Rib Arrangements Research Articles

Effects of Rib Arrangements on Pressure Drop and Heat Transfer in a Rib-Roughened Channel With a Sharp 180 deg Turn

The objective of this study was to investigate, through experiments, the combined effects of a sharp 180 deg turn and rib patterns on the pressure drop performance and distributions of the local heat transfer coefficient in an entire two-pass rib-roughened channel with a 180 deg turn. The rib pitch-to-equivalent diameter ratio P/de was 1.0, the rib-height-to-equivalent diameter ratio e/de was 0.09, and the rib angle relative to the main flow direction was varied from 30 ∼ 90 deg with an interval of 15 deg. Experiments were conducted for Reynolds numbers in the range 4000 ∼ 30,000. It was disclosed that, due to the interactions between the bend-induced secondary flow and the rib-induced secondary flow, the combination of rib patterns in the channel before and after the turn causes considerable differences in the pressure drop and heat transfer performance of the entire channel.

Heat Transfer and Friction in a Low-Aspect-Ratio Rectangular Channel With Staggered Perforated Ribs on Two Opposite Walls

Experiments are conducted to study the turbulent heat transfer and friction in a low-aspect-ratio rectangular channel in which two opposite walls are roughened by perforated ribs. The perforated ribs are arranged in a staggered manner. Effects of perforated rib open-area ratio (β = 10, 22, 38, 44, and 50 percent), rib pitch-to-height ratio (PR = 5, 10, 15, and 20), rib height-to-channel hydraulic diameter ratio (H/De = 0.063 and 0.081), rib alignment (staggered and symmetric), and Reynolds number (10,000 ≤ Re ≤ 50,000) are examined. It is found that approximately the same heat transfer enhancement and pressure drop penalty are obtained between symmetric and staggered rib arrangements. A permeability criterion is proposed by tracing heat transfer coefficient distributions, which compares well with previous flow-visualization results. Results also show that ribs with β = 44 percent give the best thermal performance under either the constant friction power or the constant flow rate constraint. Roughness functions for friction and heat transfer are further developed in terms of rib and flow parameters.

高精度ファンリブ型メッシュ展開鏡面

This paper describes the performance of fan rib type highly accurate, highly reproducible mesh deployable reflector with precision screw type adjustment element for surface drawing and motor and link type deployment system. Surface error and its reproducibility for repeated deployment decreased less than 1/2 of previously developed fan rib type mesh reflector with spring type deployment system. No periodic distortion which corresponds to rib arrangements can be seen and thus mesh reflector with very low gore lobe and side lobe characteristics, which is very useful for frequency reuse, is achieved in C band. This paper also presents measured higher order passive intermodulation (PIM) products of mesh developed and used for this deployable reflector with the mesh tension as a parameter.

Pneumatic tire generating musical pattern sound

In a pneumatic tire having at least two ribs in a tread portion, one of these ribs is a basic rib constructed by arranging plural basic pitch elements having the same pitch in the circumferential direction of the tire, and any one of the remaining ribs is a chord rib constructed by arranging plural chord pitch elements having the same pitch in the circumferential direction. In this rib arrangement, the total number of chord pitch elements in the chord rib is a positive integer obtained by counting or emitting a product of a value of 2n/12 (n: 1-24) and a total number of basic pitch elements in the basic rib, and pattern sound from the basic rib and the chord rib have a consonance relation, whereby the noise from the tire can be reduced.

Effect of ribs in the radial feedline on the external characteristics of helical-centrifugal stage of pump

Pump design for thermal and atomic power, chemical and petroleum industries and other uses means increasing the unit capacity. Experimental investigations were carried out showing that the feedline influences the power, cavitation, vibration, and pulsation characteristics of the stage of the pump. Pump feedlines with five types of rib arrangement are shown and discussed. It is found that power, cavitation, and vibration characteristics of the helical-centrifugal stage could be altered by varying the number of ribs and their arrangement in the radial feedline.

Some effects of rib-reinforcement arrangement on spherical-dome buckling

This paper describes some experiments conducted on some similar pressure-loaded deep-clamped thin spherical domes in order to assess the effects of different internal rib-reinforcement distributions on their buckling and collapse behavior. In the tests, several equal-weight internal-rib-reinforcement arrangements following conventionally adopted arch/hoop layout patterns around the shell membrane, have been compared with some new ‘equivalent’, rib arrangements. It has been found that, in the main, the rib layout used has little effect on the final collapse pressure obtainable. In one exceptional case, however, involving one of the new rib arrangements, significantly higher collapse pressures were observed to occur. The enhancement of the collapse load in this case appeared to depend on the formation of large local inter-rib buckles of the shell membrane in the boundary region.

Atoka Ostracodes in Glen Eyrie Formation, Colorado: DISCUSSION

McLaughlin recently suggested (FOOTNOTE 3) that a fauna found in the lower part of the Glen Eyrie formation in the Colorado Springs Quadrangle is Marmaton, upper Des Moines, in age. This fauna consists of about twelve species of ostracodes and eight of conodonts. McLaughlin was kind enough to send the writer the ostracodes, a beautiful fauna of many well preserved specimens. He did not, however, agree with the conclusions about their age. It is the writer's belief that they are much older than Marmaton and probably Atoka-Lampasas in age; they could only be older, or slightly younger, Morrow or earliest Cherokee in age. Although the fauna is for the greater part undescribed, it is not unknown, for almost every one of the Glen Eyrie species is identical with, or close to, such Oklahoma Atoka or Wapanucka species as Monoceratina ventrale Roth, Bairdia dornickhillensis Harlton, Amphissites wapanuckaensis Harlton, and A. rugosus Girty. Another Glen Eyrie Amphissites is clearly the forerunner of A. pinguis (Ulrich and Bassler) (A. geneae Roth) of Marmaton and later age: the nodes which persist from the early to the late molts of the Glen Eyrie and similar pre-Des Moines specimens are lost in the latest molts of their Marmaton descendants. The Glen Eyrie species identified by McLaughlin with the upper species Glyptopleura spinosa Harlton (now called G. coryelli Harlton) shows a striking resem lance to G. coryelli in the rib arrangement and is undoubtedly related to it, but both the Glen Eyrie and certain pre-Marmaton specimens now being examined consistently show small but important differences from G. coryelli: besides differences in size and spine development the rib of the Glen Eyrie species is well arched above the muscle scar while this rib is bent downward on G. coryelli. Geisina arcuata (Bean) is probably correctly identified by McLaughlin but the given range is inaccurate as Bradfield found it to be characteristic of lower Dornick Hills beds of pre-Des Moines age. Headia formosa Harlton found in the Glen Eyrie is a much misunderstood species, Marmaton forms commonly referred to this species being much smaller and with much shorter spines, and in most cases referable t the Marmaton species Healdia limacoidea Knight. The type of H. formosa is probably not from Gaptank sediments, but, as suggested by Harlton in a footnote to his original description, it is probably Dimple (Morrow) in age. The Wapanucka-Johns Valley fauna contains many large, fancifully ornamented ostracode species, of which the slightly more conservative descendents are found in Atoka faunas. Few of these species occur in the Marmaton, and this latter formation contains many Kansas City-Canyon species, so that the contrast between the two faunas is more marked than is ordinary between faunas of so nearly the same age. The Marmaton ostracodes are among the best known faunas, assemblages of this age having been described from Nebraska, Illinois, and Missouri, and down through Oklahoma and into Texas. Most if not all of the common and typical Marmaton species are absent in the Glen Eyrie formation; also absent is the Des Moines ostracode fauna (and significantly FOOTNOTE 3. Kenneth P. McLaughlin, Pennsylvanian Stratigraphy of Colorado Springs Quadrangle, Colorado, Bull. Amer. Assoc. Petrol. Geol., Vol. 31, No. 11 (November, 1947), pp. 1982-2020. End_Page 129------------------------------ all fusulinids) found in the McCoy formation of Colorado and described by Roth and Skinner. An Atoka age for the Glen Eyrie beds is not surprising in view of the thick pre-Des Moines beds described by Maher and others from deep wells in westernmost Kansas and eastern Colorado. These beds are not lithologically unlike the Glen Eyrie, and they also contain early ostracodes. End_of_Article - Last_Page 130------------