Numerical Computation of Nonstationary Aerodynamics of Flat Plate Cascades in Compressible Flow

1976 ◽  
Vol 98 (2) ◽  
pp. 165-170 ◽  
Author(s):  
R. H. Ni ◽  
F. Sisto
Keyword(s):  
Flat Plate ◽  
Numerical Computation ◽  
Compressible Flow ◽  
Computational Domain ◽  
Two Dimensional ◽  
Order Of Accuracy ◽  
Fluid Properties ◽  
Time Marching ◽  
Interblade Phase Angle ◽  
Good Agreement

The “time marching” technique is successfully applied to the numerical computation of the nonstationary aerodynamics of a flat plate cascade for compressible flow of either subsonic or supersonic nature. The unsteady perturbation amplitudes of fluid properties are used as the dependent variables so that the computational domain can be reduced to a two-dimensional channel guided by two adjacent blades for any interblade phase angle. A new method of handling the boundary condition is developed in which the order of accuracy for the boundary points will be the same as the interior points. The wake region behind the trailing edge of each blade is treated as a “slip plane” as done in two-dimensional steady state supersonic flow. Results are in good agreement with existing analytical solutions.

Natural Convection in Two-Dimensional Horizontal Channel With Heat Sources

2003 ◽  
Author(s):  
Tito Dias ◽  
Luiz Fernando Milanez
Keyword(s):  
Natural Convection ◽  
Flux Ratio ◽  
Horizontal Channel ◽  
Maximum Temperature ◽  
Computational Domain ◽  
Heat Sources ◽  
Two Dimensional ◽  
Temperature Excess ◽  
Fluid Properties ◽  
Laminar Natural Convection

Laminar natural convection in a two-dimensional horizontal channel is very important in laptop design, since optimizing the utilization of the cooler saves energy from the battery. In this work, this configuration has been numerically studied. Three cases were studied according to the position of the heat sources in the lower wall, upper wall and both. The computational domain consisted of two adiabatic walls where the heat sources were positioned, and two open boundaries, where the manometric pressure and normal gradient of velocity were zero. Ambient temperature was prescribed for the entering fluid and zero normal gradient for the exiting fluid. Fluid properties were assumed constant except for the density change with temperature on the buoyancy term. The influence of the modified Rayleigh number, position of the heat sources and heat flux ratio between the sources were analyzed for Prandtl number of 0.7. The maximum temperature excess on the heat source is lower for the case with two heat sources and Ra = 104. This preliminary study showed the existence of a minimum value of the excess temperature for the studies aspect ratio (0.1).

MODELLING WATER ENTRY OF A WEDGE BY MULTIPHASE SPH METHOD

2011 ◽  
Vol 1 (32) ◽  
pp. 10 ◽  
Author(s):  
Kai Gong ◽  
Benlong Wang ◽  
Hua Liu
Keyword(s):  
Water Entry ◽  
Computational Domain ◽  
Two Dimensional ◽  
Hydrodynamic Problem ◽  
Sph Method ◽  
Two Phase ◽  
Boundary Treatment ◽  
Sph Model ◽  
Reflection Boundary ◽  
Good Agreement

The hydrodynamic problem of two-dimensional wedge entering water is studied based on SPH model. A non-reflection boundary treatment for SPH method is proposed to reduce the size of computational domain. The details of water entry and enclosing are simulated using two phase SPH model. Both the water flow around the cavity and wedge and air flow inside the cavity are predicted simultaneity. Good agreement is obtained comparing experimental data in terms of both the hydrodynamics force exerting on the wedge and geometry of the cavity and jet.

Computation and Simulation of Wake-Generated Unsteady Pressure and Boundary Layers in Cascades: Part 1—Description of the Approach and Validation

1996 ◽  
Vol 118 (1) ◽  
pp. 96-108 ◽  
Author(s):  
S. Fan ◽  
B. Lakshminarayana
Keyword(s):  
Boundary Layer ◽  
Unsteady Flow ◽  
Flat Plate ◽  
Boundary Layers ◽  
Numerical Procedure ◽  
Computational Domain ◽  
Two Dimensional ◽  
Unsteady Pressure ◽  
Blade Row ◽  
Euler Solver

The unsteady pressure and boundary layers on a turbomachinery blade row arising from periodic wakes due to upstream blade rows are investigated in this paper. A time-accurate Euler solver has been developed using an explicit four-stage Runge–Kutta scheme. Two-dimensional unsteady nonreflecting boundary conditions are used at the inlet and the outlet of the computational domain. The unsteady Euler solver captures the wake propagation and the resulting unsteady pressure field, which is then used as the input for a two-dimensional unsteady boundary layer procedure to predict the unsteady response of blade boundary layers. The boundary layer code includes an advanced k–ε model developed for unsteady turbulent boundary layers. The present computational procedure has been validated against analytic solutions and experimental measurements. The validation cases include unsteady inviscid flows in a flat-plate cascade and a compressor exit guide vane (EGV) cascade, unsteady turbulent boundary layer on a flat plate subject to a traveling wave, unsteady transitional boundary layer due to wake passing, and unsteady flow at the midspan section of an axial compressor stator. The present numerical procedure is both efficient and accurate in predicting the unsteady flow physics resulting from wake/blade-row interaction, including wake-induced unsteady transition of blade boundary layers.

On the Application of Linearized Theory to Multi-Element Aerofoils Part I: Tandem Flat Plate Aerofoils

1983 ◽  
Vol 34 (1) ◽  
pp. 46-60 ◽  
Author(s):  
G.D. Watt ◽  
G.V. Parkinson
Keyword(s):  
Flat Plate ◽  
Potential Flow ◽  
Flow Theory ◽  
Two Dimensional ◽  
Potential Flow Theory ◽  
Linearized Theory ◽  
Good Agreement ◽  
Hand Calculator

SummaryA linearized two-dimensional incompressible potential flow theory for two-element uncambered tandem aerofoil sections is developed. It leads to formulas for lift and moment which can be calculated rapidly on a programmable hand calculator, and which reduce, when the two aerofoil elements come together, to the familiar thin-aerofoil formulas for an aerofoil with a simple flap. The theory is shown to give lift and moment predictions which are in good agreement with predictions of numerical potential flow theory.

Experiments on Circular-Arc and Flat-Plate Hydrofoils

1958 ◽  
Vol 2 (01) ◽  
pp. 34-67
Author(s):  
Blaine R. Parkin
Keyword(s):  
Flat Plate ◽  
High Speed ◽  
Cavity Flow ◽  
Hydrodynamic Characteristics ◽  
Water Tunnel ◽  
Pitching Moment ◽  
Two Dimensional ◽  
Circular Arc ◽  
Wide Range ◽  
Good Agreement

An investigation in the High-Speed Water Tunnel of the two-dimensional hydrodynamic characteristics of sharp-edged hydrofoils is described. The lift, drag, and pitching moment were measured in cavitating and noncavitating flows for flat-plate and circular-arc profiles. The theory of Wu for the forces on sharp-edged profiles in full-cavity flow and the experimental results showed good agreement over a wide range of attack angles.

scholarly journals Modeling Transient Flows in Heterogeneous Layered Porous Media Using the Space–Time Trefftz Method

2021 ◽  
Vol 11 (8) ◽  
pp. 3421
Author(s):  
Cheng-Yu Ku ◽  
Li-Dan Hong ◽  
Chih-Yu Liu ◽  
Jing-En Xiao ◽  
Wei-Po Huang
Keyword(s):  
Porous Media ◽  
Time Domain ◽  
Numerical Solutions ◽  
Space Time ◽  
Two Dimensional ◽  
Transient Flows ◽  
Layered Porous Media ◽  
Time Marching ◽  
Time Basis ◽  
Marching Scheme

In this study, we developed a novel boundary-type meshless approach for dealing with two-dimensional transient flows in heterogeneous layered porous media. The novelty of the proposed method is that we derived the Trefftz space–time basis function for the two-dimensional diffusion equation in layered porous media in the space–time domain. The continuity conditions at the interface of the subdomains were satisfied in terms of the domain decomposition method. Numerical solutions were approximated based on the superposition principle utilizing the space–time basis functions of the governing equation. Using the space–time collocation scheme, the numerical solutions of the problem were solved with boundary and initial data assigned on the space–time boundaries, which combined spatial and temporal discretizations in the space–time manifold. Accordingly, the transient flows through the heterogeneous layered porous media in the space–time domain could be solved without using a time-marching scheme. Numerical examples and a convergence analysis were carried out to validate the accuracy and the stability of the method. The results illustrate that an excellent agreement with the analytical solution was obtained. Additionally, the proposed method was relatively simple because we only needed to deal with the boundary data, even for the problems in the heterogeneous layered porous media. Finally, when compared with the conventional time-marching scheme, highly accurate solutions were obtained and the error accumulation from the time-marching scheme was avoided.

scholarly journals Nonlinear two-dimensional free surface solutions of flow exiting a pipe and impacting a wedge

2021 ◽  
Vol 126 (1) ◽  
Author(s):  
Alex Doak ◽  
Jean-Marc Vanden-Broeck
Keyword(s):  
Surface Tension ◽  
Integral Equation ◽  
Free Surface ◽  
Boundary Integral ◽  
Boundary Integral Method ◽  
Two Dimensional ◽  
Numerical Schemes ◽  
Additional Advantage ◽  
Infinite Wedge ◽  
Good Agreement

AbstractThis paper concerns the flow of fluid exiting a two-dimensional pipe and impacting an infinite wedge. Where the flow leaves the pipe there is a free surface between the fluid and a passive gas. The model is a generalisation of both plane bubbles and flow impacting a flat plate. In the absence of gravity and surface tension, an exact free streamline solution is derived. We also construct two numerical schemes to compute solutions with the inclusion of surface tension and gravity. The first method involves mapping the flow to the lower half-plane, where an integral equation concerning only boundary values is derived. This integral equation is solved numerically. The second method involves conformally mapping the flow domain onto a unit disc in the s-plane. The unknowns are then expressed as a power series in s. The series is truncated, and the coefficients are solved numerically. The boundary integral method has the additional advantage that it allows for solutions with waves in the far-field, as discussed later. Good agreement between the two numerical methods and the exact free streamline solution provides a check on the numerical schemes.

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