The Coriolis mass flowmeter study the dynamic characteristics
Published on:2015-1-12 8:56:44 Hits:

Abstract modal analysis method, the Coriolis mass flowmeter (CMF) single straight tube simplified model modal analysis. This is a study of the impact of modal CMF casing and support tube, single straight tube CMF overall model, based on the structural characteristics of its axis of symmetry, the use of existing 2D CAD view, Marc imported to generate three-dimensional model of the rotation, modulo modal analysis. Using Lanczos method for solving modality. Finally, the influence of the type of support on the measuring tube modal calculation results show that different boundary conditions, a large modal frequency.

Keywords Coriolis mass flowmeter finite element modal analysis of dynamic characteristics

0 Introduction

Coriolis mass flowmeter (CMF) is a flow meter for direct measurement of mass flow, which eliminates the effect of changes in the parameters of temperature, pressure, fluid state, the density of the measurement accuracy in principle, can be adapted to the gas measuring liquid, two-phase, high-viscosity fluids and pasty media, is an adaptation to a wide range of high-precision measurement methods, it has

Pressure loss is small, self-emptying, many features to keep clean, is one of the development direction of flow measurement.

Coriolis mass flowmeters, the Coriolis effect is the impact on the ends of the pipe when the vibration phase of the vibration by the fluid flow through the fluid flowing through the conduit to measure the quality of the conduit. To understand the depth of the work of the CMF and CMF improved performance, it is necessary to study the vibration mode CMF. Its role are:

① To easily excited, generally choose the resonant frequency of the measuring tube as the excitation frequency;

② Select the appropriate excitation frequency to avoid interference industrial site, will bring convenience signal separation;

③ exciter, pick-up and circuit design and signal processing are required to understand the vibration frequency;

④ vibration pickup arrangement need to know CMF modal;

⑤ structural optimization, stress, strain and fatigue life calculation;

⑥ can use the CMF system vibration signal status monitoring and fault forecasting;

⑦ understand the process of vibration to obtain compensation from the ideal error and vibration under;

⑧ understand the error caused by interference vibration, take measures to eliminate or prevent possible interference vibration system to ensure the accuracy and reliability of the CMF's heart

A Coriolis mass flowmeter measurement principle Overview

Coriolis flowmeter has many forms, following a single straight tube Coriolis flowmeter as an example to discuss.

Shown in Figure l, in the middle of the measuring tube is provided with an exciting means, is provided at both ends of the pick-up sensor. When no fluid flows through the vibration of the tube as shown in Fig. La, the tube ends of the same vibration state. When the fluid flows through the vibrating pipe, and the same excitation frequency generated Coriolis acceleration and Coriolis force, as shown in Figure lb, the Coriolis force is the same size segment AC and CB segment, in the opposite direction role superimposed on the measuring tube, the tube will produce distortion and vibration phase changes. Coriolis force is proportional to the fluid density and velocity and flow through the pipeline (ie, mass flow rate). For linear systems, but we can see the phase difference is proportional to the mass flow rate.

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