Mechanical elements, vibration and acoustics technologies

Vibration and noise are inevitably generated during the operation of industrial machinery, but excessive vibration and noise can cause product failures and are not favorable for their operating environment. Therefore, technology for vibration and noise reduction, as well as technology for mechanical elements such as bearings and seals that affect the performance and vibration of rotating machinery, are extremely important in order to ensure high reliability of products mass produced.

We are engaged in the research and development of mechanical elements, vibration and acoustics technologies, which we consider to be common fundamental technology for our company.

In the processes for designing turbomachinery including pumps and compressors in today’s industry, great importance is placed on maximizing power efficiency. It is common practice to adjust the shape and placement of flow channels, and then carry out detailed design of mechanical elements for rotating components, such as bearings and seals. In this research project, a different approach was taken from conventional design methods which emphasize efficiency. In addition to multi-objective optimization which focuses on matters such as reliability (vibration) and cost, and optimization to address compound issues in multiple fields such as fluids, vibration, and structures, research was also conducted on morphological optimization*, which has the potential to tremendously expand the design space for optimization problems.

The figure shows an example of application of morphological optimization technology to a conventional vertical centrifugal pump. By changing the impeller and bearings to have a placement order and position which would have been unthinkable with conventional approaches, results of both reduced vibration and lower cost have been achieved while maintaining the pump efficiency.

”Morphological optimization” is a technology developed through joint research with the Japan Aerospace Exploration Agency (JAXA). EBARA is working on its application and deployment to industrial turbomachinery.

Rotor dynamics (vibration of rotors) is a key technology that affects the reliability of turbomachinery. Conventionally, almost all examples of rotor dynamics technology have been applied to horizontal rotors. For vertical rotors, since the vibration characteristics of their mechanical elements and their rotor behavior differ from horizontal types, one significant challenge was the existence of various problems which had yet to be defined.

EBARA is participating in joint research with universities to improve technology for the analysis and evaluation of vertical rotor dynamics.

The example below predicts the occurrence of self-excited vibration when the vibration characteristics of the stationary side structure of the vertical rotor are taken into consideration. It was clarified that self-excited vibration occurs as the rotating speed increases, but disappears at higher speed condition.

For rotating machines that handle fluids such as pumps, the influence of fluids on the vibration characteristics of the machine is large, and technology for predicting this effect is required. At EBARA, it is studying the effects of fluids on various vibration phenomena (additional mass effect, additional damping effect, excitation force caused by fluids, etc.), and is working to prevent vibrations of rotating machines that are improving in performance every day.

The figure is an example of predicting the natural frequency (frequency that easily vibrates) of a centrifugal pump impeller in water.The natural frequency of the impeller during operation can be less than 50% of that in the air, and the change is greatly changed by the gap with the casing.