Theory for the Determination of Flutter Speed of a Class of Hydrofoils

1972 ◽  
Vol 94 (1) ◽  
pp. 76-80 ◽  
Author(s):  
J. Mahig
Keyword(s):  
Experimental Study ◽  
Drag Coefficient ◽  
Constant Speed ◽  
Flutter Speed ◽  
Drag Forces ◽  
Lift Curve ◽  
Theoretical Results

A theory is given for the determination of the flutter frequency and speed of a hydrofoil traveling at a constant speed. This work used the work of Sears to determine the fluctuating lift and combined it with the chordwise and transverse drag forces to determine flutter speeds. It is shown that flutter speed is sensitive to the drag coefficient as well as lift curve slopes. The theoretical results obtained are shown compared with an experimental study conducted by Huang.

Experimental Study of the Vertical Hydraulic Drag Force on Regular Tetrahedron

2013 ◽  
Vol 860-863 ◽  
pp. 1547-1550
Author(s):  
Rui Le ◽  
Wei Jiang ◽  
Qi Liu ◽  
Nan Chang Sun ◽  
Bing Xu
Keyword(s):  
Experimental Study ◽  
Drag Coefficient ◽  
Drag Force ◽  
Vertical Velocity ◽  
Hydraulic Engineering ◽  
Hydraulic Drag ◽  
Regular Tetrahedron ◽  
Impact Effect ◽  
Drag Forces ◽  
The Impact

It is well known that the hydraulic drag force on objects cant be ignored in computing the movement of objects in water. And the drag forces on sphere and cuboids have long been studied. While in hydraulic engineering, objects with regular tetrahedron shape are widely used to form the foundation and temporary dam for they can interlock each other to obtain a compacted integral. In this article the vertical hydraulic drag force on regular tetrahedron is studied by indoor experiments, the relation of the vertical hydraulic drag coefficient and the vertical velocity is proposed. And the max vertical speeds of different materials are deduced. The result is helpful to compute the movement of regular tetrahedron in water and estimate the impact effect on the groundwork.

scholarly journals Determination of Physical Properties, Moisture Absorption Process and Aerodynamic Properties of Grain and Cluster Straw of Two Wheat Cultivars

2020 ◽  
Vol 68 (5) ◽  
pp. 831-840
Author(s):  
Mohammad Jafari ◽  
Gholam Reza Chegini ◽  
Javad Khazaei
Keyword(s):  
Physical Properties ◽  
Drag Coefficient ◽  
Moisture Absorption ◽  
Mass Density ◽  
Terminal Velocity ◽  
Wheat Cultivars ◽  
Projected Area ◽  
Drag Forces ◽  
Aerodynamic Properties

In this study, physical properties of grain and cluster straw including geometric dimensions, moisture absorption and aerodynamic properties of two wheat cultivars were investigated. The effect of cultivar on width, thickness, geometric diameter, spheroid coefficient and mass density was significant at 1% probability level whilst there were no significant effect on grain projected area, length and weight. Moisture absorption of the grains was rapid during the first 30–40 min and then turned to zero. The terminal velocity of wheat grain and straw in three shapes was measured by calculating the projected area in horizontal, lateral and perpendicular directions and then, the drag coefficient was obtained by the equilibrium of the gravity and drag forces at the terminal velocity. Results also showed that increasing moisture content resulted in an increase in the terminal velocity and a decrease in the drag coefficient. Results obtained in this study can be used in designing wheat- cluster straw separation and processing.

Experimental Determination of the Roller Chain Load Distribution

1983 ◽  
Vol 105 (3) ◽  
pp. 331-338 ◽  
Author(s):  
M. R. Naji ◽  
K. M. Marshek
Keyword(s):  
Experimental Study ◽  
Experimental Determination ◽  
Elastic Properties ◽  
Load Distribution ◽  
Noticeable Effect ◽  
Roller Chain ◽  
Chain Link ◽  
A Chain ◽  
Theoretical Results

An experimental study was conducted to determine the effect of elastic properties, geometric variations, and lubrication on roller chain load distribution. Comparison was made with the theoretical results for a test chain on a 20-tooth sprocket. The load distribution was found for a large number of cases to be independent of the elastic properties of the chain and the sprocket. The load distribution for the chain on a driver sprocket differed from that for a chain on a driven sprocket because of the change in direction of the friction force. Lubrication had no noticeable effect. A large pitch for the sprocket teeth was found to amplify the tension in the chain link.

Experimental Study on the Failure Criterion for Brittle Materials in Compression

2011 ◽  
Vol 320 ◽  
pp. 259-262
Author(s):  
Xu Ran ◽  
Zhe Ming Zhu ◽  
Hao Tang
Keyword(s):  
Thin Film ◽  
Experimental Study ◽  
Compressive Strength ◽  
Fracture Mechanics ◽  
Failure Criterion ◽  
Brittle Materials ◽  
Experimental Results ◽  
Experiment Study ◽  
Confining Stress ◽  
Theoretical Results

The mechanical behavior of multi-cracks under compression has become a very important project in the field of fracture mechanics and rock mechanics. In this paper, based on the previous theoretical results of the failure criterion for brittle materials under compression, experiment study is implemented. The specimens are square plates and are made of cement, sand and water, and the cracks are made by using a very thin film (0.1 mm). The relations of material compressive strength versus crack spacing and the lateral confining stress are obtained from experimental results. The experimental results agree well with the failure criterion for brittle materials under compression, which indicates that the criterion is effective and applicable.

scholarly journals Determination of apoptosis through Bax expression in cryptorchid testis: an experimental study

2005 ◽  
Vol 11 (3) ◽  
pp. 170-173 ◽  
Author(s):  
Mehmet Dündar ◽  
Izzet Koçak ◽  
Nil Çulhaci ◽  
Haluk Erol
Keyword(s):  
Experimental Study ◽  
Cryptorchid Testis

Experimental Investigation of Microcutting Mechanisms in Marble Grinding

2009 ◽  
Vol 131 (6) ◽  
Author(s):  
LJ. Tanovic ◽  
P. Bojanic ◽  
R. Puzovic ◽  
S. Klimenko
Keyword(s):  
Experimental Study ◽  
Experimental Investigation ◽  
Cutting Force ◽  
Surface Finish ◽  
Normal Component ◽  
Natural Material ◽  
Grinding Process ◽  
Force Component ◽  
Diamond Grain

This paper offers an experimental study of the microcutting mechanisms in marble grinding to aid the optimization of the marble grinding process. The necessity for investigating these mechanisms is dictated by the increased use of marble in many applications and the fact that grinding and polishing processes are the dominant technologies used to meet surface finish requirements in this natural material. The experiments are aimed at the determination of the normal component of the cutting force and of the grain traces in microcutting with a single diamond grain. The investigations carried out make provisions for establishing critical grain penetration and cutting depths and allow the prediction of the normal cutting force component as a function of grain penetration speed and depth.

scholarly journals IV. On the dynamical theory of incompressible viscous fluids and the determination of the criterion

1895 ◽  
Vol 186 ◽  
pp. 123-164 ◽  
Keyword(s):  
Singular Solution ◽  
Physical State ◽  
Theoretical Calculations ◽  
Equations Of Motion ◽  
Dynamical Theory ◽  
Viscous Fluids ◽  
Linear Functions ◽  
Incompressible Viscous Fluids ◽  
Theoretical Results

1. The equations of motion of viscous fluid (obtained by grafting on certain terms to the abstract equations of the Eulerian form so as to adapt these equations to the case of fluids subject to stresses depending in some hypothetical manner on the rates of distortion, which equations Navier seems to have first introduced in 1822, and which were much studied by Cauchy and Poisson) were finally shown by St. Venant and Sir Gabriel Stokes, in 1845, to involve no other assumption than that the stresses, other than that of pressure uniform in all directions, are linear functions of the rates of distortion, with a co-efficient depending on the physical state of the fluid. By obtaining a singular solution of these equations as applied to the case of pendulums in steady periodic motion, Sir G. Stokes was able to compare the theoretical results with the numerous experiments that had been recorded, with the result that the theoretical calculations agreed so closely with the experimental determinations as seemingly to prove the truth of the assumption involved. This was also the result of comparing the flow of water through uniform tubes with the flow calculated from a singular solution of the equations so long as the tubes were small and the velocities slow. On the other hand, these results, both theoretical and practical, were directly at variance with common experience as to the resistance encountered by larger bodies moving with higher velocities through water, or by water moving with greater velocities through larger tubes. This discrepancy Sir G. Stokes considered as probably resulting from eddies which rendered the actual motion other than that to which the singular solution referred and not as disproving the assumption.

Sign in / Sign up

Export Citation Format

Share Document