Pipe radius estimation using Kinect range cameras

2019 ◽  
Vol 99 ◽  
pp. 197-205 ◽  
Author(s):  
Mohammad Nahangi ◽  
Thomas Czerniawski ◽  
Carl T. Haas ◽  
Scott Walbridge
Keyword(s):  
Pipe Radius

scholarly journals Net-exergetic, hydraulic and thermal optimization of coaxial heat exchangers using fixed flow conditions instead of fixed flow rates

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Tobias Blanke ◽  
Markus Hagenkamp ◽  
Bernd Döring ◽  
Joachim Göttsche ◽  
Vitali Reger ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Laminar Flow ◽  
Mass Flow ◽  
Flow Rate ◽  
Heat Exchangers ◽  
Circular Ring ◽  
Flow Conditions ◽  
Flow Rates ◽  
Mass Flow Rates ◽  
Pipe Radius

AbstractPrevious studies optimized the dimensions of coaxial heat exchangers using constant mass flow rates as a boundary condition. They show a thermal optimal circular ring width of nearly zero. Hydraulically optimal is an inner to outer pipe radius ratio of 0.65 for turbulent and 0.68 for laminar flow types. In contrast, in this study, flow conditions in the circular ring are kept constant (a set of fixed Reynolds numbers) during optimization. This approach ensures fixed flow conditions and prevents inappropriately high or low mass flow rates. The optimization is carried out for three objectives: Maximum energy gain, minimum hydraulic effort and eventually optimum net-exergy balance. The optimization changes the inner pipe radius and mass flow rate but not the Reynolds number of the circular ring. The thermal calculations base on Hellström’s borehole resistance and the hydraulic optimization on individually calculated linear loss of head coefficients. Increasing the inner pipe radius results in decreased hydraulic losses in the inner pipe but increased losses in the circular ring. The net-exergy difference is a key performance indicator and combines thermal and hydraulic calculations. It is the difference between thermal exergy flux and hydraulic effort. The Reynolds number in the circular ring is instead of the mass flow rate constant during all optimizations. The result from a thermal perspective is an optimal width of the circular ring of nearly zero. The hydraulically optimal inner pipe radius is 54% of the outer pipe radius for laminar flow and 60% for turbulent flow scenarios. Net-exergetic optimization shows a predominant influence of hydraulic losses, especially for small temperature gains. The exact result depends on the earth’s thermal properties and the flow type. Conclusively, coaxial geothermal probes’ design should focus on the hydraulic optimum and take the thermal optimum as a secondary criterion due to the dominating hydraulics.

Calculation of Variable Property Turbulent Friction and Heat Transfer in Rough Pipes

1979 ◽  
Vol 101 (3) ◽  
pp. 469-474 ◽  
Author(s):  
A. T. Wassel ◽  
A. F. Mills
Keyword(s):  
Roughness Element ◽  
Gas Flows ◽  
Mixing Length ◽  
Variable Properties ◽  
Turbulent Friction ◽  
Variable Property ◽  
Comparison With Experiment ◽  
Large Roughness ◽  
Pipe Radius ◽  
Numerical Calculation Method

A numerical calculation method for turbulent flow in rough pipes is developed. A mixing length model is used in the turbulent core while a roughness element drag coefficient and a sub-layer Stanton number are used to characterize transport to the wall. Sample wall relations are developed for sandgrain roughness and transverse repeated rib roughness, and it is shown that large roughness heights require accounting for terms of order of roughness height divided by pipe radius. For gas flows with cooling, the effects of variable properties are investigated for smooth walls and both roughness patterns. For smooth walls, comparison with experiment is satisfactory; for rough walls experimental data is not available. Simple power law formulae representing variable property effects for fully rough flows are presented.

Maximization of Exergy Gain in High Temperature Solar Thermal Receivers by Choice of Pipe Radius

1991 ◽  
Vol 113 (2) ◽  
pp. 337-340 ◽  
Author(s):  
P. Bannister
Keyword(s):  
Power Systems ◽  
Thermal Power ◽  
Solar Thermal ◽  
Working Fluid ◽  
Pumping Power ◽  
Design Values ◽  
Parabolic Dish ◽  
Solar Thermal Collectors ◽  
Pipe Radius ◽  
Typical Design

The problem of optimizing the radius of boiler tubes in a radiation-dominated environment such as a solar thermal power receiver is examined. The trade-off between heat transfer and pumping power is investigated, resulting in an explicit expression for the radius that maximizes the net exergy gain under turbulent flow conditions. The effect of the pumping power being generated on site is included, thus making the result particularly applicable to the design of stand-alone power systems. Examples using typical design values for small parabolic dish solar thermal collectors using water and steam as the working fluid are given to illustrate the characteristics of the problem.

Plastic Limit Loads for Piping Branch Junctions

2007 ◽  
Vol 345-346 ◽  
pp. 1377-1380 ◽  
Author(s):  
Yun Jae Kim ◽  
Kuk Hee Lee ◽  
Chi Yong Park
Keyword(s):  
Three Dimensional ◽  
Limit Load ◽  
Plastic Limit ◽  
Perfectly Plastic ◽  
Plastic Materials ◽  
Wide Range ◽  
Pipe Radius ◽  
Plastic Limit Load ◽  
The Mean ◽  
Elastic Perfectly Plastic

The present work presents plastic limit load solutions for branch junctions under internal pressure and in-plane bending, based on detailed three-dimensional (3-D) FE limit analyses using elastic-perfectly plastic materials. The proposed solutions are valid for a wide range of branch junction geometries; ratios of the branch-to-run pipe radius and thickness from 0.0 to 1.0, and the mean radius-to-thickness ratio of the run pipe from 5.0 to 20.0.

Direct Numerical Simulation of Gas-Particle Turbulent Swirling Flows in an Axially Rotating Pipe

2003 ◽  
Author(s):  
Kazuyoshi Matsuzaki ◽  
Mizue Munekata ◽  
Hideki Ohba
Keyword(s):  
Numerical Simulation ◽  
Direct Numerical Simulation ◽  
Turbulent Flows ◽  
Particle Concentration ◽  
Fluid Motion ◽  
Swirling Flows ◽  
Particle Collisions ◽  
Pipe Radius ◽  
The One ◽  
Very High

The purpose of this study is to investigate the effect of the turbulent structure of the swirling flows on the particle motions using numerical simulation. In this work, we deal with the swirling turbulent flows in an axially rotating pipe because of focusing on the influence of swirl effect on the particle motions. Direct numerical simulation (DNS) of gas-particle turbulent swirling flows in the axially rotating pipe at the Reynolds number 180, based on the friction velocity and the pipe radius, and the rotating ratios 0.25 and 0.3 based on the bulk velocity was performed. Particle motions were treated by a Lagragian method with inter-particle collisions calculated by a deterministic method. In order to investigate the influence of swirl effect on the particle motions in detail, the one-way method in which fluid motion is not affected by particles is adopted. In particular, the effect of the inter-particle collisions on particle motions was carefully investigated because it is considered that particles accumulate near the wall due to the centrifugal force and local particle concentration is very high in the region.

scholarly journals The three-dimensional structure of swirl-switching in bent pipe flow

2017 ◽  
Vol 835 ◽  
pp. 86-101 ◽  
Author(s):  
Lorenz Hufnagel ◽  
Jacopo Canton ◽  
Ramis Örlü ◽  
Oana Marin ◽  
Elia Merzari ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Three Dimensional ◽  
Low Frequency ◽  
Dimensional Structure ◽  
Pipe Bend ◽  
Dean Vortices ◽  
Dean Vortex ◽  
Piping Systems ◽  
Bent Pipe ◽  
Pipe Radius

Swirl-switching is a low-frequency oscillatory phenomenon which affects the Dean vortices in bent pipes and may cause fatigue in piping systems. Despite thirty years worth of research, the mechanism that causes these oscillations and the frequencies that characterise them remain unclear. Here we show that a three-dimensional wave-like structure is responsible for the low-frequency switching of the dominant Dean vortex. The present study, performed via direct numerical simulation, focuses on the turbulent flow through a $90^{\circ }$ pipe bend preceded and followed by straight pipe segments. A pipe with curvature 0.3 (defined as ratio between pipe radius and bend radius) is studied for a bulk Reynolds number $Re=11\,700$, corresponding to a friction Reynolds number $Re_{\unicode[STIX]{x1D70F}}\approx 360$. Synthetic turbulence is generated at the inflow section and used instead of the classical recycling method in order to avoid the interference between recycling and swirl-switching frequencies. The flow field is analysed by three-dimensional proper orthogonal decomposition (POD) which for the first time allows the identification of the source of swirl-switching: a wave-like structure that originates in the pipe bend. Contrary to some previous studies, the flow in the upstream pipe does not show any direct influence on the swirl-switching modes. Our analysis further shows that a three-dimensional characterisation of the modes is crucial to understand the mechanism, and that reconstructions based on two-dimensional POD modes are incomplete.

Process Planning for the Lateral Extrusion of a Pipe with a Lost Core

2017 ◽  
Vol 735 ◽  
pp. 3-7
Author(s):  
Takahiro Ohashi ◽  
Wataru Kimura
Keyword(s):  
Process Planning ◽  
Pipe Material ◽  
Trial And Error ◽  
Forming Process ◽  
Extrusion Speed ◽  
Lateral Extrusion ◽  
Truncated Cone ◽  
Longitudinal Length ◽  
Pipe Radius ◽  
Free Bulging

In this paper, the authors discuss process planning for the lateral extrusion of a pipe with a lost core. In this process, maximum longitudinal length of the bulged part is restricted by the balance of the extrusion speed of the material and the lost core. In the free bulging condition, longitudinal length is limited to the pipe radius, because the extrusion speed of the core is slower than that of the pipe material when the longitudinal length of the bulged part is longer. The authors designed a two-stage forming process using the transit shape of a truncated cone to solve this problem. The dimensions of the truncated cone were estimated through trial-and-error using a commercial FEM simulator and considering the stretch effect for wrinkles of the pipe by deformation and traveling of the lost core. Finally, the authors conducted experiments to confirm the design’s validity. As a result, a longer longitudinal length of the bulged part than the pipe radius was successfully obtained.

Finite Element Analyses of Circumferential Cracks in Thin-Walled Cylinders: T-Stress Solutions

2006 ◽  
Author(s):  
Timothy Lewis ◽  
Xin Wang ◽  
Robert Bell
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Fracture Mechanics ◽  
Fracture Analysis ◽  
Finite Element Analyses ◽  
The Finite Element Method ◽  
T Stress ◽  
Bending Loads ◽  
Pipe Radius ◽  
Thin Walled

The elastic T-stress is a parameter used to define the level of constraint at a crack tip. It is important to provide T-stress solutions for practical geometries in order to apply the constraint-based fracture mechanics methodology. In the present paper, T-stress solutions are provided for circumferential through-wall cracks in thin-walled cylinders. Cylinders with a circumferential through-wall crack were analyzed using the finite element method. Three cylinder geometries were considered; defined by the pipe radius (R) to wall thickness (t) ratios: R/t = 5, 10, and 20. The T-stress was obtained at eight crack lengths (θ/π = 0.0625, 0.1250, 0.1875, 0.2500, 0.3125, 0.3750, 0.4375, and 0.5000) for remote tension and remote bending loads. These results are suitable for constraint-based fracture analysis for cylinders with circumferential cracks.

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