Static Calibration and Dynamic Behaviour of a Six-Component Force Balance for Variable Pressure Water Tunnel Facilities

2021 ◽  
Author(s):  
D. Butler ◽  
S. M. Smith ◽  
P. A. Brandner ◽  
D. B. Clarke ◽  
B. W. Pearce
Keyword(s):  
Dynamic Behaviour ◽  
Force Balance ◽  
Variable Pressure ◽  
Water Tunnel ◽  
Static Calibration ◽  
Pressure Water ◽  
Component Force

Numerical Versus Experimental Cavitation Tunnel (A Supercavitating Hydrofoil Experiment)

1993 ◽  
Vol 115 (4) ◽  
pp. 760-765 ◽  
Author(s):  
S. A. Kinnas ◽  
C. H. Mazel
Keyword(s):  
Variable Pressure ◽  
Cavity Surface ◽  
Water Tunnel ◽  
Analysis Method ◽  
Cavitation Tunnel ◽  
Pressure Water ◽  
Nonlinear Cavity

A supercavitating hydrofoil experiment is performed at the MIT Variable Pressure water tunnel, at several angles of attack and cavitation numbers. The velocity is measured on a rectangular contour surrounding the foil and cavity as well as in the vicinity of the cavity surface. The measurements are compared to the predicted results from a nonlinear cavity analysis method in which the effects of the tunnel walls are included via images. Forces are inferred from momentum integrations of the measured velocities and compared to those predicted from the analysis.

Cavitating Propeller Experiment (CAPREX III): Measurement and Prediction of Tunnel Pressures

1998 ◽  
Vol 42 (03) ◽  
pp. 233-248
Author(s):  
Spyros A. Kinnas ◽  
Richard W. Kimball ◽  
Jin-Keun Choi
Keyword(s):  
Numerical Method ◽  
Pressure Field ◽  
Phase Iii ◽  
Variable Pressure ◽  
Water Tunnel ◽  
Time Varying ◽  
Tunnel Wall ◽  
Unsteady Pressure ◽  
Pressure Water ◽  
Three Components

This paper first describes Phase III of the CAvitating PRopeller Experiment (CAPREX) performed at MIT's variable pressure water tunnel. The three components of the screen-generated nominal wake inflow were measured using an LDV system. The unsteady pressure field on the upper tunnel wall for the first three blade harmonics was also measured in a 5 × 5 grid above the propeller tip, for various propeller cavitation conditions from fully wetted to supercavitating. Then, a recently developed numerical method which models the flow of a cavitating propeller inside a tunnel is used for the calculation of the pressures on the tunnel walls. The effects of a time-varying blade cavity source and of the flexibility of the tunnel walls are included in the calculation. Lastly, the amplitudes of the first blade harmonics of the predicted pressures are compared directly with those measured in the experiment.

Propeller Sheet Cavitation Predictions Using a Panel Method

1999 ◽  
Vol 121 (2) ◽  
pp. 282-288 ◽  
Author(s):  
A. C. Mueller ◽  
S. A. Kinnas
Keyword(s):  
Boundary Element Method ◽  
Boundary Element ◽  
Panel Method ◽  
Time Dependent ◽  
Variable Pressure ◽  
Water Tunnel ◽  
Sheet Cavitation ◽  
Pressure Water ◽  
Element Method ◽  
Blade Geometry

A boundary element method is used to predict the time-dependent cavitation on a propeller subject to nonaxisymmetric inflow. The convergence of the method is studied. The predicted cavities agree well with those observed in CAPREX, an experiment performed at MIT’s variable pressure water tunnel. The method is modified so that prediction of cavities detaching at mid-chord regions is possible. An algorithm for predicting the cavity detachment location on the blade is described and applied on a blade geometry which exhibits mid-chord cavitation.

Cavitation Inception Behind a Jet-Propelled Body

2007 ◽  
Author(s):  
William Hambleton ◽  
Eduard Amromin ◽  
Roger E. A. Arndt ◽  
Svetlana Kovinskaya
Keyword(s):  
Velocity Ratio ◽  
The Body ◽  
Force Balance ◽  
Water Tunnel ◽  
Minimum Diameter ◽  
Cavitation Inception ◽  
Initial Comparison ◽  
Jet Velocity ◽  
Good Agreement

Cavitation inception behind an axissymmetric body driven by a waterjet has been studied experimentally and numerically. Water tunnel tests have been performed with the body mounted on a force balance. The transom of the body contained a nozzle located along the centerline. Tests were carried out for various water tunnel speeds such that jet velocity ratio, VJ/U, could be varied in the range 0 to 2. Distinctly different cavitation patterns were observed at zero jet velocity (when cavitation appeared in spiral vortices in such flows) and at a various jet velocity ratios (when cavitation appeared between counter-rotating vortices around the jet in such flows). Cavitation inception/disappearance has been determined visually. The body drag was also measured. An analytical method for determination of cavitation inception index has been developed on the basis of a viscous-inviscid interaction concept, with employment of special semiempirical approximations for vortices and consideration of surface tension. These approximations have been preliminarily validated for nozzle jet cavitation (for nozzle discharge in co-flow). It was assumed that visualization allows detection of cavities (bubbles) of 0.4mm-0.5mm diameter or larger. The cavitation inception index is defined as the cavitation index for cavities of such minimum diameter when these cavities are located between counter-rotating vortices. The initial comparison of predicted and measured values of the cavitation inception index shows good agreement.

Research and Design of a Pre-Stressed Six-Component Force/Torque Sensor Based on the Stewart Platform

2005 ◽  
Author(s):  
Yong-Sheng Zhao ◽  
Yu-Lei Hou ◽  
Zhi-Wei Yan ◽  
Hui-Ling Yuan ◽  
Jin Gao
Keyword(s):  
Mathematical Model ◽  
Screw Theory ◽  
Parallel Architecture ◽  
Stewart Platform ◽  
Influence Coefficient ◽  
Torque Sensor ◽  
Static Calibration ◽  
The Mathematical Model ◽  
Research And Design ◽  
Component Force

This paper presents the research and design of a novel parallel architecture of pre-stressed six-component force/torque sensor based on the Stewart platform. The mathematical model of the structure was build by using the screw theory. The influence of joint frictional moment on the performances of the sensor is analyzed by using the concept of kinematic influence coefficient. In this paper, we define the indices of force/torque isotropy and generalized amplifying index to evaluate the performances of the sensor and discuss the optimal design of the sensor dimensions considering these indices. The prototype sensor was designed and manufactured. The theoretical and experimental study of the static calibration of the prototype is carried out, and the problem of the hyperstatic is solved perfectly. The results from the static calibration experimentation validate the correctness of the theoretical analysis.

scholarly journals Development of a Sensitivity-Adjustable Three-Component Force Balance and Its Application to Wind Tunnel Testing

2013 ◽  
Vol 8 (2) ◽  
pp. 209-218 ◽  
Author(s):  
Gouji YAMADA ◽  
Hiromitsu KAWAZOE ◽  
Hiroshi SUEMURA ◽  
Takashi MATSUNO ◽  
Shigeru OBAYASHI
Keyword(s):  
Wind Tunnel ◽  
Force Balance ◽  
Wind Tunnel Testing ◽  
Component Force ◽  
Tunnel Testing

Three-component force balance for flows of millisecond duration

AIAA Journal ◽  
1996 ◽  
Vol 34 (3) ◽  
pp. 590-595 ◽  
Author(s):  
David J. Mee ◽  
William J. T. Daniel ◽  
John M. Simmons
Keyword(s):  
Force Balance ◽  
Component Force

Design of the Novel Calibration Platform for Piezoelectric Dynamometers

2012 ◽  
Vol 580 ◽  
pp. 3-6
Author(s):  
Chang Yin Gao ◽  
Wan Quan Li
Keyword(s):  
High Precision ◽  
Force Sensor ◽  
Vertical Force ◽  
The Novel ◽  
Calibration Standard ◽  
Static Calibration ◽  
High Rigidity ◽  
Two Component ◽  
Torque Load ◽  
Component Force

In order to accomplish the static calibration of piezoelectric dynamometer, the principle and structure of a multifunctional high-precision, high rigidity static calibration platform is manufactured in this paper. The screw loading mechanisms are used to achieve vertical force and horizontal forces, and its value can directly obtained by the standard measuring ring. The torque load adopts “force × lever arm" law, that is, the two horizontal loading mechanisms are relatively shifted to form force arm, and at the same time two parallel forces that have the same magnitude and opposite directions are generated. After accuracy and rigidity experiments, the static calibration platform has reached the calibration standard stipulated by CIRP-STCC. Undoubtedly, the calibration platform can use to calibrate unidirectional force, two component force sensor, three-component piezoelectric dynamometer and the drilling dynamometer, such as sensitivity, linearity, repeatability, hysteresis and crosstalk.

The Effect of a Mass Height and Centre of Gravity on the Re-Righting of Sailing Yachts

2005 ◽  
Author(s):  
Jonathan R. Binns ◽  
Paul Jonathan
Keyword(s):  
Wave Height ◽  
Degree Of Freedom ◽  
Force Balance ◽  
Centre Of Gravity ◽  
Factors Influencing ◽  
Free Model ◽  
Six Degree Of Freedom ◽  
Component Force

The effects of mast height and centre of gravity on re-righting have been investigated experimentally using free and captive models. Free model motions were measured using six degree of freedom photogrammetry. Captive model forces were measured using a six component force balance. The results have shown that a relatively small increase in mast height has a much greater effect than the increase in limit of positive stability used in the experiments. It would appear from the results that the overriding factors influencing re-righting in these experiments are the mast height and the wave height and steepness.

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