Computation of Viscous Flow Around Propeller-Body Configurations: Series 60 CB = 0.6 Ship Model

1994 ◽  
Vol 38 (02) ◽  
pp. 137-157 ◽  
Author(s):  
F. Stern ◽  
H. T. Kim ◽  
D. H. Zhang ◽  
Y. Toda ◽  
J. Kerwin ◽  
...  
Keyword(s):  
Viscous Flow ◽  
Turbulence Modeling ◽  
Critical Evaluation ◽  
Three Dimensional ◽  
Inviscid Flow ◽  
Ship Model ◽  
Flow Method ◽  
Critical Issues ◽  
Three Dimensional Configuration ◽  
Extensive Experimental Data

Validation of a viscous-flow method for predicting propeller-hull interaction is provided through detailed comparisons with recent extensive experimental data for the practical three-dimensional configuration of the Series 60 CB = 0.6 ship model. Modifications are made to the k-e turbulence model for the present geometry and application. Agreement is demonstrated between the calculations and global and some detailed aspects of the data; however, very detailed resolution of the flow is lacking. This supports the previous conclusion for propeller-shaft configurations and axisymmetric bodies that the present procedures can accurately simulate the steady part of the combined propeller-hull flow field, although turbulence modeling and detailed numerical treatments are critical issues. The present application enables a more critical evaluation through further discussion of these and other relevant issues, such as the use of radial-and angular-varying body-force distributions, the relative importance of turbulence modeling and grid density on the resolution of the harmonics of the propeller inflow, and three-dimensional propeller-hull interaction, including the differences for the nominal and effective inflows and for the resulting steady and unsteady propeller performance. Also, comparisons are made with an inviscid-flow method. Lastly, some concluding remarks are made concerning the limitations of the method, requirements and prognosis for improvements, and application to the design of wake-adapted propellers.

Calculations of Three-Dimensional, Viscous Flow and Wake Development in a Centrifugal Impeller

1981 ◽  
Vol 103 (2) ◽  
pp. 367-372 ◽  
Author(s):  
J. Moore ◽  
J. G. Moore
Keyword(s):  
Viscous Flow ◽  
Pressure Field ◽  
Three Dimensional ◽  
Inviscid Flow ◽  
Calculation Procedure ◽  
Wake Flow ◽  
Centrifugal Impeller ◽  
Duct Flow ◽  
Reduced Pressure ◽  
Flow Calculation

A partially-parabolic calculation procedure is used to calculate flow in a centrifugal impeller. This general-geometry, cascade-flow method is an extension of a duct-flow calculation procedure. The three-dimensional pressure field within the impeller is obtained by first performing a three-dimensional inviscid flow calculation and then adding a viscosity model and a viscous-wall boundary condition to allow calculation of the three-dimensional viscous flow. Wake flow, resulting from boundary layer accumulation in an adverse reduced-pressure gradient, causes blockage of the impeller passage and results in significant modifications of the pressure field. Calculated wake development and pressure distributions are compared with measurements.

Three-dimensional thermochemical nonequilibrium viscous flow over blunt bodies with catalytic surface

AIAA Journal ◽  
2001 ◽  
Vol 39 ◽  
pp. 626-636
Author(s):  
S. Peigin ◽  
V. Kazakov ◽  
M.-C. Druguet ◽  
S. Seror ◽  
D. E. Zeitoun
Keyword(s):  
Viscous Flow ◽  
Three Dimensional ◽  
Catalytic Surface ◽  
Blunt Bodies

Optimization of the Three-Dimensional Flow Path in the Scroll-Nozzle System of a Radial Inflow Turbine

1984 ◽  
Vol 106 (2) ◽  
pp. 511-515 ◽  
Author(s):  
E. A. Baskharone
Keyword(s):  
Flow Analysis ◽  
Three Dimensional ◽  
Inviscid Flow ◽  
Three Dimensional Flow ◽  
Multiply Connected ◽  
Dimensional Flow ◽  
Nozzle Configuration ◽  
Flow Domain ◽  
Radial Inflow Turbine ◽  
Compressibility Effects

A three-dimensional inviscid flow analysis in the combined scroll-nozzle system of a radial inflow turbine is presented. The coupling of the two turbine components leads to a geometrically complicated, multiply-connected flow domain. Nevertheless, this coupling accounts for the mutual effects of both elements on the three-dimensional flow pattern throughout the entire system. Compressibility effects are treated for an accurate prediction of the nozzle performance. Different geometrical configurations of both the scroll passage and the nozzle region are investigated for optimum performance. The results corresponding to a sample scroll-nozzle configuration are verified by experimental measurements.

Three-dimensional inviscid flow analysis of turbofan forced mixers

1985 ◽  
Author(s):  
T. BARBER ◽  
G. MULLER ◽  
S. RAMSAY ◽  
E. MURMAN
Keyword(s):  
Flow Analysis ◽  
Three Dimensional ◽  
Inviscid Flow

scholarly journals Improvement on Permeability of Cyclic Peptide/Peptidomimetic: Backbone N-Methylation as A Useful Tool

Marine Drugs ◽  
2021 ◽  
Vol 19 (6) ◽  
pp. 311
Author(s):  
Yang Li ◽  
Wang Li ◽  
Zhengshuang Xu
Keyword(s):  
Cyclic Peptides ◽  
Cyclic Peptide ◽  
Three Dimensional ◽  
Conformational Space ◽  
Cell Permeability ◽  
Relative Importance ◽  
Intrinsic Properties ◽  
Surface Areas ◽  
Synthetic Methodologies ◽  
Three Dimensional Configuration

Peptides have a three-dimensional configuration that can adopt particular conformations for binding to proteins, which are well suited to interact with larger contact surface areas on target proteins. However, low cell permeability is a major challenge in the development of peptide-related drugs. In recent years, backbone N-methylation has been a useful tool for manipulating the permeability of cyclic peptides/peptidomimetics. Backbone N-methylation permits the adjustment of molecule’s conformational space. Several pathways are involved in the drug absorption pathway; the relative importance of each N-methylation to total permeation is likely to differ with intrinsic properties of cyclic peptide/peptidomimetic. Recent studies on the permeability of cyclic peptides/peptidomimetics using the backbone N-methylation strategy and synthetic methodologies will be presented in this review.

Effects of Inlet Distortion on the Flow Field in a Transonic Compressor Rotor

1996 ◽  
Author(s):  
Chunill Hah ◽  
Douglas C. Rabe ◽  
Thomas J. Sullivan ◽  
Aspi R. Wadia
Keyword(s):  
Boundary Layer ◽  
Flow Field ◽  
Viscous Flow ◽  
Total Pressure ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Aerodynamic Loss ◽  
Transonic Compressor ◽  
Inlet Distortion ◽  
Compressor Rotor

The effects of circumferential distortions in inlet total pressure on the flow field in a low-aspect-ratio, high-speed, high-pressure-ratio, transonic compressor rotor are investigated in this paper. The flow field was studied experimentally and numerically with and without inlet total pressure distortion. Total pressure distortion was created by screens mounted upstream from the rotor inlet. Circumferential distortions of 8 periods per revolution were investigated at two different rotor speeds. The unsteady blade surface pressures were measured with miniature pressure transducers mounted in the blade. The flow fields with and without inlet total pressure distortion were analyzed numerically by solving steady and unsteady forms of the Reynolds-averaged Navier-Stokes equations. Steady three-dimensional viscous flow calculations were performed for the flow without inlet distortion while unsteady three-dimensional viscous flow calculations were used for the flow with inlet distortion. For the time-accurate calculation, circumferential and radial variations of the inlet total pressure were used as a time-dependent inflow boundary condition. A second-order implicit scheme was used for the time integration. The experimental measurements and the numerical analysis are highly complementary for this study because of the extreme complexity of the flow field. The current investigation shows that inlet flow distortions travel through the rotor blade passage and are convected into the following stator. At a high rotor speed where the flow is transonic, the passage shock was found to oscillate by as much as 20% of the blade chord, and very strong interactions between the unsteady passage shock and the blade boundary layer were observed. This interaction increases the effective blockage of the passage, resulting in an increased aerodynamic loss and a reduced stall margin. The strong interaction between the passage shock and the blade boundary layer increases the peak aerodynamic loss by about one percent.

Obstacle drag in stratified flow

1990 ◽  
Vol 429 (1876) ◽  
pp. 119-140 ◽  
Keyword(s):  
Experimental Study ◽  
Linear Density ◽  
Three Dimensional ◽  
Inviscid Flow ◽  
Force Balance ◽  
Video Recordings ◽  
Lee Waves ◽  
Time Variations ◽  
Obstacle Height ◽  
Stable Linear

This paper describes an experimental study of the drag of two- and three-dimensional bluff obstacles of various cross-stream shapes when towed through a fluid having a stable, linear density gradient with Brunt-Vaisala frequency, N . Drag measurements were made directly using a force balance, and effects of obstacle blockage ( h / D , where h and D are the obstacle height and the fluid depth, respectively) and Reynolds number were effectively eliminated. It is shown that even in cases where the downstream lee waves and propagating columnar waves are of large amplitude, the variation of drag with the parameter K ( = ND /π U ) is qualitatively close to that implied by linear theories, with drag minima existing at integral values of K . Under certain conditions large, steady, periodic variations in drag occur. Simultaneous drag measurements and video recordings of the wakes show that this unsteadiness is linked directly with time-variations in the lee and columnar wave amplitudes. It is argued that there are, therefore, situations where the inviscid flow is always unsteady even for large times; the consequent implications for atmospheric motions are discussed.

Experimental and Numerical Investigations on Flow Characteristics of the KVLCC2 at 30° Drift Angl

2015 ◽  
Author(s):  
Moustafa Abdel-Maksoud ◽  
Volker Müller ◽  
Tao Xing ◽  
Serge Toxopeus ◽  
Frederick Stern ◽  
...  
Keyword(s):  
Numerical Methods ◽  
Turbulence Modeling ◽  
Flow Characteristics ◽  
Flow Structures ◽  
Local Flow ◽  
Drift Angle ◽  
Vortical Structures ◽  
Ship Model ◽  
University Of Technology ◽  
Global And Local

Investigations of flow characteristics around ship hulls at large drift angle are very important for understanding the motion behavior of ships during maneuvers. At large drift angles, the flow is dominated by strong vortical structures and complex three-dimensional separations. An accurate prediction of these flow structures is still a challenge for modern computational fluid dynamics (CFD) solvers. Hull forms with high block coefficients are blunt and have strong curvatures, which leads to large area flow separations over smooth surfaces. These areas are sensitive to the relative angle between the flow and the ship motion direction. The paper is concerned with a collaborative computational study of the flow behavior around a double model of KVLCC2 at 30 degrees drift angle and Fr=0 condition, including analysis of numerical methods, turbulence modeling and grid resolution, and their effects on the mean flow and separation onset as well as formation of the vortical structures. This research is an outcome of a multi-year collaboration of five research partners from four countries. The overall approach adopted for the present study combines the advantages of CFD and EFD with the ultimate goal of capturing the salient details of the flow around the bluff hull form. The experiments were performed at the low - speed wind tunnel of the Hamburg University of Technology (TUHH). The main features of the global and local flow were captured in the experimental study. To determine the global flow characteristics, two different flow visualization techniques were used. The first one is a smoke test, which allows the visualization of vortex structures in vicinity of the ship model. The second test is a classic oil film method, which yields the direction of the limiting wall streamlines on the surface of the model. The analysis of the experimental results helped identify the separation zones on the ship model. To resolve the local flow-fields, LDA and PIV measurements were carried out in a selected number of measuring sections. Subsequently, the EFD and CFD results for the global and local flow structures were compared and analyzed. The numerical simulations were carried out by 5 institutions: Iowa Institute of Hydraulic Research of the University of Iowa (IIHR), USA, Maritime Research Institute Netherlands (MARIN), The Netherlands, Hamburg University of Technology (TUHH), Germany, Naval Surface Warfare Center, Carderock Division (NSWCCD) West Bethesda, USA and Swedish Defense Research Agency (FOI), Sweden. For the comparison with the experimental results, seven submissions of steady and unsteady CFD results are included in the present study. The participating codes include CFDShip-Iowa, ReFRESCO, FreSCo+, Edge, OpenFOAM (FOI) and NavyFoam. The size of the computational grids varies between 11 and 202 million control volumes or nodes. The influence of turbulence modeling on the predicted flow is studied by a wide variety of models such as isotropic eddy viscosity models of k-w family, Explicit Algebraic Reynolds Stress Model (EARSM), hybrid RANS-LES (DES), and LES. Despite notable differences in the grid resolutions, numerical methods, and turbulence models, the global features of the flow are closely captured by the computations. Noticeable differences among the computations are found in the details of the local flow such as the vortex strength and the location and extent of the flow separations.

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