ◽  
Vol 136 (6) ◽  
Author(s):  
Andrew Gill ◽  
Theodor W. Von Backström ◽  
Thomas M. Harms
Keyword(s):  
Flow Direction ◽  
Tangential Velocity ◽  
Axial Compressor ◽  
Axial Flow ◽  
Pressure Rise ◽  
Flow Fields ◽  
Time Dependent ◽  
Axial Flow Compressor ◽  
Compressor Rotor ◽  
Flow Compressor

It has been shown in previous investigations that when all combinations of both positive and negative direction of rotation and flow direction are allowed in operating a multistage axial flow compressor, the operating point may be in any of the four quadrants of the pressure rise versus flow characteristic. The present paper is the first discussion of the flow field of all possible modes of operation of an axial flow compressor. During the present study interstage time dependent hot film velocity measurements and five hole pneumatic probe measurements were combined with steady and time dependent CFD solutions to investigate the flow fields in the three-stage axial compressor. Results are presented in terms of mean-line velocity triangles, mean stream surface plots, midspan radial velocity contours right through the compressor, rotor-downstream radial distributions of axial and tangential velocity, stator-downstream axial velocity contours and midspan entropy contours through the compressor. Main flow features are pointed out and discussed. The study was instigated in an effort to understand possible accident scenarios in a three-shaft closed cycle nuclear powered helium gas turbine.

Blocking in the Rotating Axial Flow in a Corotating Flexible Shell

2008 ◽  
Vol 76 (1) ◽  
Author(s):  
F. Gosselin ◽  
M. P. Païdoussis
Keyword(s):  
Traveling Waves ◽  
Physical Phenomenon ◽  
Axial Flow ◽  
Critical Value ◽  
Inviscid Fluid ◽  
Shell Wall ◽  
Stagnation Region ◽  
Linear Dynamics ◽  
Shell Equations ◽  
Rotating Cylindrical Shell

By coupling the Donnell–Mushtari shell equations to an analytical inviscid fluid solution, the linear dynamics of a rotating cylindrical shell with a corotating axial fluid flow is studied. Previously discovered mathematical singularities in the flow solution are explained here by the physical phenomenon of blocking. From a reference frame moving with the traveling waves in the shell wall, the flow is identical to the flow in a rigid varicose tube. When the ratio of rotation rate to flow velocity approaches a critical value, the phenomenon of blocking creates a stagnation region between the humps of the wall. Since the linear model cannot account for this phenomenon, the solution blows up.

Numerical Simulation of Cold Swirl Field for Solid Fuel Ramjet with NACA Airfoil

2014 ◽  
Vol 716-717 ◽  
pp. 711-716
Author(s):  
Jie Yu ◽  
Xiong Chen ◽  
Hong Wen Li
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Radial Velocity ◽  
Solid Fuel ◽  
Velocity Gradient ◽  
Pressure Loss ◽  
Total Pressure ◽  
Swirl Flow ◽  
Total Pressure Loss ◽  
Swirl Number

In order to study the swirl flow characteristics in the solid fuel ramjet chamber, a new type of annular vane swirler with NACA airfoil is designed. The cold swirl flow field in the chamber is numerically simulated with different camber and t attack angle, while the swirl number , swirl flow field structure, total pressure recovery coefficient were studied. According to numerical simulation result, the main factors in swirl number are camber and angle of attack, the greater angle of attack, the greater the camber ,the stronger swirl will be. Results show that the total pressure loss is mainly concentrated in the inlet section, the total pressure loss cause by vane swirler is small. Radial velocity gradient exists in swirling flow, and increases with the swirl number. With the influence of centrifugal force and combustion chamber structure, the radial velocity gradient increases.

Impact of the Expansion Ratio on the Unsteady Aerodynamics and Performance of a HP Axial Turbine

2016 ◽  
Author(s):  
P. Gaetani ◽  
G. Persico ◽  
A. Spinelli ◽  
A. Mora
Keyword(s):  
Flow Field ◽  
Incidence Angle ◽  
Flow Direction ◽  
Axial Flow ◽  
Unsteady Aerodynamics ◽  
Fast Response ◽  
Expansion Ratio ◽  
Operating Conditions ◽  
Inlet Temperature ◽  
And Performance

In the frame of the European research project RECORD, the flow field within a HP axial-flow turbine model was investigated experimentally for several operating conditions. A number of studies on stator-rotor interaction in HP turbines for subsonic as well as transonic/supersonic conditions were proposed in the last decades, but none of them compared different conditions for the same geometry. In this paper, the transonic condition is investigated and compared to three subsonic ones, in the frame of an entirely new experimental campaign. The research was performed at the Laboratorio di Fluidodinamica delle Macchine of the Politecnico di Milano (Italy), where a cold-flow, closed-loop test rig is available for detailed studies on turbines and compressors. The boundary conditions resulted in keeping constant both the turbine inlet temperature and the stage outlet absolute flow direction; so far, while the expansion ratio was varied, the rotational speed was also modified accordingly. The analysis was performed by means of a conventional five hole probe in the stator – rotor axial gap and by a fast response aerodynamic probe downstream of the rotor. The local time-averaged and phase-resolved flow field was then derived and used to analyze the stage aerodynamics and performance. Results show that the stage expansion ratio has a dramatic impact on both the rotor aerodynamics and stage performance. In particular, Mach number effects are recognized in the stator cascade that passes from transonic to low subsonic conditions. On the rotor cascade the reduction of expansion ratio reduces significantly the Mach and Reynolds numbers and increases the incidence angle as well; the rotor loss mechanics as well as the vane-rotor interaction are greatly amplified. Correspondingly a significant variation of stage overall efficiency is recorded.

Interception of two spheres with slip surfaces in linear Stokes flow

2007 ◽  
Vol 581 ◽  
pp. 129-156 ◽  
Author(s):  
H. LUO ◽  
C. POZRIKIDIS
Keyword(s):  
Integral Equations ◽  
Stokes Flow ◽  
Fourier Coefficients ◽  
Tangential Velocity ◽  
Critical Value ◽  
Element Distribution ◽  
Spherical Particles ◽  
Polar Coordinate System ◽  
Simple Shear Flow ◽  
Time Step

The interception of two spherical particles with arbitrary size in an infinite linear ambient Stokes flow is considered. The particle surfaces allow for slip according to the Navier–Maxwell–Basset law relating the shear stress to the tangential velocity. At any instant, the flow is computed in a frame of reference with origin at the centre of one particle using a cylindrical polar coordinate system whose axis of revolution passes through the centre of the second particle. Taking advantage of the axial symmetry of the boundaries of the flow in the particle coordinates, the problem is formulated as a system of integral equations for the zeroth, first, and second Fourier coefficients of the boundary traction with respect to the meridional angle. The force and torque exerted on each particle are determined by the zeroth and first Fourier coefficients, while the stresslet is determined by the zeroth, first, and second Fourier coefficients. The derived integral equations are solved with high accuracy using a boundary element method featuring adaptive element distribution and automatic time step adjustment according to the inter-particle gap. The results strongly suggest the existence of a critical value for the slip coefficient below which the surfaces of two particle collide after a finite interception time. The critical value depends on the relative initial particle positions. The particle stress tensor and coefficients of the linear and quadratic terms in the expansion of the effective viscosity of a dilute suspension in terms of the concentration in simple shear flow are discussed and evaluated. Surface slip significantly reduces the values of both coefficients and the longitudinal particle self-diffusivity.

CFD-Analysis of the Combustion in the Primary Stage of a Two-Stage Combustion Chamber

2002 ◽  
Author(s):  
Klaus Hoerzer ◽  
Hermann Haselbacher ◽  
Anthony J. Griffiths ◽  
Nick Syred ◽  
Thomas A. Fraser
Keyword(s):  
Combustion Chamber ◽  
Mixture Fraction ◽  
Three Dimensional ◽  
Tangential Velocity ◽  
Reynolds Stress Model ◽  
Swirl Flow ◽  
Wood Powder ◽  
Two Stage ◽  
Primary Stage ◽  
Combustion Flow

Combustion of wood powder may be applied in a two-stage multi-inlet combustion chamber. The primary stage of the combustion chamber has tangential air inlets to provide high swirl flow. The wood powder and its conveying air enter the gasification chamber axially through a center inlet in the bottom. The aim of the investigation was the analysis of the combustion flow of the primary stage of the combustion chamber. The calculation grid was three-dimensional and unstructured. Turbulence was modelled with the Reynolds-Stress-Model, species with mixture fraction/pdf-approach, radiation with the P1-model. Postprocessing has been done for particle tracks, the temperature distribution and tangential velocity distribution and for the species distributions of solid carbon, carbon monoxide, carbon dioxide and oxygen as well.

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