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.

Determination of Three-Dimensional Body Forms from Given Pressure Distribution Over Their Surfaces

1996 ◽  
Vol 40 (01) ◽  
pp. 22-27
Author(s):  
V. M. Pashin ◽  
V. A. Bushkovsky ◽  
E. L. Amromin
Keyword(s):  
Pressure Distribution ◽  
Three Dimensional ◽  
Bodies Of Revolution ◽  
Design Constraints ◽  
Pressure Distributions ◽  
Axisymmetric Bodies

A method for solving inverse three-dimensional problems in hydromechanics is proposed which makes it possible to fit desired pressure distributions within design constraints immediately in the course of calculations. Examples of the method of application are given for bodies of revolution in flows at nonzero drift angles. These flows are not axisymmetric. Bodies of revolution in them are very handy examples of demonstrations of the method, and these examples have many technical applications.

scholarly journals Calculation of Three-Dimensional Unteady Sheet Cavitation by a Simple Surface Panel Method

2000 ◽  
Vol 2000 (188) ◽  
pp. 91-103 ◽  
Author(s):  
Jun Ando ◽  
Takashi Kanemaru ◽  
Kunihide Ohashi ◽  
Kuniharu Nakatake
Keyword(s):  
Three Dimensional ◽  
Panel Method ◽  
Surface Panel Method ◽  
Sheet Cavitation ◽  
Simple Surface

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.

Fluid Dynamic Study in a Femoral Artery Branch Casting of Man With Upstream Main Lumen Curvature for Steady Flow

1985 ◽  
Vol 107 (3) ◽  
pp. 240-248 ◽  
Author(s):  
M. R. Back ◽  
Y. I. Cho ◽  
L. H. Back
Keyword(s):  
Steady Flow ◽  
Fluid Transport ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Pressure Distributions ◽  
Flow Investigation ◽  
Measured Pressure

An in-vitro, steady flow investigation was conducted in a hollow, transparent vascular replica of the profunda femoris branch of man for a range of physiological flow conditions. The replica casting tested was obtained from a human cadaver and indicated some plaque formation along the main lumen and branch. The flow visualization observations and measured pressure distributions indicated the highly three-dimensional flow characteristics with arterial curvature and branching, and the important role of centrifugal effects in fluid transport mechanisms.

A Three Dimensional Iterative Panel Method for Bio-Inspired Multi-Body Wings

2014 ◽  
Author(s):  
Akash Dhruv ◽  
Christopher J. Blower ◽  
Adam M. Wickenheiser
Keyword(s):  
Three Dimensional ◽  
Panel Method ◽  
Preliminary Design ◽  
Turbulent Environments ◽  
Pressure Distributions ◽  
Constant Strength ◽  
Aerial Vehicle ◽  
Experimental Values ◽  
Multi Body ◽  
Surface Loads

The continuing growth of Unmanned Aerial Vehicle (UAV) use in reconnaissance and surveillance has led to an increased demand for novel flight systems that improve vehicle flight capabilities in cluttered and turbulent environments. Bio-inspired wings with feather-like flaps have been proposed to enable bird-scale UAVs to fly robustly in such environments. This paper presents the development of a three-dimensional iterative constant strength doublet Adaptive Panel Method (APM) for calculating the flight characteristics of a multi-body wing operating in any of its possible configurations. A three-dimensional wake relaxation algorithm is incorporated into the model, which enables accurate wake shapes and down-stream roll-up for each flap configuration to be derived. Wake modeling is shown to improve the accuracy of the pressure distributions induced by the wake-body interactions. The flight coefficients calculated using this method are validated by experimental values obtained from a low speed suction wind tunnel operating at a Reynolds number of 300,000. Finally, it is shown that the APM aids in determining accurate surface loads for the preliminary design process of multi-body wings.

Instability and Transition in a Separation Bubble Under a Three-Dimensional Freestream Pressure Distribution

2011 ◽  
Vol 134 (3) ◽  
Author(s):  
M. I. Yaras
Keyword(s):  
Boundary Layer ◽  
Pressure Distribution ◽  
Pressure Field ◽  
Separation Bubble ◽  
Three Dimensional ◽  
Test Surface ◽  
Two Dimensional ◽  
Transition Processes ◽  
Pressure Distributions ◽  
Separation Bubbles

This paper presents measurements of the instability and transition processes in separation bubbles under a three-dimensional freestream pressure distribution. The measurements are performed on a flat plate on which a pressure distribution is imposed by a contoured surface facing the flat test-surface. The three-dimensional pressure distribution that is established on the test-surface approximates the pressure distributions encountered on swept blades. This type of pressure field produces crossflows in the laminar boundary layer upstream of the separation and within the separation bubble. The effects of these crossflows on the instability of the upstream boundary layer and on the instability, transition onset, and transition rate within the separated shear-layer are examined. The measurements are performed at two flow-Reynolds numbers and relatively low level of freestream turbulence. The results of this experimental study show that the three-dimensional freestream pressure field and the corresponding redistribution of the freestream flow can cause significant spanwise variation in the separation-bubble structure. It is demonstrated that the instability and transition processes in the modified separation bubble develop on the basis of the same fundamentals as in two-dimensional separation bubbles and can be predicted with the same level of accuracy using models that have been developed for two-dimensional separation bubbles.

Instability and Transition in a Separation Bubble Under a Three-Dimensional Freestream Pressure Distribution

2008 ◽  
Author(s):  
M. I. Yaras
Keyword(s):  
Boundary Layer ◽  
Pressure Distribution ◽  
Pressure Field ◽  
Separation Bubble ◽  
Three Dimensional ◽  
Test Surface ◽  
Two Dimensional ◽  
Transition Processes ◽  
Pressure Distributions ◽  
Separation Bubbles

This paper presents measurements of the instability and transition processes in separation bubbles under a three-dimensional freestream pressure distribution. Measurements are performed on a flat plate upon which a pressure distribution is imposed by a contoured surface facing the flat test surface. The three-dimensional pressure distribution that is established on the test surface approximates the pressure distributions encountered on swept blades. This type of pressure field produces crossflows in the laminar boundary layer upstream of separation and within the separation bubble. The effects of these crossflows on the instability of the upstream boundary layer and on the instability, transition onset and transition rate within the separated shear layer are examined. The measurements are performed at two flow Reynolds numbers and relatively low level of freestream turbulence. The results of this experimental study show that the three-dimensional freestream pressure field and the corresponding redistribution of the freestream flow cause significant spanwise variation of the separation-bubble structure. It is demonstrated that the instability and transition processes in the modified separation bubble develop on the basis of the same fundamentals as in two-dimensional separation bubbles, and can be predicted with the same level of accuracy using models that have been developed for two-dimensional separation bubbles.

Three-Dimensional Analysis of Surface Cracks in an Elastic Half-Space

1996 ◽  
Vol 63 (2) ◽  
pp. 287-294 ◽  
Author(s):  
Quanxin Guo ◽  
Jian-Juei Wang ◽  
R. J. Clifton
Keyword(s):  
Integral Equation ◽  
Numerical Method ◽  
Half Space ◽  
Crack Opening ◽  
Three Dimensional ◽  
Elastic Half Space ◽  
Surface Cracks ◽  
Opening Displacement ◽  
Near Surface ◽  
Total Potential

A numerical method is presented for analyzing arbitrary planar cracks in a half-space. The method is based on the fundamental solution for a dislocation loop in a half-space, which is derived from the Mindlin solution (Mindlin, Physics, Vol. 7, 1936) for a point force in a half-space. By appropriate replacement of the Burgers vectors of the dislocation by the differential crack-opening displacement, a singular integral equation is obtained in terms of the gradient of the crack opening. A numerical method is developed by covering the crack with triangular elements and by minimizing the total potential energy. The singularity of the kernel, when the integral equation is expressed in terms of the gradient of the crack opening, is sufficiently weak that all integrals exist in the regular sense and no special numerical procedures are required to evaluate the contributions to the stiffness matrix. The integrals over the source elements are converted into line integrals along the perimeter of the element and evaluated analytically. Numerical results are presented and compared with known results for both surface breaking cracks and near surface cracks.

Stress Analysis of the Multi-Layered System of a Truck Tire

2002 ◽  
Vol 30 (4) ◽  
pp. 240-264 ◽  
Author(s):  
X. Zhang ◽  
S. Rakheja ◽  
R. Ganesan
Keyword(s):  
Pressure Distribution ◽  
Contact Pressure ◽  
Normal Load ◽  
Three Dimensional ◽  
Stress Fields ◽  
Layered System ◽  
Contact Pressure Distribution ◽  
Pressure Distributions ◽  
Truck Tire ◽  
Stress And Deformation

Abstract In this paper, a nonlinear finite element tire model is developed as an effective fast modeling approach to analyze the stress fields within a loaded tire structure, with the contact patch geometry and contact pressure distribution in the tire-road interface as functions of the normal load and the inflation pressure. The model considers the geometry and orientations of the cords in individual layers and the stacking sequence of different layers in the multi-layered system to predict the interply interactions in the belts and carcass layers. The study incorporates nearly incompressible property of the tread rubber block and anisotropic material properties of the layers. The analysis is performed using ANSYS software, and the results are presented to describe the influence of the normal load on the various stress fields and contact pressure distributions. The computed footprint geometry is qualitatively compared with the measured data to examine the validity of the model. It is concluded that the proposed model can provide reliable predictions about the three-dimensional stress and deformation fields in the multi-layered system and the contact pressure distribution in the tire-road interface.

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