This study presents a basic idea for the self·excitation mechanism of reed valves in refrigerant compressors used for air conditioners or refrigera· tors. The detailed experimental data on the phase lag of fluid pressure, which were obtained from a forced vibration test on a simple axisymmetrical model, namely a resonator, composed of the valve, the valve plate, the cylinder and the piston, wer...

The physiological mechanisms by which vibration and other physiotherapy interventions may clear secretions in subjects with cystic fibrosis are unknown. The main aim of this study was to compare the expiratory flow rates and frequencies of airflow oscillation of vibration to those of Acapella(R), Flutter(R), positive expiratory pressure and percussion. Respiratory flow rates were measured durin...

When a cylinder is mounted on an elastic support within current, vortex-induced vibrations (VIV) may occur down to Reynolds number ( Re ) close $20$ , based the body diameter $D$ and inflow velocity $U$ ), i.e. below critical value of $47$ reported for onset flow unsteadiness when fixed. The impact forced rotation elastically system behaviour explored numerically $Re \leqslant 30$ over wide ran...

the evaluation and control of the trains induced vibrations needs even more attention in the case of underground tracks which passes near to monuments and historical sites. the rail corrugations which occur due to the wheels’ impulse loads during the operation period of underground railway tracks, usually amplify the ground borne noise and vibration. in the current study, the mentioned phenomen...

It has been suggested that poststenotic weakening of arterial walls is caused by arterial wall vibration and structural fatigue initiated by pressure disturbances in turbulent blood flow. We examined the frequency spectra of wall vibration downstream from experimental arterial stenoses and compared them with the natural resonant vibration characteristics of the artery walls. Spectra of arterial...

VIV model test results are presented for a bundle of three parallel pipes all lying in the same plane, similar to a riser with large kill and choke lines. The rigid model was attached to a spring-mounted frame in the MIT towing tank. The horizontal model was towed in the tank and allowed to respond in free vibration to vortex-induced vibration in the cross-flow direction. The angle of attack of...

Subsea jumpers connecting the underwater wellhead and nearby manifold commonly undergo flow-induced vibration (FIV) due to spatially frequent alteration in flow direction, velocity, pressure phase volume fraction of oil–gas two-phase flow, potentially leading fatigue damage. This paper reports numerical results FIV a reversed U-shaped jumper excited by gas–liquid which evolves from initial slug...