Valve Vibration Research Articles

弁の流体振動

弁の流体振動

One-dimensional model of diastolic semilunar valve vibrations productive of heart sounds

Abstract The vibrations of the closed semilunar valves were modeled mathematically. The factors which affect diastolic vibration which were identified in the mathematical model relate to the characteristics of the second heart sound.

One-dimensional model of diastolic semilunar valve vibrations productive of heart sounds

One-dimensional model of diastolic semilunar valve vibrations productive of heart sounds

Preliminary Observations on Interventricular Septum Vibrations

In previous experimental and clinical studies on aortic valvular stenosis it has been suggested that in addition to the degree of stenosis, other factors, such as the pathoanatomy of the valve and turbulence-induced vibrations, might be of importance. Using echocardiography, vibrations of the interventricular septum were demonstrated in six consecutive patients with congenital aortic stenosis. In comparable normal subjects no such vibrations could be seen. The clinical significance of ventricular wall vibrations has not yet been established.

A General Method for Simulating the Flow Dependent Nonlinear Vibrations of Compressor Reed Valves

A mathematical model is developed for the nonlinear vibrations of automatic reed valves in high-speed refrigeration compressors. Specifically considered are a general class of values which wrap about curved backer plates. Two simple experiments are described which allow the nonlinearities of the valve system to be defined by a single nonlinear second order differential equation. Valve oscillation frequencies inside an operating compressor are predicted through a linearization of the valve equation. Comparisons with experiment are included.

Acoustically induced safety valve vibration

Safety valve manufacturers generally recommend installing safety valves a minimum of eight to ten pipe diameters down stream of a fitting. Space limitations often require their installation much closer to a fitting. When so installed, acoustically induced vibration often leads to problems with noise, vibration, valve chattering, or valve integrity. Based upon measurements of safety valves exhibiting acoustically induced vibration, a procedure for installing safety valves was developed. This procedure involved alternating the lengths of inlet nozzles and specific details for their attachment to the steam line. Measurements of a successful installation of this procedure at a fossil‐fueled power plant are presented and compared with the measurements made before the revised installation.

Acoustic radiation from pipes, excited by internal turbulent flow: Comparison of experimental results with theory

The analysis of acoustic radiation from piping systems is complicated by the presence of multiple excitation sources; for example, mechanical valve vibration, acoustic near- and farfields, and the random pressure field of fully-developed turbulent flow will normally act together. This latter pressure field is well defined, and was chosen as the excitation for an initial parametric investigation of the response of and radiation from piping systems. An intermittent induced-flow pipe facility, mounted across an anechoic chamber, was used to obtain extensive measurements of the radiation from steel and P.V.C. pipes for a wide range of flow speeds and several pipe wall thicknesses. Theoretical predictions compare favourably with experimental measurements. The main conclusions are: the acoustic power radiation is resonant and well-described by considering only acoustically fast pipe vibration modes; this radiation is proportional to the modal loss factors and to the fifth power of flow Mach number. Comparisons between excitation by fully developed flow and propagating acoustic fields are given, which demonstrate their relative importance.

Erratum for “Analysis of Vibration of Hollow-Cone Valves”

Erratum for “Analysis of Vibration of Hollow-Cone Valves”

Analysis of Vibration of Hollow-Cone Valves

The theoretical analysis of vibration of hollow-cone valves is developed using conformal mapping to find the potential function with and without circulation. Hydrodynamic forces are obtained by integrating the unsteady Bernoulli equation. The equations of motion with two degrees-of-freedom are considered and are based on the assumption that the displacements of the vane and valve are small. Vibrational frequency, amplitude, acceleration, and pressure distribution on the vanes are calculated and compared with field experiments. A safety parameter is introduced to ensure that valves can operate in a satisfactory condition without undue vibration.

On an Example of Vibration of Circular Disc Valve which has an Overlap between Valve Disc and Seat

Making use of a theoretical formula which expresses approximately, under the consideration of viscosity, the relation of floating force F and the lift of the circular disc valve which has an overlap between valve disc and seat, the equation of motion on valve is established, and the condition of valve vibration is discussed by means of Routh's criterion. Then as an example, the vibration of a water-supply cock is studied. The results obtained reveal that, in case where the radius of valve disc is relatively larger, when compared with the radius of valve seat. the effective pressure P is high and ∂F/∂P is negative, a selfexcited vibration appears, if the lift of valve is smaller, and then chattering occurs owing to the disappearance of a restoring force, if the lift is higher. In order to stop the vibration, it is effective to make small the overlap of valve disc and seat.

Vibration of Automatic Fuel Valves

Vibration of Automatic Fuel Valves

無気噴油機関の自動燃料弁の振動

無気噴油機関の自動燃料弁の振動