The Research On Resonant Cylindrical Of Liquid Density Sensor

The detection of liquid density has embedded into every aspect in our daily life. In areas such as industrial production and scientific research, density sensor is required to have more superior performance. The subject stems from the “10th Five-Year Plan” defense pre-research project, aiming at the research on the vibration principle of cylinder shell and the development of the resonating cylinder shell liquid density meter that can meet the requirements of industrial production.Resonant cylinder liquid density sensor with short-thin cylinder harmonic oscillator as the core, constitutes a high quality closed-loop resonance system based on the principle of the positive feedback. Density is measured according to the strict corresponding relation of the vibration period of resonance tube and the liquid density in sensitive area.This dissertation focuses on the design of the sensor measurement system, based on in-depth analysis of the working principle of the resonant cylindrical of liquid density sensor. The specific contents are as follows:1. This paper introduced and compared some common methods of liquid density measurement, determined the research method and task of the subject by understanding the current situation of development and research at home and abroad;2. The measurement principle of the cylinder shell resonant liquid density sensor was analyzed and deduced. A mathematical model of the resonance tube which is the core component of the sensor is established, and the resonance tube is simulated by finite element analysis software, analyzing the vibration regularity and influence factors of the resonant cylinder. The structure parameters, constraint conditions and the vibration modal of the resonance tube are determined according to the results of the analysis;3. According to the theoretical analysis and simulation results, the mechanical structure of the existing sensor is optimized. The main work is the choice of the materials, structure and processing technology of the resonance tube. The incentive and detect method of the sensor is improved, using piezoelectric excitation detection plan;4. A closed loop interface circuit of the sensor based on phase-locked loop is designed, in order to meet the amplitude and phase condition of system self-excited oscillation, the circuit can be applied to meet different frequency range measurement requirements by simple adjustment;5. Sensor system experiments including the vibration experiment, stability experiment and calibration experiment are presented. The influential factors on the vibration of the cylinder shell resonator, such as temperature, pressure, viscosity are analyzed. The uncertainty of measurement of the transducer at 20 degrees Celsius is indicated.