Showing papers on "Bend radius published in 1969"

Improved relations describing directional control in electromagnetic wave guidance

Abstract: The direction-changing capability of electromagnetic waveguides may be limited not only by mode conversion but also by radiation if the transverse field extends indefinitely into a freely propagating region. This paper gives new, more accurate expressions for the permitted bending radius with respect to mode conversion, using coupled-wave theory to categorize the wide variety of transmission media possible. This paper also makes a suggestion for estimating the permitted bending radius when radiation is a limitation. In single-mode “open” waveguides that have transverse fields extending indefinitely into a freely propagating region (such as a dielectric waveguide), the permitted bending radius is limited by radiation effects, whereas in either the open or completely shielded multimode waveguides, the permitted bending radius is usually limited by mode conversion.

Studies on Fluid Flow in Three-Dimensional Bend Conduits

Abstract: This paper gives the results of the experimental study of loss and secondary circulation due to various combinations of commercial elbows, and discussed the relationship between the loss and the circulation. Three general combinations are ; One where the two elbows produce a complete reversal in the direction of flow, termed the"U"bend ; and two where the two elbows produce an offset but no change in direction, termed the"S"bend ; and three where the two elbows produce both an offset and a 90 degree change in the direction of flow, termed the"twisted S"bend. The last combination gives rise to a strong single spiral motion in the straight pipe of curved pipes downstream and shows the maximum bend loss.

Coiling method and apparatus

Abstract: A coil made of a continuous piece of elongated material such as tubing, prebent into pancakelike spirals called radial layers, each radial layer made up of several concentric and coplanar convolutions, with several radial layers stacked axially, and method and apparatus for making such coils. The material is bent prior to coiling at predetermined bending radii which are different for different convolutions within a radial layer. One or more of the convolutions within each radial layer may be bent at constant bending radius; the rest may be bent at gradually changing radii. The bending radius is controlled by an electric and hydraulic network employing both timed and feedback controls. The coil may be built either upwardly, with the most recently made radial layer always at the bottom of the coil, or it can be built downwardly, with the most recently made radial layer always on the top of the coil.

Apparatus for the cold-bending of pipes

Abstract: A pipe bending apparatus including an anvil of a desired radius and a hammer ram having spaced hammer elements spaced from one another to have a bending radius larger than the radius of the anvil. The pipe is adapted to be incrementally fed through the apparatus between hammering actions.

Pressure Drop in the Hydraulic Conveyance of Solid Materials through a Bend in a Vertical Plane

Abstract: A formula for pressure drop caused by a bend is derived from analysis of energy relation in flow. The additive term in this formula, corresponding to the change of the fluid motion, is determined by the results of experiment, and is discussed in connection with patterns of flow through a bend. This formula is in good agreement with the results of experiment within the errors of measurement. The range of a pipe line in which flow is affected by a bend is similar to the case of pure fluid. Velocity of a particle through a bend and the optimum curvature of a bend with less pressure loss are also discussed in the present paper.