Showing papers on "Axial compressor published in 1973"

Gas turbine theory

Abstract: 1. Introduction 2. Shaft power cycles 3. Gas turbine cycles for aircraft propulsion 4. Centrifugal compressors 5. Axial flow compressors 6. Combustion systems 7 Axial and radial flow turbines 8. Prediction of performance of simple gas turbines 9. Prediction of performance - further topics Appendix A Some notes on gas dynamics Appendix B Problems Appendix C References Index

Axial Flow in Laminar Trailing Vortices

Abstract: The structure of laminar trailing vortices behind a lifting wing is considered The inviscid roll up of the trailing vortex sheet is examined, and the nature of the singularity at the centre of the spiral is determined It is shown that viscosity removes the singularity and the structure of the viscous core is obtained The pressure in the viscous core is found and used to calculate the axial velocities produced by streamwise pressure gradients It is found that the perturbation of axial velocity can be either away from the wing or towards the wing depending on the distribution of tip loading on the wing For elliptic loading, the perturbation is towards the wing The axial flow deficit in the core due to the boundary layers on the wing is also estimated A comparison with experiment is made and reasonable agreement is found

Small Turbomachinery Compressor and Fan Aerodynamics

Abstract: This paper discusses aerodynamic considerations in the design of small turbomachinery axial and centrifugal compressors and fans. Test results are presented to show the effect of scaling on compressor performance. Correlations are presented which relate compressor efficiency to Reynolds Number and clearance. It is shown that clearance effects are more prominent when scaling designs, and Reynolds Number effects are more prominent as density is lowered.

Stall protector system for a gas turbine engine

Abstract: A stall protector system is provided for a gas turbine engine wherein the compressor pressure is measured, differentiated, and compared with a reference indicative of the maximum rate at which the compressor pressure decreases during normal operation. When the actual rate of decrease of compressor pressure exceeds the reference rate, then the signal is integrated and compared with a second reference indicative of the minimum change in compressor pressure before a stall occurs. If the second reference is exceeded, the fuel flow to the combustor is automatically restricted.

Abating exhaust noises in jet engines

Abstract: A noise abating improvement for jet engines including the provision of apparatus in the primary flow stream of gas turbine engines such as turbojet, turbofan, turboprop, and other jet engines such as ram jets, scram jets and hybrid jet engines, or in either the primary and/or secondary flow streams of turbofan engines or the like, for imparting to the exhaust gases a component rotation or swirl about the engine''s longitudinal axis. The rotary component in the exhaust gases has the effect of substantially suppressing the build up on sound energy normally produced by an axial flow exhaust system.

High energy axial flow transfer stage

Abstract: Axial flow apparatus for transferring substantial energy to a fluid utilizing a stage having two sets of pluralities of blades secured to and extending radially from a rotor. The first set of energy adding blades, called the main blades, incorporates an airfoil section that is warped or twisted from its root at the rotor to its tip adjacent the housing. The airfoil shape and other design characteristics of the main blades may be conventional and of the type commonly found in axial flow pumps, blowers, and compressors. A second plurality of energy adding blades, which may be referred to as auxiliary blades, is provided and is positioned downstream from the main blades without intervening stationary vanes and may be located either directly behind corresponding main blades or may be circumferentially displaced forward or backward in the direction of blade travel. The leading edges of the auxiliary blades are angled with respect to, or are not parallel, to the trailing edges of the main blades. The blades are warped or twisted from a root cross section that exhibits a chord forming an angle of greater than 90* with the plane of rotation of the blades. The trailing edge of the auxiliary blades at the respective blade roots is thus placed away from the main blades and points into the direction of rotation.

Dynamoelectric machine ventilating system

Abstract: A dynamoelectric machine, such as a salient pole motor, wherein a cooling fluid, typically air, is directed through a plurality of substantially radial ducts extending through the field windings or the rotor. A flow of fluid coolant is provided by suitable means, such as a fan or blower apparatus. The axial flow of coolant fluid is directed through a plurality of radial ducts disposed in the field windings of the rotor by means of a baffle and an axial header. The axial flow of coolant fluid may also be introduced into a central passage in the rotor shaft, with a plurality of radial conduits in the shaft directing the fluid coolant through the radial ducts in the field windings of the rotor. The coolant fluid is either collected by an axial discharge header and directed into an interpolar spaces lying between the plurality of pole pieces which comprise the rotor, or permitted to pass through a plurality of radial passages extending through the pole pieces of the rotor.

Stability of a viscous fluid between rotating cylinders with axial flow and pressure gradient round the cylinders

Abstract: The stability of a viscous fluid between two concentric cylinders with an axial flow is investigated for the case in which the azimuthal velocity is the sum of a velocity distribution due to the rotation of the cylinders and a “pumping” velocity distribution due to the pressure gradient acting round the cylinders. The outer cylinder is stationary and the spacing between the cylinders is assumed small. For various small Reynolds numbers associated with the axial flow the Taylor number is computed for a large range of values of the ratio of the average pumping velocity to the average velocity of the rotation.

Blading for axial flow turbo-machine

Abstract: Turbine blading for the rotors of turbo-machines of the axialflow type in which the blades are twisted to allow for a high ratio of external to internal diameter of the flow passageway, the amount of the twist being so selected that it will neither untwist nor increase its twist when subjected to the centrifugal forces which act on the blade when the rotor is operating.

FORTRAN program for calculating velocities and streamlines on the hub-shroud mid-channel flow surface of an axial-or mixed-flow turbomachine. 2: Programmer's manual

Abstract: A FORTRAN-IV computer program, MERIDL, has been developed that obtains a subsonic or shock-free transonic flow solution on the hub-shroud mid-channel flow surface of a turbomachine. The blade row may be fixed or rotating and may be twisted and leaned. Flow may be axial or mixed, up to 45 deg from axial. Upstream and downstream flow variables can vary from hub to shroud, and provision is made to correct for loss of stagnation pressure. The results include velocities, streamlines, and flow angles on the flow surface and approximate blade surface velocities. Subsonic solutions are obtained by a finite-difference stream-function solution. Transonic solutions are obtained by a velocity-gradient method, using information from a finite-difference stream-function solution at a reduced mass flow.

An Investigation of Supersonic Swirling Jets

Abstract: A theoretical and experimental investigation has been made into the effect of swirl on a supersonic jet. In certain circumstances a core of reversed flow can occur along the axis of symmetry and the jet mixes much more quickly with the ambient air than does the corresponding non-rotating jet. A characteristic calculation has been performed for the first cell in the case where the axial flow is not reversed. This indicates a shortening of the cell length and the formation of shocks nearer the nozzle.

Some aspects of inlet/engine flow compatibility

Abstract: The aim of this paper is to contribute to the growing subject of inlet/engine compatibility a discussion of some of the more interesting results of research and development testing of rig compressors and engines carried out at the Bristol Engine Division of Rolls-Royce (1971) Ltd, and to discuss these against a now extensive background literature. The effects of an inlet system on an axial flow gas turbine are principally on performance, stability and mechanical integrity. In this paper attention is focused on the effects of total pressure distortion on the compressor system's performance and stability.

Investigation of Rotating Stall in Axial Flow Compressors and the Development of a Prototype Rotating Stall Control System

Abstract: : The report summarizes the results of a three year program on rotating stall in axial flow compressors conducted at Calspan Corporation (formerly Cornell Aeronautical Laboratory). The work encompassed both experimental and theoretical investigations of rotating stall and the development of a prototype rotating stall control system. The experimental portion of the program included investigation of the effects of blade chord and solidity upon rotating stall properties and inception as well as an investigation of the effect of blade row rotation on blade row performance. In addition, an experiment to determine the stability of the flow through a blade row was conducted. A two-dimensional small-disturbance stability theory was developed to predict the inception of rotating stall. A single balde row and two blade row version of the theory were developed.

Upstream Attenuation and Quasi-Steady Rotor Lift Fluctuations in Asymmetric Flows in Axial Compressors

Abstract: This paper examines the quasi-steady lift variations experienced by a compressor rotor working in a circumferential inlet flow distortion. It is shown that for a given axial velocity distortion at the compressor face, the phase and magnitude of the lift fluctuations are strongly dependent not only on the geometry of the specified rotor, but on the total compressor configuration in which the rotor is operated. A simple numerical example is presented to illustrate this point. It is then demonstrated that the differences in the rotor lift fluctuation occur due to the upstream circumferential velocity component which is associated with the upstream attenuation of inlet velocity distortion. It is also pointed out that proper consideration of the circumferential component resioves an apparent discrepancy between two previous analyses of this problem. Finally, arguments are presented concerning the influence of the bound (blading) and downstream shed (wake) vorticity on the flow field upstream of the compressor. For the cases considered, it is shown that the induced velocity field associated with the upstream attenuation of inlet flow distortion is due equally to the bound and shed vorticity.Copyright © 1973 by ASME

Unsteady Fluid Dynamic Response of an Axial-Flow Compressor Stage with Distorted Inflow

Abstract: : A nonlinear, large disturbance theory has been developed which couples, interactively, the flow through the blade passages of a turbomachine blade row and an axially distorted flow field. The blade row analysis is based on the time-dependent energy equation of the flow through the passage and includes a nonlinear description of cascade loss and turning correlations from available experimental sources. The flow field analysis involves the nonlinear, time-dependent equations for the vorticity and the stream function. Coupling of the two is accomplished through the boundary conditions by mutual relationships between the pressure change across the blade row and the change in vorticity in the flow field analyses. Within the assumptions that the flow is two- dimensional and incompressible, the numerical solution is capable of predicting the influence of an upstream axial distortion on the onset of a circumferentially rotating stall pattern for a single blade row. The speed of rotation of the stall cell and the spatial attenuation of the distortion wave are also predicted, and although the observed experimental data are generally available only for multistage systems, the predicted results for the single blade row are in qualitively good agreement with the data.

Noise Generated by Low Pressure Axial Fans

Abstract: Noise generated by a fan consists of the rotating noise and the turbulent noise. These two kinds of noise have entirely different characters with respect to decay in an axisymmetric pipe. In this paper the generation and decay of these two kinds of noise are experimentally examined by changing various factors, such as the suction pipe geometry, the location and the thickness of struts, and the combination of the number of impeller blades and the number of struts. The rate of decay of the rotating noise is predictable and in most cases the noise quickly decreases in proportion to the distance from the rotor, providing that the number of impeller blades and the number of struts are properly chosen. Therefore, the noise observeda way from a low pressure axial flow fan is mostly the turbulent noise.

Free turbine pump

Abstract: A free turbine pump for a well including: an axial flow turbine and an axial flow pump interconnected in axially aligned, end-toend relation with the turbine above the pump, the turbine having a power fluid intake adjacent its lower end and having a power fluid exhaust adjacent its upper end for spent power fluid, the pump having a well fluid inlet adjacent its lower end, and having a production fluid outlet adjacent its upper end and adjacent the power fluid intake; and means between the power fluid intake and the production fluid outlet for balancing axial thrust forces on the turbine and pump. This balancing means includes upperwardly and downwardly facing areas to which the production fluid pressure and the power fluid pressure are applied to achieve axial thrust balance.

Performance Characteristics of a Centrifugal Compressor with Air Injection

Abstract: The parameters which influence the performance characteristics of centrifugal compressors with air injection through nozzles at the rotor tip are developed using both dimensional analysis and a simple model. Experiments on a small centrifugal compressor show that the injection air pressure is the main influence on the overall performance such as excess torque, increased delivery pressure and increased delivery flow. With air injection the pressure-mass flow characteristics are displaced to the right with surge occurring at increased total mass flow rates and the overall pressure ratio across the compressor is increased for the same total mass flow.

An Experimental Evaluation of Unsteady Flow Effects on an Axial Compressor. P3 Generator Program

Abstract: : A test program has been successfully completed to obtain fundamental information concerning the behavior of a fan compressor unit when subjected to planar pressure and flow pulses. Testing was conducted at two corrected fan speeds over a range of input pressure amplitudes and frequencies. A total of 24 fan surges and approximately fifty-seven 'steady-state' data points were obtained. The General Electric developed Planar Pressure Pulse Generator (P3G) was used to produce a sinusoidal type pressure disturbance to a current technology two-stage fan inlet. A thorough complement of dynamic instrumentation, consisting of approximately 45 transducers, was utilized throughout the testing. Data reduction is complete and several fundamental results have been obtained.

Gas turbine start-up fuel control system

Abstract: The gas turbine start-up fuel control system provides for a characterizer which is programmed to provide a desired sequential acceleration of the engine in accordance with a signal representing corrected compressor speed. The characterizer functions also to effecting, through a current-to-pressure controller, flow of pressurized fluid, simulating compressor outlet pressure, to a compressor inlet temperature sensor, the latter, in turn, controlling the position of a fuel control valve in relation to compressor inlet temperatures through a servovalve mechanism.

Device for producing angular momentum in a flow of working fluid upstream of the first rotor blade of an axial-flow turbomachine

Abstract: To produce angular momentum in a flow of working fluid at a location of an axial-flow turbomachine upstream of the first rotor blade ring thereof, there is provided a ring space located upstream of the first rotor blade ring in flow direction of a flow of working fluid which acts in axial direction directly upon the first rotor blade ring without first impinging on a preceding guide vane ring, at least one working fluid inlet extending tangentially to and communicating with the ring space, and being provided, if desired, with a throttling member for controlling the flow of working fluid through the working fluid inlet.

The prevention of separation and flow reversal in the corners of compressor blade cascades

Abstract: From tests on tunnel cascades one of the sources of loss in axial compressors could be corner stall, i.e. local separation of the flow in and near the corners between the annulus walls and the convex surfaces of the blades. Tests on a tunnel cascade at entry Mach numbers of 0·5 and 0·6 show that, at least in a tunnel, the stalling may be cured by boundary layer control. The present tests obtain control by suction through a corner slot. The tests show that removal through the slot of 1·3% of the flow decreases the total losses of the cascade by about 25%. A more detailed examination of the losses in the tunnel cascade without suction suggests that about three-quarters of the end losses are due to the separation and reverse flow. Much of the remaining end loss appears to result from the fact that the low energy stream tubes in the entry boundary layer would experience a disproportionately large increase in cross-sectional area during diffusion, even in attached two-dimensional flow. The suction corner control can eliminate the greater part of the end losses, by eliminating the separation.

Overall and blade-element performance of a multiple-circular-arc bladed transonic compressor rotor with tip speed of 1375 feet per second

Abstract: The design and experimental performance of a 20-inch-diameter multiple-circular-arc bladed axial-flow transonic compressor rotor is presented. Radial surveys of the flow conditions were made. At design speed the peak efficiency was 0.882 and occurred at a weight flow of 64.0 pounds per second. At this point the total-pressure and total-temperature ratios were 1.79 and 1.205, respectively. The stall margin at design speed was 8 percent based on weight flows and total-pressure ratios at experimental peak efficiency and near stall. The measured stall margin was 20 percent at design weight flow and speed.

Some aspects of deviation angle estimation for axial-flow compressors

Abstract: Some aspects of deviation angle estimation for axial-flow compressors " (1973). Retrospective Theses and Dissertations. Paper 4960. INFORMATION TO USERS This material was produced from a microfilm copy of the original document. While the most advanced technological means to photograph and reproduce this document have been used, the quality is heavily dependent upon the quality of the original submitted. The following explanation of techniques is provided to help you understand markings or patterns which may appear on this reproduction. 1. The sign or "target" for pages apparently lacking from the document photographed is "Missing Page(s)". If it was possible to obtain the missing page(s) or section, they are spliced into the film along with adjacent pages. This may have necessitated cutting thru an image and duplicating adjacent pages to insure you complete continuity. 2. When an image on the film is obliterated with a large round black mark, it is an indication that the photographer suspected that the copy may have moved during exposure and thus cause a blurred image. You will find a good image of the page in the adjacent frame. 3. When a map, drawing or chart, etc., was part of the material being photographed the photographer followed a definite method in "sectioning" the material. It is customary to begin photoing at the upper left hand corner of a large sheet and to continue photoing from left to right in equal sections with a small overlap. If necessary, sectioning is continued again — beginning below the first row and continuing on until complete. 4. The majority of users indicate that the textual content is of greatest value, however, a somewhat higher quality reproduction could be made from "photographs" if essential to the understanding of the dissertation. Silver prints of "photographs" may be ordered at additional charge by writing the Order Department, giving the catalog number, title, author and specific pages you wish reproduced.

Compressor geometry control apparatus for gas turbine engine

Abstract: A fluid pressure responsive actuator responsive to first and second air pressures, at least one of which is compressor generated and varies as a function of engine speed, and connected to actuate compressor geometry varying means such as compressor pressurized air bleed means or compressor air inlet ''''flow fence or restriction'''' means thereby varying mass air flow through one or more of the compressor stages to avoid characteristic unstable operation of the compressor during an engine acceleration. A compressor bleed valve may be actuated to an open position in response to a predetermined ratio of the first and second air pressures during an engine acceleration to a selected speed and closed in proportion to a decreasing ratio of the first and second air pressures as the engine approaches the selected value. A compressor air inlet ''''flow fence or restriction'''' may be held in a closed position until a predetermined ratio of the first and second air pressures is reached and subsequently opened in proportion to an increasing ratio of the first and second air pressures to cause an increase in effective flow area of the compressor air inlet during an acceleration of the engine to a selected speed.

Centrifugal separator - uses tangential flow to generate vortex in axial flow chamber

Abstract: The parent patent describes an apparatus for centrifugally separating suspended substances from a gaseous or liquid medium; the separated substances are removed axially, the general flow of the fluid being along a curved duct with a vortex zone opening into it on the concave side; so that the remainder of the vortex zone constitutes a semicircle fitting against the concave side. In the patent of addition the curved duct, tangential to the vortex zone, is an endless recirculation duct flowing past and supplying a number of similar vortex zones; it thus continuously generates the vortex in each zone. The medium to be treated is supplied into each zone axially, and the purified liquid is removed from the zone also axially, either in the same direction (i.e. from the opposite end) or in contraflow. The tangential flow used to generate the vortex is a portion of the fluid flow before treatment.

The Design of Axial Compressor Airfoils Using Arbitrary Chamber Lines

Abstract: : The report describes a technique which has been developed for use in the design of axial compressor airfoils with camber lines of arbitrary shape The slope of the camber line at several points on a streamsurface is determined from the air angles at these points as well as the incidence and deviation angle distributions for the blade A camber line is produced by fitting a smooth curve segment through each pair of points from the leading to the trailing edge A thickness distribution is applied to this camber line to produce the blade element A computer program which uses this technique to produce blade elements, stack them, and then determine coordinates for plane surfaces through the resultant blade is also described