Showing papers on "Diffuser (thermodynamics) published in 1982"

Diffuser throttle ring control

Abstract: A centrifugal vapor compressor having a two-position, pressure controlled diffuser throttle ring is disclosed. The throttle ring is positively maintained in a minimum or a maximum throttling position by supplying either a relatively low pressure or a relatively high pressure, respectively, to a cavity behind the throttle ring. The throttle ring may be one of any of a variety or types of throttle rings including a new, improved throttle ring having a back portion with a sealing means which facilitates sliding movements of the throttle ring and which prevents vapor flow between the cavity behind the throttle ring and the diffuser passageway.

Spoiler for fluid turbine diffuser

Abstract: A passive means for controlling the power augmentation of a diffuser augmented wind turbine is disclosed. Spoiler tabs for the boundary layer control slots of a diffuser augmented wind turbine include a lifting surface responsive to the fluid flow velocity through the slot and operate to block the slot when fluid flow velocity through the slot exceeds a predetermined level.

Free spool inducer pump

Abstract: Fluid pumping apparatus comprises (a) a housing, (b) an impeller rotatable in the housing to discharge fluid centrifugally outwardly, (c) a rotary spool having an inducer section through which intake fluid passes to the impeller, (d) a rotary diffuser associated with the rotary spool and having driving vanes located at the inlet of the diffuser and outwardly of the impeller periphery for rotatably driving the spool in response to outward flow of said discharged fluid against and between the vanes.

Anti-gas locking apparatus

Abstract: An anti-gas locking apparatus for a downhole pump comprises a sleeve disposed below the pump and in fluid communication with the pump inlet, a housing disposed about the sleeve and fluidly communicating at its upper end with the well in which the pump is disposed, and a cross-over assembly communicating lower portions of the housing with the lower end of the sleeve. The cross-over assembly comprises a cross-over diffuser including a jacket member, the upper end of which mates with the lower end of the sleeve, and a dome member within the jacket member. Apertures are formed through the jacket member and dome member and webs extend between these members to form inlet passages into the interior of the dome member from the annulus between the housing and the sleeve and outlet passages about the dome member to the sleeve. An impeller is disposed within the jacket member below the dome member. Disclosed is an improved geometry of the cross-over diffuser in which webs forming the walls of the inlet and outlet passage spiral about the dome member with ever increasing vertical slope to a substantially vertical disposition and the diffuser is provided with similarly shaped flow shaping vanes within the outlet passages. The impeller is provided with vanes that increase in vertical dimension fromm the center of the impeller toward the periphery thereof so that, with the improved geometry of the diffuser, turbulence of well fluids passing through the diffuser is avoided to prevent evolution of gases in the diffuser.

Outfall diffuser behavior in stratified ambient fluid.

Abstract: A method for the preparation of design charts for estimating the mixing behavior from outfall diffusers in stagnant stratified ambient fluids is presented. Numerical analyses by traditional integral methods which consider the interaction and merging of individual port charges are used to predict the diffuser behavior. Predictions for the maximum height of plume rise and minimum dilution at that point are presented in the form of design curves. Experimental data for the cases of a single and opposing rows of horizontal ports are presented and compared to the numerical results. Additional data of the thickness and vertical location of the horizontally spreading layer developed after the maximum reached are presented. The numerical model was found to be inaccurate for cases of discharges with significant initial momentum. A criterion is developed to indicate when this effect will be important.

Arc welding gun with gas diffuser and external cooling conduit

Abstract: A welding wire gun operable in the high temperature environment of a high current density welding system. The welding gun includes a tubular member through which welding wire and shielding gas are adapted to pass. A gas diffuser member is mounted upon one end of the tubular member and, in turn, supports a welding tip therein such that the end of the welding tip projects beyond the diffuser in the direction of the joint to be welded. Additionally, the welding gun is constructed to provide for flowing of a coolant material around the tubular member proximate the diffuser member for maintaining the welding tip below its melting or distortion temperature. A tubular nozzle member is supported at one end from the diffuser member and extends beyond both the diffuser member and the welding tip in such a way as to define an annular shielding gas chamber about the diffuser and welding tip. Gas passages formed through the diffuser communicate with the annular gas chamber and are angularly oriented with the central axis of the diffuser and welding tip so as to maximize the velocity and minimize turbulence of the gas flow through the gun to thereby maintain a high energy shielding gas envelope around the welding wire and weld puddle.

Control of Self-Excited Flow Oscillations in Vaneless Diffuser of Centrifugal Compression Systems

Abstract: Experiments were conducted to evaluate the effectiveness of axisymmetric diffuser exit throttle in delaying the occurrence of self-excited flow oscillation in vaneless diffusers. Sharp edge rings were installed at diffuser exit in order to change the exit flow area. Tests were carried out with the rings attached to one or both of the diffuser walls. Steady and unsteady flow measurements were used to determine the flow field in the diffuser at the onset of the flow oscillations. Results showed that the occurrence of flow oscillation was continuously delayed as the diffuser exit flow area was reduced for all these configurations and impeller speeds. Comparison between the performance of the compression system with and without diffuser exit blockage indicated that although large losses occur at high flow rates, the use of diffuser exit rings resulted in overall diffuser performance improvement at low flow rates. Retractable diffuser exit rings would therefore be ideal for centrifugal compression systems with vaneless diffuser.Copyright © 1982 by ASME

Plural turbochargers having a common exhaust housing

Abstract: The twin exhaust-gas-powered turbines (9, 10) driving intake air compressors (1, 2) for an internal-combustion engine are connected together and mounted on central support brackets (47, 48) by a common turbine discharge housing (20) that deflects the discharge of each turbine separately towards an outlet funnel (24) with the help of a guiding structure that contains a median wall (33). Diffuser horns (31, 32) and hollow central plugs provide, in a short axial distance, for establishing a static pressure for causing the gas to flow with uniform pressure distribution out through the discharge funnel (24). The latter portion of the outflow path is enlarged by side pieces (26, 27) fitting over holes in the central piece (20) of the discharge casing through which the diffuser horns (31, 32) protrude with ample spacing from other components. The static pressure just mentioned creates a back pressure that improves the efficiency of the turbo-superchargers in their extraction of dynamic energy from the exhaust gas stream. The air compressors are provided with a "floating" suspension from brackets (49, 50) that is tolerant of thermal expansion.

Shock wave suppressing flow plate for pulsed lasers

Abstract: A flow plate positioned upstream of the lasing cavity of an electrically pulsed gas laser blocks the transmission of shock waves generated in the laser cavity. The flow plate has a plurality of passages which are shaped to form a supersonic nozzle at the upstream end of the passage, a subsonic diffuser at the downstream end of the passage and a supersonic diffuser in the central region of the passage.

Diffuser case for a gas turbine engine

Abstract: The strut supporting the diffuser to the engine outer case wall which also supports the shaft bearing of a turbine engine is conically shaped having its base located downstream with respect to the flow of the engine working medium and is judiciously angled so that the line of action for the bearing load is aligned to coincide with this angle, pass through the strut and intersect the centerline of the engine and the midpoint of the bearing. This enhances the stiffness of the support, reducing the weight necessary to support the same load. The diffuser case and support from the diffuser to the bearing is offset from the strut to minimize direct radial thermal incompatibility and the diffuser is spaced from the outer engine case wall reducing thermal stresses.

Gas blow lamp for shrinkage of wrapping material - has needle valve to control fuel flow from injector

Abstract: The gas blow lamp has a Venturi diffuser pipe (10) at the rear of which is an injection hole (24), fed by gas. At the front is a pipe (33) with a flame outlet grille, surrounded by a protective hood (30). The injector (22) has a needle (24) moving in the hole. This gives full heat, when out of the hole, and minimum heat when in it. The grille support and hood have a flat transverse section, two to six times higher than its width. The air entry section is variable and larger when the needle is in the minimum flow position.

Aerodynamic Performance of Large Centrifugal Compressors

Abstract: The aerodynamic performance of impellers and diffusers of the large centrifugal compressor were studied. A performance design procedure based on the quasi-three-dimensional flow analysis which is combined with the boundary layer theory was developed. The conditions of the boundary layer at the impeller exit and at the diffuser vane throat were calculated, and the three-dimensional measurements were carried out. This result shows that the low momentum flow is accumulated at the corner of the shroud and the blade suction side of the impeller. These results were applied to the development of a large four-stage isothermal compressor which handles the air for an air separation apparatus. This was tested in the field and showed an isothermal efficiency of 76 percent.

Unsteady Transonic Flow in a Two-Dimensional Diffuser: Interpretation of Experimental Results.

Abstract: : Experimental data obtained over a four-year period on transonic, oscillatory diffuser flows were examined and compared with the predictions of simple, one-dimensional theories. Acoustic theory, accounting for upstream- and downstream-propagating acoustic waves, correctly describes pressure perturbations in attached flows, provided the wave reflection process at the shock is properly modeled. Unsteady boundary layers strongly influence pressure perturbations in separated flows and velocity perturbations in both attached and separated flows, with the result that acoustic theory fails in these cases. The boundary layers display slow, transverse, downstream-moving waves (termed interface waves) that strongly influence the core flow velocity and pressure perturbations through displacement effects. The Eulerian velocity perturbations associated with this wave motion are large within the boundary layer. A one-dimensional model was constructed, incorporating both acoustic waves and the interface waves: their effect is most evident in the phase-angle distributions and in the predicted natural frequencies.

High area ratio, variable entrance geometry compressor diffuser

Abstract: Aerodynamically tapered spike is positioned for controlled axial movement in the conical portion of a composite gas turbine engine diffuser controlling engine air mass flow rate by adjusting diffuser area ratio. Also, a straight pipe transition diffuser portion is positioned between the conical portion and a flat plate diffuser portion to flatten the velocity profile.

Forced air baseboard heater and air duct diffuser

Abstract: An electric heater adapted to be used as a space heater or to be mounted over the discharge end of a hot air duct to diffuse air flowing into a room from the hot air duct and to heat the air in the room. The electric heater includes a housing adapted to be positioned over the discharge end of a hot air duct, the housing including an air outlet opening, and an elongated chamber therein. An elongated heating element is housed in an elongated chamber defined by the housing. An air conduit is also located in the housing and extends parallel to the elongated heating element. Air outlet openings are provided along the length of the air conduit, and a centrifugal fan blows air into the air conduit and this air is forced through the air outlet openings toward the elongated heating element and such that air is directed toward the heating element along a substantial portion of the length of the heating element.

Gas to liquid mass transfer device and method

Abstract: A mass of energy transfer device is disclosed which is adapted for intermixing a liquid and a gas phase for the purpose of mass, heat or kinetic energy transfer between the phases. The transfer device includes a plurality of individual substantially tubular mixing elements each of which receives a high velocity spray of the liquid phase for substantially longitudinal travel therein and draws the gas phase into a throat and diffuser through a substantially axisymmetrical opening. The mixing elements are mounted into an enveloping vessel the interior of which is in fluid communication with a source of the gas phase. Efficiency of the device is disclosed to depend exponentially on the ratio of the momentum range of the liquid spray to the throat diameter which is related to the ratio of the slip velocity of the liquid and gas to the velocity of the gas. Throat diameters of approximately ten inches or less of each of the individual mixing elements provide capability for efficient mass transfer on practically any scale of design of the overall transfer device.

Aerodynamic Performance of Large Centrifugal Compressors

Abstract: The aerodynamic performance of impellers and diffusers of the large centrifugal compressor were studied. A performance design procedure based on the quasi-three-dimensional flow analysis which is combined with the boundary layer theory was developed. The conditions of the boundary layer at the impeller exit and at the diffuser vane throat were calculated, and the three-dimensional measurements were carried out. This result shows that the low momentum flow is accumulated at the corner of the shroud and the blade suction side of the impeller. These results were applied to the development of a large four-stage isothermal compressor which handles the air for an air separation apparatus. This was tested in the field and showed an isothermal efficiency of 76 percent.Copyright © 1982 by ASME

Effects of Approaching Flow Types on the Performances of Straight Conical Diffusers

Abstract: This paper describes the effects of types of an approaching flow on the performances of straight conical diffusers. Also, the relationships among inlet boundary layer thickness, inlet swirling components and diffuser performances are investigated. Tests are carried out on straight conical diffusers with total divergence angles ranging from 6° to 18° and with diffuser area ratios ranging from 2.1 to 15.9. According to the result, good performances are obtained if the approaching flow has a symmetrical axial velocity profile with one directional swirling component or a distorted axial velocity profile with double spiral swirling components, and the performances are not so good if it has a simple distorted axial velocity profile without swirling components or with one directional swirling component.

Pressure recovery in a constant-area, two-stream supersonic diffuser

Abstract: The quasi-one-dimensional theoretical analysis is based on the assumption of steady, uniform flow at the inlet and outlet locations The primary and secondary streams are assumed to behave as perfect gases, and the base area between the two streams at the diffuser entrance plane is assumed to be zero The fundamental equations of continuity, momentum, and energy are applied to the control volume shown in the inset of Fig 1 Knowledge of the inflow conditions and manipulation of these equations produces -a series of equations which determines flow properties such as static pressure and Mach number at the diffuser exit plane for the case of maximum compression Based on the "equivalent" entering Mach number concept, the analysis provides theoretical values of the subsonic Mach number and the maximum static pressure at the diffuser exit plane for comparison with experimentally measured values Details of the analysis are covered in Ref 9 Experimental Program

Design and Investigations of a Three Dimensionally Twisted Diffuser for Centrifugal Compressors

Abstract: For a 90-deg centrifugal compressor impeller with an extremely distorted exit flow distribution a vaned diffuser has been designed. The maximum flow angle difference across the diffuser width at the entrance is 29 deg. In order to match the vane inlet angle to this flow angle distribution the diffuser vanes are three dimensionally twisted. The map of the compressor with the twisted diffuser is compared with those using a commonly designed cambered vane diffuser and a straight channel diffuser. On the basis of detailed flow field measurements directly before and behind the diffuser and of the static pressure distribution along the diffuser, the performance of the twisted diffuser is discussed.Copyright © 1982 by ASME

Investigation of Flows in Rectangular Diffusers With Inlet Flow Distortion

Abstract: The results of an experimental study on the influence of severely distorted velocity profiles on the performance of a straight two-dimensional diffuser are reported The data cover entry Mach numbers ranging from 01 to 06 and several inlet distortion levels The pressure recovery progressively deteriorates as the inlet velocity is distortedCopyright © 1982 by ASME

Controller for capacity of centrifugal compressor

Abstract: PURPOSE:To heighten the operation efficiency of a centrifugal compressor under capacity control, by providing a linkage in the slit of the diffuser vane of the compressor to drive the diffuser vane and inlet guide vane in connection with each other and by determining the form of the slit in terms of a prescribed formula. CONSTITUTION:The diffuser vane 25 of a compressor is provided with a slit 28 which does not extend in parallel with a camber line 15 defined by a formula DELTAbetax=DELTAl/Lx where DELTAbetax denotes the difference between betax (diffuser vane angle determined by link) and betax' (optimal mounted angle of diffuser vane), DELTAl denotes the distance between camber line and center of guide pin in slit and Lx denotes the distance between center of guide pin and tip of diffuser vane at inlet guide vane angle of theta. The guide pin 29 secured on an adjuster ring 22 is slidably inserted in the slit 28. The adjuster ring 22 is interlocked with the driving inlet guide vane 4 through a linkage consisting of a link 19, a pin 20 and so forth. According to this constitution, when the flow rate of the compressor is changed by altering the angle of the inlet guide vane 4, the mounted angle of the diffuser vane 25 can be equalized to the angle of inflow to the vane in connection with the change in the flow rate.

Numerical simulations of unsteady transonic flow in diffusers

Abstract: Forced and naturally occurring, self-sustaining oscillations of transonic flows in two-dimensional diffusers were computed using MacCormack's hybrid method. Depending upon the shock strengths and the area ratios, the flow was fully attached or separated by either the shock or the adverse pressure gradient associated with the enlarging diffuser area. In the case of forced oscillations, a sinusoidal plane pressure wave at frequency 300 Hz was prescribed at the exit. A sufficiently large amount of data were acquired and Fourier analyzed. The distrbutions of time-mean pressures, the power spectral density, and the amplitude with phase angle along the top wall and in the core region were determined. Comparison with experimental results for the forced oscillation generally gave very good agreement; some success was achieved for the case of self-sustaining oscillation despite substantial three-dimensionality in the test. An observation of the sequence of self-sustaining oscillations was given.

Measuring apparatus of water level of nuclear reactor

Abstract: PURPOSE:To eliminate an error of water level measurement due to a velocity head component by the flow speed, by providing a means for measuring a pressure difference of lower and upper parts of cooling material in BWR vessel and moving flow rate of jet pump and carrying out operational proceessing of both values CONSTITUTION:An upper side nozzle 12 and a lower side nozzle 13 are attached to the inner part of a pressure vessel of nuclear reactor 1 and a pressure difference DELTAP is obtained by a pressure difference detector 14 Also, a pressure measuring tap 22 is provided to a throat and diffuser parts of a jet pump 6 at lower part of a downcommer part 5 in the vessel 1 and its pressure difference is measured by a detector 23 A relative water level WL is shown by the equation obtained by applying Bernoulli's equation at the part 5 between the surface of the water 11 and the nozzle 13 Accordingly, the pressure difference DELTAP between the nozzles 12 and 13 is found by the detector 14 and moreover, the pressure difference of pressure taps 21, 22 provided to the pump 6 is found by the detector 23 Then, by integrating its output, the water level WL is obtained by finding a flow rate of cooling material W of the nozzle 13

Diffuser for centrifugal compressor

Abstract: PURPOSE:To make it possible to operate a compressor with a high efficiency ever a wide range of flow rate by attaching a multi blade rib consisting of a plurality of ribs to the side plate of an impeller inside a difuser and by streightening the flow of fluid discharged from the impeller CONSTITUTION:Multi blade ribs numbering from several pieces to over ten pices are installed to the side plate 1a of the impeller inside a defuser 4 One multi rib consists of three ribs 5a to 5c The angle of the rib 5a on the most inward side diameter is designed to conform to the flow angle of fluid discharge from the impeller 1 at the design point The shape of the multi blade rib 5 consisting of the three ribs 5a to 5c is so formed that it may conform to almost a logarithm spiral shape Each rib 5a to 5c has a height of about 30% of a flow channel width of the defuser 4 This construction makes it possible to straighten a turbulent flow of fluid discharged from the impeller 1

Total flow turbine device

Abstract: PURPOSE:To unify a two-phase turbine and a steam turbine in one as well as to aim at a distinct improvement in heat cycle efficiency, by installing a steam turbine blade on the outer circumference of a rotary separation drum which separates a high-speed two-phase flow into steam and hot water, respectively. CONSTITUTION:A two-phase flow WS entered in a total flow turbine 5 turns to a high-speed two-phase flow after being swollen out of a two-shase flow nozzle 6 and separated into steam S and hot water W through a rotary separation drum 10. The separated hot water W is decelerated by the rotary separation drum 10, then converted into driving force for a rotor 9 and recovered from a diffuser 11. On the other hand, the separated steam S is as well converted into driving force for the rotor 9 through a nozzle 12A and a blade 12B of the steam turbine 12 installed on the outer circumference of the rotary separation drum 10.

Centrifugal type fluid machinery for turbo refrigerator

Abstract: PURPOSE:To enable to reduce the surging region by a method wherein the optimum width of diffuser is determined by the opening degree signal of inlet guide vane and the inlet temperature signal of cooling water. CONSTITUTION:The opening degrees of guide vane D are divided into steps and, at each step and with every inlet temperature of cooling water around the step, the optimum width of diffuser W is determined by means of a controller 10. By means of the controller 10 serving as memtioned above, as the opening degree of guide vane D decreases with the decrease of refrigeration load, the signal of optimum width of diffuser determined by the opening degree signal of guide vane and the inlet temperature signal of cooling water is outputted from the controller 10 and the location of a movable diffuser 4 is determined with a control motor 7. In such a manner as mentioned above, the surging region can be reduced.

Experimental and analytical results of tangential blowing applied to a subsonic V/STOL inlet

Abstract: Engine inlets for subsonic V/STOL aircraft must operate over a wide range of conditions without internal flow separation. Experimental and analytical investigations were conducted to evaluate the effectiveness of tangential blowing to maintain attached flow to high angles of attack. The inlet had a relatively thin lip with a blowing slot located either on the lip or in the diffuser. The height and width of these slots was varied. Experimentally determined flow separation boundaries showed that lip blowing achieved higher angle of attack capability than diffuser blowing. This capability was achieved with the largest slot circumferential extent and either of the two slot heights. Predicted (analytical) separation boundaries showed good agreement except at the highest angles of attack.

Unsteady flow phenomena in industrial centrifugal compressor stage

Abstract: The results of an experimental investigation on a typical centrifugal compressor stage running on an atmospheric pressure test rig are shown. Unsteady flow was invariably observed at low flow well before surge. In order to determine the influence of the statoric components, the same impeller was repeatedly tested with the same vaneless diffuser, but varying return channel geometry. Experimental results show the strong effect exerted by the return channel, both on onset and on the behavior of unsteady flow. Observed phenomena have been found to confirm well the observed dynamic behavior of full load tested machines when gas density is high enough to cause appreciable mechanical vibrations. Therefore, testing of single stages at atmospheric pressure may provide a fairly accurate prediction of this kind of aerodynamic excitation.

Velocity-type compressor

Abstract: PURPOSE:To enhance the pressure recovery rate of a velocity-type compressor over a wide range by blowing gas upon the stream of a main gas flow between a blade outlet and a diffuser outlet so that the flowing angle of the main gas flow is changed. CONSTITUTION:Low pressure gas from an intake pipe 1 is applied with both pressure energy and velocity energy, is introduced into a diffuser 7 and then is led to the outlet of the compressor through a vortex chamber 23. A part of gas having its pressure raised in the vortex chamber 23 is led into a high pressure chamber 24 defined in a cover 2 via a through hole 11 and is jetted through nozzles 5 formed in the shroud side so that the part of high pressure gas is expanded to the outlet pressure of the impeller 4, and is blown upon and mixed with a main gas flow passing through the impeller 4. Accordingly, the flowing angle of the main gas flow is changed for guiding the main gas flow in a proper flowing direction, thereby the pressure recovery rate is improved over a wide range.