Showing papers on "Vortex-induced vibration published in 1977"

Fluid velocity measuring device

Abstract: A fluid velocity measuring device which when placed in a freestream fluid flow causes vortices to be formed at a frequency proportional to the flow rate of the fluid. Sensors on the device generate electric signals with frequency proportional to the rate of vortex creation and with relative mean amplitudes indicative of fluid flow direction. Electric circuitry translates the electric signals into indications of fluid speed and direction.

Experiments on fluidelastic vibrations of tube arrays

Abstract: The overall objective of the activity is to develop new and/or improved, experimentally-validated analytical methods and guidelines for designing LMFBR components to avoid detrimental flow induced vibration. Many reactor system components, such as heat exchanger tubes and reactor fuel pins are susceptible to flow induced vibration. Due to fluid coupling, the tubes will respond in one or several of coupled modes. Therefore, understanding the coupled modes is essential in design to avoid detrimental flow-induced vibrations. Four series of tube arrays are tested. The arrangements of the tubes are as follows: (a) a row of five tubes with the gap to tube radius ratio (G/R) equal to 2.0, 1.0, and 0.25; (b) three-tube arrays in the staggered arrangement with G/R equal to 2.0, 1.0 and 0.5; (c) seven-tube arrays in the staggered arrangement with G/R equal to 1.5, 1.0 and 0.4; and (d) four-tube array in a square pattern with G/R = 0.5. The fourth series is tested under five different conditions: (1) fully submerged in unconfined water; (2) partially submerged in water; (3) near a flat wall; (4) contained in a circular cylinder; and (5) fully submerged in a liquid of high viscosity (mineral oil). A means to excite themore » tubes is provided by an electromagnetic exciter assembly. A servo system can be used to control input. Response in the form of tube acceleration is measured using two accelerometers mounted on each tube. The data is processed in a fast Fourier Transform Analyzer. An analysis is made for each test case. The detailed information for uncoupled and coupled natural frequencies, mode shapes, damping, and tube response are presented in the report. The experimental data and analytical results are found to be in good agreement.« less

Fluid structure interaction phenomena in pressure vessel and piping systems

Abstract: The volume contains seven papers, in which the fluid-structure interaction phenomena is considered with respect to a number of pressure vessel and piping problems which are of particular interest to the power generation industry, but no less important to many other applications. The papers address such problems as the fluid-elastic vibration of heat exchanger tube banks and nuclear reactor fuel rods; flow-induced vibration of nuclear reactor internal components; vibration of piping systems containing fluid; crack extension of tubes containing pressurized fluid; and the response of fluid-filled vessels or pipes to incident pressure waves. The methods used by the authors encompass analytical, numerical (with large digital computers), and experimental together with dimensional analysis. Individual papers are indexed separately.

Computer Modeling of Flow Induced In-Reactor Vibrations

Abstract: An assessment of the reliability of finite element method computer models, as applied to the computation of flow induced vibration response of components used in nuclear reactors, is presented. The prototype under consideration was the East Flux Test Facility reactor being constructed for US-ERDA. Data were available from an extensive test program which used a scale model simulating the hydraulic and structural characteristics of the prototype components, subjected to scaled prototypic flow conditions as well as to laboratory shaker excitations. Corresponding analytical solutions of the component vibration problems were obtained using the NASTRAN computer code. Modal analyses and response analyses were performed. The effect of the surrounding fluid was accounted for. Several possible forcing function definitions were considered. Results indicate that modal computations agree well with experimental data. Response amplitude comparisons are good only under conditions favorable to a clear definition of the structural and hydraulic properties affecting the component motion.