Investigation of the Axial Velocity Density Ratio in a High Turning Cascade

1975 ◽  
Author(s):  
H. Starken ◽  
F. A. E. Breugelmans ◽  
P. Schimming
Keyword(s):  
Axial Velocity ◽  
Density Ratio ◽  
Two Dimensional ◽  
Flow Conditions ◽  
Circular Arc ◽  
Blade Row ◽  
Two Dimensional Flow ◽  
Blade Section ◽  
Stator Blade ◽  
Density Ratios

Subsonic cascade tests of a stator blade row are presented. A 48-deg cambered double circular arc blade section has been investigated at different inlet Mach numbers (M1 = 0.5, 0.64, 0.74), different inlet flow angles and various axial velocity density ratios. Optimum cascade performance has been obtained at negative incidence angles and near two-dimensional flow condition. The cascade results are compared with stator tests of the same blade section at corresponding flow conditions.

The Effect of the Axial Velocity Density Ratio on the Aerodynamic Coefficients of Compressor Cascades

1981 ◽  
Vol 103 (1) ◽  
pp. 210-219 ◽  
Author(s):  
J. Starke
Keyword(s):  
Axial Velocity ◽  
Density Ratio ◽  
Compressor Blade ◽  
Momentum Thickness ◽  
Two Dimensional ◽  
Aerodynamic Coefficients ◽  
Minimum Loss ◽  
Turning Angle ◽  
Two Dimensional Flow ◽  
Inlet Angle

The aerodynamic coefficients of compressor blade sections in two-dimensional flow can easily and very accurately be determined by use of the well-known Lieblein correlations. The flow across the compressor blade sections is often quasi-two-dimensional with the axial velocity density ratio (AVDR) differing from unity. To establish simple correlations for this type of flow as well, the AVDR effect on the aerodynamic coefficients of compressor cascades is theoretically and experimentally investigated. This results in simple but accurate formulae for the calculation of the AVDR effect on the turning angle, the reference minimum-loss inlet angle, and the losses in terms of the wake momentum thickness and the diffusion ratio.

scholarly journals The Effect of the Axial Velocity Density Ratio on the Aerodynamic Coefficients of Compressor Cascades

1980 ◽  
Author(s):  
J. Starke
Keyword(s):  
Axial Velocity ◽  
Density Ratio ◽  
Compressor Blade ◽  
Momentum Thickness ◽  
Two Dimensional ◽  
Aerodynamic Coefficients ◽  
Minimum Loss ◽  
Turning Angle ◽  
Two Dimensional Flow ◽  
Inlet Angle

The aerodynamic coefficients of compressor blade sections in two-dimensional flow can easily and very accurately be determined by use of the well-known Lieblein correlations. Very often the flow across the compressor blade sections is quasi-two-dimensional with the axial velocity density ratio (AVDR) differing from unity. To establish simple correlations for this type of flow as well, the AVDR effect on the aerodynamic coefficients of compressor cascades is theoretically and experimentally investigated. This results in simple but accurate formulas for the calculation of the AVDR effect on the turning angle, the reference minimum-loss inlet angle, and the losses in terms of the wake momentum thickness and the diffusion ratio.

scholarly journals Generalized two-dimensional Lagally theorem with free vortices and its application to fluid–body interaction problems

2012 ◽  
Vol 698 ◽  
pp. 73-92 ◽  
Author(s):  
C. T. Wu ◽  
F.-L. Yang ◽  
D. L. Young
Keyword(s):  
Hydrodynamic Force ◽  
Density Ratio ◽  
Vortex Pair ◽  
The Body ◽  
Body Motion ◽  
Liquid Density ◽  
Two Dimensional ◽  
Fixed Target ◽  
Two Dimensional Flow ◽  
Neutrally Buoyant

AbstractThe Lagally theorem describes the unsteady hydrodynamic force on a rigid body exhibiting arbitrary motion in an inviscid and incompressible fluid by the properties of the singularities employed to generate the flow and the body motion and to meet the boundary condition. So far, only sources and dipoles have been considered, and the present work extends the theorem to include free vortices in a two-dimensional flow. The present extension is validated by reproducing the system dynamics or the force evolution of three literature problems: (i) a free cylinder interacting with a free vortex; (ii) the moving Föppl problem; and (iii) a cylinder in constant normal approach to a fixed identical cylinder. This work further extends the bifurcation analysis on the moving Föppl problem by including the solid-to-liquid density ratio as a new parameter, in addition to the system total impulse and the vortex strength. We then apply the theorem to the problem where a moving Föppl system is made to approach a fixed or a free neutrally buoyant target cylinder of identical size from far away. The force developed on each cylinder is examined with respect to the vortex pair configuration and the target mobility. When approaching a fixed target, a greater force is developed if the vortex pair has stronger circulation and larger structure. The mobility of the target cylinder, however, can modify the hydrodynamic force by reducing its magnitude and reversing the force ordering with respect to the vortex pair configuration found for the case with fixed target. Possible mechanisms for such a change of force nature are given based on the currently derived equation of motion.

Universality of finger growth in two-dimensional Rayleigh–Taylor and Richtmyer–Meshkov instabilities with all density ratios

2015 ◽  
Vol 786 ◽  
pp. 47-61 ◽  
Author(s):  
Qiang Zhang ◽  
Wenxuan Guo
Keyword(s):  
Density Ratio ◽  
Classical Problem ◽  
Significant Feature ◽  
Dimensional System ◽  
Surprising Result ◽  
Universal Curve ◽  
Two Dimensional ◽  
Past Half Century ◽  
Theoretical Predictions ◽  
Density Ratios

Interfacial fluid mixing driven by an external acceleration or a shock wave are common phenomena known as Rayleigh–Taylor instability and Richtmyer–Meshkov instability, respectively. The most significant feature of these instabilities is the penetrations of heavy (light) fluid into light (heavy) fluid known as spikes (bubbles). The study of the growth rate of these fingers is a classical problem in fundamental science and has important applications. Research on this topic has been very active over the past half-century. In contrast to the well-known phenomena that spikes and bubbles can have quantitatively, even qualitatively, different behaviours, we report a surprising result for fingers in a two-dimensional system: in terms of scaled dimensionless variables, all spikes and bubbles at any density ratio closely follow a universal curve, up through a pre-asymptotic stage. Such universality holds not only among bubbles and among spikes of different density ratios, but also between bubbles and spikes of different density ratios. The data from numerical simulations show good agreement with our theoretical predictions.

Design and Performance Evaluation of Four Transonic Compressor Rotors

1971 ◽  
Vol 93 (1) ◽  
pp. 33-41 ◽  
Author(s):  
J. P. Gostelow
Keyword(s):  
The Other ◽  
Peak Efficiency ◽  
Design Efficiency ◽  
Circular Arc ◽  
Diffusion Factor ◽  
Transonic Compressor ◽  
Blade Row ◽  
Blade Section ◽  
And Performance ◽  
Blade Element

A set of four compressor rotors was designed as a means of optimizing blade camberline shape in the high-transonic Mach number region. One blade row was designed for a tip diffusion factor of 0.35 with the supersonic camber minimized. The other three blade rows were designed for a tip diffusion factor of 0.45 with tip ratios of supersonic to total camber varying from zero to the value corresponding to a double-circular-arc blade section. Performance maps and blade element data were generated as a result of testing on the four rotors. All rotors exceeded design efficiency and flow at conditions corresponding to design point operation. Operating range, from peak efficiency to stall, is highest in rotors designed for a low tip diffusion factor and which have the minimum amount of supersonic camber.

Effect of Separation on Partial Cavitation

1988 ◽  
Vol 110 (2) ◽  
pp. 182-189 ◽  
Author(s):  
C. Pellone ◽  
A. Rowe
Keyword(s):  
Boundary Layer ◽  
Calculation Method ◽  
Cavitating Flow ◽  
Experimental Results ◽  
Separation Point ◽  
Two Dimensional ◽  
Flow Conditions ◽  
Partial Cavitation ◽  
Two Dimensional Flow ◽  
Cavitating Hydrofoil

Partially cavitating flow around a hydrofoil in a confined two-dimensional flow is presented. The calculation method, based on the singularities technique combined with a minimisation method, is adapted to open configurations. With this extension, cavity wakes not necessarily merging with the upper-side of the foil can be treated. In the case of subcavitating flow, a boundary layer calculated is made, indicating a separation point downstream of which the flow becomes separated. In this area, an imaginary streamline (wake) is introduced to simulate the effect of separation. The choice of different forms of wake clearly shows the influence of wake form on the value of results. The process is extended to the case of cavitating flow for wakes developing behind the cavity. The method is applied to a test cavitating hydrofoil placed in a tunnel. Several cavity wakes progressively diverging from the foil were tested. The results obtained, compared with experimental results, show the great importance of achieving more accurate modelling of flow conditions behind cavities.

Effect of Axial Velocity Variation in Aerofoil Cascades

1971 ◽  
Vol 13 (2) ◽  
pp. 92-99 ◽  
Author(s):  
S. Soundranayagam
Keyword(s):  
Wind Tunnel ◽  
Incompressible Flow ◽  
Axial Velocity ◽  
Three Dimensional ◽  
Velocity Variation ◽  
Two Dimensional ◽  
Dimensional Flow ◽  
Two Dimensional Flow ◽  
Wind Tunnel Data ◽  
Flow Through

The effect of the variation of axial velocity in the incompressible flow through a cascade of aerofoils is discussed and it is shown that changes take place in the flow angles and in the blade circulation. A method is proposed by which the effect of axial velocity variation on a known two-dimensional flow or alternatively the two-dimensional equivalent of a flow with axial velocity variation can be calculated. The method is very easy to apply. The deviation may increase or decrease depending on the change in blade circulation and the stagger. An increase in apparent deflection through the cascade can be accompanied by a reduction in the blade force. The method would be particularly useful for the interpretation of cascade wind tunnel data and in the design of impeller stages where three-dimensional flows occur.

Choking Effects in the Blade Rows of Turbomachines

1980 ◽  
Vol 22 (4) ◽  
pp. 161-173 ◽  
Author(s):  
J. H. Horlock
Keyword(s):  
Shear Flows ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Entry And Exit ◽  
Transonic Compressor ◽  
Dimensional Flow ◽  
Blade Row ◽  
Two Dimensional Flow ◽  
Flow Through

Three-dimensional flows through cascades of blades are studied, the blading being fully choked internally. Initially the two-dimensional flow through a ‘zero stagger, zero camber’ blade row, with subsonic entry and exit flow, is described. The radial flows are produced by radial variations in throat area, or by a variety of entry shear flows. Subsequently, the analysis is developed to describe similar fully choked flows through staggered blade rows, particularly the first rotating row of a transonic compressor.

scholarly journals Asymmetric Inlet Flow in Axial Turbomachines

1964 ◽  
Vol 86 (1) ◽  
pp. 18-28 ◽  
Author(s):  
Barry S. Seidel
Keyword(s):  
Equations Of Motion ◽  
Present Theory ◽  
Two Dimensional ◽  
Previous Theory ◽  
Flow Equations ◽  
Compressor Rotor ◽  
Spacing Ratio ◽  
Blade Row ◽  
Two Dimensional Flow ◽  
Flow Through

A modified actuator disk analysis is made which, through an improved prediction of the blade forces, attempts to give closer correspondence with experiment than the previous theory. The fluid is assumed inviscid and incompressible. Perturbations to the two-dimensional flow through an isolated blade row are considered. The steady flow equations of motion and continuity are linearized. According to experiments conducted on an isolated compressor rotor, the present theory offers an improvement, compared to previous theory, in the prediction of distortion attenuation, effects of flow rate, and effects of varying chord/spacing ratio.

Experimental Cascade Analysis of a Transonic Compressor Rotor Blade Section

1984 ◽  
Vol 106 (2) ◽  
pp. 288-294 ◽  
Author(s):  
H. A. Schreiber ◽  
H. Starken
Keyword(s):  
Rotor Blade ◽  
Flow Behavior ◽  
Density Ratio ◽  
Axial Flow ◽  
Flow Angle ◽  
Transonic Compressor ◽  
Compressor Rotor ◽  
Blade Row ◽  
Blade Section ◽  
Transonic Cascade

A transonic compressor rotor blade cascade was tested in order to elucidate the flow behavior in the transonic regime and to determine the performance characteristic in the whole operating range of a rotor blade section. The experiments have been conducted in a transonic cascade wind tunnel, which enables tests even at sonic inlet velocities. The influence of the upstream Mach number between 0.8 and 1.1 and the inlet flow angle between choking and stalling of the blade row was investigated. The effect of the axial velocity density ratio (AVDR) could be studied by applying an endwall suction device. Furthermore, the level of the shock losses was determined from a wake analysis. A final comparison of cascade losses and those of the corresponding rotor blade element shows good agreement which underlines the applicability of the cascade model in the design of axial flow turbomachines.

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