New Type Of Tube Research Articles

Axial crushing of novel hierarchical multi-cell square tubes

Inspired by the concept of hierarchy, two types of hierarchical multi-cell square tubes (HMSA and HMSB) are proposed. The crashworthiness of HMSA and HMSB tubes with various wall thicknesses and hierarchical orders is numerically studied. It has been found that the peak crushing force of HMSA and HMSB tubes is smaller than that of single square tubes, which is preferred to minimize the possible injury or damage caused by the initial peak force. Moreover, the mean crushing force, energy absorption, crushing force efficiency and specific energy absorption of HMSA and HMSB tubes increase with the hierarchical order and wall thickness. Compared with single square tubes, the specific energy absorption of the 3rd order HMSA and HMSB tubes increases by more than 1.5 and 1.7 times, respectively. Moreover, the 3rd order HMSB tubes show slightly greater specific energy absorption than that of the 3rd order HMSA tubes. In addition, theoretical models are developed which can well predict the mean crushing force of two new types of tubes.

Analytical calculation of sheet curvature in four-roll mills at tubes production

Stationary bending of sheet metal on the electromechanical rolling mills demonstrates high productivity and efficiency, relevant for any modern enterprise. Regardless of the number of shafts, the operating principle of the mills is not complicated. The sheet blank is installed in the gap between the shafts, which rotate in different directions. Passing between the cylinders, the sheet bends and takes the desired shape. The main assortment of finished products, produced with the help of rollers, are details in the form of a cylinder, cone or oval. The cold bending method, which is the basis of the working process, does not destroy the metal and does not have a negative influence on its structure, as it sometimes happens during prolonged thermal exposure on metal alloys. The popularity of roller mills is largely due to their relatively low cost, as well as minimal outlay on maintenance and exploitation. If the company needs a cheaper and more economical mills, it is worth paying attention to manual models. For larger companies, the four-roller mills equipped with CNC-systems and operating in automatic regime are recommended. Modern models, produced by leading manufacturers, are favorably distinguished by visibility and ease of exploitation, attractive design, guaranteed safety and reliability. Such equipment is in demand in mass production, where high productivity and trouble-free operation of mills are appreciated. It is impossible to guess the sheet blank curvature in rolling new type of tube. This paper is devoted to the solution of this important problem and to analytical calculation of blank curvature in the four-roller mills.

Convective Heat Exchange of Single-Row Bundles from Tubes with Rolled Aluminum Fins of Various Height at a Low Values of the Reynolds Number

The experimental study of the heat flow intensity of a single-row horizontal air-cooled tubular bundle of heat exchanger with spiral aluminum rolling fins at low Reynolds numbers (Re < 2000) is performed. The geometrical dimensions of the bimetallic finned tubes of the bundle, the following: the outer diameter of the fins d = 56.0 mm; the diameter of the tube at the base d0 = 26.8 mm; fin height h = 14.6 mm; pitch of fins s = 2.5 mm; the average fin thickness Δ = 0.5 mm; the coefficient of finned tubes φ = 19.3; heat transfer length l = 300 mm. The outer diameter of the load-bearing steel tube dн = 25 mm; wall thickness d = 2 mm. The research was carried out by the method of full thermal modeling at a specially designed experimental stand with electric heating of tubes and an exhaust shaft installed above the bundle. The air flow rate through the bundle was regulated by changing the height and cross-sectional area of the exhaust shaft. Calibration experiments were carried out and confirmed the reliability of the data obtained. Then the fins were sanded so to form new types of tubes, which were arranged in a single-row six-tube bundle with a constant relative cross-step σ1 = S1/d = 1.14 = const, and the thermal studies were repeated. As a result, a generalized criterion equation for heat transfer of a finned horizontal single-row bundle at small Reynolds numbers for various heights of the tube finning h = 0-14.6 mm was obtained. The effective height of the tube finning (h = 8 mm) for a single-row horizontal bundle was determined by dimensional and metal-intensive criteria.

Experimental studies of the efficiency of a single-row bundle of bimetallic finned tubes with different finning heights in free convective heat exchange with air

Considerer the influence of a change in the height of the height of the finning of bimetallic finned tubes of a single-row bundle on the thermal, overall and metal-capacity characteristics in the mode of free air convection at different angles of inclination (γ = 0, 15, 30, 45, 60 and 90°) to the horizontal plane. The investigated tubes have the following characteristics: the material of the supporting tube was carbon steel (outer diameter d out = 25 mm, wall thickness δ = 2 mm), the material of the rolling finned shell was aluminum alloy AD1M. Geometric parameters of the fins: d×d 0 ×h×s×Δ×φ× l = 56,0×26,8×14,6×2,5× 0,5×19,3×300 mm (type I). The studies were carried out by the method of complete thermal modeling on a specially designed experimental stand. Then the fins were ground by grinding with the formation of new types of tubes (II–VI), which were assembled into a single-row bundle with a constant relative transverse pitch σ 1 = S 1 / d = 1,14 = const. The article describes the criterion dependences for heat transfer of a finned single-row bundle of tubes with different finning heights at different angles of inclination to the horizontal plane, as well as a graphical dependenc e of the correction factor for the angle of inclination of bundle (γ = 0–90°) were obtained. It has been established that an increase in the angle of inclination and the height of the finning of tubes of a single -row bundle is generally accompanied by a decrease in heat transfer. In terms of overall and metal-capacity characteristics, the most effective is a single-row bundle at various angles of inclination to the horizontal plane with a tube finning height 2,0 mm.

Numerical study on the heat transfer enhancement and pressure drop inside deep dimpled tubes

Heat transfer enhancement is important from the industry point of view. In this study, a new configuration of enhanced tubes has been investigated numerically. The geometry of this new type of tube was provided by exerting deep dimples on the conventional plain tube. Flow-field and heat transfer characteristics of deep dimpled tubes have been studied, and the effects of the various configuration of dimples comprising three different pitches, diameters, and depths of dimples resulting in twenty-seven configurations have been investigated. Performance Evaluation Criteria (PEC), which is commonly used in heat transfer enhancement subjects, has been studied for all geometries. Local temperature, velocity, streamline, and Nusselt number of the deep dimpled tube have been depicted in comparison to the plain tube to study thermo-fluid characteristics. The investigation for each configuration has been done in three different Reynolds numbers: Re = 500, 1000 and 2000, and k-ɛ turbulent model has been utilized in numerical studies. The higher heat transfer rate of deep dimpled tubes has been seen in higher depth and diameter and lower pitch up to 600%, while this lead to the intense growth of friction factor. It has been observed that PEC of the deep dimpled tubes generally varies from PEC = 1.15–3.3 in different cases. Furthermore, increase in the diameter, pitch and Reynolds number, and decrease in the depth, lead to augmentation of PEC of deep dimpled tubes which escalates up to PEC = 3.3 at Re = 2000 when Diameter = 18 mm, depth = 2 mm, and pitch = 4D.

Experimental study on energy absorption of bionic tubes inspired by bamboo structures under axial crushing

We report an experimental study on three new types of tubes inspired by the cross-section and nodes of bamboo with the aim of improving the crashworthiness of three types of cylindrical metal tubes: Bionic Tubes of Variable Thickness (BTVTs), Bionic Tubes with Rib (BTRs), and Bionic Tubes with Bamboo Cross-section (BTBCs), respectively. The EA capacity and deformation modes of the bionic tubes and a cylindrical tube were experimentally investigated in this study by drop-weight test. The drop test results revealed that 8 of the 14 bionic specimens exhibited greater SEA than the CT. And these results indicate that the bionic method can improve crashworthiness and affect the deformation mode under certain conditions. Different bionic feature have different effects on the deformation of thin-walled tube. Further research is required to optimize the bionic cross-section, rib, and thickness for the new types of tubes.

Compressive behavior of concrete-filled FRP tube columns: Assessment of critical column parameters

A comprehensive experimental program has been underway at the Structures Laboratory of the University of Adelaide to investigate the behavior of concrete-filled fiber-reinforced polymer (FRP) tubes (CFFTs) under concentric compression. This paper presents the results from a group of 92 selected circular, square, and rectangular CFFTs and discusses the influence of the critical column parameters on the compressive behavior of CFFTs. These parameters include concrete strength, amount and type of FRP tube material, manufacture method of the tubes, and size and shape of the CFFTs. In addition to conventional FRP tubes, new types of tubes with integrated internal FRP reinforcement have been designed and tested. Results indicate that concrete strength, cross-sectional shape, and the amount and type of tube material significantly affect the behavior of CFFTs. The manufacture method of FRP tube also has some, but less significant, influence on the behavior of CFFTs. The influence of specimen size has been found to be small. No apparent difference has been found between the compressive behaviors of circular CFFTs and companion FRP-wrapped cylinders. The results also indicate that newly developed square and rectangular CFFTs, with internal FRP reinforcement, exhibit significantly improved behavior over conventional CFFTs.

Polyester Connecting Ring Improves Outcome in Nitinol Composite Artificial Esophagus

In a previous study, we replaced a thoracic esophagus with nitinol composite artificial esophagus. Two major problems of anastomotic leakage and early sloughing of the grafted prostheses were noted. We have developed a new type of nitinol composite artificial esophagus with polyester connecting ring, and in this study, we test the effectiveness of replacing a thoracic esophagus with this new type of tube. We experimented with two groups: with polyester connecting ring (experimental) and without (control). The shedding time of artificial esophagus in the experimental group was significantly delayed compared with the control group (127.2 +/- 51.8 days vs. 27.6 +/- 15.7 days, respectively, p < 0.05). The incidence of the two major postoperative complications in the experimental group was significantly decreased compared with the control group: anastomotic leakage (0% vs. 33.3%, respectively, p < 0.05) and severe neoesophageal stenosis after prostheses sloughing (10% vs. 50%, respectively, p < 0.05). The long-term survival rate (>6 months) in the experimental group was significantly increased compared with the control group (100% vs. 10%, respectively, p < 0.05). These results suggest that the polyester connecting ring improves outcome of replacement of the thoracic esophagus with nitinol composite artificial esophagus.

Capillary optics and their use in x-ray analysis

The use of polycapillary lenses in X-ray microanalysis and X-ray diffractometry is considered. Lenses with focal spot diameters from 0.5-1 mm down to 5-10 μm ensure an increased flux on the sample under investigation by 2-3 orders of magnitude. The combination of a standard microfocus X-ray tube of 50-100 W power with such a lens permits fluxes to be obtained comparable to those at workstations for microanalysis attached to a synchrotron. The use of polycapillary lenses requires specialized X-ray tubes. A new type of tube for obtaining a high photon flux with low divergence has been developed. The possibility of realizing new high-efficiency portable X-ray spectrometers and diffractometers based on polycapillary optics is considered.

Experimental investigation on forced convective heat transfer and pressure drop of ethylene glycol in tubes with three-dimensional internally extended surface

A new type of tube is introduced that has a three-dimensional internally extended surface used to enhance convective heat transfer inside the tube. Results are presented from experimental investigations into heat transfer performance in seven copper tubes of about 13.5 mm I.D. with three-dimensional internally extended surfaces (3-DIESTs) varying in axial pitch, circumferential pitch, height, width, and fin arrangement. The heat transfer and pressure drop characteristics of ethylene glycol flowing in the 3-DIESTs were tested in the Re range 250–7000 and Pr range 60–90. The average Stanton number in the most superior 3-DIEST can be increased by about 2.8-fold in laminar flow and 4.5-fold in transitional and turbulent flow compared with that in the smooth tube. The corresponding friction factor is 1.7-fold as high in laminar flow and fourfold in transitional and turbulent flow inside the 3-DIEST compared to that inside a smooth tube. The correlations of heat transfer and friction factor are obtained separately in the different flow regions that can be used in practical design.

Experimental investigation of forced convective heat transfer and pressure drop of ethylene glycol in tubes with three-dimensional internally extended surface

Abstract A new type of tube is introduced that has a three-dimensional internally extended surface used to enhance convective heat transfer inside the tube. Results are presented from experimental investigations into heat transfer performance in seven copper tubes of about 13.5 mm I.D. with three-dimensional internally extended surfaces (3-DIESTs) varying in axial pitch, circumferential pitch, height, width, and fin arrangement. The heat transfer and pressure drop characteristics of ethylene glycol flowing in the 3-DIESTs were tested in the Re range 250–7000 and Pr range 60–90. The average Stanton number in the most superior 3-DIEST can be increased by about 2.8-fold in laminar flow and 4.5-fold in transitional and turbulent flow compared with that in the smooth tube. The corresponding friction factor is 1.7-fold as high in laminar flow and fourfold in transitional and turbulent flow inside the 3-DIEST compared to that inside a smooth tube. The correlations of heat transfer and friction factor are obtained separately in the different flow regions that can be used in practical design.

A unique device to measure lower esophageal sphincter pressure in unsedated infants

A new type of tube is described for measuring lower esophageal sphincter pressures in nonsedated infants and children. Pressure measurements may help in predicting those infants who will require surgery for gastroesophageal reflux.

A modified tube method for the cultivation and enumeration of anaerobic bacteria

A new type of tube (the Lee tube) has been developed for use in the cultivation and enumeration of obligate anaerobes. The Lee tube is a double-walled, screw-capped tube which allows the formation of a thin cylinder of agar medium between the two walls. Anaerobiosis is achieved through deoxygenation of the deep cylinder of agar during sterilization, a minimum of head space, and use of a reducing agent to absorb oxygen introduced during the inoculation procedure. For several species of Clostridium, Bacteroides fragilis, Fusobacterium necrophorum, Veillonella alcalescens, and Pectinatus cerevisiiphilus, colony counts of cultures in the Lee tubes were comparable with those obtained in pour plates incubated in a BBL GasPak system and in anaerobic roll tubes.

NEW TYPE OF TUBE FOR TRACHEOTOMY WITH INFLATABLE CUFF AND INNER CANNULA.

For several years the use of intermittent positive-pressure breathing in the postoperative period has been used on neurosurgical patients at this hospital with increasing frequency. The positive pressure with resultant alveolar inflation has helped prevent postoperative atelectasis and pneumonitis. Intermittent positive-pressure breathing has been particularly useful in patients with quadriplegia who lack intercostal respiratory action and for the first 48 hours after a prolonged neurosurgical procedure. Adequate inflation of the alveoli, however, was impossible utilizing the Chevalier Jackson type of tube for tracheotomy as there was no way to prevent air from escaping from around the tube. Small-cuff type of tubes for endotracheal anesthesia were utilized next, but these had no inner cannula and hence secretions would form on the inside of the tube that were impossible to remove. The tube for tracheotomy that is pictured (Figs. I and ~) has been developedt and used with coinplete success. I t provides not only an inner cannula for cleansing but an inflatable cuff for coinplete occlusion when the intermittent positivepressure breathing is administered (usually for a period of 10 minutes every ~ hours) with a Byrd type of respirator, and an adapter to receive a Byrd type of respirator or fitting for anesthesia. The adapter is a standard size-15 Foregger adapter for anesthesia and is coupled permanently to the cannula for tracheotomy so that there is no

Industrial Electronic Developments in the Last Two Decades and a Glimpse into the Future

During the past two decades significant improvements have been made in all types of electron tubes. Small tubes became still smaller, and the output of large tubes has been increased. Greater reliability has been achieved, and frequency limits have been extended upward. Hydrogen thyratrons have been developed, providing high power for pulse work. Ignitron ratings have been increased significantly. The problem of shutting off gas tubes by grid control has received attention and has led to two new types of tubes which at this time have, however, only limited output. To the list of photosensitive devices have been added the leadsulfide and similar cells, providing means of detecting infrared radiation of long wave length. A host of ingenious transducers has extended the use of electron tubes in the measurement and control field; smaller magnitudes of physical quantities, such as distance, pressure and magnetic field intensity can be observed and recorded. On the other end of the scale, tubes have provided HF power for induction and dielectric heating. But by far the most outstanding development of the last 15 years has been in the field of solid state or semiconductor devices. Here the transistor, announced in 1948, occupies first place, and improvements in its characteristics are coming at a breath-taking pace. In 1957 the silicon-controlled rectifier, aptly called a solid-state thyratron, joined the march. These two devices are giving industrial electronics a tremendous new drive.

A New Type of Tube for Ureteral Intubation

A New Type of Tube for Ureteral Intubation

The application of image converters to high speed photography

Until recently the characteristics of image converters have confined their use almost entirely to the conversion of infra-red to visible radiation. The idea of using such a tube as an optical shutter is not new, but the application has awaited the development of a suitable tube.The paper compares the performance of various types of image converters and discusses in detail the characteristics of a new type of tube with special emphasis on its use for high-speed photography.

A photographic investigation of the transmutation of lithium and boron by protons and of lithium by ions of the heavy isotope of hydrogen

In the preceding paper, p. 722, Oliphant, Kinsey and Rutherford have given an account of the examination of the disintegration of lithium by protons and by ions of the heavy isotope of hydrogen, using electrical counting methods, and have shown that the results of their experiments lend strong support to the views of the modes of disintegration which they there suggest. Certain of these conclusions may be more completely examined by photographing the tracks of the disintegration particles in an expansion chamber and with that object we have made the experiments described below. In the course of this work a great amount of experimental data has been collected which will require a more detailed analysis; in the present paper the photographs described have been selected with the object of testing the above-mentioned theories. It is possible that the photographs show evidence of other modes of disintegration, but in view of the time required for a full analysis, we publish here only an account of the more obvious phenomena. The apparatus used for the production of the high voltage and its application to the tubes used for accelerating the bombarding particles was that described by Cockcroft and Walton, and potentials up to about 400 kilovolts were used. The first attempts to work an expansion chamber in conjunction with that apparatus showed that the maximum number of disintegrations produced per second was much too small, and considerable time was spent in attempting to obtain a more intense beam of protons. The form of discharge tube finally adopted was that described by Oliphant and Rutherford, This has been found much more definite in behaviour than the glass discharge tube used in the early work of Cockcroft and Walton. The total positive ion current measured at the target is at least ten times greater than could be obtained from the latter tube, and the number of disintegrations produced per second has been increased by an even larger factor. It is probable that the new type of tube gives a larger ratio of protons to molecular ions in the beam—this ratio being more liable to fluctuation with the glass discharge tubes. With the present arrangement, using the maximum output of current and voltage, it is possible to obtain over 100 tracks per expansion from a lithium target a few square millimetres in area.

Microphonic Improvement in Vacuum Tubes

The paper contains a discussion of the causes and effects of microphonic disturbances in small receiving tubes and the nature of these disturbances, and gives methods of testing for microphonic disturbance whereby the sources of the disturbance may be located and corrected, as well as methods of testing tubes as a means of comparison of individual tubes of different types. A new type of tube with low microphonic output but with low filament power for uses where microphonic troubles may be serious is also described and its characteristics are given.