Research On A Velocity Attenuation Based Viscometer And Its Related Technologies

The liquid viscosity detection is in wide-spread needs for the modern industry. Different types of viscosity instrument, resulting from different application requirements, play important roles in the relative test occasions. However it is very difficult for the current viscometers to satisfy simultaneously the viscosity test requirements including rapid several detections, rapid several detections under different shear rate and low shear rate. Therefore, it is of great significance for the modern industry to enrich the theory and technology of viscosity measurement and to develop new type of viscometer that satisfies the above industrial requirements.A velocity attenuation based viscometer is proposed in this thesis. The fluid viscosity can be calculated by detecting the velocity and time of attenuation. In the operation of viscosity detection, the requirements mentioned above could be satisfied simultaneously.In this thesis, the mathematical model of the viscometer is established and the structure of viscometer based on the method is presented. The mathematical model of the velocity attenuation based viscometer is simulated in the MATLAB environment. The basic motion laws of the velocity attenuation based viscometer are obtained by the simulation. They provide a theoretical basis for design and manufacture of the viscometer.On the analysis for the main error sources of the viscometer, the mathematical models of the errors action mechanism are established. These mathematical models are simulated in the MATLAB environment, which reveals the laws of influence on the result of the viscosity detection by the error sources. Finally, methods of the error control are proposed.The requirements on the technique of driving, supporting and detecting for the velocity attenuation based viscometer are analyzed. A cascade motor, the rotor of which is supported by the designed air bearing, is presented as the driving system. Results of driving test show that the driving system can not only achieve the minimum speed of5rpm, which satisfies the requirement of viscosity detection under low shear rate, but also meets other driving requirements of the velocity attenuation based viscometer, such as low friction, low vibration and low impact. The smooth velocity governing in a wide range is also achieved. The detection groups of the velocity attenuation based viscometer are designed, and the constant temperature protection system is designed by considering the requirement on the temperature in viscosity detection process. Based on these technologies, a prototype of the velocity attenuation based viscometer is designed and manufactured. The effects on measurement results, caused by the end effect and misalignment of the detection groups, are appealed by experiments. Based on those laws, the mathematical model of detection principle is modified, and the limited conditions of viscosity detection are proposed. The velocity attenuation based viscometer is calibrated with the standard viscosity liquids and viscosity test experiments are carried out. The results show that the fluid viscosity can be measured by the velocity attenuation based viscometer, and the detection error is under5%, which meets the requirements of common viscosity measurement. Additionally, in once of the velocity attenuation of sensor rotor, several measurements can be conducted with no need to restart the viscometer. In the process of attenuation of the sensor rotor velocity, the rapid detection of fluid viscosity with different shear rates could be achieved in variable range of velocity attenuation. All of those have satisfied the requirements of several rapid viscosity detections under different and low shear rate.