Abstract Finite element analysis mode, the Coriolis mass flow meter (CMF)-straight simplified model of the modal analysis. This inspection of the casing and the support of the CMF, such as the impact on modal, the CMF-straight overall model, based on their structural characteristics of axial symmetry, using off-the-shelf two-dimensional CAD view, import into Marc generate three-dimensional model of the rotation, Modal analysis. Lanczos method used mode. Finally on the type of support measured the impact of the modal, the results show that the boundary conditions are different, modal frequency of great changes.
Key words: Coriolis mass flow meter dynamic characteristics of finite element analysis of modal
0 INTRODUCTION
Coriolis mass flow meter (CMF) is a direct measurement of mass flow to the flow meter, in principle, eliminate the temperature, pressure, fluid, density and other parameters of change on the impact of measurement accuracy, can adapt to gas, Liquid, two-phase, high viscosity of the fluid and paste media measurement, is a high-precision to a wide range of measurement method,It also has
Small loss of pressure, since emptying, and maintain a clean, and many other features, flow measurement is one of the direction of development.
Coriolis mass flow meter is the use of fluid flow through pipelines vibration generated Coriolis effect on the pipeline at both ends of vibration phase to measure the impact of the flow of the fluid quality of the pipeline. CMF deep understanding of people to work and to improve the performance of CMF, it is necessary to study the CMF vibration mode. Its role is:
to easily exciting, are generally the choice of measuring the resonant frequency as the excitation frequency;
choose a suitable excitation frequency to avoid interference from the industrial scene, will facilitate signal separation;
Vibrator, pick-up and circuit design and signal processing all need to know frequency;
pick-up-need to know the layout of the CMF modal;
structural optimization, stress, strain and fatigue life calculations;
can use the CMF system of vibration signals condition monitoring and failure prediction;
understanding of the process of vibration, have deviated from the ideal vibration error and compensation;
vibration interference understand the error and take measures to eliminate or prevent the system from possible interference from vibration, so as to ensure the accuracy and reliability of CMF heart
1 Coriolis mass flow meter measuring principle outlined
Coriolis flowmeter take many forms, the following in a single straight tube Coriolis flowmeter as an example for discussion.
as shown in Figure l, measurement of the middle set up a vibration device, set up at both ends of a pick-up sensor. No fluid flow through the time, the tubes of vibration shown in Figure la, the two ends of the tubes in the same state of vibration. When the fluid flow through pipelines vibration, the vibration frequency of the same generation and the Coriolis acceleration and the Coriolis force, as shown in Figure lb, AC, and the CB of the same size as the Coriolis force, the opposite direction , Superimposed on the role of measurement, the tubes would have distorted and vibration phase change. Coriolis force and fluid flow through the pipeline density and velocity is directly proportional (that is, the quality of traffic). The linear system shows phase difference is directly proportional to the quality of traffic. |
