A Subsonic Panel Method for Design of 3-Dimensional Complex Configurations with Specified Pressure Distribution

1988 ◽  
pp. 137-146
Author(s):  
Krzysztof Kubryński
Keyword(s):  
Pressure Distribution ◽  
Panel Method ◽  
3 Dimensional

scholarly journals Investigation of the Unsteady Flow Behaviour on a Wind Turbine Using a BEM and a RANSE Method

2016 ◽  
Vol 2016 ◽  
pp. 1-12
Author(s):  
Israa Alesbe ◽  
Moustafa Abdel-Maksoud ◽  
Sattar Aljabair
Keyword(s):  
Unsteady Flow ◽  
Wind Turbine ◽  
Pressure Distribution ◽  
Three Dimensional ◽  
Panel Method ◽  
Flow Behaviour ◽  
Viscous Effects ◽  
Horizontal Axis Wind Turbine ◽  
Local Flow ◽  
Ranse Solver

Analyses of the unsteady flow behaviour of a 5 MW horizontal-axis wind turbine (HAWT) rotor (Case I) and a rotor with tower (Case II) are carried out using a panel method and a RANSE method. The panel method calculations are obtained by applying the in-house boundary element method (BEM) panMARE code, which is based on the potential flow theory. The BEM is a three-dimensional first-order panel method which can be used for investigating various steady and unsteady flow problems. Viscous flow simulations are carried out by using the RANSE solver ANSYS CFX 14.5. The results of Case I allow for the calculation of the global integral values of the torque and the thrust and include detailed information on the local flow field, such as the pressure distribution on the blade sections and the streamlines. The calculated pressure distribution by the BEM is compared with the corresponding values obtained by the RANSE solver. The tower geometry is considered in the simulation in Case II, so the unsteady forces due to the interaction between the tower and the rotor blades can be calculated. The application of viscous and inviscid flow methods to predict the forces on the HAWT allows for the evaluation of the viscous effects on the calculated HAWT flows.

Aerodynamic Degradation of Iced Airfoils: Experiments and CFD Simulations

2009 ◽  
Author(s):  
Z. Chara ◽  
V. Horak ◽  
D. Rozehnal
Keyword(s):  
Wind Tunnel ◽  
Pressure Distribution ◽  
Cfd Simulation ◽  
Panel Method ◽  
Ice Accretion ◽  
Cfd Simulations ◽  
Ansys Cfx ◽  
Lift And Drag ◽  
Naca 0012 ◽  
Ice Shapes

The phenomenon of in-flight icing may affect all types of aircraft. Presence of ice on wings can lead to a number of aerodynamic degradation problems. Thus, it is important to understand the different ice shapes that can form on the wings and how they affect aerodynamics. When compared to wings without ice, wings with ice indicate decreased maximum lift, increased drag, changes in pressure distribution, stall occurring at much lower angles of attack, increased stall speed, and reduced controllability. The in-house ice accretion prediction code R-ICE using 2-D panel method was developed. The CFD simulation with the software ANSYS CFX 11.0 was used to simulate flow around iced airfoils NACA 0012. These airfoils were experimentally investigated in a wind tunnel. The paper presents a comparison of lift and drag coefficients experimentally observed and numerically simulated.

scholarly journals Comparison of Linear Vortex Panel Method and Finite Volume Method for Calculation of Generated Lift in Potential Flow Over Two-Dimensional Car Bodies

2020 ◽  
Author(s):  
Saeid Moammaei ◽  
Mehran Khaki Jamei ◽  
Morteza Abbasi
Keyword(s):  
Pressure Distribution ◽  
Lift Coefficient ◽  
Control Point ◽  
Panel Method ◽  
The Body ◽  
Aerodynamic Load ◽  
Two Dimensional ◽  
Algebraic Equations ◽  
Linear Algebraic Equations ◽  
The Impact

Abstract This paper describes one of the aspects of the panel method to analyze the aerodynamic characteristics of a sedan. The linear vortex panel method has been developed to simulate the ideal flow over a two-dimensional arbitrary car and, it also calculates the aerodynamic load on the body. By satisfying the boundary conditions on each control point, our linear algebraic equations are obtained. The results are sensitive to the distribution of the panels over the body thus the body is broken up equally into very small panels. After solving the set of equations, the vortices strength is obtained and the pressure distribution for the upper and the lower surface of the body is calculated. The impact of the angle of attack on the aerodynamic behavior of the intended car is investigated and it is found that the lift coefficient increases with the free stream angle from -4 to 4. The accuracy of the results has been determined by checking them against the standard CFD data. The pressure distribution trend is found very much in confirmation with the CFD results, however, a discrepancy at the rear end is observed. Therefore, it can be concluded that this method does not seem practical for geometries with steep slopes in the rear part of the car. Finally, both methods are applied to the other modified geometries with lower slopes at the rear section and the results compare well with the fluent.

Numerical Estimation of the Unsteady Force on Rotor Blades in a Partial Arc Admission Stage of an Axial Turbine

2014 ◽  
Author(s):  
Takeshi Yoshida ◽  
Naoto Sakai ◽  
Atsushi Matsumoto ◽  
Yosuke Kitajima
Keyword(s):  
Pressure Distribution ◽  
3D Model ◽  
Tip Clearance ◽  
Leakage Flow ◽  
Numerical Estimation ◽  
3 Dimensional ◽  
Partial Admission ◽  
Cfd Analyses ◽  
Analysis Models ◽  
Circumferential Pressure

A study for numerical estimation about the unsteady blade force in a partial arc admission stage of an axial turbine is presented in this paper. Firstly, in order to investigate the influence of modeling domains in CFD (Computational Fluid Dynamics) analysis upon unsteady blade forces and turbine performance in partial admission stages, CFD analyses of three models were carried out. The analysis models consist of “2D” model; only on a mean diameter, “Simple-3D” model; 3-Dimensional passages without a tip clearance and a disc cavity, and “Full-3D” model; 3-Dimensional passages with a tip clearance and a disc cavity. It results in clear difference in unsteady blade forces among these models. And it was revealed that numerical estimations of unsteady blade forces in partial admission stages should be carried out with analysis models that include disc cavities and tip clearances. In a partial admission stage there is extremely large circumferential pressure distribution and it causes the typical leakage flow through the gaps around a blade row. The leakage flow affects the circumferential pressure distribution that is a dominant factor in the unsteady blade forces. Air turbine experiments were conducted to validate the accuracy of the CFD analyses. Turbine efficiency of the Full-3D model with the disc cavity and the tip clearance is the closest to that of the experiment among the three models. In addition, comparison of pressure histories on a blade surface between an experiment and a calculation of the Full-3D model shows remarkably good agreements. Next, CFD analyses with two different cascade setups (Cascade A and Cascade B) of partial admission stages were conducted in order to reveal the relationship between unsteady blade forces and cascade geometries such as a pitch of blades and a pitch of nozzles. These results show that there are clear differences in unsteady blade forces in an admission arc and those at leaving an admission arc. And some of trade-off relationships among the unsteady blade forces due to the geometries in partial admission stages are pointed out.

Analysis of the Flow Around Supercavitating Hydrofoils with Midchord and Face Cavity Detachment

1991 ◽  
Vol 35 (03) ◽  
pp. 198-209
Author(s):  
Spyros A. Kinnas ◽  
Neal E. Finer
Keyword(s):  
Pressure Distribution ◽  
Integral Equations ◽  
Inviscid Flow ◽  
Panel Method ◽  
Pressure Side ◽  
Flow Conditions ◽  
Trailing Edge ◽  
Pressure Distributions ◽  
Work First ◽  
Flow Criterion

In this work, first the linearized supercavitating hydrofoil problem with arbitrary cavity detachment points is formulated in terms of unknown source and vorticity distributions. The corresponding integral equations are inverted analytically and the results are expressed in terms of integrals of quantities which depend only on the hydrofoil shape. These integrals are computed numerically, in an accurate and efficient way, to produce cavity shapes and pressure distributions on the foil and cavity. The effect of the cavity detachment points on the shape of the cavity and the foil pressure distribution is investigated. An inviscid flow criterion for the cavity detachment point is derived for the case where the cavity detaches in front of the trailing edge on the pressure side of the hydrofoil. Finally, the accuracy of the linearized cavity theory is assessed for different foils and flow conditions, by analyzing the produced cavity shapes with a nonlinear panel method.

A Surface Panel Method for Design of Hydrofoils

1994 ◽  
Vol 38 (03) ◽  
pp. 175-181
Author(s):  
Chang-Sup Lee ◽  
Young-Gi Kim ◽  
Jung-Chun Suh
Keyword(s):  
Integral Equation ◽  
Boundary Value Problem ◽  
Pressure Distribution ◽  
Three Dimensional ◽  
Panel Method ◽  
Simultaneous Equations ◽  
Surface Panel Method ◽  
Total Potential ◽  
Pressure Distributions

A surface panel method treating a boundary-value problem of the Dirichlet type is presented to design a hydrofoil corresponding to a prescribed pressure distribution. An integral equation is derived from Green's theorem, giving a relation between the total potential of known strength and the unknown local flux. Upon discretization, a system of linear simultaneous equations is formed and solved for an assumed geometry. The pseudo local flux, present due to the incorrect positioning of the assumed geometry, plays a role of the geometry corrector, with which the new geometry is computed for the next iteration. Sample designs for a series of pressure distributions of interest are performed to demonstrate the fast convergence, effectiveness and robustness of the procedure. The method is shown equally applicable to designing two- and three-dimensional hydrofoil geometry.

Three-Dimensional Reconstruction Using Stereo Pairs from Serial Thick Sections

1977 ◽  
Vol 35 ◽  
pp. 562-563
Author(s):  
Robert Glaeser ◽  
Thomas Bauer ◽  
David Grano
Keyword(s):  
Three Dimensional ◽  
Dimensional Structure ◽  
Serial Sections ◽  
Thin Sections ◽  
3 Dimensional ◽  
Transmission Electron ◽  
Freeze Dried ◽  
Dimensional Reconstruction ◽  
Stereo Imagery ◽  
Whole Mounts

In transmission electron microscopy, the 3-dimensional structure of an object is usually obtained in one of two ways. For objects which can be included in one specimen, as for example with elements included in freeze- dried whole mounts and examined with a high voltage microscope, stereo pairs can be obtained which exhibit the 3-D structure of the element. For objects which can not be included in one specimen, the 3-D shape is obtained by reconstruction from serial sections. However, without stereo imagery, only detail which remains constant within the thickness of the section can be used in the reconstruction; consequently, the choice is between a low resolution reconstruction using a few thick sections and a better resolution reconstruction using many thin sections, generally a tedious chore. This paper describes an approach to 3-D reconstruction which uses stereo images of serial thick sections to reconstruct an object including detail which changes within the depth of an individual thick section.

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