scholarly journals FIELD MEASUREMENT OF SURFACE VELOCITY DISTRIBUTION BY GRADIENT METHOD USING SPATIOTEMPORAL IMAGES

2002 ◽  
Vol 46 ◽  
pp. 821-826 ◽  
Author(s):  
Ichiro FUJITA ◽  
Ryota TSUBAKI
Keyword(s):  
Velocity Distribution ◽  
Gradient Method ◽  
Field Measurement ◽  
Surface Velocity

Pure Design Method for Aerofoils in Cascade

1969 ◽  
Vol 11 (5) ◽  
pp. 454-467 ◽  
Author(s):  
K. Murugesan ◽  
J. W. Railly
Keyword(s):  
Exact Solution ◽  
Velocity Distribution ◽  
Design Problem ◽  
Design Method ◽  
Tangential Velocity ◽  
Surface Velocity ◽  
Normal Velocity ◽  
Blade Design ◽  
Blade Shape

An extension of Martensen's method is described which permits an exact solution of the inverse or blade design problem. An equation is derived for the normal velocity distributed about a given contour when a given tangential velocity is imposed about the contour and from this normal velocity an initial arbitrarily chosen blade shape may be successively modified until a blade is found having a desired surface velocity distribution. Five examples of the method are given.

An inverse design method of diffuser blades by genetic algorithms

1998 ◽  
Vol 212 (4) ◽  
pp. 261-267 ◽  
Author(s):  
H-Y Fan
Keyword(s):  
Neural Network ◽  
Genetic Algorithm ◽  
Velocity Distribution ◽  
Design Method ◽  
Back Propagation ◽  
Inverse Design ◽  
Surface Velocity ◽  
Target Velocity ◽  
Constant Height ◽  
Inverse Design Method

A genetic algorithm incorporating a neural network technique is proposed to search for a turbo-machinery diffuser blade profile that produces a given velocity distribution on its surface. Such a new inverse design method works through minimizing the error between the surface velocity distribution of candidate blades and the target velocity distribution. For ease of employing the genetic algorithm, the blade profiles to be searched are parameterized by Bezier curves. To fix the surface velocity distribution of a candidate blade, a special type of back propagation (BP) neural network is implemented. The proposed approach is illustrated by a diffuser having two-dimensional blades with constant height and thickness. The simulations show that the new method is not only feasible but also reliable and efficient.

scholarly journals FIELD MEASUREMENT OF A SURFACE VELOCITY AND ITS TURBULENCE DURING A FLOOD IN THE YODO RIVER BY USING PIV

2000 ◽  
Vol 44 ◽  
pp. 455-460
Author(s):  
Shirou AYA ◽  
Hajime TSUYUGUCHI ◽  
Satoshi KAKINOKI ◽  
Yuki MUROTA ◽  
Ichiro FUJITA
Keyword(s):  
Field Measurement ◽  
Surface Velocity

Acoustic Design Sensitivity for Structural Radiators

1992 ◽  
Vol 114 (2) ◽  
pp. 178-186 ◽  
Author(s):  
K. A. Cunefare ◽  
G. H. Koopmann
Keyword(s):  
Velocity Distribution ◽  
Design Sensitivity ◽  
Characteristic Dimension ◽  
Surface Velocity ◽  
Element Formulation ◽  
Acoustic Intensity ◽  
Acoustic Design ◽  
Sensitivity Distribution ◽  
Maximum Value ◽  
Rigid Surfaces

An analysis technique designated as acoustic design sensitivity (ADS) analysis is developed via the numerical treatment of a discrete quadratic expression for the total acoustic power radiated by a three-dimensional extended structure. A boundary element formulation of the Helmholtz Integral Equation is the basis of the analysis leading to the quadratic power expression. Partial differentiation of the quadratic power expression with respect to a known surface velocity distribution leads to a sensitivity distribution, represented by a distribution of values on the surface of a structure. The sensitivity values represent a linear approximation to the change in the total radiated power caused by changes in the surface velocity distribution. For a structure vibrating with some portions of its surface rigid and such that the acoustic wavelength is long compared to a characteristic dimension of the structure, ADS analysis reveals that the rigid surfaces strongly influence the sensitivity distribution, as expected. Under such conditions, the rigid surfaces can exhibit the maximum value of the entire sensitivity distribution, even though the acoustic intensity is identically zero on a rigid surface. As the frequency increases, and the acoustic wavelength becomes comparable to a characteristic dimension of the structure, the position of the maximum value of the sensitivity distribution will coincide with the region of the maximum surface acoustic intensity.

A Method for Inverse Aerofoil and Cascade Design by Surface Vorticity

1982 ◽  
Author(s):  
R. I. Lewis
Keyword(s):  
Velocity Distribution ◽  
Incompressible Flow ◽  
Design Tool ◽  
The Body ◽  
Surface Velocity ◽  
Classical Solutions ◽  
Analysis Tool ◽  
Attached Flow ◽  
Turbomachine Blade

Surface vorticity theory, normally considered as an analysis tool, has been modified to operate as a design tool whereby the shapes of components may be found to produce a prescribed surface velocity in incompressible flow. The basis of the method is presented and checked against classical solutions for cylindrical and diamond shaped struts with fully attached flow. A procedure for turbomachine blade or aerofoil design is outlined and illustrated with back checks via Martensen’s method. The method allows specification of velocity distribution on either or both surfaces of the body. If only one surface of an aerofoil or blade is prescribed, the user is allowed to specify profile thickness also.

Design of Cascades for Incompressible Plane Potential Flows With Prescribed Velocity Distribution

1971 ◽  
Vol 93 (3) ◽  
pp. 321-331 ◽  
Author(s):  
W. Schwering
Keyword(s):  
Velocity Distribution ◽  
Surface Velocity ◽  
Two Dimensional ◽  
Blade Profile ◽  
Method Of Calculation ◽  
Potential Flows ◽  
Loss Coefficients ◽  
Optimum Velocity ◽  
Made In

A method of calculation in designing two-dimensional cascades with given velocity distribution is described. An iterative method of the solution for the integral equation to determine the coordinate function for the blade profile is presented. A parametric formulation for the surface velocity distribution is developed. Some design examples for deceleration cascades with given flow angles and prescribed velocity distribution are discussed. Calculations of the boundary layers along the surfaces of the airfoil and cascade loss coefficients are made in order to obtain information on the quality of cascades designed by this method. Proceeding from the results of boundary layer calculations, it should be possible to further improve the parametric formulation for the surface velocity distribution and in this way prescribe better or even “optimum” velocity distributions.

scholarly journals Application of an Entropic Method Coupled with STIV for Discharge Measurement in Actual Rivers

2021 ◽  
Vol 945 (1) ◽  
pp. 012036
Author(s):  
Yoshiro Omori ◽  
Ichiro Fujita ◽  
Ken Watanabe
Keyword(s):  
Velocity Distribution ◽  
Flow Velocity ◽  
River Flow ◽  
Measurement Techniques ◽  
Vertical Direction ◽  
Acoustic Doppler Current Profiler ◽  
Surface Flow ◽  
Surface Velocity ◽  
Cross Sectional ◽  
Current Profiler

Abstract In recent years, due to the frequent occurrence of floods that exceed the facility maintenance level due to climate change, non-contact flood flow measurement techniques have been paid attention and actually some measurements have been conducted by applying them instead of the conventional float method. The space-time image velocimetry (STIV) which can measure the surface flow velocity distribution from video images is one of such techniques. In order to calculate the river flow from the surface velocity distribution, it is necessary to determine an appropriate surface velocity coefficient, which is the ratio of the average depth velocity to the surface velocity. However, at present, empirical default value has been still used in practice. In this study, the cross-sectional velocity distribution was calculated using an entropic method by utilizing the surface velocity distribution measured by STIV and compared with Acoustic Doppler Current Profiler (ADCP) observation. It was confirmed that the introduction of the velocity dip system express the flow velocity distribution in the vertical direction, where the velocity dip occurs due to the influence of vegetation.

Sign in / Sign up

Export Citation Format

Share Document