Outlet Holes Research Articles

Limiting condition of plastic material in a plane converging channel

The importance of the problem of plastic material flow through a converging channel is due to the extensive use of this method for deformation in many production processes (metal forming, discharge of loose materials from bunkers, etc.). In the last ten years this problem has come the attention of researchers. This attention is justified by new test data [I, 2] clearly showing the asymmetry of these flows. Flow asymmetry is due to localization of deformation, i.e. formation of isolated slip lines which break down the deformable region into individual blocks sliding over each other. This fact has placed in doubt the universality of theoretical solutions based on the hypothesis of radial (symmetrical) flow of material particles. In many recent works (e.g. [3, 4]) a study has been made of features of the block structure of material and engineering methods axe suggested for working out the problem where there is use of some ideas about the size of blocks which is one of the main factors in obtaining a numerical result. It is natural that since the relationships of solid material theory do not contain a dimension of length in 'pure' form the sizes of blocks should be determined by material properties and the geometry of the problem, in particular by the sizes of the inlet and outlet holes of the converging channel. From this point of view it is interesting to construct an asymmetrical solution of the problem of limiting equilibrium for plastic material in a converging channel under the action of an applied load (Fig. 1). The solution is constructed on the basis of limiting analysis theory, i.e., theorems about the upper estimate of limiting load P [5]. The material described by the model is an ideally incompressible rigidly-plastic body (the St. Venant-Mises model). In the prescribed kinematically acceptable field of velocities v(k) the limiting load is determined from the equilibrium equation in integral form

Micromachined valve with hydraulically, actuated membrane, subsequent to a thermoelectrically controlled bimorph cantilever

Abstract We report on the design, fabrication and performance of a micromachined valve for hydraulic applications. The valve is composed of a stack of four silicon wafers and utilizes a new actuation principle, which to our knowledge is presented for the first time in this paper: a fluid jet formed at a nozzle is passing along a bimorph cantilever; electrical actuation of this cantilever causes a deflection of the fluid jet towards a volume below a bossed membrane, where its kinetic energy is partially retransformed into pressure energy; this pressure lifts the membrane, thus opening the outlet hole of the valve; i.e., the valve is open or closed corresponding to whether the bimorph cantilever is heated or not. The outer dimensions of the valve are 14.5 × 8.5 × 1.43 mm 3 . It is designed for flow rates of about 75 ml/min at a system pressure level of about 6 bar. Efficient cooling of the cantilever by the fluid jet allows a maximum operating frequency as high as 1 kHz.

A new type of vacuum pump for corrosive gases and vapors

A vacuum pump is described based on a novel gas pumping principle. A rotating drum is partially filled with a liquid, which is made to flow round the outside of the drum, as in a liquid ring pump, leaving the center clear. A probe is held in the rotating liquid and is shaped to create a low-pressure region on its surface where there is a hole which connects, through the static hub of the drum, to the vessel to be evacuated. The center of the drum is connected, through suitably placed holes in the central hub, to atmosphere. Gas is drawn from the vessel thought the hole in the probe into the circulating liquid. Centripetal force acts on the gas bubbles in the liquid ring to propel them towards the center where they burst at the gas/liquid interface. The gas then escapes to atmosphere through the outlet hole system. Small experimental pumps have achieved vacua better than 0.1 mbar and speeds of 10 m3/h. Higher vacua and faster pumping speeds are thought to be attainable. There are no rubbing components inside the pump and there is, therefore, no need for the working liquid to be a lubricant. Also, choice of materials in contact with the possibly aggressive gases is not restricted by the need for rubbing compatibility. A corrosion-resistant laboratory pump is described with a 3 m3/h pumping speed and a 0.5 mbar ultimate vacuum.

Effects of Chip Splitting Nicks in Drilling

When adequately designed nicks are engraved on the cutting edges of a twist drill, chips produced by the drill are split into narrow ones which can easily flow out of the hole through the twisted flutes of the drill. This brings on considerable improvements in the drilling performance such as (1) lower drilling torque, (2) better surface finish of hole, (3) smaller burr at the outlet of hole, and (4) longer drill life. These improvements are remarkable especially in the drilling of a relatively deep hole with HSS twist drill. In this paper, the mechanism and the conditions for these improvements are indicated.

Experiences with a 3.3 MW heat pump using sewage water as heat source

In the town of Sala, situated in the middle part of Sweden 100 km west of Stockholm, a 3.3 MW heat pump extracting heat from purified sewage water is used to feed the district heating system. The heat pump which is equipped with a screw compressor was put into operation in June 1981. During the first year the need for maintenance was extensive. The reliability growth was delayed mainly because of vibrations in the slide valve used for capacity control of the compressor which caused damages in pipes and valves. After this initial period the heat pump has reached expected availability and performance. For 1983 the heat production was 25.6 GWh, the mean annual coefficient of performance 2.6 and the availability 93%. The profit for 1983 was calculated to 750,000 Sek, which indicates a pay-off time of 6.5 yr. Performance and operation of heat pump systems are generally sensible to temperatures and heat demand. The experiences from Sala confirm this and show the importance of having detailed information on the actual conditions already in the design phase. The evaporator which is made of galvanized carbon steel shows no signs of corrosion damage due to the sewage water. Heavy fouling of the evaporator has been observed at two occasions, both times in connection with the use of water from the nearby river as a supplementary heat source. Fouling of the evaporator due to the sewage water seems to be a minor problem. The water distributor outlet holes are easily clogged by larger particles from the sewage water and must be cleaned several times per year.

ニックによるドリル性能の向上

Nicks engraved on the cutting edges of a twist drill split the chips into narrow bands which can easily flow out of the hole through the flutes of drill. As the result, the performance of the drill is improved considerably, especially when the depth of hole exceeds its diameter. Experiments in this paper show the effects of nicks such as lowered torque, smoother surface finish, diminished bur at the outlet of hole and the prolonged drill life : In a series of drilling test of φ 6 holes in 0. 45% C steel, nicks prolong the drill life up to ten times as long or even more. For the higher productivity, feed rate can be increased by about 30% without shortening drill life.

Full-Coverage Discrete Hole Wall Cooling: Discharge Coefficients

Factors influencing the design of full coverage drilled plate wall cooling systems for gas turbine combustors are studied. It is shown that the large number of small diameter holes required result in a low Reynolds number operating regime. The physical features giving rise to the hole pressure loss are examined, and it is shown that under hot conditions heat transfer within the hole can appreciably alter the hole mass flow for a fixed pressure loss. It is shown that this effect may be used to estimate the hole outlet temperature and the results show that the heat transfer within the combustor wall may be very significant. The rise in coolant temperature within the wall appreciably alters the blowing rate and hence influences the hot gas side convective heat transfer to the plate. The influence of an impingement plate on hole discharge coefficients is also investigated and shown to be small.

Theoretical study of hydraulically fractured penny‐shaped cracks in hot, dry rocks

AbstractA simple and analytical method of solving the problem of heat extraction from a penny‐shaped crack having both inlet and outlet holes is developed by using a two‐dimensional flow model when fluid is injected at a constant flow rate. Temperature distributions in both rock and fluid are obtained by taking into account the hydraulic and thermal growth of the crack. The outlet fluid temperature and energy extraction rate versus time are shown by some illustrative examples. Although the effect of thermal, contraction of rock upon the crack width is large, its influence upon flow rate and crack tip stress intensity factor is sufficiently small within the first several years so that the crack radius can be determined mainly by the mechanical deformation of, the rock.

On the effect of cutting fluid on drilling aluminum alloy

Several sorts of cutting fluids having various viscosities were used in drilling of aluminum alloys and their effects on drilling resistance, drilling temperature, drilling accuracy, state of drilled surface, disposal of chips, etc. were discussed. Since the reproducibility in supplying the fluid was not reliable, the drilling tests were conducted by dipping the whole specimen in the fluid. The results were summarized as follows.Nose angle of 118° and lip clearance of 12° were effective in drilling of aluminum alloys with cutting fluids when the effects on drilling temperature and roughness of drilled surface were taken into consideration. Among some kinds of drilling resistance, the viscosity of the liquid had little effects on torque; but the effects on thrust and drilling time were more powerful than those in dry drilling. (These values were higher than those in dry drilling). However, high viscous fluids were more effective, because they gave the lower values than those in dry drilling. When cutting speed was low, the drilling temperature was lower than that in dry drilling. The roughness of drilled surface was finished better than that in dry drilling, and also better effects were given on the disposal of chips, appearance of burrs at the outlet of hole, etc. However, no remarkable effects were found on the enlargement of hole diameter.

Equipment for the recovery of precipitates from tubular centrifuges

AbstractEquipment has been developed for the recovery of precipitates from rotors of industrial tubular centrifuges. A double piston is described for nonaseptic discharge of precipitates through the outlet holes of the clarifier rotor. For the aseptic resuspension or dissolving of valuable precipitates a closed‐circulation system has been developed, which is applied without opening of the clarifier rotor.

Drilling of aluminum 2S plate with special type point drill

The effects of shape and dimensions of drill on the figure and accuracy in dimensions of drilled hole, drilling resistance, etc. are discussed for drilling of aluminum alloy plates with a fishtail point drill.The results obtained were as follows.Some heaps at the hole inlet and burrs at the hole outlet were produced in drilling of soft plates such as 2S and 3S, but they were not so large in height as those produced by the conventional drills. However, the worked hole surface obtained by the point drill was superior to that by the conventional drills. The drilling machinability with respect to drilling resistance, enlargement of hole diameter, heaps and burrs, etc. of hard plates such as G4 and 52S by the fishtail point drill was superior to that of soft plates such as 2S and 3S, and the machinability of 14S, 61S, etc. was arranged in medium order. Of course, there is no trouble in drilling of hard plates such as G4 and 52S with the fishtail point drill, but the conventional drills can be used for this purpose. Then, it is concluded that the fishtail point drill is not so favorable for these hard materials.

Studies on the Deterioration of Frying Oils in Continuous Water-spraying and Heating System. VII.

When fat surface is covered with a certain hood and the steam vaporizes from the fat surface, the fat surface is protected from contact with air, resulting that the thermal oxidation of fat is prevented according to the lessened degree of air contact. In the present study, as shown in Fig.-3, fat surface was covered with a funnel shape hood, and water was sprayed through the small side opening. The sprayed water was vaporized from the fat surface into the hood, and discharged out through the outlet hole on the top of hood into atmosphere. Relation between the flow rate of steam at the outlet hole of hood and the thermal oxidative deterioration was examined (Fig.-5, 6). As a result, no thermal oxidative deterioration was observed when the flow rate of steam was over 10 g/cm2/hr. This indicates that the leak of the air into the hood space can be completely prevented. However, if the contact of the edge of hood bottom with fat surface was not complete, such effect was not observed (Fig.-7, 8). Under such steam protection by means of hood, the rate of increase in acid value was less as compared with the case of metal float protection, although slightly increased than the case without protection. This hood system is considered suitable as a practical mean to protect frying oil from thermal oxidative deterioration during deep fat frying because of its simplicity and reliable effect.

Low-compliance diaphragm-capacitance gauge for measurement of liquid pressures of the order of 1 in. water

The construction of a compact diaphragm-capacitance gauge suitable for pressure measurement in viscous liquids is described. Sensitivities in the range 1 to 12 pF/in. water are obtained by using different diaphragm units, and the overall zero stability is about 0.002 in. water over a few hours. The response time is about 5 s when the gauge is filled with a 50 P liquid and the outlet hole is 0.5 mm in diameter and 2 mm in length.

Preliminary studies on the sponge-oxygenator; an improved simple method for extracorporeal blood oxygenation.

I N the development of an apparatus for extracorporeal circulation, the blood oxygenating device is the most difficult problem to be solved. Until now many ways have been followed to attain the aim of constructing a safe and efficient oxygenator, and some encouraging and praiseworthy results have been reached in bloodless open heart operations in man. Nevertheless the problem is still open and research for an even more perfect method is being continued. We began our experimental studies on this subject about 10 years ago, and during this time we have constructed and systematically tested on dogs many oxygenators based on the various principles pointed out by other authors and on our ideas.l-14 Recently 2 of us (A. B. and P. L. P.) have devised and realized a new system, the sponge-oxygenator, which proved to be the most safe and efficient we have experimented with to this time, In this report we shall not deal with the blood propelling parts of our apparatus, because the problem of the pumps may be regarded as a separate one. We shall expose only the structural features of the “artificial lung” and the first results experimentally obtained with it. The true oxygenation device is very simple. It is composed of a methyl methacrylate (Lucite; Plexiglas) 13 cm. long tube, with a 4 cm. internal diameter, containing a cylindrical piece of polynrethan spongei with large porosity. This cylinder is 10 cm. long and juts out from one end of the tube leaving a little unoccupied space at the other extremity (Fig. 1). The described device is fixed by simple pressure in the center of a bored support through which the venous blood and the oxygen enter the oxygenating tube by separate ways; the venous blood enters through 2 lateral channels and the oxygen through a long multiperforated needle fixed in a small renewable silicon rubber disc (Fig. 2). All around the central oxygenating tube, a deep circular groove acts as a collecting space for the arterialized blood ; the bottom is inclined toward the outlet hole (Fig. 3). The support