Showing papers on "Diffuser (thermodynamics) published in 1988"

Axial flow gas turbine

Abstract: The cooling-air ducting of the axial flow gas turbine runs in the area of the last blading stage (9+14) radially inwards of the heat-accumulation segments (23, 24) inside the outer boundary of the rotor (4) and through blade root channels (21) in the blade roots of the last moving blade ring (9) and finally through a cooling-air blade ring (28) fixed to the rotor into the diffuser into which the cooling-air flow enters with a velocity vector which essentially corresponds to the average velocity vector of the exhaust-gas flow entering into the diffuser. This avoids the flow losses which occur when the cooling-air flow passes out into the exhaust-gas flow in the area of the last stage or stages. At the same time, the temperature difference between the rotor circumference and the last rotor disk (4), likewise cooled by tapped air from the compressor, is in this way reduced, as a result of which the thermal stresses in the rotor are also reduced.

Open top compact dryer oven for a web

Abstract: A compact web dryer oven (A) is disclosed which is heat efficient, may be open for convenient cleaning, and raises automatically under the effects of an explosion to relieve pressure and reduce damage to the oven interior. The oven includes a lower housing (B) and an upper housing (C) which are essentially identical. Each housing includes an air distribution system having a short path and recycle time which includes a hot air discharge blower (H), an air reducing plenum (I), and a redirecting chamber (J) which directs the air in a vertical direction. An elongated air diffuser manifold (K) extends the length of the housing and includes a radial arrangement of pipes (71) and radial air openings (72) which distribute the air (45) in equal parts across the width of web (W). Lower and upper hot air registers (E,F) receive the proportioned air flow. The air registers include spaced tubular members (22) transverse to the air diffuser manifold having an air divider nozzle (G) positioned between each member. A first nozzle (32), second nozzle (34), and third nozzle (42) are defined relative to tubular members (22) and nozzle bodies (G) which accelerate the flow of air in a manner to balance the air currents at the web. Equal but opposite air flows (26,28) are produced by the nozzle body. A spring assembly (96) and pivot (94) provide for release of upper housing (C) upon exertion of an initial lifting force either manually or by explosion.

Weak rotating flow disturbances in a centrifugal compressor with a vaneless diffuser

Abstract: A theory is presented to predict the occurrence of weak rotating waves in a centrifugal compression system with a vaneless diffuser. As in a previous study of axial systems, an undisturbed performance characteristic is assumed known. Following an inviscid analysis of the diffuser flow, conditions for a neutral rotating disturbance are found. The solution is shown to have two branches; one with fast rotation, the other with very slow rotation. The slow branch includes a dense set of resonant solutions. The resonance is a feature of the diffuser flow, and therefore such disturbances must be expected at the various resonant flow coefficients regardless of the compressor characteristic. Slow solutions seem limited to flow coefficients less than about 0.3, where third and fourth harmonics appear. Fast waves seem limited to a first harmonic. These fast and slow waves are described, and effects of diffuser-wall convergence, backward blade angles, and partial recovery of exit velocity head are assessed.

Diffuser for centrifugal compressor

Abstract: A diffuser centrifugal compressor of a comprising a plurality of stator blades provided outside an impeller thereof, and which converts kinetic energy of fluid from the impeller into pressure energy by operation of the stator blade. The diffuser is provided with sub-blades near the inner ends of the stator blades, and intermediate blades near outer ends of and between the stator blades.

Integrated engine air cleaner and venturi resonator

Abstract: An integral air cleaner-noise silencer assembly includes a filter element (22) dividing the assembly into lower and upper parts (14,16), the upper part (16) constituting a lid or cover for the filter and including a funnel-like clean air outlet (44) containing a venturi (38) with as small a throat (40) as practical to provide a maximum restriction of noise with a minimum restriction to air flow, the air outlet and venturi being overlaid by a resonator chamber (28) having an annular inlet (50) surrounding and concentric with the venturi diffuser outlet (44) for dampening the acoustical energy of engine sound waves, the venturi diffuser walls also reflecting the waves back toward the engine.

A control-volume method for analysis of unsteady thrust augmenting ejector flows

Abstract: A method for predicting transient thrust augmenting ejector characteristics is presented. The analysis blends classic self-similar turbulent jet descriptions with a control volume mixing region discretization to solicit transient effects in a new way. Division of the ejector into an inlet, diffuser, and mixing region corresponds with the assumption of viscous-dominated phenomenon in the latter. Inlet and diffuser analyses are simplified by a quasi-steady analysis, justified by the assumptions that pressure is the forcing function in those regions. Details of the theoretical foundation, the solution algorithm, and sample calculations are given.

Highly compact inlet diffuser technology

Abstract: The potential benefits of short, highly compact inlet diffuser systems extend from efficient propulsion/airframe performance to improved survivability The cost of these benefits may be excessively high engine face distortion This highlights the importance of accurate preliminary design methods that assure low distortion engine face flow Therefore, compact/offset subsonic diffuser performance and operational characteristics have been investigated, with the general goal of developing preliminary design guidelines and providing a useful perspective for advanced aircraft designers Incorporated are important prior works that extend the database by introducing the results of recent experiments, including passive and active BLC methods for providing separation-free diffuser flow Diagnostic pressure measurements, in conjunction with CFD calculations, are used to demonstrate the flow mechanisms responsible for the engine face distortion profile Surprisingly good comparisons of measured engine face pressure characteristics with CFD results are shown for the severely separated flow of the test article

The relation between losses and entry-flow conditions in short dump diffusers for combustors

Abstract: An experimental correlation is presented between the losses and the inlet flow conditions in short dump diffusers for turbojet combustors. Cascades of compressor blades upstream of the diffuser were used to make the flow field at inlet similar to that in a real jet engine. The flow field was altered in two ways — by varying the distance between the cascades and the diffuser inlet plane and by changing the blade aspect ratio. The measurements show clearly that distortions in the radial direction affect the losses to a much larger extent than non-uniformities in the circumferential direction. In consequence, the performance can be correlated to a satisfactory degree of accuracy simply by using the radial blockage factor at inlet.

Low pressure drill bit

Abstract: A drill bit includes a drill bit body, a cutting member and a fluid course extending in front of the cutting member. The fluid course includes a progressively widening diffuser having a particular design which allows pressure recovery in a fluid flowed through an axial bore of the drill bit body, through a narrow throat of the fluid course in front of the cutting member, and out the progressively widening diffuser of the fluid course. As a result, a significantly reduced pressure is obtained in front of the cutting member, which reduced pressure is below a borehole pressure where the drill bit is used.

Oil submersible pump

Abstract: A multi-stage centrifugal pump mainly used for oil extraction, which incls two essential components, namely, a rotational impeller comprising several blades and a stationary diffuser. The shapes of blades and flow passages are designed by using three-dimensional flow theory. The configuration is characterized by the impeller length and the diffuser length being almost equal, with the moving blade being provided with an extension at the trailing edge, smaller wrap angle of the stationary diffuser blade, shorter single-stage and smaller outside diameter, and so forth.

Fluidization patient support control system

Abstract: Disclosed herein is a fluidization patient support system that enables decrease and elimination of the unpleasant and aggravating "pinging" sensation to which patients are presently exposed. The flow rate of air to the plenum chamber beneath the diffuser and fluidization material is controlled by a valve in the air flow conduit, there being a diversionary discharge outlet at the valve, such that the valve can control the ratio of air flow to the diversionary outlet and to the plenum.

Laminar flow apparatus

Abstract: Apparatus is permanently mounted in the deck adjacent to a swimming pool and connected to the water in the pool to generate a laminar flow of water near the surface of the pool at a rate sufficient for exercise and therapy purposes. Two openings are provided in a wall of the pool, one near the surface and one near the bottom. The openings are connected by a flow conduit which includes an arcuately curved section and a straight section, the latter connected to the upper opening. Diffuser vanes are provided along the flow conduit and in the upper opening. A flow generating means, including a rotating impeller disposed within the flow conduit, draws water in through the lower opening, passes it through the flow conduit and past the diffuser vanes, and discharges it through the upper opening as laminar flow.

Performance characteristics of single-stage steam jet ejectors using two simple models

Abstract: Two simple models, one of Hougen, Watson and Ragatz (HWR) and the other by Dotterweich and Mooney (DM), are used to compute the motive steam requirements of single-stage steam jet ejectors. Non-idealities associated with the performance of nozzle, diffuser and that of mixing process are accounted for by nozzle and diffuser efficiency factors. Nozzle and diffuser efficiencies between 0.7-0.9 and 0,75-1.0 respectively, are studied for systems, steam-water vapor, steam-air, and steam-hydrocarbons (n-paraffins: C1 to C5). The results are compared with the empirical correlations of Power and Ludwig. In addition, the effect of motive steam pressure on steam consumption is investigated. It is found that predicted steam consumptions, when DM model is employed, agree closely with literature data. It is suggested that model predicted values, rather than the empirical plots, be used in any specific case, since empirical correlations represent only averaged values.

The Influence of Diffuser Channel Length-Width Ratio on the Efficiency of a Centrifugal Compressor:

Abstract: A series of experiments was carried out on a turbocharger compressor aimed at determining the optimum diffuser channel length-width ratio. It was found that increasing the length-width ratio beyond...

Hot air heater for welding plastic materials together and method of handling the hot air flow

Abstract: An air guiding arrangement for welding materials having plastic films includes a device to supply a uniform hot-air stream at any given air velocity. The air guiding arrangement has a nozzle which contains a swirl chamber functioning as a diffuser which tapers in the shape of a funnel. The nozzle is preceded by an adjustable air divider through which the amount of air to be supplied to the welding site is varied. The hot-air welding machine serves for a seam-shaped connection of plastic containing materials providing uniform heat distribution in the welding gap. In accordance with the inventive method, air is generated in a hot-air generator and delivered through an air divider in which only the quantity of air necessary for correct heating of a plastic material is permitted to flow further to a nozzle and wherein in the nozzle the air is directed through a plurality of radial openings through a swirl chamber which converges to an opening which is of a much larger area than all of the openings so that the hot air is permitted to swirl in the chamber between the sets of openings in which the air is guided so that it can be directed more precisely onto the welding materials and the air may be concentrated as desired over a welding strip.

Furnace for drawing optical fiber

Abstract: PURPOSE:To keep an atmospheric gas flow in a furnace constant and obtain an optical fiber with hardly any fluctuation in wire diameter, by combining a discharge outlet of an inert gas in a gas diffuser and a flow passage communicating with the discharge outlet and preheating part so as to provide specific action. CONSTITUTION:A high-pressure part is formed by retention of flow in a space sandwiched between an upper sealing gas and lower sealing gas. Thereby, the upper sealing gas mainly discharges upward to seal the opening at the upper end of a diffuser 8 from the outside air. The lower sealing gas mainly discharges downward to seal an opening 14 of a shutter provided at the opening of the lower end of the furnace body from the outside air. At this time, since the lower sealing gas is heated by radiant heat from the atmosphere in the furnace or furnace core tube 3 and heat transfer from the furnace body 12, the gas flows down while minimizing the occurrence of turbulent flow without cooling an optical fiber preform 1. Furthermore, the flow rate and flow velocity of the upper sealing gas and lower sealing gas can be respectively regulated to control the respective flows and enhance sealing effects. As a result, stabilization of the atmosphere in the furnace can be simultaneously contrived.

Analysis of Measurements in Vaned Diffusers of Centrifugal Compressors

Abstract: In vaned diffusers of centrifugal compressors many different flow phenomena interfere with one another, and different geometric parameters influence the flow field. Variations of these parameters allow the designer to optimize the diffuser for a certain application or to use a variable geometry for controlling the stage over a wide range. Two vaned diffusers that differ only in their passage widths are investigated using different types of measuring technique, in order to analyze the flow structure and to use it as a verification of a calculation method that allows detailed predictions of flow field parameters inside the diffuser, by taking into account geometric variations. Using this method predictions of the flow field of a variable geometry diffuser are made and are compared with the measured performance curves of the stage.

Laser Velocimetry Measurementsat the Diffuser Exit of a Coal-Fired MHD Channel

Abstract: Field measurements using a two-component dual beam laser velocimeter, in both backscatter and forward scatter modes, were made at the diffuser exit of a coal-fired magnetohydrodynamic (MHD) channel under a very harsh flow environment with restricted space availability and port accessibility. The measurements are the first of their kind since no previous velocity measurements at the coal-fired facility, either intrusive or nonintrusive, have been performed. The results serve as a data base for the engineering design of MHD flow train components and also for theoretical modeling. Presented in this paper are the profiles of the mean velocities and the turbulence levels and spectral characteristics of the flow. This paper also highlights some of the practical problems encountered in making the laser velocimetry measurements under conditions of a harsh environment such as MHD flows.

Driving linkage device

Abstract: An improved driving linkage device for adjusting a variable nozzle mechanism in a supercharger turbine or a variable diffuser mechanism in a compressor. The driving linkage device is provided with a driving ring for driving a variable nozzle mechanism in a supercharger turbine or a variable diffuser mechanism in a compressor, one or more sets of adjusting links, each set consisting of three levers connected in a U-shape and having two opposed ones coupled to the driving ring and a fulcrum for supporting the lever not coupled to the driving ring. One end of one adjusting link is coupled to an actuator to achieve the adjustment of a variable nozzle mechanism in a supercharger or of a variable diffuser mechanism in a compressor.

Control method for centrifugal compressor

Abstract: PURPOSE:To carry out the flow rate control so that the flow rate becomes close to an aimed flow rate, always maintaining a high efficiency, by directly searching the operation point optimum for efficiency, in the flow rate control by the angle control for the inlet guide vanes and diffuser vanes. CONSTITUTION:A plurality of inlet guide vanes 11-14 and diffuser guide vanes 15-18 are driven by a plurality of driving devices 19a-19d and 19e-19h for exclusive use. Each driving device 19a-19h is controlled by a controller 28 on the basis of each detection signal supplied from the sensors 20-22, 24, and 27 for detecting the operation states of the centrifugal compressor 1. In this case, the actual flow rate and actual efficiency are measured at least at three points by operating each vane, and a plurality of extrapolation points are developed for the angle of each vane so as to surround these fundamental points. The flow rate and efficiency for each extrapolation point are estimated from a basic point, and the extrapolation point having a high efficiency close to an aimed flow rate is selected from each extrapolation point.

Rail mounted ejector

Abstract: The invention relates to an ejector to be placed in rooms which are inaccible to human beings. It comprises a casing with a diffuser bore, a head chamber, and a space for a working fluid including a lateral working fluid connection. The working fluid nozzle comprises a working fluid chamber which is connected through bores with the working fluid space and, inside the casing, it seals the head chamber from the working fluid space. The nozzle of the working fluid chamber opens into the head chamber and faces the diffuser bore. The invention is characterized in that the ends of the casing and of the working fluid nozzle each are embodied as a radial flange which flanges are held together by bolts adapted to be operated by a manipulator. At the end of the working fluid nozzle flange there is a handle which is operable by a manipulator to pull the working fluid nozzle out of the casing and to reintroduce it, respectively.

Method of detecting degassed state in mold and system therefor

Abstract: The present invention relates to a method of detecting a degassed state in a mold and a system therefor. A gas release opening is formed between a movable mold part and stationary mold part, and a diffuser block having a path for releasing the gas to atmosphere is disposed on the mold. A secondary flow path capable of generating a secondary flow when the gas is released is formed in this diffuser block, and a wind velocity sensor is disposed in this path. Wind velocities of the secondary flow, which are detected by the wind velocity sensor, serve as indications of a cast state and the like in a die cast machine or the like. The secondary flow path is suitably shut off by a shut-off mechanism, and connected to an air cleaner, so that the wind velocity sensor can be effectively protected from dust and the like.

Fuel cell power generating system

Abstract: PURPOSE:To use one blower for two lines by arranging an ejector to which a reaction gas line is connected through a heat exchange line, a blower, and a starting burner installed in the heat exchange line or a gas supply line. CONSTITUTION:An ejector 15 is united with a starting burner 11 in the inlet of a nozzle 18. The combustion air supplied from an air supply passage 33 and fuel are burned in the starting burner 11, and the ejector 15 is driven by the combustion gas. The combustion gas is jetted into a mixing chamber 19 from the nozzle 18, and the pressure is recovered by a diffuser 19a, and supplied to a cooling chamber 5 through an air supply passage 36 to heat a fuel cell 1. The low temperature combustion gas exhausted from the cooling chamber 5 is sucked from an inlet 17 by negative pressure in the nozzle to circulate through a circulation passage 38, and to conduct heat exchange. One blower is used in the reaction gas line and the heat exchange line.

The relation between losses and entry-flow conditions in short dump diffusers of combustors

Abstract: An experimental correlation is presented between the losses and the inlet flow conditions in short dump diffusers for turbojet combustors. Cascades of compressor blades upstream of the diffuser were used to make the flow field at inlet similar to that in a real jet engine. The flow field was altered in two ways − by varying the distance between the cascades and the diffuser inlet plane and by changing the blade aspect ratio

Fuel pump and radial-flow impeller therefor

Abstract: A single stage centrifugal fuel pump which can provide a large range of flow, 1 to 300 gpm, while maintaining low flow, high speed operation with pressure instability at minimum values comprises a radial-flow impeller having a front shroud and a discharge for discharging fuel from the impeller. A diffuser ring has a throat entrance located opposite and in spaced relation to the discharge of the impeller. The front shroud is provided with an extension which extends into the vaneless space between the impeller discharge and the throat entrance of the diffuser ring thereby reducing the flow at which pressure instability inception occurs.

Exhaust diffuser cascade of axial-flow turbine

Abstract: PURPOSE:To reduce any exhaust loss by providing a diffuser cascade in an exhaust passage so as the width between diffuser blades widens gradually towards the downstream. CONSTITUTION:A diffuser cascade is formed by arranging plural number of stationary blades 5 circumferentially in an exhaust passage at the downstream of the final stage moving blade 1. The passage with between the adjoining diffuser blades 5 is gradually widened from an entrance passage width 14 towards an exist passage width 15. The diffuser cascade recovers the pressure and the leaving loss. The exhaust loss can be reduced by this system.

Apparatus for the contactless guiding of webs of material

Abstract: The invention relates to an apparatus for the contactless guidance of webs of material 1. The apparatus has at least two blow nozzles 2, 3, designed as slits or rows of holes, arranged one behind the other in running direction of the web of material 1 and extending transversely to it. The blow jets of these blow nozzles 2, 3 are directed in the same direction and obliquely against the web of meterial 1. On the side towards the web of material 1, flow baffles 12, 12a, 12b, 13 are provided, of which the flow baffle 12 adjoining the rear blow nozzle 2 in running direction of the web of material 1 is curved convexly toward the web of material 1. The flow baffle 12a, 12b between the convexly curved flow baffle 12 and the front blow nozzle 3 is designed as a shock diffuser. With such an apparatus, a web of material 1 is guided free from fluttering even under difficult circumstances. This effect is further improved if the flow baffle 13 adjoining the front nozzle lip 8 of the front blow nozzle 3 is curved convexly toward the web of material 1.

Performance Curve Instability of a Diffuser Pump at Low Flow-Rates

Abstract: Low specific speed pumps with vaned diffusers sometimes encounter performance curve instabilities at flow rates smaller than 30 percent of the optimum one. In order to determine the cause of this phenomena, measurements of the steady and unsteady flow characteristics at the impeller outlet and the diffuser vane inlet were performed using a single-stage diffuser pump with a specific speed of 34 min-1. The results have revealed that the present instability is caused by a rotating stall at the diffuser vane inlet, and that a sharp drop of the head curve is caused by a rotating stall at the diffuser vane inlet, and that a sharp drop of the head curve is caused by a sudden deceleration of the peripheral velocity of the main flow at the diffuser inlet. With an increase in the deviation of the impeller center toward the suction side, the reverse flow regime at the diffuser inlet becomes considerably larger and a periodic reverse flow is forced into the impeller, which increases the performance curve instability. In such cases on of the effective ways of avoiding the instability is to install a spacer at the back of the front shroud.

Hot air diffuser of burner

Abstract: PURPOSE:To reduce the irregularity of the temperature of drying hot air and thus to excellently dry grains without dry spots and checked grains by providing a resistance wall the upper part of which is formed wider than the lower part thereof on the inner peripheral edge of the tip end of a guide cylinder CONSTITUTION:An external air flow passing the periphery of a burner 1 is sucked up by an air flow discharger 9 and formed into a drying hot air flow The drying hot air flow is changed in its direction downward by the resistance wall 4 of guide cylinder 3 of a burner case 2 and diffused into a hot air flow chamber 14, thus passing through a drying chamber 12 from the hot air flow chamber 14 and being sucked by the air flow discharger 9 Grains accommodated into a storage chamber 21 of a drier 5 are exposed to the hot air flow and dried, while flowing down within the drying chamber 12 By the difference in the width between the upper part and the lower part of the resistance wall 14, the direction of the drying hot air flow is changed into the downward direction, and irregularity in the temperature of the drying hot air flow within the hot air flow chamber 14 is reduced and excellent drying of grains is possible at all times