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Azbil Corporation
Achieving Size Miniaturization and Noise Reduction of Control Valves

Azbil uses CFD analysis to design control valves and explains how implementation of this highly accurate ­fluid analysis design system that employs frequently upgraded analysis functions has helped them to successfully reduce cost. Mr. Yoshio Nomaguchi from Azbil (Development 1, Valve Product Development Dept.) tells the story behind Azbil’s success.

Achieved Faster Development

 Azbil's traditional design process involved determining the specifications first, then planning the basic structure. Several different valve sizes are designed, depending on the flow conditions and the flow rate required. Sometimes there are more than ten variations. Prototype development and experimental tests after this phase are always costly and time-consuming. But Mr. Nomaguchi says that introducing SC/Tetra reduced the number of prototype tests and shortened the development time dramatically. He further recalls that it also helped engineers to better understand the physical phenomena by reviewing visual results generated by SC/Tetra.

 ​For match-up between the analysis and test results, they use the immense body of data obtained from past experiments. Mr. Nomaguchi notes that the analysis and test values mostly matched, within the error range of plus/minus 5-10%.

Figure 3: Cavitation experiment (above) and SC/Tetra analysis (below). Click to enlarge.

Designing a New Model from Scratch with CFD Analysis

 Another example that demonstrates how CFD analysis was effective was for the design of the rotary control valve (figure 3). This valve is used to adjust the flow rate by rotation of the inner plug. When the pressure rapidly decreases inside the valve, cavitation is generated. To prevent cavitation, perforated plates are often used, but they have never been enough to prevent cavitation. SC/Tetra was used to help Azbil design a cone-shaped diffuser, which reduced the cavitation and noise while maintaining sufficient flow.

 For this particular case, SC/Tetra was used throughout the entire design process, from reviewing the diffuser thickness to sizing of the holes, as well as determining manufacturability. Azbil engineers reviewed about ten patterns for each size and finally determined the most fitting design.

Figure 4: Comparison on analysis and real experimental result (left)
Experimental results of FL (Liquid pressure recovery factor) change
​(right). Click to enlarge.

 As shown in figure 4, the results show a correlation between flow rate and pressure. The place where the results deviate from the straight line on the graph indicates choked flow due to the growth of cavitation. By applying the cavitation model, Azbil was able to match the experimental results with the analytical predictions.

Figure 5: Comparison on analysis results between usual ball
valve and comb-shaped ball valve. Click to enlarge.

 To further demonstrate effectiveness, applying SC/Tetra shortened the time required for prototype testing and experiment, from approximately four weeks to three days when testing five different samples.
* Two Xeon 3.6GHz×2 (installed Dual- CPU) used for analysis




 Another example where SC/Tetra has been used involves the design of control valves for fan coil units. A fan coil unit is an air-conditioning unit used for a hotel or hospital room. Fluid noise increases because of turbulence flow and cavitation in control valves. Since fan coil units are usually placed close to the room, near the ceiling in each individual room, the noise must be kept low, although this has always been diffi­cult to achieve.

 Attempts have been made to maintain the flow characteristic, such as opening a round or fan-shaped hole on a ball of a rotary control valve, but it was insufficient to satisfy customers' needs for reducing fluid noise. To solve this problem, Mr. Nomaguchi used SC/Tetra to examine various shapes of a hole on the ball inside the control valve. He discovered that applying multiple comb-shaped slits for the hole on the ball would maintain the flow characteristics as well as reduce the fluid noise (shown in figure 5). This led him to successfully design the control valves that reduce turbulence of flow and produce less noise.

SC/Tetra Evolves Further

 ​Mr. Nomaguchi says that his division actively implemented new analysis functions in the software when they were released (e.g. cavitation model). He expects Cradle to develop further advanced function of SC/Tetra. “It used to take a half hour to generate a mesh when we first started using SC/Tetra, but now, with hardware becoming more improved, it only takes a few minutes. I’m positive that more can be done and I’m looking forward to seeing further development of SC/Tetra.”

* All product and service names mentioned are registered trademarks or trademarks of respectable companies.
* Contents and specifications of products are as of April 1, 2013 and subject to change without notice. We shall not be held liable for any errors in figures and pictures, or any typographical errors.

Company Details





 

Azbil Corporation
Established 1906
Businesses Development and designing measurement and control equipment
Representatives

Seiji Onoki (Chairman)

Hirozumi Sone (President, CEO)

Headquarters Chiyoda-ku, Tokyo, Japan
Number of Employees 5,335 (as of March 2013)
Capital Approx. 10.5 billion JPY
(as of April 2013)

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