Effect of Curved Bar Properties on Bending of Curved Pipes

2000 ◽  
Vol 68 (4) ◽  
pp. 650-655 ◽  
Author(s):  
V. P. Cherniy
Keyword(s):  
Experimental Data ◽  
General Solution ◽  
Total Energy ◽  
Neutral Line ◽  
Radius Of Curvature ◽  
Thin Shells ◽  
Large Curvature ◽  
Curved Pipe ◽  
Curved Pipes ◽  
Thin Walled

A general solution is presented for in-plane bending of a thin-walled short-radius curved pipe. The problem is solved considering the properties of a curved bar—an actual radius of curvature of longitudinal fibers and the neutral line displacement. The theory is developed using minimization of the total energy. The relationships of the theory of elastic thin shells are used. The obtained results for the strains and stresses in curved short-radius pipe bends are compared with published theoretical and experimental data. The properties of a curved bar being taken into account enable to correct seriously the distribution and peak values of the strains which take place in curved pipes of large curvature subjected to bending.

scholarly journals Numerical Investigation on Fluid Flow in a 90-Degree Curved Pipe with Large Curvature Ratio

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
Yan Wang ◽  
Quanlin Dong ◽  
Pengfei Wang
Keyword(s):  
Fluid Flow ◽  
Internal Flow ◽  
Fluid Flows ◽  
Detached Eddy Simulation ◽  
Number Range ◽  
Curvature Ratio ◽  
Large Curvature ◽  
Curved Pipe ◽  
Eddy Simulation ◽  
Curved Pipes

In order to understand the mechanism of fluid flows in curved pipes, a large number of theoretical and experimental researches have been performed. As a critical parameter of curved pipe, the curvature ratioδhas received much attention, but most of the values ofδare very small (δ<0.1) or relatively small (δ≤0.5). As a preliminary study and simulation this research studied the fluid flow in a 90-degree curved pipe of large curvature ratio. The Detached Eddy Simulation (DES) turbulence model was employed to investigate the fluid flows at the Reynolds number range from 5000 to 20000. After validation of the numerical strategy, the pressure and velocity distribution, pressure drop, fluid flow, and secondary flow along the curved pipe were illustrated. The results show that the fluid flow in a curved pipe with large curvature ratio seems to be unlike that in a curved pipe with small curvature ratio. Large curvature ratio makes the internal flow more complicated; thus, the flow patterns, the separation region, and the oscillatory flow are different.

The Bending of Curved Pipes With Variable Wall Thickness

2003 ◽  
Vol 70 (2) ◽  
pp. 253-259 ◽  
Author(s):  
V. P. Cherniy
Keyword(s):  
Cross Section ◽  
Wall Thickness ◽  
Shell Theory ◽  
Neutral Line ◽  
Radius Of Curvature ◽  
Curved Pipes ◽  
Variable Wall Thickness ◽  
Previous Solution ◽  
Variable Wall ◽  
Thin Shell Theory

A general solution is presented for the in-plane bending of short-radius curved pipes (pipe bends) which have variable wall thickness. Using the elastic thin-shell theory, the actual radius of curvature of the pipe’s longitudinal fibers and displacement of the neutral line of the cross section under bending are taken into account. The pipe’s wall thickness is assumed to vary smoothly along the contour of the pipe’s cross section, and is a function of an angular coordinate. The solution uses the minimization of the total energy, and is compared to our previous solution for curved pipes with constant wall thickness.

Flow Visualization Experiments on Secondary Flow Patterns in an Isothermally Heated Curved Pipe

1987 ◽  
Vol 109 (1) ◽  
pp. 55-61 ◽  
Author(s):  
K. C. Cheng ◽  
F. P. Yuen
Keyword(s):  
Flow Visualization ◽  
Secondary Flow ◽  
Theoretical Models ◽  
Flow Patterns ◽  
Radius Of Curvature ◽  
Dean Number ◽  
Number Range ◽  
Curved Pipe ◽  
Curved Pipes ◽  
Numerical Predictions

Secondary flow patterns at the exit of a 180 deg bend (tube inside diameter d = 1.99 cm, radius of curvature Rc = 10.85 cm) are presented to illustrate the combined effects of centrifugal and buoyancy forces in hydrodynamically and thermally developing entrance region of an isothermally heated curved pipe with both parabolic and turbulent entrance velocity profiles. Three cases of upward, horizontal, and downward-curved pipe flows are studied for constant wall temperatures Tw=55–91°C, Dean number range K=22–1209 and ReRa=1.00×106–8.86×107. The flow visualization was realized by the smoke injection method. The secondary flow patterns shown are useful for future comparison with numerical predictions and confirming theoretical models. The results can be used to assess qualitatively the limit of the applicability of the existing correlation equations for laminar forced convection in isothermally heated curved pipes without buoyancy effects.

Experimental Investigations of Droplet Deposition and Coalescense in Curved Pipes

2012 ◽  
Author(s):  
Hung Nguyen ◽  
Shoubo Wang ◽  
Ram S. Mohan ◽  
Ovadia Shoham ◽  
Gene Kouba
Keyword(s):  
Kinetic Energy ◽  
Radius Of Curvature ◽  
Droplet Deposition ◽  
Straight Pipe ◽  
Pipe Bend ◽  
Horizontal Pipe ◽  
Curved Pipe ◽  
Curved Pipes ◽  
Pipe Section ◽  
Pipe Fittings

Even though there have been several studies conducted by the industry on the use of different inlet devices for gas-liquid separation there have been limited laboratory and field evaluations on the use of external piping configurations as flow conditioning devices upstream of a separator inlet. The results of a systematic study of droplet deposition and coalescence in curved pipe and pipe fittings are reported in this paper. A facility has been designed consisting of two main test sections: a fixed horizontal straight pipe section and an interchangeable 180° return pipe section (or curved pipe section) of the same length. Both inlet and outlet to the 180° return are horizontal, but the plane of the 180° return pipe section can pivot about the axis of the inlet horizontal pipe to an angle as much as 10° downwards allowing downward flow in the return section. Various pipe fittings of different radius of curvature can be installed for comparison in the 180° return. Fittings evaluated in this study included: 180° pipe bend, 2 standard radius elbows (with radius of curvature of 1.5D), 2 long radius elbows (with radius of curvature of 6D), 2 target tee bend, and 2 cushion tee bend. Experiments have been carried out using water and air and varying gas velocities and liquid loadings. In order to compare the performance of geometries, Droplet Deposition Fractions (DDF) were measured in the horizontal straight pipe section and in the 180° return pipe section as a measure of coalescence efficiency. The results demonstrate that higher DDF occurs for curved fittings as compared to the straight pipe section. Two standard (short) radius elbows bend have approximately 10% DDF higher, whereas two long radius elbows along with 180° pipe bend perform better (by 15–20% DDF) than straight pipe. Additionally, no significant differences between DDF’s in three different inclination angles of a curved pipe were observed. It was found that the cushion tees and target tees can coalesce droplets at lower gas velocities but break up droplets at higher gas velocities. It can be concluded that 180° pipe bend or two 6D long radii elbows can serve as a droplet coalescer, a pair of cushion tees or target tee can also work as coalescer at low kinetic energy but as atomizers at high kinetic energy.

Analysis of Axially Loaded Annular Shells With Applications to Welded Bellows

1960 ◽  
Vol 82 (3) ◽  
pp. 741-753 ◽  
Author(s):  
M. Hetenyi ◽  
R. J. Timms
Keyword(s):  
Experimental Data ◽  
General Solution ◽  
Cross Section ◽  
Circular Cross Section ◽  
Radius Of Curvature ◽  
Approximate Design ◽  
Axial Forces ◽  
The Mean ◽  
Maximum Stresses ◽  
Toroidal Shells

A method is presented for the calculation of stresses and deflections in ring-shaped shells of circular cross section, subjected to axial forces. The solution is derived without the restriction imposed for toroidal shells by previous investigators, that the radius of curvature of the cross section is to be small in comparison with the mean radius of the torus. The range of applicability of the method is extended hereby to include the slightly arched convolutions used in the construction of welded bellows. By a rational reduction of the general solution approximate design formulas are obtained for the maximum stresses and deflections in bellows under axial forces and the calculated values are compared with experimental data.

Experimental Investigations of Droplet Deposition and Coalescence in Curved Pipes

2014 ◽  
Vol 136 (2) ◽  
Author(s):  
Hung Nguyen ◽  
Shoubo Wang ◽  
Ram S. Mohan ◽  
Ovadia Shoham ◽  
Gene Kouba
Keyword(s):  
Kinetic Energy ◽  
Radius Of Curvature ◽  
Droplet Deposition ◽  
Straight Pipe ◽  
Pipe Bend ◽  
Horizontal Pipe ◽  
Curved Pipe ◽  
Curved Pipes ◽  
Pipe Section ◽  
Pipe Fittings

Even though there have been several studies conducted by the industry on the use of different inlet devices for gas–liquid separation, there have been limited laboratory and field evaluations on the use of external piping configurations as flow conditioning devices upstream of a separator inlet. The results of a systematic study of droplet deposition and coalescence in curved pipe and pipe fittings are reported in this paper. A facility has been designed consisting of two main test sections: a fixed horizontal straight pipe section and an interchangeable 180 deg return pipe section (or curved pipe section) of the same length. Both inlet and outlet to the 180 deg return are horizontal, but the plane of the 180 deg return pipe section can pivot about the axis of the inlet horizontal pipe to an angle as much as 10 deg downwards allowing downward flow in the return section. Various pipe fittings of different radius of curvature can be installed for comparison in the 180 deg return. Fittings evaluated in this study included: 180 deg pipe bend, short elbow bend (with standard radius of curvature of 1.5D), long elbow bend (with custom radius of curvature of 6D), target tee bend, and cushion tee bend. Experiments have been carried out using water and air, and varying gas velocities and liquid loadings. In order to compare the performance of geometries, Droplet Deposition Fractions (DDF) were measured in the horizontal straight pipe section and in the 180 deg return pipe section as a measure of coalescence efficiency. The results demonstrate that higher DDF occurs for curved fittings as compared to the straight pipe section. The short elbow bend has approximately 10% DDF higher, whereas long elbow bend along with 180 deg pipe bend perform better (by 15–20% DDF) than straight pipe. It was found that the cushion tee and target tee bends can coalesce droplets at lower gas velocities but break up droplets at higher gas velocities. Additionally, no significant differences between DDF's in three different inclination angles of a curved pipe were observed. It can be concluded that 180 deg pipe bend or two 6D long radius elbow bend can serve as a droplet coalescer; a pair of cushion tees or target tees can also work as coalescers at low kinetic energy but as atomizers at high kinetic energy.

On the steady laminar flow of an incompressible viscous fluid in a curved pipe of elliptical cross-section

1985 ◽  
Vol 158 ◽  
pp. 329-340 ◽  
Author(s):  
H. C. Topakoglu ◽  
M. A. Ebadian
Keyword(s):  
Secondary Flow ◽  
Cross Section ◽  
Circular Cross Section ◽  
Elliptical Cross Section ◽  
Radius Of Curvature ◽  
Elliptical Cross ◽  
Curved Pipe ◽  
Curved Pipes ◽  
Ellipticity Ratio ◽  
Explicit Expressions

A literature survey (Berger, Talbot & Yao 1983) indicates that laminar viscous flow in curved pipes has been extensively investigated. Most of the existing analytical results deal with the case of circular cross-section. The important studies dealing with elliptical cross-sections are mainly due to Thomas & Walters (1965) and Srivastava (1980). The analysis of Thomas & Walters is based on Dean's (1927, 1928) approach in which the simplified forms of the momentum and continuity equations have been used. The analysis of Srivastava is essentially a seminumerical approach, in which no explicit expressions have been presented.In this paper, using elliptic coordinates and following the unsimplified formulation of Topakoglu (1967), the flow in a curved pipe of elliptical cross-section is analysed. Two different geometries have been considered: (i) with the major axis of the ellipse placed in the direction of the radius of curvature; and (ii) with the minor axis of the ellipse placed in the direction of the radius of curvature. For both cases explicit expressions for the first term of the expansion of the secondary-flow stream function as a function of the ellipticity ratio of the elliptic section have been obtained. After selecting a typical numerical value for the ellipticity ratio, the secondary-flow streamlines are plotted. The results are compared with that of Thomas & Walters. The remaining terms of the expansion of the flow field are not included, but they will be analysed in a future paper.

In-Plane Bending of Curved Circular Tubes

1968 ◽  
Vol 90 (4) ◽  
pp. 666-670 ◽  
Author(s):  
D. H. Cheng ◽  
H. J. Thailer
Keyword(s):  
Experimental Data ◽  
General Solution ◽  
Compatibility Condition ◽  
Circular Tube ◽  
Series Expansions ◽  
Center Line ◽  
Complementary Energy ◽  
Circular Tubes ◽  
Binomial Expansion ◽  
Plane Bending

A general solution is presented for a thin, curved circular tube under in-plane bending. It includes the solution given by Clark and Reissner as a particular case in which the ratio of the radius of the tube to the radius of its center line is very small. The series expansions satisfy the equilibrium equation for any radius ratio while the compatibility condition is guaranteed by minimizing the complementary energy. The minimization is achieved in the manner of Raileigh-Ritz whereas the evaluation of integrals are facilitated by the use of binomial expansion. Numerical results correlate well with the experimental data. The solution is more rapidly convergent as compared to the existing analytical methods.

scholarly journals Numerical and experimental investigations of steel-concrete beams with thin-walled section

Vestnik MGSU ◽  
2019 ◽  
pp. 22-32
Author(s):  
Farit S. Zamaliev
Keyword(s):  
Experimental Data ◽  
Computer Simulation ◽  
Strain State ◽  
Concrete Beams ◽  
Concrete Structures ◽  
Stress Strain ◽  
Stress Strain State ◽  
Numerical Studies ◽  
Field Samples ◽  
Thin Walled

Introduction. Conducted is to the evaluation of the stress-strain state of the steel-concrete beams with thin-walled section. In recent times, steel-reinforced concrete structures have become widely used in civilian buildings (beams, slabs, columns). Thin-walled section have not found wide application in steel concrete structures, unlike steel structures. Presents the results of numerical studies of beams consisting of concrete, anchors and steel beams. Two investigating of the location of anchors are given. Numerical investigations are presented of steel-concrete beams with thin-walled section based on numerical studies. Testing procedure and test result are given. Results of calculations, comparison of numerical and experimental studies are presented. Materials and methods. For full-scale experiments, steel I-beams with filling of side cavities with concrete were adopted, screws are used as anchor ties, with varied both the lengths and their location (vertically and obliquely). As steel curved C-shaped steel profiles were used steel profiles from the range of the company “Steel Faces”. ANSYS software package was used for computer modeling. A total of 16 steel concrete beams were considered, for which the results of strength and stiffness evaluation were obtained in ANSYS. Results. The data of the stress-strain state of beams on the basis of computer simulation are obtained. The results are used for the production of field samples. Data of computer simulation are compared with the indicators of field experiments. Conclusions. The stress-strain state of steel-concrete structures was studied on the basis of numerical and experimental data. The proposed calculation method gives good convergence with the experimental data. Anchor connections made from self-tapping screws can be used in studies for modeling in steel-concrete beams structures and other anchor devices, ensuring the joint operation of concrete and steel profiles in structures.

scholarly journals A Method of Predicting the Energy Losses in Vaneless Diffusers of Centrifugal Compressors

1989 ◽  
Author(s):  
Huashu Dou
Keyword(s):  
Experimental Data ◽  
Energy Loss ◽  
Total Energy ◽  
Wall Friction ◽  
Energy Losses ◽  
Flow Conditions ◽  
Centrifugal Compressors ◽  
Flow Losses ◽  
Vaneless Diffusers ◽  
Good Agreement

The flow losses in the veneless diffusers of centrifugal compressors is investigated. It is found that the total energy loss in vaneless diffusers is a function of Bsin2 α0 when inlet flow conditions and radius ratio between inlet and outlet are given. A wall friction coefficient equation is derived and a method of predicting the total energy loss excepting mixing loss is presented. A comparison is made between results obtained from this method and experimental data generated by the author as well as data from the literature. Good agreement is obtained.

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