Showing papers on "Diffuser (thermodynamics) published in 1970"

Axial flow diffuser

Abstract: A vaneless diffuser for turbomachinery wherein a pair of spacedapart walls form three annular diffuser portions along a generally cylindrical downstream flow path. The walls converge together within a diffuser inlet portion, then diverge within a diffuser intermediate portion with a diffuser outlet portion being configured to maintain a condition of imminent boundary layer separation established by the first two portions. Although the diffuser is particularly described with reference to a cylindrical flow path, the flow path may also be generally conical for use in mixed flow turbomachinery, for example.

Internal Hydraulics of Thermal Discharge Diffusers

Abstract: The TVA Browns Ferry Nuclear Plant will discharge its heated condenser cooling water into the Wheeler Reservoir. To protect the plant, and to keep within state and federal temperature limits, the warm effluent will be mixed with the reservoir water through a subsurface diffuser system. The diffusers consist of three approximately 20-ft diameter corrugated steel pipes each with 7,800 2-in. holes in the wall through which all the warm water discharges. The multiple discharge jets create turbulence which promotes the mixing. The writers describe a model study from which was obtained the discharge coefficient for lateral flow through holes drilled in the valley—as viewed from inside the pipe—of the corrugations. Tests were made for various hole sizes and numbers of holes in the axial and circumferential direction. Also described is the method used to compute the pipe diameter and hole configuration necessary to obtain uniform spatial distribution of discharge for a given flow rate and head. A description is included of the diffuser system recommended for the Browns Ferry installation.

Ejector apparatus and method of utilizing same

Abstract: A compound ejector apparatus comprising a primary nozzle, primary mixing chamber, secondary nozzle, secondary mixing chamber and diffuser, the primary nozzle functioning mainly as a super charger and the secondary nozzle functioning mainly as a mixer and which furnishes a major portion of the kinetic energy for the compression work taking place in the diffuser, each nozzle being supplied with a part of the motive fluid, wherein the motive fluid supplied to the secondary nozzle has a higher pressure than that supplied to the primary nozzle and wherein the amount of motive fluid supplied to the primary nozzle is only a small part of the total motive fluid supplied to the apparatus.

Ducted spike diffuser

Abstract: A ducted spike diffuser for reducing forebody drag and rain erosion of blunt bodies operating at supersonic speeds. The spike has a directed conical front section to receive high-pressure oncoming air. This air is ejected at substantially right angles to the freeflow from an annular gap at the rear of the conical front section. This not only decreases pressure drag on the conical section but causes the conical bow shock wave-shear layer to occur radially further from the blunt body, resulting in better rain dispersion and decreased erosion of the blunt body.

Diffuser including vaneless and vaned sections

Abstract: A diffuser for use in turbomachinery to improve overall efficiency, the diffuser including a vaneless diffuser section for reducing supersonic fluid flow to subsonic speed and a multichannel diffuser section for achieving maximum pressure recovery and delivering the fluid to a suitable collector, one of the diffuser sections providing a flow path of decreasing and then increasing cross section configured to minimize boundary layer losses.

Diffuser valve mechanism for centrifugal gas compressor

Abstract: AN ANNULAR SUPPORT MEMBER IS FIXEDLY MOUNTED CONCENTRICALLY OF THE IMPELLER AND HAS AN ANNULAR SURFACE FORMING ONE SIDE WALL OF THE DIFFUSER PASSAGE. A SLEEVE VALVE IS MOUNTED AT THE BORE OF THE SUPPORT MEMBER FOR MOVEMENT TRANSVERSELY OF THE DIFFUSER PASSAGE. A VALVE ACTUATING MECHANISM IS CARRIED BY THE SUPPORT MEMBER AND OPERABLE EXTERIORLY OF THE MACHINE CASING FOR MOVING THE VALVE TRANSVERSELY OF THE DIFFUSER PASSAGE. THE VALVE ACTUATING MECHANISM INCLUDES A PLURALITY OF CRANKSHAFTS JOURNALED FOR ROTATION IN THE SUPPORT. A DRIVE SHAFT IS PROVIDED TO EFFECT ROTATION OF THE CRANKSHAFTS IN UNISON, THE DRIVE SHAFT HAVING AN END PORTION EXTENDING EXTERIORLY OF THE MACHINE CASING.

Method of changing capacity of fluid reaction device

Abstract: The capacity of a centrifugal compressor having an overhung rotor with a plurality of separate stage impellers is changed by machining the free curved edge of each impeller blade by an equal amount for each impeller along the entire curved edge length from the radially extending axial flow edge to the axially extending radial flow edge. Additional separate shrouds are provided that differ in diameter from the shrouds supplied with the impellers before machining by an amount equal to the diametric change occurring during machining. Further, separate annular diffusers are provided, with each diffuser having integral blades with free terminal edges lying in a common plane perpendicular to the axis of rotation and engaging the adjacent shroud, so that these radially extending diffuser blade edges may be machined by an amount equal to the axial component of machining on the corresponding impeller blades.

Annular combustor systems

Abstract: An annular combustor system is illustrated in a gas turbine engine environment. Compressor discharge air is diffused in a short length diffuser into a closely spaced plenum formed by a bluff bodied, annular array of fuel injectors and the upstream ends of liners which define, in part, an annular combustion zone. The compressor discharge air is evenly distributed in the plenum and then passes through and around the fuel injectors to break up the fuel and support its combustion in a short flame front having a uniform temperature distribution. Plenums surround the liners. Air from the diffuser pressurizes these plenums and is then metered by holes in the liners to provide cooling films on the inner surfaces thereof.

Shock wave sensor

Abstract: As the shock wave in a diffuser passes over a pressure sensing orifice it causes a self-biased fluid amplifier to change state. The position of the shock wave within the diffuser may be determined by detecting the outputs of a plurality of the selfbiased fluid amplifiers and a logic circuit is used to translate this information into a signal which will operate a servomechanism causing a bypass valve in the diffuser to open or close to reposition the shock wave into the desired position.

Rotating Vaneless Diffuser Study.

Abstract: : An analytical and experimental investigation of the free vaneless rotating diffuser concept demonstrated both mechanical feasibility and aerodynamic effectiveness. The objectives of the program were to design, manufacture, and test a model rotating vaneless diffuser in a simulated compressor environment, to measure the performance gains, and to establish and verify an analytical design and performance method. The conclusions of the program are: (1) The free rotating vaneless space diffuser is mechanically feasible; (2) The free rotating vaneless space diffuser reduces diffusion losses by an amount depending on compressor pressure ratio and specific speed; (3) The analytical predictions of loss reduction were verified; (4) The exit traverse test results support the argument that the rotating diffuser will tend to smooth out distorted inlet flow profiles. (Author)

Radial inflow turbine performance with an exit diffuser designed for linear static pressure variation

Abstract: Radial inflow turbine performance with exit diffuser designed for linear static pressure variation

Improved air velocity measuring system and method for its calibration

Abstract: A rapid response air velocity measuring system having a shunting probe adapted to be placed into a flow of air and coupled to a measuring apparatus, such as an air flow meter. A handle portion as constructed to receive the shunting probe as well as other forms of probes, such as diffuser probes, and couple the probe to the measuring apparatus. A range adjusting switch is mounted in the handle portion and places one of a plurality of resistances, in the form of one of a plurality of needle valves, into the path of the air flow trough the measuring apparatus. Push button vent means also is carried in the handle portion for enabling the system to employ diffuser as well as shunting probes. The probes are fine tuned and specially calibrated to a pitot standard, then the probes, the range adjusting switch, and the measuring apparatus are calibrated to the pitot standard as a system. Once calibrated, the individual elements of the system are interchangeable with the corresponding elements of similarly pitot-calibrated, mass produced systems, without requiring subsequent recalibration of each system.

Centrifugal and mixed flow discharge apparatus

Abstract: 1,205,514. Centrifugal and mixed-flow compressors and pumps. UNITED AIRCRAFT OF CANADA Ltd. June 20, 1968, No.29479/68. Heading F1C. In the compressor or pump described in Specification 1,040,385, the extension means 31 for directing the flow from the diffuser passages 24 from an initial direction circumferentially and radially outward from the axis of the impeller 10 to a subsequent direction having an axial component each comprise an inner tube 32 and an outer tube 33, the inner tube being straight and the tubes being separately formed. Each outer tube 33 has a substantially right-angle bend and tapers constantly from its inner end to its outer end, the outer end being of an elliptical or flattened cross-section.

Valve flow transition

Abstract: A valve construction in which the flow transition region extending from a valve port to the end of the valve body comprises a diffuser section diverging to give cross-sectional area change equivalent to that produced in a cone with an included cone angle of from 6* to less than 20* from the port to a location at or near the end of the body where it terminates in an abrupt discontinuous section which enlarges the flow transition region substantially to the flow area of the conduit to which the valve is connected.

A procedure for the calculation of boundary layers confined in ducts

Abstract: It is shown that confined boundary layers can be calculated by a marching-integration procedure, if the unknown pressure gradient is determined from a formula valid for one-dimensional flow, and account is taken, in subsequent steps, of errors in the pressure gradients employed in earlier steps. The errors can be held down to any desired magnitude. The method is illustrated by reference to turbulent pipe flow and to the plane diffuser; calculations are provided of friction coefficients, Stanton numbers, and velocity and temperature profiles. Some comparisons with experiment are provided.

Determination of the Position of the Supersonic Flow Closing Shock Wave in the Channels of an Air-Breathing Jet Engine

Abstract: The following problems are planned to be discussed in the paper: (1) Static stability of the closing shock in the diffuser and the nozzle. (2) Interaction of the shock wave with the turbulent and boundary layers. (3) Limiting pressure ratios for a bridgelike shock.

Fire extinguishing foam

Abstract: 1,207,506. Foam generator; spray producers. E. HAFTKE. 13 June, 1968 [22 June, 1967], No. 28944/67. Headings B1C and B2F. A foam generator has a coupling 2 for connection to a source of foam-forming liquid under pressure, a cylindrical mixing chamber 1 of uniform cross-section A, a liquid diffuser tube 3, an intermediate chamber 6 of volume V and increasing diameter, and a delivery nozzle 8 of decreasing diameter and volume 2V/5 the cross-section of the outlet being 6/5 A. There are air intakes 4, 5 in the mixing chamber and a gauze or perforate plate baffle 7 in the intermediate chamber. The apparatus provides a foam of air/water ratio of 9:1.

Thermal Effects on Separation of Flow

Abstract: Publisher Summary This chapter highlights thermal effects on separation of flow. The heat transfer of separated flows at subsonic speeds is important for the design of heat-transfer equipment. But with increases of speed of airborne vehicles, the aerodynamic heating becomes very important in the estimation of spoiler effectiveness, hinge moment of flap-type controls when flow separation is present, and diffuser performance. The chapter also explores the position of compressible flow separation and heat transfer on separated flow at supersonic and hypersonic speeds. Because of flow separation, a hot spot exists in a particular region such as reattachment and the heat transfer of the separated flow attracts attention. Various analytical investigations of thermal effects on flow separation have been concerned mostly with laminar flow.

Gas turbine engine

Abstract: 1,210,113. Gas turbine engine combustion chambers. GENERAL ELECTRIC CO. Jan. 25, 1968, No.3929/68. Heading F1L. The invention relates to a means for improving air flow from the compressor outlet diffuser of a gas turbine engine to the combustion section thereof. The outlet diffuser of an axial flow compressor is defined by mutually divergent outer wall 24 and inner wall 26, vanes 27 being disposed between the walls. The compressor outlet guide vanes are indicated at 20. The combustion section comprises outer and inner annular walls 40, 42 and outer and inner annular flame tube walls 44, 46, the flame tube walls being inter-connected adjacent their upstream ends by wall 48 through which fuel burners 52 project. The upstream portions 40a, 42u of the combustion chamber walls 40, 42 are mutually divergent, the wall portions being connected to the diffuser walls 24, 26 at 40b, 42b respectively, the junctures being formed as sharp angles. The upstream portions 44a, 46a of the flame tube walls are also mutually divergent, the upstream ends thereof being indicated at 44b, 46b. The adjacent wall portions 40a, 44a define a divergent air flow path as indicated by arrow V and the flame tube wall extends at least to the plane B-B, Fig. 3 which is normal to the air flow path V and passes through the point 40b where the diffuser wall 24 and combustion chamber wall portion 40a meet. The flame tube wall 44a preferably extends beyond the plane B-B by a distance 0A1 to 0.3 h where h is one half the radial height H at the outlet of the diffuser. The spacing between the wall portions 40a and 44a is between 0.8 to 1A0h and the wall portions 40a and 44a are parallel for a length 2h. The angle α between the walls 24 and 40a is between 135 degrees and 145 degrees. The air flow breaks away from the wall 40a as indicated at s. The ratio of the outlet to inlet area of the diffuser is between 1.6 and 1.7.

Flow Field Analysis and Performance Assessment Inside a Vanned Diffuser of a Laboratory-Type Centrifugal Pump

Abstract: The paper refers to the analysis of flow fields inside a vaned diffuser and performance assessment of a laboratory-type centrifugal pump operating with air. The study deals with numerical simulation of the flow at design flow rate, with focus on velocity and pressure distributions across a diffuser passage. The aim is to highlight the flow structure how it leaves the impeller and evolves through the diffuser to understand the mechanism of pressure recovery. The performance assessment consists of evaluating diffuser effectiveness. The numerical results are compared to experimental measurements for validation.