A Theory for the Vibratory Effects Produced by a Propeller on a Large Plate

1959 ◽  
Vol 3 (04) ◽  
pp. 1-10
Author(s):  
John P. Breslin
Keyword(s):  
High Speed ◽  
Infinite Plate ◽  
Rate Of Change ◽  
Infinite Plane ◽  
Time Rate ◽  
Transverse Axis ◽  
Elastic Wall ◽  
The Moment ◽  
Ship Propeller ◽  
Speed Computer

The flow generated on an infinite plane or wall by a single-bladed ship propeller rotating on a shaft parallel to the plane in a uniform superposed stream is first considered. After demonstrating that the pressure on the wall depends only on blade position and not upon the time-rate-of-change of blade position, the force and the moment on the plane about a transverse axis are computed and found to be given by very simple formulas. Under the assumed neglect of the interferences arising from the image of the propeller in the wall, it is shown that the net force and moment on the wall are zero for all lightly loaded propellers having two or more blades. The case of nonuniform inflow is considered and shown to give nonzero vibratory forces. The case of uniform inflow is still of interest because the zero force and moment result does not mean that an elastic wall would not vibrate, and to substantiate this, a formula for the deflections of a thin "infinite" plate is given. This formula has not been evaluated because of its complexity. It is recommended that numerical evaluation be undertaken through the use of a high-speed computer.

Sound and turbulence modulation by particles in high-speed shear flows

2019 ◽  
Vol 875 ◽  
pp. 254-285 ◽  
Author(s):  
David A. Buchta ◽  
Gregory Shallcross ◽  
Jesse Capecelatro
Keyword(s):  
Gas Phase ◽  
High Speed ◽  
Pressure Fluctuations ◽  
Sound Radiation ◽  
Rate Of Change ◽  
Intensity Increase ◽  
Mass Loading ◽  
Local Pressure ◽  
Time Rate ◽  
Particle Laden Flows

High-speed free-shear-flow turbulence, laden with droplets or particles, can radiate weaker pressure fluctuations than its unladen counterpart. In this study, Eulerian–Lagrangian simulations of high-speed temporally evolving shear layers laden with monodisperse, adiabatic, inertial particles are used to examine particle–turbulence interactions and their effect on radiated pressure fluctuations. An evolution equation for gas-phase pressure intensity is formulated for particle-laden flows, and local mechanisms of pressure changes are quantified over a range of Mach numbers and particle mass loadings. Particle–turbulence interactions alter the local pressure intensity directly via volume displacement (due to the flow of finite-size particles) and drag coupling (due to local slip velocity between phases), and indirectly through significant turbulence changes. The sound radiation intensity near subsonic mixing layers increases with mass loading, consistent with existing low Mach number theory. For supersonic flows, sound levels decrease with mass loading, consistent with trends observed in previous experiments. Particle-laden cases exhibit reduced turbulent kinetic energy compared to single-phase flow, providing one source of their sound changes; however, the subsonic flow does not support such an obvious source-to-sound decomposition to explain its sound intensity increase. Despite its decrease in turbulence intensity, the louder particle-laden subsonic flows show an increase in the magnitude and time-rate-of-change of fluid dilatation, providing a mechanism for its increased sound radiation. Contrasting this, the quieter supersonic particle-laden flows exhibit decreased gas-phase dilatation yet its time-rate-of-change is relatively insensitive to mass loading, supporting such a connection.

Information retrieval on a high-speed computer

1959 ◽  
Author(s):  
A. R. Barton ◽  
V. L. Schatz ◽  
L. N. Caplan
Keyword(s):  
Information Retrieval ◽  
High Speed ◽  
Speed Computer

Angular Momentum Requirements of the Twisting and Nontwisting Forward 1 1/2 Somersault Dive

1987 ◽  
Vol 3 (1) ◽  
pp. 47-62 ◽  
Author(s):  
Ross H. Sanders ◽  
Barry D. Wilson
Keyword(s):  
Angular Momentum ◽  
High Speed ◽  
Center Of Gravity ◽  
Transverse Axis ◽  
Free Position ◽  
High Speed Cinematography ◽  
The Difference ◽  
Hip Flexion ◽  
Commonwealth Games

This study investigated the in-flight rotation of elite 3m springboard divers by determining the angular momentum requirement about the transverse axis through the divers center of gravity (somersault axis) required to perform a forward 1 1/2 somersault with and without twist. Three elite male divers competing in the 1982 Commonwealth Games were filmed using high-speed cinematography while performing the forward 1 1/2 somersault in the pike position and the forward 1 1/2 somersault with one twist in a free position. The film was digitized to provide a kinematic description of each dive. An inclined axis technique appeared to be the predominant means of producing twist after takeoff from the board. The angular momentum about the somersault axis after takeoff was greater for the forward 1 1/2 somersault with twist than the forward 1 1/2 somersault without twist for all three divers. The difference in angular momentum between the two dives of each diver ranged from 6% to 19%. The most observable difference between the dives during the preflight phases was the degree of hip flexion at takeoff. There was more hip flexion at takeoff in 5132D than 103B for all three divers. This difference ranged from 9° to 18° (mean = 14°).

STUDY OF PHASE PROPAGATION IN SUPERCONDUCTING ALUMINUM BY ULTRASONIC ATTENUATION MEASUREMENTS

1959 ◽  
Vol 37 (5) ◽  
pp. 614-618 ◽  
Author(s):  
K. L. Chopra ◽  
T. S. Hutchison
Keyword(s):  
Magnetic Field ◽  
Eddy Current ◽  
Ultrasonic Attenuation ◽  
Cylindrical Specimen ◽  
Current Theory ◽  
Superconducting Phase ◽  
Rate Of Change ◽  
Time Rate ◽  
Phase Propagation ◽  
The Magnetic Field

The phase propagation in superconducting aluminum has been studied by measuring the time rate of change of ultrasonic attenuation. The time taken for the destruction of the superconducting phase in a cylindrical specimen, by means of a magnetic field, H, greater than the critical field, Hc, is approximately proportional to{H/(H–Hc)} in agreement with eddy-current theory. In the converse case, where the superconducting phase is restored by switching off the magnetic field H (>Hc), the total time taken is nearly independent of the temperature (or Hc) as well as H. The superconducting phase grows at a non-uniform volume rate which is considerably less than the uniform rate of collapse.

Chemical and Clinical Evaluation of the Continuous-flow Analyzer "SMAC"

1974 ◽  
Vol 20 (8) ◽  
pp. 1062-1070 ◽  
Author(s):  
Morton K Schwartz ◽  
Victor G Bethune ◽  
Martin Fleisher ◽  
Gina Pennacchia ◽  
Celia J Menendez-Botet ◽  
...  
Keyword(s):  
Continuous Flow ◽  
High Speed ◽  
Total Bilirubin ◽  
Carbon Dioxide Content ◽  
Protein Matrix ◽  
Sodium Potassium ◽  
Calcium Phosphorus ◽  
Matrix Reference Material ◽  
Computer Controlled ◽  
Speed Computer

Abstract "SMAC" (Sequential Multiple Analyzer plus Computer) is a high-speed computer-controlled multitest analyzer. A 20-channel prototype SMAC (glucose, urea nitrogen, creatinine, carbon dioxide content, total bilirubin, calcium, phosphorus, cholesterol, iron, uric acid, chloride, sodium, potassium, total protein, albumin, creatine kinase, alkaline phosphatase, lactate dehydrogenase, and aspartate and alanine aminotransferases) has been evaluated for: (a) method precision during within-day runs and on a day-to-day basis over a period of time; (b) method linearity over a range established on a chemical basis and related to clinical requirements, with use of both aqueous standards and protein matrix reference material; and (c) correlation of SMAC values with those obtained by the methods routinely in use in our department.

scholarly journals High Speed, High Temperature, Fault Tolerant Operation of a Combination Magnetic-Hydrostatic Bearing Rotor Support System for Turbomachinery

2004 ◽  
Author(s):  
Mark Jansen ◽  
Gerald Montague ◽  
Andrew Provenza ◽  
Alan Palazzolo
Keyword(s):  
High Temperature ◽  
High Speed ◽  
Closed Loop ◽  
Fault Tolerant ◽  
Active Vibration Control ◽  
Control Algorithms ◽  
Displacement Sensors ◽  
Rotor Support ◽  
Active Vibration ◽  
Speed Computer

Closed loop operation of a single, high temperature magnetic radial bearing to 30,000 RPM (2.25 million DN) and 540°C (1,000°F) is discussed. Also, high temperature, fault tolerant operation for the three axis system is examined. A novel, hydrostatic backup bearing system was employed to attain high speed, high temperature, lubrication free support of the entire rotor system. The hydrostatic bearings were made of a high lubricity material and acted as journal-type backup bearings. New, high temperature displacement sensors were successfully employed to monitor shaft position throughout the entire temperature range and are described in this paper. Control of the system was accomplished through a stand alone, high speed computer controller and it was used to run both the fault-tolerant PID and active vibration control algorithms.

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