A Calculation Procedure for Three-Dimensional, Time-Dependent, Inviscid, Compressible Flow through Turbomachine Blades of any Geometry

1979 ◽  
Vol 21 (1) ◽  
pp. 39-49 ◽  
Author(s):  
C. Bosman ◽  
J. Highton
Keyword(s):  
Secondary Flow ◽  
Compressible Flow ◽  
Subsonic Flow ◽  
Three Dimensional ◽  
Experimental Results ◽  
Time Dependent ◽  
Two Dimensional ◽  
Through Flow ◽  
Flow Through ◽  
Inviscid Compressible Flow

A method for calculating three-dimensional, time-dependent, inviscid, subsonic flow is presented. Application is made to flow through the rotor of a small radial inflow turbine and comparison with conventional through-flow calculations and experimental results is made. The nature of the strong secondary flow in this rotor indicates the probable inadequacy of the two-dimensional calculations which is confirmed by the comparison.

The Compressible Flow Through Cascade Actuator Discs

1958 ◽  
Vol 9 (2) ◽  
pp. 110-130 ◽  
Author(s):  
J. H. Horlock
Keyword(s):  
Shear Flow ◽  
Compressible Flow ◽  
Incompressible Flow ◽  
Three Dimensional ◽  
Approximate Solutions ◽  
Two Dimensional ◽  
Guide Vanes ◽  
The Past ◽  
Flow Through ◽  
Annular Cascade

SummaryA theory of the incompressible flow through two- and three-dimensional cascade actuator discs has been developed by several workers over the past ten years, and its accuracy has been confirmed in several experiments. This theory is briefly reviewed, and a parallel theory for subsonic compressible flow through actuator discs is developed. Approximate solutions for several examples are considered, including a compressible shear flow through a two-dimensional cascade, and a compressible flow through an annular cascade of guide vanes.

Inviscid Flow Through a Cascade of Thick, Cambered Airfoils: Part 2—Compressible Flow

1973 ◽  
Vol 95 (3) ◽  
pp. 227-232 ◽  
Author(s):  
D. A. Frith
Keyword(s):  
Numerical Methods ◽  
Compressible Flow ◽  
Stream Function ◽  
Inviscid Flow ◽  
Two Dimensional ◽  
Regular Array ◽  
Unique Method ◽  
Flow Through ◽  
Grid Points ◽  
Inviscid Compressible Flow

Evaluation of two-dimensional, inviscid, compressible flow through a cascade of airfoils must involve numerical methods. Some of the associated problems are avoided if the flow field is mapped to the interior of a unit circle as the airfoil boundaries become grid points of the regular array in this domain. Further, far upstream and far downstream map to points in this circle so the uniform inlet and outlet flows are simply defined. For a solution obtained in terms of a stream function the compressible flow may be derived as a numerical perturbation from an analytical, incompressible stream function. A method incorporating these features is described in detail and some results for thick, cambered airfoils in cascade are presented. As supersonic patches can exist on the airfoils for high subsonic inlet Mach numbers, a unique method of relating the density to the stream function is employed in order to enable such flows to be calculated.

Nonlinear dynamics of a two dimensional airfoil with freeplay in an inviscid compressible flow

2000 ◽  
Vol 4 (2) ◽  
pp. 125-133 ◽  
Author(s):  
Zoran Dimitrijević ◽  
Guy Daniel Mortchéléwicz ◽  
Fabrice Poirion
Keyword(s):  
Nonlinear Dynamics ◽  
Compressible Flow ◽  
Two Dimensional ◽  
Inviscid Compressible Flow

Upstream motions in stratified flow

1988 ◽  
Vol 187 ◽  
pp. 487-506 ◽  
Author(s):  
I. P. Castro ◽  
W. H. Snyder
Keyword(s):  
Body Height ◽  
Three Dimensional ◽  
Time Dependent ◽  
Experimental Measurements ◽  
Two Dimensional ◽  
Towing Tank ◽  
First Order ◽  
Density Perturbations ◽  
Small Obstacle ◽  
Obstacle Height

In this paper experimental measurements of the time-dependent velocity and density perturbations upstream of obstacles towed through linearly stratified fluid are presented. Attention is concentrated on two-dimensional obstacles which generate turbulent separated wakes at Froude numbers, based on velocity and body height, of less than 0.5. The form of the upstream columnar modes is shown to be largely that of first-order unattenuating disturbances, which have little resemblance to the perturbations described by small-obstacle-height theories. For two-dimensional obstacles the disturbances are similar to those found by Wei, Kao & Pao (1975) and it is shown that provided a suitable obstacle drag coefficient is specified, the lowest-order modes (at least) are quantitatively consistent with the results of the Oseen inviscid model.Discussion of some results of similar measurements upstream of three-dimensional obstacles, the importance of towing tank endwalls and the relevance of the Foster & Saffman (1970) theory for the limit of zero Froude number is also included.

scholarly journals TSUNAMI GENERATION AND PROPAGATION

1972 ◽  
Vol 1 (13) ◽  
pp. 146
Author(s):  
Joseph L. Hammack ◽  
Frederic Raichlen
Keyword(s):  
Linear Theory ◽  
Source Region ◽  
Three Dimensional ◽  
Frequency Dispersion ◽  
Nonlinear Effects ◽  
Its Region ◽  
Experimental Results ◽  
Specific Class ◽  
Two Dimensional ◽  
Three Dimensional Models

A linear theory is presented for waves generated by an arbitrary bed deformation {in space and time) for a two-dimensional and a three -dimensional fluid domain of uniform depth. The resulting wave profile near the source is computed for both the two and three-dimensional models for a specific class of bed deformations; experimental results are presented for the two-dimensional model. The growth of nonlinear effects during wave propagation in an ocean of uniform depth and the corresponding limitations of the linear theory are investigated. A strategy is presented for determining wave behavior at large distances from the source where linear and nonlinear effects are of equal magnitude. The strategy is based on a matching technique which employs the linear theory in its region of applicability and an equation similar to that of Korteweg and deVries (KdV) in the region where nonlinearities are equal in magnitude to frequency dispersion. Comparison of the theoretical computations with the experimental results indicates that an equation of the KdV type is the proper model of wave behavior at large distances from the source region.

An Investigation of the Predicting Capabilities of a Variable Flow Stress Machining Theory

2001 ◽  
Author(s):  
P. Mathew
Keyword(s):  
Flow Stress ◽  
Material Flow ◽  
Three Dimensional ◽  
Experimental Results ◽  
Two Dimensional ◽  
Variable Flow ◽  
Comparative Results ◽  
Intermittent Cutting ◽  
Theoretical Results ◽  
Modelling Approach

Abstract The Oxley Machining Theory, which has been developed over the last 40 years, is presented in this paper. The capability of the model is described with its initial two-dimensional machining approach followed by the extension to the generalised model for three-dimensional machining. The theoretical results from the model are compared with the experimental results to determine the model capability. A brief description of the work associated with the effect of strain hardening at the interface is presented and comparative results are shown. A further extension of the model to intermittent cutting process of reaming is also presented and a comparison with the experimental results indicates the model developed is quite capable of predicting cutting forces for reaming. In explaining the results obtain, the assumptions made are explained and the inputs required. The limitations of the modelling approach are presented. It is pointed out that the Oxley model is a versatile model as long as proper description of the material flow stress properties is presented.

Numerical Calculation of Pressure Fluctuations in the Volute of a Centrifugal Fan

2005 ◽  
Vol 128 (2) ◽  
pp. 359-369 ◽  
Author(s):  
Rafael Ballesteros-Tajadura ◽  
Sandra Velarde-Suárez ◽  
Juan Pablo Hurtado-Cruz ◽  
Carlos Santolaria-Morros
Keyword(s):  
Fluid Dynamics ◽  
Pressure Fluctuations ◽  
Three Dimensional ◽  
Power Spectra ◽  
Operating Conditions ◽  
Experimental Results ◽  
Time Dependent ◽  
Centrifugal Fan ◽  
Wall Pressure Fluctuations ◽  
Good Agreement

In this work, a numerical model has been applied in order to obtain the wall pressure fluctuations at the volute of an industrial centrifugal fan. The numerical results have been compared to experimental results obtained in the same machine. A three-dimensional numerical simulation of the complete unsteady flow on the whole impeller-volute configuration has been carried out using the computational fluid dynamics code FLUENT®. This code has been employed to calculate the time-dependent pressure both in the impeller and in the volute. In this way, the pressure fluctuations in some locations over the volute wall have been obtained. The power spectra of these fluctuations have been obtained, showing an important peak at the blade passing frequency. The amplitude of this peak presents the highest values near the volute tongue, but the spatial pattern over the volute extension is different depending on the operating conditions. A good agreement has been found between the numerical and the experimental results.

scholarly journals Two- and three-dimensional numerical simulations of the transition to oscillatory convection in low-Prandtl-number fluids

1998 ◽  
Vol 374 ◽  
pp. 145-171 ◽  
Author(s):  
DANIEL HENRY ◽  
MARC BUFFAT
Keyword(s):  
Prandtl Number ◽  
Relative Concentration ◽  
Three Dimensional ◽  
Power Spectra ◽  
Hadley Circulation ◽  
Time Dependent ◽  
Two Dimensional ◽  
General Behaviour ◽  
Shallow Cavities ◽  
Dependent Flow

The convective flows which arise in shallow cavities filled with low-Prandtl-number fluids when subjected to a horizontal temperature gradient are studied numerically with a finite element method. Attention is focused on a rigid cavity with dimensions 4×2×1, for which experimental data are available. The three-dimensional results indicate that, after a relative concentration of the initial Hadley circulation, a transition to time-dependent flows occurs in the form of a roll oscillation with a purely dynamical origin. This transition corresponds to a Hopf bifurcation with a breaking of symmetry that gives some specific properties to the time evolution of the flow: these properties are shown to be the result of the general behaviour of the dynamical systems. Calculations performed in the case of mercury compare well with the experiments with similar power spectra of the temperature, and this validates the analysis of the nature of the global flow performed in the limiting case Pr=0. All these results are discussed with respect to the linear and nonlinear analyses and to other computational experiments. Numerical results obtained in the corresponding two-dimensional situation give a different transition to the time-dependent flow: it is shown that in the three-dimensional cavity this type of two-dimensional transition is less probable than the observed transition with breaking of symmetry.

Excess Streamwise Vorticity and Its Role in Secondary Flow

1987 ◽  
Vol 201 (6) ◽  
pp. 413-420 ◽  
Author(s):  
P W James
Keyword(s):  
Secondary Flow ◽  
Gas Turbines ◽  
Three Dimensional ◽  
Point Of View ◽  
Streamwise Vorticity ◽  
Three Dimensional Flow ◽  
Approximate Methods ◽  
Blade Row ◽  
Flow Through ◽  
Loss Term

The purpose of this paper is, firstly, to show how the concept of excess secondary vorticity arises naturally from attempts to recover three-dimensional flow details lost in passage-averaging the equations governing the flow through gas turbines. An equation for the growth of excess streamwise vorticity is then derived. This equation, which allows for streamwise entropy gradients through a prescribed loss term, could be integrated numerically through a blade-row to provide the excess vorticity at the exit to a blade-row. The second part of the paper concentrates on the approximate methods of Smith (1) and Came and Marsh (2) for estimating this quantity and demonstrates their relationship to each other and to the concept of excess streamwise vorticity. Finally the relevance of the results to the design of blading for gas turbines, from the point of view of secondary flow, is discussed.

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