scholarly journals Computation of Transonic Flows in and About Turbine Cascades With Viscous Effects

1984 ◽  
Author(s):  
U. K. Singh
Keyword(s):  
Inviscid Flow ◽  
Viscous Effects ◽  
Trailing Edge ◽  
Pressure Surface ◽  
Integral Methods ◽  
Interaction Treatment ◽  
Time Marching ◽  
Flow Through ◽  
Turbine Cascades ◽  
Good Agreement

An inviscid-viscous interaction treatment has been developed to predict the flow through transonic axial turbine blade cascades. The treatment includes a trailing-edge base pressure model. This model is based on treating the area between the points of flow separation on the blade surfaces at the trailing-edge and the point of downstream confluence of the suction and pressure surface flows as a region of constant pressure. A time marching technique is used to calculate the inviscid flow and viscous flow is calculated by integral methods for laminar and turbulent boundary layers. Good agreement with experimental data has been obtained.

scholarly journals Navier-Stokes Analysis of Unsteady Transonic Flows Through Gas Turbine Cascades With and Without Coolant Ejection

1997 ◽  
Author(s):  
T. Tanuma ◽  
N. Shibukawa ◽  
S. Yamamoto
Keyword(s):  
Gas Turbine ◽  
Stokes Equations ◽  
Viscous Flows ◽  
Navier Stokes ◽  
Implicit Time ◽  
Trailing Edge ◽  
Navier Stokes Equations ◽  
Time Marching ◽  
Turbine Cascades ◽  
Annular Cascade

An implicit time-marching higher-order accurate finite-difference method for solving the two-dimensional compressible Navier-Stokes equations was applied to the numerical analyses of steady and unsteady, subsonic and transonic viscous flows through gas turbine cascades with trailing edge coolant ejection. Annular cascade tests were carried out to verify the accuracy of the present analysis. The unsteady aerodynamic mechanisms associated with the interaction between the trailing edge vortices and shock waves and the effect of coolant ejection were evaluated with the present analysis.

A wake singularity potential flow model for airfoils experiencing trailing-edge stall

1993 ◽  
Vol 251 ◽  
pp. 203-218 ◽  
Author(s):  
W. W. H. Yeung ◽  
G. V. Parkinson
Keyword(s):  
Potential Flow ◽  
Inviscid Flow ◽  
Near Wake ◽  
Trailing Edge ◽  
Pressure Distributions ◽  
Free Streamlines ◽  
Potential Flow Model ◽  
Theoretical Pressure ◽  
Simple Sequence ◽  
Good Agreement

An incompressible inviscid flow theory for single and two-element airfoils experiencing trailing-edge stall is presented. For the single airfoil the model requires a simple sequence of conformal transformations to map a Joukowsky airfoil, partially truncated on the upper surface, onto a circle over which the flow problem is solved. Source and doublet singularities are used to create free streamlines simulating shear layers bounding the near wake. The model's simplicity permits extension of the method to airfoil-flap configurations in which trailing-edge stall is assumed on the flap. Williams’ analytical method to calculate the potential flow about two lifting bodies is incorporated in the Joukowsky-arc wake-singularity model to allow for flow separation. The theoretical pressure distributions from these models show good agreement with wind-tunnel measurements.

Calculation of Three-Dimensional, Inviscid, Rotational Flow in Axial Turbine Blade Rows

1984 ◽  
Vol 106 (2) ◽  
pp. 430-436 ◽  
Author(s):  
W. Van Hove
Keyword(s):  
Complex Geometry ◽  
Three Dimensional ◽  
Rotational Flow ◽  
Flow Angle ◽  
Cylindrical Coordinate ◽  
Time Marching ◽  
Flow Through ◽  
Outflow Boundary ◽  
Volume Method ◽  
Good Agreement

This paper describes a fully explicit, time marching, corrected viscosity, finite volume method to solve the Euler equations in a cylindrical coordinate system. The rotational character of the incoming flow can be taken into account. On the outflow boundary, a generalized radial equilibrium condition is imposed. Blade rows of complex geometry can be handled. At present, the method has been used to calculate the flow through the nozzle vanes of the VKI low-speed turbine facility. The calculated results show good agreement with the experimental data for the spatial distribution of both the static pressure and the flow angle.

Wall Pressure Profile Around Cylindrical Rods in Yawed Gas Flow

2011 ◽  
Vol 133 (7) ◽  
Author(s):  
R. G. Marino ◽  
A. Clausse ◽  
V. A. Herrero ◽  
N. Silin ◽  
G. Saravia
Keyword(s):  
Flow Rate ◽  
Inclination Angle ◽  
Atmospheric Pressure ◽  
Gas Flow ◽  
Pressure Coefficient ◽  
Pressure Profile ◽  
Inviscid Flow ◽  
Cylindrical Tubes ◽  
Flow Through ◽  
Good Agreement

The distribution of wall pressures in yawed flow through an array of cylindrical tubes inclined at different angles between 30° and 90° was experimentally studied using air at atmospheric pressure for 2290 ≤ Re ≤ 6100. The experiments show that the pressure coefficient is strongly influenced by the inclination angle, and only marginally affected by the flow rate within the tested range. The pressure behavior at the gap was calculated by assuming curved streamlines and inviscid flow, showing good agreement with measurements performed at the rod wall in the gap position.

An Inviscid-Viscous Interaction Method to Predict the Blade-to-Blade Performance of Axial Compressors

1980 ◽  
Vol 31 (3) ◽  
pp. 173-196 ◽  
Author(s):  
W.J. Calvert ◽  
M.V. Herbert
Keyword(s):  
Inviscid Flow ◽  
Surface Boundary ◽  
Interaction Method ◽  
Suction Surface ◽  
Surface Boundary Layer ◽  
Axial Compressors ◽  
Pressure Loss Coefficient ◽  
Viscous Interaction ◽  
Integral Methods ◽  
Time Marching

SummaryAn inviscid-viscous interaction method has been developed to predict the blade-to-blade flow in axial compressors. The method is primarily intended for high deflection, transonic (but substantially shock-free) blades where the suction surface boundary layer may be separated near the trailing edge. The inviscid flow is calculated by a time marching method and the viscous flow by integral methods for laminar and turbulent boundary layers. A mixing calculation is then carried out to determine the blade deviation angle and pressure loss coefficient. Predictions have been compared with test results for three high deflection, transonic cascades and there is generally good agreement.

Numerical Prediction of Turbine Profile Loss

1990 ◽  
Author(s):  
L. Xu ◽  
J. D. Denton
Keyword(s):  
Turbine Blades ◽  
Surface Friction ◽  
Trailing Edge ◽  
Integral Boundary ◽  
Wide Range ◽  
Boundary Layer Method ◽  
Time Marching ◽  
Flow Through ◽  
Euler Solver ◽  
Profile Loss

A simple numerical method for predicting the profile loss of turbine blades in subsonic and transonic flows is presented. A time marching Euler solver is used to obtain the main flow through the blade passages, the loss due to the surface friction is calculated using an integral boundary layer method, the total mixed out loss is evaluated from the mass flow and momentum balances between the trailing edge plane and an imaginary downstream plane where the flow is uniform. The base pressure acting on the trailing edge of the blade is calculated directly from the inviscid calculation without empirical correlations. The spurious numerical loss in the Euler calculation is separated from the real loss. The rationality of the approach is justified by the agreement of the prediction with a wide range of experimental measurements.

scholarly journals Effects of the outlet position of splitter blade on the flow characteristics in low-specific-speed centrifugal pump

2018 ◽  
Vol 10 (7) ◽  
pp. 168781401878952 ◽  
Author(s):  
Jinfeng Zhang ◽  
Guidong Li ◽  
Jieyun Mao ◽  
Shouqi Yuan ◽  
Yefei Qu ◽  
...  
Keyword(s):  
Centrifugal Pump ◽  
Pressure Coefficient ◽  
Flow Characteristics ◽  
Internal Flow ◽  
Suction Side ◽  
Trailing Edge ◽  
Pressure Surface ◽  
Low Specific Speed ◽  
Specific Speed ◽  
Good Agreement

To elucidate the influences of the outlet position of splitter blades on the performance of a low-specific-speed centrifugal pump, two different splitter blade schemes were proposed: one located in the middle of the channel and the other having a deviation angle at the trailing edge of splitter blade toward the suction side of the main blade. Experiments on the model pump with different splitter blade schemes were conducted, and numerical simulations on internal flow characteristics in the impellers were studied by means of the shear stress transport k- ω turbulence model. The results suggest that there is a good agreement between the experimental and numerical results. The splitter blade schemes can effectively optimize the structure of the jet-wake pattern and improve the internal flow states in the impeller channel. In addition, the secondary flow and inlet circulation on the pressure surface of main blade, the flow separation on the suction side of splitter blade, the pressure coefficient distributions on blade surface can achieve an evident amelioration when the trailing edge of splitter blade toward the suction side of the main blade is mounted at an appropriate position.

Inviscid Flow Through a Cascade of Thick, Cambered Airfoils: Part 1—Incompressible Flow

1973 ◽  
Vol 95 (3) ◽  
pp. 220-226 ◽  
Author(s):  
D. A. Frith
Keyword(s):  
Degrees Of Freedom ◽  
Mapping Function ◽  
Integral Form ◽  
Inviscid Flow ◽  
Picture Plane ◽  
Trailing Edge ◽  
Mapping Functions ◽  
Two Dimensional Flow ◽  
Flow Through ◽  
Basic Features

Conformal mapping is one means of determining the inviscid, incompressible, two-dimensional flow through a cascade of airfoils. The complex potential flow about a unit circle is a convenient picture plane. The form of mapping function required to transform this circle to thick, cambered airfoils in cascade is derived and then compared with the analogous mapping function for the isolated airfoil. Two analytical mapping functions that conform to this form are derived. One, which is in differential form and so necessitates numerical integration to yield the profile shape, has seven free parameters giving the solidity and stagger of the cascade and the camber and leading and trailing edge radii of the blading: the two remaining parameters control the thickness and camber distributions. The second analytical mapping function is in an integral form but has only five degrees of freedom corresponding to solidity, stagger, camber, leading and trailing edge radii in its basic form. Due to its simplicity, the second of these mapping functions is useful in determining basic features of the flow through cascades. These features are illustrated by some results.

scholarly journals Particulate Flow in the Rotor and Stator Elements of Turbomachines

1985 ◽  
Author(s):  
A. F. Abdel Azim ◽  
W. T. Rouleau
Keyword(s):  
Centrifugal Compressor ◽  
Fine Particles ◽  
Large Diameter ◽  
Three Dimensional ◽  
Internal Surface ◽  
Inviscid Flow ◽  
Viscous Effects ◽  
Pressure Surface ◽  
Erosion Rates ◽  
Internal Surfaces

In order to examine both primary and secondary erosion of turbomachines, two examples were studied: the impeller of a centrifugal compressor and the stationary straight infinite cascade. The first example was examined when particulates of large diameters bombarded its internal surface, thus providing a primary erosion pattern. An inviscid flow is assumed since the trajectories of large diameter particles are slightly influenced by viscous effects. Tracing these trajectories for silica and alumina particles defined four areas on the internal surfaces of the impeller which experienced the highest rate of material removal due to the successvie impacts. The viscous model of a centrifugal compressor is also under investigation by the authors. The stationary infinite cascade of a typical turboexpander was subjected to fine particulate impacts. These fine particles were greatly influenced by both the viscous effects and secondary flow. Thus three-dimensional viscous flow was defined experimentally using a laser-Doppler anemometer (LDA). The pressure surface, especially the turning section, suffered from the highest erosion damage. These results compared favorably with the experimental results of the Ruston and Hornsby turbine operating with Greta Coal. The erosion rates of the first stage Ruston Turbine after 124.8 hours of operation showed similar results.

Upward Vertical Two-Phase Flow Through an Annulus—Part II: Modeling Bubble, Slug, and Annular Flow

1992 ◽  
Vol 114 (1) ◽  
pp. 14-30 ◽  
Author(s):  
E. F. Caetano ◽  
O. Shoham ◽  
J. P. Brill
Keyword(s):  
Flow Pattern ◽  
Annular Flow ◽  
Two Phase Flow ◽  
Flow Behavior ◽  
Bubble Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Flow Through ◽  
Physical Phenomena ◽  
Good Agreement

Mechanistic models have been developed for each of the existing two-phase flow patterns in an annulus, namely bubble flow, dispersed bubble flow, slug flow, and annular flow. These models are based on two-phase flow physical phenomena and incorporate annulus characteristics such as casing and tubing diameters and degree of eccentricity. The models also apply the new predictive means for friction factor and Taylor bubble rise velocity presented in Part I. Given a set of flow conditions, the existing flow pattern in the system can be predicted. The developed models are applied next for predicting the flow behavior, including the average volumetric liquid holdup and the average total pressure gradient for the existing flow pattern. In general, good agreement was observed between the experimental data and model predictions.

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