Showing papers on "Diffuser (thermodynamics) published in 1978"

Fluid Dynamics of Diffuser-Augmented Wind Turbines

Abstract: The diffuser-augmented wind turbine (DAWT) is one of the advanced concepts being investigated to improve the economics of wind energy conversion systems (WECS). Application of modern boundary-layer control techniques has reduced the surface area requirements of an efficient diffuser by an order of magnitude. Many parameters that affect the performance of the diffuser system have been examined in small-scale wind tunnel tests with a family of compact diffusers, using screens and centerbodies to simulate the presence of a turbine. Flowfield surveys, overall performance, the effect of ground proximity, and the prospects for further improvement are described. The baseline configuration is a conical, 60 deg included angle diffuser with an area ratio of 2.78 controlled by two tangential injection slots. This first-generation DAWT can provide about twice the power of a conventional WECS with the same turbine diameter and wind. Economic estimates show that this DAWT can be as much as 50% cheaper than coventional WECS for the same rated power.

Self stabilizing sonic inlet

Abstract: There is disclosed an air inlet for a turbine engine suitable for use on a short takeoff and landing (STOL), a vertical takeoff and landing (VTOL) or a conventional takeoff and landing (CTOL) type of aircraft. A critical region in which critical flow occurs under certain conditions communicates with a less critical region of lower static pressure. Air is drawn away from the critical region and reinjected into the air flow at the less critical region. In one embodiment a circumferentially extended slot is provided in the inner surface of the air inlet at the windward side and downstream of the throat region. The slot communicates with a circumferential plenum chamber formed in the front of the air inlet just behind the lip. Circumferentially extending rows of apertures are provided on the lip establishing two sets of apertures spaced circumferentially away from the slot in opposite directions. The slot removes the boundary layer from the critical portion of the diffuser to minimize or eliminate flow pressure loss or separations resulting from diffusion or turning. The apertures are in a region of low static pressure on the lip of the inlet and serve as a source of suction to cause air flow into the slot.

Combustor support structure

Abstract: A combustor assembly for a gas turbine engine includes a tubular, multi-layered porous metal wall with pores therethrough for distribution of compressor discharge air into a combustion chamber and wherein a rigid combustor support ring is connected to one end of the wall to receive an inlet diffuser member including an ovate inlet and a circular outlet connected to the support ring for axially directing primary air flow into the combustion chamber; and the diffuser member including a flow divider on one outer surface thereof including means for fixedly securing the inlet diffuser member with respect to a wall of a gas turbine engine and wherein coacting means are provided between the inlet diffuser member and the rigid combustor support ring of the combustor to radially connect it in place at one end thereof and wherein further coacting means are provided between the inner engine wall and a portion of the porous sleeve for axially indexing of the combustor assembly.

Influence of Compressor Exit Conditions on Diffuser Performance

Abstract: Results are presented of an experimental investigation into the way in which compressor exit conditions influence the performance of two optimum combustor-dump diffusers. In an optimum system nearly all of the pressure rise occurs in a relatively long prediffuser which is designed to produce a symmetrical outlet velocity profile at the design flow split. One diffuser was tested downstream of a seven-stage axial flow compressor and, for comparative purposes, retested with fully developed flow at inlet. The second diffuser was tested downstream of an annular tandem cascade which could be sited at a number of positions relative to diffuser inlet. The overall performance, measured when the wakes from the outlet guide vanes had decayed considerably, was the same as that achieved with fully developed inflow.

Nozzle structure with notches

Abstract: A nozzle for a jet stream in which the rear edge of the nozzle has a number of notches spaced therealong to widen the jet stream while directing the jet stream rearwardly of the nozzle. Each notch has a narrow front apex and a rear opening substantially wider than the apex, and each notch widens substantially smoothly and progressively from its apex to its rear opening, each notch having sides which at least over a major portion of their length diverge from each other at an angle of at least 60 degrees, and preferably at least 90 degrees. The nozzle will commonly blow into a diffuser to provide thrust augmentation but may also be used simply to blow over a flap, or it may be used without any diffusers or flaps, simply to provide noise reduction. So long as the notch divergence angle is wide enough, loss of nozzle efficiency is minimized, and when a diffuser is used, thrust augmentation is increased. In another embodiment, fairings are placed between the notches to guide and confine the flow to the notches, permitting a large reduction in the notch angle.

Particulate spray nozzle with diffuser

Abstract: A particulate spray nozzle is disclosed having an internal mixing chamber with a liquid spray orifice on one side and a liquid and particulate discharge bore opening the opposite side to ambience. A liquid supply passage upstream of the orifice contains a disc-like diffuser with the plane of the disc parallel to and aligned with the longitudinal axis of the orifice. The diffuser is spaced axially from the orifice and the orifice is spaced axially from the discharge bore for causing a high pressure liquid to be discharged from the orifice in the form of a narrow gradually diverging spray which picks up particulate material in the mixing chamber and propels it out of the discharge bore by uniformly engaging only the outer most portion of the discharge bore. The apparatus can function as an abrasive blasting assembly or a chemical foaming gun. A method of discharging particulate materials, which may be either solid or liquid, is also disclosed.

Prediction of boundary-layer flow separation in v/stol engine inlets

Abstract: The paper provides a theoretical description of the development of the boundary layer on the lip and diffuser surface of a subsonic inlet at arbitrary operating conditions of mass flow rate, freestream velocity, and incident angle. Both laminar separation on the lip and turbulent separation in the diffuser are discussed. The agreement of the theoretical results with model experimental data illustrates the capability of the theory to predict separation location. The effects of throat Mach number, inlet size, and surface roughness on boundary-layer development and separation are illustrated.

Exhaust gas diffuser

Abstract: An exhaust gas diffuser to be connected to the discharge end of an exhaust pipe of an engine, having a tubular body of a relatively flattened cross-sectional shape and having opposite open axial ends, wherein the discharge end of the exhaust pipe is connected to one of the open opposite ends while the openings left at opposite sides of the discharge end of the exhaust pipe form first external air inlet ports, wherein second external air inlet ports are provided at opposite flattened wall portions of the tubular body with upstream edges of the second external air inlet ports being obliquely bent inwardly so as to define a throttling nozzle, while the other open axial end of the tubular body forms an exhaust port through which exhaust gases discharged from the exhaust pipe are discharged mixed with air entrained principally through the second external air inlet ports.

Pressure accumulative spraying pump and spray head

Abstract: A supercharging pump and a diffuser for this, for the atomisation of the fluid, comprising a shell (1) which has an inlet (13) at one of its ends and the other end of which retains, with the possibility of movement towards the inlet (13), a diffuser (28) with a port (34) shut off by a shutter (36) which moves for opening purposes in the direction of the inlet (13). The port (34) opens into a first chamber (52) contained between the diffuser (28) and a flexible sealing diaphragm (24) which is fastened to it by its periphery (5) and which is fixed to a piston (20) subdividing the interior of the shell (1) into a compartment (65) on the one hand and on the other hand into a second chamber (56), called a compression chamber, not communicating with the compartment (65), but communicating with the first chamber (52) via a passage (38), this piston (20) being fixed to the shutter (36) which also shuts off the inlet (13) and which is stressed towards the said other end by a spring (43) calibrated in such a way that, beyond a given pressure threshold for the fluid, the diaphragm (24) is moved towards the inlet (13), at the same time shifting the shutter (36) away from the port (34).

Air sprayer apparatus for vineyards and the like

Abstract: A vineyard air sprayer includes an axial fan type of blower assembly which is vertically mounted upon a trailer rearwardly of a spray tank. The blower assembly has a cylindrical outer shell having an annular discharge ring mounted to the bottom end thereof. An inner shell is coaxially mounted within the outer shell, and a truncated annular diffuser is secured to the bottom end of the inner shell in a coaxial relationship therewith. The outer edge of the diffuser is spaced from the outer edge of the discharge ring to form two arcuate discharge openings at opposite sides of the blower assembly. The diffuser includes an upwardly projecting annular lip portion which is truncated by a vertical wall at its front end. The edge of the lip at each side of the diffuser is cut along a convolute helical path so as to be highest at the rear end of each discharge opening, to slope downwardly and forwardly therefrom to a point where the lip is notched away, and to slope upwardly from such notched portion until its juncture with the vertical wall at the front of the discharge opening. Spray nozzles are positioned in each discharge opening to deliver atomized spray solution to the air blast emanating therefrom. The air blast generated from each discharge opening is moderated by the convolute helical edge of the diffuser so as to impinge upon the foliage being sprayed with varying angles of impingement as the sprayer is pulled by such foliage.

Electrostatic liquid spraying nozzle

Abstract: An air-assisted electrostatic round-spray nozzle for liquids, wherein, except for the charging electrode(s), the diffuser, as also the whole of the outer part of the nozzle, is made of electrically insulating material, and whereon the said electrode(s) is/are formed by one or more points or pin-point zones located substantially in the atomizing plane, on or very near the axis of the nozzle.

High fidelity loudspeaker

Abstract: The loudspeaker includes a front panel of expanded polystyrene resiliently connected to side walls of the speaker enclosure. A standard loudspeaker is connected to the front panel, and there is a small diffuser cone concentric with the standard cone. The front panel is driven by the standard cone to reproduce low and medium frequencies and the diffuser cone reproduces high frequencies. Both speakers are driven by a common driver fixed to a rear panel or cross-beam of the enclosure.

Discharge assembly for an axial flow compressor

Abstract: A discharge assembly for an axial flow compressor which places a diffuser which extends radially outwardly and axially outwardly adjacent the last row of rotatable blades to efficiently convert the swirl energy of the fluid into pressure energy without utilizing one or more arrays of stationary blades to straighten the flow before it enters the diffuser.

Method of determining the quantitative content of gaseous or vaporous impurity in a gas mixture and a device for accomplishing same

Abstract: The method of the present invention provides for an acceleration of a gas mixture jet to supersonic velocity ensuring the emergence of a shock wave in the absence of impurity, the recording of the total head of said jet and determination of the impurity from a variation of the shock wave position and intensity. The device for accomplishing said method comprises intercommunicated hollow bodies of a sensing element and of an ejector. Coaxially mounted in the walls of the sensing element body is a feed nozzle made in the form of a Laval nozzle and an inlet nozzle communicated with a vacuum meter. In the ejector walls there are coaxially arranged a mixing chamber communicated with a diffuser, and a working nozzle with a pressure regulator coupled thereto.

Flow momentum reversing fire abatement system

Abstract: Disclosed is an apparatus and method for extinguishing fires consuming combustible fluids, particularly gaseous fluids, issuing from wells, pipes or vent stacks. The apparatus comprises an extinguisher body typically having a cylindrical passageway which is connected in inline flow relationship with the well, pipe or vent stack and through which the flow of combustible fluid must pass. A diffuser cone is mounted within the extinguisher body passageway in coaxial alignment, the apex of the cone directed towards the outlet of the extinguisher body. An extinguisher fluid nozzle is mounted within the extinguisher body passageway for directing a flow of high momentum inert gas against the apex of the conical diffuser. High momentum inert gas is supplied to the nozzle when it is required to extinguish a fire consuming the combustible fluid passing through the extinguisher body and out of the well, pipe or vent stack. The high momentum flow of inert gas directed against the apex of the cone effectively blocks the flow of the combustible fluid through the extinguisher body while purging the combustible fluid from the extinguisher body to the outlet of the well, pipe or vent stack. The invention has particular applicability to vent stacks connected to the ullage spaces of tanks containing cryogenically liquefied combustible fluids such as liquid hydrogen or liquefied natural gas.

Air diffuser for ceiling air outlet

Abstract: The present air diffuser has a generally rectangular bottom panel mounted immediately below the outlet of a ceiling air duct. Along each side an inverted wedge strip is positioned to project across the ceiling a coherent blanket of the supply air which has been deflected horizontally outward by the bottom panel. The wedges are arranged to substantially equalize the air supply along each side, avoiding air "starvation" at the corners, thus providing a continuous coherent blanket of radial air flow. At the downstream side of each wedge strip, the altitude of each inverted wedge at its apex is substantially twice its spacing there from the bottom panel, in order to project the desired coherent blanket of air. The base of each wedge strip and the adjacent periphery of the bottom panel are inclined downward and outward to accomplish rapid induction and velocity reduction before the coherent blanket returns to the ceiling, assuring fast temperature blending and avoiding ceiling soilage. The bottom panel has a double wall construction to avoid moisture condensation and drippage from the bottom.

Vaneless Diffuser Flow With Extremely Distorted Inlet Profile

Abstract: The exit flow distribution of 90-deg centrifugal compressor impellers is distorted in peripheral direction as well as over the diffuser depth. First, there are the rotating jet-and-wake regions behind each impeller channel. Second, the flow has a completely distorted inlet profile from the front to the back wall of the diffuser. Measurements of static and total pressure, total temperature, and flow angle profiles along the whole diffuser length have been carried out in a high specific speed compressor. The results show great angle and total pressure differences in the first part of the diffuser and a backflow zone near the front wall. At the end of the diffuser, a separation zone was located. It is shown that by means of a one-dimensional calculation method, using a dissipation factor, the measured representative mean values of the diffuser flow can be determined very well in the regions where no separation occurs.Copyright © 1978 by ASME

Remote water cooled heat engine

Abstract: A method of operating a heat engine where heated gas is introduced into a venturi or a convergent/divergent nozzle. The heated gas is cooled in a low pressure region by fluid injection the resultant mixture then being passed through the divergent or diffuser part of the venturi or nozzle to a working apparatus. A heat engine is also disclosed which operates according to this method which includes a heat source coupled to a venturi or convergent/divergent nozzle. The nozzle can be substituted by a loop or cyclone. Means are provided to inject fluid into the gas stream in the nozzle loop or cyclone.

Analytical and Experimental Investigation of Diffusers for VSTOL Thrust-Augmenting Ejectors

Abstract: A THRUST-AUGMENTING ejector is a pneumatic device in which the direct transfer of kinetic energy from a primary jet to air drawn in from the atmosphere (via turbulent mixing) produces an increase in the primary thrust. For VSTOL applications, the allowable length of the ejector is small and the diffuser (sidewall flap) design has an important effect on augmentor performance. It was experimentally demonstrated that improved augmentation can be obtained with cambered flaps or straight flaps with tabs. Various combinations of tab blowing and upstream Coanda blowing were experimentally and analytically examined with centerbody and total nozzle area held constant. Nomenclature A0 = primary nozzle area (center jet + Coanda + tab) + boundary-layer control (BLC)

Flow in an Annular Axial-Radial Diffuser

Abstract: The subject-matter of interest is an annular, axial-radial diffuser with a small relative length. The diffuser is intended for the outlet of flow from the last turbine stage. Investigated are possibilities of a theoretical solution to the flow in a diffuser, based on a potential flow in the stream core and on the viscous flow in the boundary layer. Compared are two methods of solution to the potential flow in the given diffuser: a numerical calculation and a method of electrical analogy. By the method of calculation investigated are the influence of compressibility of the flowing medium upon the potential flow, and the influence of viscosity within the boundary layer. Given are the main data about a wind tunnel necessary for the research into the diffusers and the exhaust chambers, and experimental information gained in measurements taken on the diffuser. Comparison is made about the results of experiments and calculations. Pointed out is the influence of the exhaust chamber upon the diffuser. In an operating turbine, the flow in a diffuser is significantly influenced by the regime of flow in the last stage. Given are the results of the experimental research into the velocity field at the inlet into the diffuser depending on the aerodynamic loading of the last stage, and described are flow conditions within the diffuser with the turbine running idle when the last stage is in windage operation.Copyright © 1978 by ASME

Turbine engine construction

Abstract: A turbine engine construction comprising a support housing, a compressor, combustor and turbine expander contained within the support housing. The combustor includes a combustor housing defining an inner combustion chamber and an outer chamber between the combustor housing and the support housing. Compressed air from the compressor outlet is communicated to the combustion chamber into which fuel is injected and ignited so that the resulting combustion products expand through a turbine nozzle and into the turbine expander. The novelty of the present invention resides in the construction of a diffuser assembly integrated with both the turbine nozzle and combustor. The diffuser assembly comprises a plurality of diffuser tubes, each tube having one end open to and in registration with the compressed air outlet of the compressor. The other ends of the tubes are arranged in at least two discharge planes for the combustor to improve and increase induced mixing and swirl in the combustion chamber. Preferably, at least one set of diffuser tubes discharges compressed air within the mixing zone of the combustion chamber and at a predetermined axial angle with respect to the turbine engine axis to provide a more uniform temperature into and through the turbine nozzle. The angular discharge from this set of diffuser tubes enables the turbine nozzle to be unwrapped from the conventional axial direction thus reducing both the axial length of the combustor and also the aerodynamic loading on the turbine nozzle.

Air pump with primary and secondary inlet flow channels

Abstract: An air pump useful in pumping gases containing abrasive particles is disclosed. A housing is constructed with a primary flow channel centered around the pump axis and a secondary flow channel annularly surrounding the primary channel just inside the outer housing wall. Within the midsection of the pump a powered impeller rotating within an axially symmetric shroud accelerates air drawn from the primary flow channel causing it to be discharged through an annular shaped ejector nozzle into a suction chamber. Presence of the high velocity airstream in the suction chamber draws the contents of the secondary flow channel into the suction chamber. The entrained contents of the primary and secondary flow channels are carried into the diffuser where the velocity energy of the mixture is converted into pressure. The pressurized mixture is then discharged through the exhaust section.

Vaned Diffuser Inlet Flow Conditions for a High Pressure Ratio Centrifugal Compressor

Abstract: This paper contains a theoretical and experimental investigation of the flow in the vaneless and semi-vaneless space of a transonic radial compressor diffuser, especially for working points corresponding to the mass flow below choking values, in the efficient operating regimes. A type-dependent finite difference calculation has been developed for the inviscid flow. This method has been combined with a shock-boundary layer-interaction theory, which allows a more realistic calculation of the velocity distribution, taking into account the boundary layer variation along the sidewalls. In parallel with this analytical study, several diffuser geometries were also performance tested. A special data-reduction program allowed calculation of the throat blockage and the velocity distribution throughout the diffuser based on static and total pressure measurements. Schlieren pictures were also taken in order to have a better insight in the real flow phenomena at the diffuser entrance. From this experimental data, a detailed comparison with the analytical study was made. This combined theoretical and experimental study made it possible to show the influence of the geometrical parameters of the vaneless and semi-vaneless space on the velocity distribution, and on the throat blockage. Together with the data available in literature for channel diffusers, it allows a better prediction of the overall performances of diffuser systems.Copyright © 1978 by ASME

Further Investigation of Conical Diffusers with Annular Injection

Abstract: A comprehensive investigation is made, for a wide range of incompressible flows, into the merits of annular injection as a means of obtaining a high-performance diffuser with short axial length.Results show that injection yields considerable improvements in both the quality of the discharging flow and the magnitude of the pressure recovery. Accordingly, the technique is strongly recommended when a short, high-performance diffuser is required and when a suitable secondary supply is available. Recommendations are also made regarding the optimum cone angle and the geometry of the injection slot.

Performance of a short annular dump diffuser using suction-stabilized vortices at inlet Mach numbers to 0.41

Abstract: A short, annular dump diffuser was designed to use suction to establish stabilized vortices on both walls for improved flow expansion in the region of an abrupt area change. The diffuser was tested at near ambient inlet pressure and temperature. The overall diffuser area ratio was 4.0. The inlet height was 2.54 cm and the exit pitot-static rakes were located at a distance from the vortex fence equal to two or six times the inlet height. Performance data were taken at near ambient temperature and pressure for nominal inlet Mach numbers of 0.18 to 0.41 with suction rates of 0 to 18 percent of the total inlet airflow. The exit velocity profile could be shifted toward either wall by adjusting the inner- or outer-wall suction rate. Symmetrical exit velocity profiles were unstable, with a tendency to shift back to hub- or tip-weighted profile. Diffuser effectiveness was increased from about 47 percent without suction to over 85 percent at a total suction rate of about 14 percent. The diffuser total pressure losses at inlet Mach numbers of 0.18 and 0.41 decreased from 1.1 and 5.6 percent without suction to 0.48 and 5.2 percent at total suction rates of 14.4 and 5.6 percent, respectively.

Ejector utilizing a vortex flow

Abstract: An improved ejector utilizing a vortex flow for pumping a fluid. The ejector includes a funnel shaped fluid chamber circumscribing a longitudinal axis and converging from a wide end to a narrow end. A venturi-like throat circumscribing the longitudinal axis is in fluid communication with the narrow end of the funnel shaped chamber. A pair of diametrically opposed fluid inlets are disposed in the wide end of the chamber for directing a driver fluid tangentially into the wide end of the funnel shaped chamber. The chamber and throat are configured to form the driver fluid into a swirling flow which advances toward the throat in the form of a vortex flow having a low pressure region. A secondary fluid inlet is in fluid communication with the low pressure region of the vortex flow. A deflector member is disposed in the funnel shaped chamber radially inward of the venturi throat. The deflector includes a surface which diverges away from the longitudinal axis. The vortex flow draws the fluid through the secondary fluid inlet and the deflector guides the fluid radially outwardly toward the throat as the fluid is drawn into the chamber, whereby the fluid is mixed with the driver fluid to form a swirling flow of mixed fluid which advances through the venturi-like throat and into a diffuser as a swirling flow. The diffuser guides the swirling flow of mixed fluids from the throat along a path of increasing radius to compress the mixed fluids to ambient pressure at the diffuser outlet and blocking flow of fluid at ambient pressure through the diffuser to the throat.

Variable diffuser for carburetors

Abstract: An improvement for internal combustion engine carburetors of the variable diffuser type with a sonic throat, the diffuser having a circular intake passage leading to an obstacle in the form of a body of revolution of maximum diameter appreciably larger than the intake passage, coaxial with the passage and axially adjustable to form, with a fixed divergent circular wall prolonging the intake passage of the carburetor barrel, a circular divergent sonic-flow nozzle, the annular throat of which is formed between the intake passage and the nearest surface of the adjustable obstacle.