Showing papers on "Diffuser (thermodynamics) published in 1981"

Self-regulating solar window device

Abstract: A window device for controlling the transmission of solar radiation therethrough, having a first diffuser means (12) forming the exterior of the device for diffusing incoming solar radiation, a second diffuser means (14) spaced interiorly from the first diffuser means for further diffusing the incoming solar radiation, a plurality of substantially planar vanes (20) situated between the first and second diffuser means, with each of the vanes having reflective surfaces and being pivotable about an axis passing through its center of gravity, the vanes being interconnected to move substantially in unison, means (40, 44, 46, 48) for automatically controlling the inclination of the vanes about their respective axes in response to the amount of solar radiation transmitted past the vanes, a plurality of substantially planar insulating panels (30) spaced interiorly from the second diffuser means, with each of the panels being pivotable about an axis passing through its center of gravity and being interconnected to move substantially in unison, and means (50, 54, 56, 58) for automatically controlling the inclination of the panels about their respective axes in response to the amount of solar radiation transmitted past the vanes, whereby the amount of solar radiation transmitted through the window is controlled. Also, active and passive solar collection systems employing such a window device.

Diffuser of centrifugal fluid machine

Abstract: A vaneless diffuser disposed on the outer periphery of an impeller of a centrifugal compressor and including a pair of opposed diffuser plates of a disk shape defining therebetween a fluid channel is formed with a plurality of guide vanes extending from the inlet of the diffuser to its outlet. The guide vanes which are disposed on at least one of the pair of diffuser plates and extend immediately from the outlet of the impeller in the direction of flow of a fluid through the fluid channel has a height smaller than one-half the width of the fluid channel and gradually decreasing in going from the inlet of the diffuser toward its outlet.

Effects of Vaneiess Diffuser Geometry on Flow Instability in Centrifugal Compression Systems

Abstract: Experiments were conducted to determine the effects of vaneless diffuser radius ratio on the occurrence of self-excited flow oscillations in a centrifugal compression system. Analysis of the results indicated the successive occurrence of two types of diffuser rotating pressure patterns as the flow rate in the system was gradually decreased. The rotational speed of the latter pattern was higher than that of the initial pattern and both speeds varied inversely with diffuser radius ratio. The critical flow angle at which each pattern was first observed increased with diffuser radius ratio. However, for diffuser radius ratio equal to and larger than 1.75 the rate of change of the critical angle with radius ratio decreased significantly. The results also showed that the minimum diffuser radius ratio necessary for self excitation of each pattern were different. Occurrence of two rotating pressure patterns confirms analytical results presented in a previous investigation.Copyright © 1981 by ASME

Effects of free-stream turbulence on diffuser performance

Abstract: An experimental evaluation of the effects of free stream turbulence on the performance of a subsonic two dimensional diffuser was made. The diffuser's static pressure recovery coefficient was increased 11.4 and 21.1 percent at total. Divergence angles of 12 and 20 degrees respectively were obtained when the value of the inlet integral free stream scale of turbulence in the flow direction was at least 7.5 times larger than the inlet boundary layer displacement thickness, and when the inlet total free stream turbulence intensity was at least 3.5 percent. It is hypothesized that a larger scale of turbulence transmits the free stream energy to the wall more effectively and when coupled with large turbulence intensities, acts to decrease the distortion and delay separation within the diffuser.

Diffuser for gas turbine engine

Abstract: In a gas turbine engine having an annular combustor and an axial flow compressor discharging compressed air through a discharge annulus upstream of said combustor, the diffuser being supported on the engine independently of the combustor between the discharge annulus and a dome on the combustor and including inner and outer walls operative to direct first and second portions of compressor discharge to radially inner and outer air plenums at the combustor and a remaining third portion of compressor discharge flow to a combustor dome feed chamber ahead of the dome, an improvement in the form of radially oriented pins on the diffuser and guides on the combustor dome slidably received on the pins, the pins and guides cooperating in maintaining a predetermined positional relationship between the diffuser and the combustor during relative thermal growth of the latter whereby at normal operating temperature the diffuser outer wall seals against the combustor while a flow balancing slot is developed between the diffuser inner wall and the combustor.

Improved Calculation of High Speed Inlet Flows. Part II: Results

Abstract: An improved numerical algorithm that solves the full mean compressible Navier-Stokes equations has been applied to the calculation of the flowfield in three separate configurations of a simulated high speed aircraft inlet. The inlet geometry consists of a converging supersonic diffuser, formed by two nonparallel plates, followed by a constant height "throat." For all cases, the freestream Mach number is 3.51, and the Reynolds number is 13.6 X10 based on the inlet length. The three configurations are characterized by different values of the angle of the converging supersonic diffuser and different boundary-layer bleed schedules. The computed results are compared with detailed experimental data for the ramp and cowl surface pressure distribution, and the boundary-layer pitot profiles at seven different streamwise locations. The agreement with the experimental results is generally good, although the experimental data display evidence of three dimensionality over a portion of the inlet flowfield.

Well production apparatus and method

Abstract: A method and apparatus for pumping a well using a jet pump. The method comprises pumping a power fluid downwardly in a first flow path in a well, directing the power fluid along a second flow path through a jet pump back to the surface, introducing produced fluids into the jet pump from below the pump, mixing the produced fluids with the power fluid in the pump, and pumping the fluid mixture to the surface through the second flow path along a substantially straight line from the zone of mixing in the pump. The apparatus includes a jet pump having a housing provided with a central bore closed at a lower end and having a transverse bore opening into the lower end of the central bore for admission of power fluid, a nozzle body and nozzle in the central bore above the transverse bore, a throat and diffuser in the bore above the nozzle, flow passages into the housing from the lower end of the housing around and separate from the transverse bore and an annular entry passage from the bypass flow passages into the housing bore between the nozzle and the throat for admission of produce fluids into the housing bore downstream from the nozzle in response to a low pressure in the throat produced by the nozzle. The nozzle body, nozzle, throat, and diffuser of the jet pump are arranged in tandem along a straight line axis.

Vortex controlled radial diffuser for centrifugal compressor

Abstract: The present invention is an improvement in radial diffusers employed in a turbine engine having a centrifugal compressor The walls of the diffuser define at least one flow passage through the diffuser having a first portion with a first cross-sectional area and a second portion having a larger, second cross-sectional area The first wall section is spaced apart from the second wall section so as to define a bleed aperture therebetween A vortex fence extends outwardly from the wall surface at the leading edge of the second wall portion Preferably, the bleed aperture and the vortex fence are disposed on the suction surface of each vane in a vaned radial diffuser

Mixer for dual register burner

Abstract: An improved pulverized fuel burning method and apparatus having means for decreasing the pressure drop through the burner nozzle and decreasing the formation of nitric oxides, including a splash plate to breakup a natural forming fuel-rope, a deflector to deflect the fuel-rope, and a diffuser to disperse the pulverized fuel into a more desirable fuel burning distribution pattern.

Recent development of a jet-diffuser ejector

Abstract: The paper considers thrust augmenting ejectors in which the processes of mixing and diffusion are partly carried out downstream of the ejector solid surfaces. A jet sheet surrounding the periphery of a widely diverging diffuser prevents separation and forms a gaseous, curved surface to provide effective diffuser ratio and additional length for mixing of primary and induced flows. Three-dimensional potential flow methods achieved a large reduction in the length of the associated solid surface; primary nozzle design further reduced the volume required by the jet-diffuser ejectors, resulting in thrust augmentation in excess of two, and an overall length of about 2 1/2 times the throat width.

Supersonic compressor with improved operation range

Abstract: A supersonic centrifugal compressor comprises a bladed rotor which delivers fluid at an absolute velocity exceeding Mach 1.2 under rated conditions to an annular radial flow diffuser. The diffuser has a casing including spaced sidewalls and vanes defining intervane channels each having a throat section located downstream of the leading edges of the channel defining vanes. A pair of common secondary spaces are formed each in one of said sidewalls and communicate with parietal slots symmetrically formed in the sidewalls and opening into the channels. The slots are located and dimensioned to overlap the throat section in the flow direction and each has a cross-sectional flow area at least equal to half the flow area of the channel at the throat.

Constant-output atomizer

Abstract: An improved constant-output atomizer (30) includes a body (38) which has a generally frustoconical expansion nozzle (36) for producing an air jet when a supply of pressurized air is connected to the nozzle upstream of the throat of the nozzle. A liquid feed line (40) supplies liquid to be atomized by the air jet, and the body includes a groove (42) which opens into the diffuser section of the nozzle downstream of the throat for conducting liquid from the feed line to the nozzle. The groove extends in a direction perpendicular to the axis of the nozzle, and radially with respect thereto; and it has a depth approximately equal to half the axial length of the nozzle. Liquid, conducted by capillary action in the groove to the nozzle, is atomized into a fine mist by the air jet in the nozzle; and the groove eliminates fluctuations in spray order.

Proportioning air diffuser and system

Abstract: A proportioning air diffuser system, and an air diffuser therefor, for venting air from a dynamic plenum having areas of relatively greater and lesser static pressure. Each diffuser has a plurality of selectively adjustable vent openings, and a corresponding plurality of air extractors extending into the plenum to divert air through the diffuser. The effective venting area is selectively adjustable, but only within limits that prevent the diffusers from being completely closed. The diffusers are distributed along the plenum, with their effective vent areas progressively increasing from plenum areas of greater to areas of lesser static pressure. The volumetric rate of air flow through the diffusers can thereby be balanced. In a preferred embodiment, two plates having alignable vent openings are positioned over each other. One of the plates is slidable over the other, thereby functioning as a damper to control the alignment between plate vent openings, and thus the effective vent area. A stop depends from the slidable plate through a vent opening of the other plate to limit the sliding range, and provides an engagement point for an adjustment handle.

Fluid flow apparatus for accommodating a pressure drop

Abstract: An apparatus is disclosed for receiving a high pressure fluid flow to accommodate a drop to a lower pressure fluid flow with attenuated noise, incorporating an initial diffuser stage followed by balance in-line stages so that each stage is subcritical to avoid shock noise. Specifically, an elongated tubular member is closed at one end and adapted to receive high pressure fluid flow at the opposed end. Perforations contiguous to the upstream end afford a diffuser stage of pressure reduction which is followed by concentrically mounted, perforated plates to accomplish staged pressure drops. Structurally, the elongate tubular member is fixed somewhat concentrically in a cylindrical housing along with a series of the perforated plates which are peripherally supported by the housing and centrally supported by the elongated tubular member. A diffuser as the first stage affords superior strength to withstand impacts and pressure loading. The subsequent perforated plate stages are balanced so that the pressure drop across each of the plates is preserved below the critical level. Supporting the plates concentrically by an extension of the elongated tubular member as well as peripherally by the housing affords an effective economical and durable pressure reduction structure.

Exhaust system for a two-cycle engine

Abstract: In the present invention, a second expansion chamber which includes a second diffuser is provided in pneumatic connection with the prior art first expansion chamber of an exhaust system for a two-cycle engine. The second expansion chamber creates a second pressure drop or relative vacuum substantially adjacent the point of pneumatic connection between the first and second expansion chambers, which acts to draw-out the exhaust gases present at the rear-cone shaped portion of the first diffuser. The second pressure drop or relative vacuum created by the second expansion chamber of the present invention thus overcomes the deficiencies caused by the pressure increase produced by the rear-cone shaped portion of the first diffuser. Several embodiments of the present invention are disclosed.

Method and apparatus for thickness control of a coating

Abstract: An improved air knife apparatus and method for controlling coating thickness on a moving metal strip. Air flow from blowers is supplied through a plenum chamber common to an air knife and a diffuser spaced along the path of strip travel. A valve between the plenum chamber and diffuser controls the relative flow of air through the knife and diffuser to establish the desired pressure and flow at the air knife to modify the thickness of the coating on the strip. The flow through the diffuser is directed against the strip at a location subsequent to the knife in the direction of strip travel, to chill the coating.

Two-dimensional, unilateral oblique shock diffuser as the air inlet for a gas turbine jet engine for the propulsion of heavy-duty aircraft

Abstract: A two-dimensional, unidirectional oblique air impact diffuser is used as an air inlet for a gas turbine jet engine for aircraft. The air inlet includes an upper rigid air inlet ramp and an air inlet bottom spaced below the ramp. An air scoop lip is pivotally attached to the air inlet bottom so that it can be pivoted from a standard setting point downwardly away from the air inlet ramp and also from the standard setting point toward the ramp. The pivotal displacement of the air scoop lip is a function of the aircraft angle of attack and the flight Mach number. The angular displacement of the air scoop lip from the standard setting point increases downwardly as the aircraft angle of attack increases and decreases as the Mach number increases.

A Study of Diffuser/Rotor Interaction in a Centrifugal Compressor:

Abstract: Experimental flow data recorded on a low speed centrifugal compressor rig are compared with theoretical predictions of the diffuser field. Results for four diffuser geometries are presented coverin...

Experimental investigation of conical wall jets

Abstract: The investigations described here pertain to the determination of the flowfields of different conical wall jet systems. The flow configuration is obtained by pushing a cone-frustum with a flow guide attached to its leading edge into a diffuser having the same included angle as the cone, creating a uniform gap. Air is blown through this gap along the conical surface to form a conical wall jet. A radial or cylindrical wall jet would occur if the apex angle a of the cone becomes 90 or 0 deg. A plane wall jet would occur if the radius of the cylinder becomes infinity for the case of a = 0. The experimental results show that the dimensionless velocity profiles and the rate of jet spread follow patterns similar to those reported for a radial, plane, or cylindrical wall jet. Based upon available skin friction data for wall jets, the velocity profiles have been satisfactorily expressed in terms of variables in the law of the wall and the defect law. No effect of transverse curvature is observed. An analytical model based upon conservation of momentum in the axial direction has been developed to predict the longitudinal decay of the maximum velocity. The experimental data conform to the trends of the predictions.

Heattresistant material testing unit

Abstract: PURPOSE:To make it possible to simulate the thermal environment, which is applied to the nozzle of a rocket motor at a high altitude, on the ground, by using a tested material for the nozzle skirt or the nozzle skirt internal layer to form the nozzle and by connecting a diffuser and a gas generating unit to the front and the rear respectively and by forming a low-pressure part in the diffuser. CONSTITUTION:Cylindrical diffuser 6 is connected to the rear of ultrasonic nozzle assembling material 1, which has nozzle skirt inside layer 2 formed with a tested material, for example, a phenolic plastic material, by flange 8, and gas generating unit 10 is fixed to the front of material 1 by screwing in 12, and assembling material 1 is constituted by fixing nozzle throat 14 consisting of graphite materials and so on and nozzle skirt inside layer 2 to box body 5. The nozzle aperture ratio and L/D of the diffuser are so set that an impulsive wave may be generated in the diffuser and may be moved to the back stream to form a low-pressure region in the diffuser. As a result, the thermal environment applied to the nozzle at a high altitude can be simulated on the ground.

Entrainment and thrust augmentation in pulsatile ejector flows

Abstract: This study comprised direct thrust measurements, flow visualization by use of a spark shadowgraph technique, and mean and fluctuating velocity measurements with a pitot tube and linearized constant temperature hot-wire anemometry respectively. A gain in thrust of as much as 10 to 15% was observed for the pulsatile ejector flow as compared to the steady flow configuration. From the velocity profile measurements, it is concluded that this enhanced augmentation for pulsatile flow as compared to a nonpulsatile one was accomplished by a corresponding increased entrainment by the primary jet flow. It is also concluded that the augmentation and total entrainment by a constant area ejector critically depends upon the inlet geometry of the ejector. Experiments were performed to evaluate the influence of primary jet to ejector area ratio, ejector length, and presence of a diffuser on pulsatile ejector performance.

Return bend of single shaft multistage centrifugal compressor

Abstract: PURPOSE:To prevent separation of the laminar flow occuring in the inner wall side of a return bend and loss due to the separation, by providing a plurality of protrusions on the inner wall face of a return bend that communicates the diffuser and return channel between impellers in each stage CONSTITUTION:A plural of impellers 2 and 3 are mounted on a rotating shaft 1 and between the impellers 2 and 3 of each stage a diffuser 4, return channel 6 and return head 5 communicating the diffuser 4 and channel 6 are provided On the inner face of the wall of the return bend 5 a plurality of protrusions 19 are provided These protrusions 19 can be triangular (column or cone), rectangular (column) or circular shaped, and they are arranged as needed in the circumferential and axial directions By this arrangement, the boundary layer on the face of the inner wall is given turbulence and it nullifies the tendency of laminar flow under the influence of centrifugal force in the boundary layer in the inner wall side and prevents separation of fluid flow or greatly weaken the extent of separation

Nearfield Performance of River Diffusers

Abstract: The flowfield induced by a submerged multiport diffuser discharging across part of the width of a river is considered. A mathematical model is formulated for the flow in the nearfield region of a diffuser plume centered in a rectangular channel. The model is used to determine nearfield dilution as a function of effluent and ambient flow parameters. A family of dilution curves is presented for a range of conditions characteristic of prototype river diffusers. A method is given for applying the mathematical model to diffuser-induced flowfields in rivers. The model is also compared with measurements made in the Mississippi River downstream from the Quad Cities Nuclear Power Station diffuser.

Temp. operated ventilation flap controller - has bellows extended by expanding fluid, with rod controlling swinging arm connected to flaps

Abstract: The automatically operating device for controlling swinging flaps for air conditioning grids, is operated by temperature changes. It carries a swinging arm (29) which can be connected to a support with the flaps attached. The flaps control discharge through an overhead air diffuser, to concentrate or diffuse the discharged air or a vertical diffuser, to control the angle of discharge. The device can have a cylinder with a lower part (13) forming a chamber for a fluid (15) which expands when heated. This part carries horizontal fins (33). The upper part houses a bellows (17) against which the fluid can act, extending it when expanded, lifting an arm (25) on top, which tilts the swinging arm. A return spring (23) fits around a piston (19) enclosing the top of the bellows.

Exhausting device for internal combustion engine

Abstract: PURPOSE:To convert kinetic energy possessed by exhaust gas effectively into pressure energy, by forming a diffuser around an exhaust-gas reservoir in a unitary manner. CONSTITUTION:The diffuser 3 is formed around the exhaust-gas reservoir 4 in a unitary manner and communicated to the reservoir 4 through an opening 4a formed at the upper part of the exhaust-gas reservoir 4. High-speed exhaust gas discharged from exhaust valves 1 disposed in a cylinder cover 10 is carried via an exhaust gas passage 2 and diffuser 3 to the exhaust-gas reservoir 4, where are velocity of the exhaust gas is lowered. The exhaust gas is discharged to the outside of engine after being used for driving an exhaust gas turbine for a supercharger 5. Thus, kinetic energy possessed by exhaust gas can be converted most effectively into pressure enregy since the entire length of the diffuser 3 can be made as long as possible.