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OVAL Corporation
Using CFD (Computational Fluid Dynamics) Upfront to Design Better Flowmeters

[Vol. 1] OVAL Corporation is a flowmeter manufacturer, who has cultivated their own advanced technology to develop a diverse range of products. They have started using SC/Tetra to improve product accuracy and quality. In this article, OVAL Corporation explains how they benefit from using CFD and also discusses challenges they experienced when introducing the tool.

Picture 1: Flowmeter - ultrasonic flowmeter on left, vortex flowmeter on right

OVAL Corporation is a fluid equipment manufacturer that produces many different kinds of fluid flowmeters. The company was founded in 1949 with the mission to manufacture an oval-shaped gear meter, which was first developed by the president of Nissan Motor Company. Since that time, in addition to their three most popular products, oval, Coriolis, and vortex flowmeters, the OVAL Corporation has developed a diverse range of products (Picture 1). As the largest pure-play manufacturer of fluid equipment, they apply highly advanced technology to the design of their products. This enables them to provide optimal flowmeters that satisfy client needs, even those with unique specifications, such as the government.


Flowmeters are used to measure the amount of fluid that passes through a pipe per unit time. They can be found in many aspects of our daily lives. They are used to measure fuel flows at gas stations, residential water flows, process flows at chemical and food plants, waste water flows from a factory, exhaust gas flows, and many others. Flowmeters can be generally categorized as either volume flowmeters or mass flowmeters. A volume flowmeter measures the fluid volume that passes through an area per unit time. A mass flowmeter measures the fluid mass that passes through the area per unit time. Volume flowmeters can be further categorized as actual measurement typed and inferential typed. OVAL Corporation's oval gear flowmeters are actual measurement typed volume flowmeters. A fixed volume of fluid is transferred by each rotation through two sets of oval gears inside the flowmeter. This enables measuring the total flow rate by monitoring the number of rotations. In contrast, OVAL Corporation's ultrasonic and vortex flowmeters, as shown in Picture 1, are inferential typed flowmeters.

Picture 2: Mr. Takeshi Motomiya,
Assistant Manager, R&D Group 1,
R&D Division, OVAL Corporation

CFD Application as a More Practical Approach

OVAL Corporation started thinking about SC/Tetra back in fall 2013. They were not satisfied with the accuracy and processing speed of the fluid analysis software they had been using, although this was the only software they had used since starting their analysis efforts.


Thinking back to just before officially introducing SC/Tetra, Mr. Motomiya (Picture 2) says: “It was good that we could use the trial version for free during the first two months. ” With thorough technical support provided by the Software Cradle staff, OVAL Corporation was able to perform thorough evaluations during the trial period. From this impression, Mr. Motomiya was convinced of the software's feasibility. “We felt that we could use the tool without problems,” says Mr. Motomiya.

Fig 1: Comparison between velocity distribution near flow inlet and outlet (experiment conditions tested by Hilgenstock et al.*2). Click to enlarge.

Positive Comparison between Measurement and Analysis Values

After officially introducing SC/Tetra, OVAL Corporation first compared analysis and measurement results for estimation-based flowmeters, which are often used in plants. The measurement accuracy of these flowmeters will be affected by the velocity distribution inside the pipe. In many cases, where components, such as elbows, joints, and valves are located upstream of the flowmeter, swirling flow and drift current can occur, undermining the flowmeter's capability. ISO (International Organization for Standardization)*1 regulations specify that sufficient pipe length must be maintained between the flow components and the flowmeters. In reality, retaining sufficient pipe length is difficult to achieve because of limitations imposed by available space. As a solution, a flow conditioner to help straighten the flow are sometimes used to achieve an ideal velocity distribution using short pipe lengths.

Fig 2: Comparison between analysis and experiment values undertaken by Hilgenstock et al.*2 Results using SST k-ω model were in closest agreement with experiment values. Click to enlarge.

Figure 1 shows an experiment using double bend pipes. The model was used for PTB (the Physikalisch-Technische Bundesanstalt, Germany's national metrology institute) standards verification. The experimental results show the velocity distribution for a complex piping configuration*2. As shown in Figure 1, the fluid inlet is located at the lower front and the outlet is located at the upper left. A Laser Doppler flowmeter was used to measure the velocity distribution inside the pipe near the outlet.


The comparison in Figure 2 shows the turbulence model that produced the closest agreement between the calculated and measured values. According to this analysis, the SST K-ω model produced the best agreement with the test results. The horizontal axis on the graph shows the distance from the center of the pipe cross section, and the vertical axis shows the velocity distribution on the cross section. Both axes are dimensionless values, which are divided by either the pipe radius or the average velocity at the cross section.

Fig 3: Comparison between velocity distribution between perforated plate and the point where 1.5 times far from pipe radius in downstream (experiment conditions tested by Xiong et al.*4).
Fluid flows from rear part towards front. Click to enlarge.

Fig 4: Streamlines shown in the analysis results calculated using SST k-ω model. Swirling flow occurs without perforated plate. Click to enlarge.

For the next step, OVAL Corporation verified the case where a perforated plate was located downstream of the pipe bend. The geometry is illustrated in Figure 3, where the flow conditioner is called an AKASHI plate*3. Fluid enters through the inlet. In this analysis, the SST K-ω model was used, based on previous analysis results which demonstrated high accuracy using this turbulence model. Figure 4 shows streamlines for the analysis results. Swirling flow occurs when no perforated plate is used. The left diagram in Figure 5 shows the velocity distribution 1.5 pipe radii*4 downstream. The vertical axis shows the distance from the center of the pipe cross section, and the horizontal axis shows the velocity distribution. The difference between the analysis and test results near the wall is likely caused by the influence of the wall on the measurement results. Regardless of which analysis tool is used, the calculated values for the velocity near the wall will be greater than the actual values when the SST k-ω model is used. With all things considered, Dr. Fujikawa (Picture 3) says that the analysis values “are in good agreement with the experiment values, except for the results near the wall.”


Fig 5: Velocity distribution. Analysis results were in close agreement with experiment when SST k-ω model was used. Click to enlarge.

Picture 3: Mr. Toshihide Fujikawa (D.Eng), Assistant Manager, R&D Group 1, R&D Division, OVAL Corporation

Continued to Vol. 2

1) I SO5167., 2003 Measurement of Flow Field by Means of Pressure Di erential Devices Inserted in Circular Cross-Section Conduits Running Full, ISO (2003).
2) A. Hilgenstock, R. Ernst, Analysis of Installation E ects by Means of Computational Fluid Dynamics – CFD vs Experiments?”, Flow Measurement Instrumentation, Vol.7 (1996), pp.161-171.
3) Koichiro Akashi, Hisao Watanabe, and Kenichi Koga: Development of flow-straightening device for flow rate measurement (Special volume for measurement and control technology), Technical report of Mitsubishi heavy industries, Vol.12, No.6 (1975), pp.665-673. (in Japanese)
4) Xiong, W,. Kalkuhler, K. and Merzkirch W., Velocity and Turbulence Measurements Downstream of Flow Conditioners, Flow Measurement and Instrumentation, Vol. 14, No.6 (2003), pp. 249-260.

*All product and service names mentioned are registered trademarks or trademarks of their respective companies.
*Contents and specifications of products are as of January 31, 2016 and subject to change without notice. We shall not be held liable for any errors in figures and pictures, or any typographical errors in this brochure.

Company Details


OVAL Corporation
Founded May 10, 1949
Businesses Manufacturing and sales of flowmeters, associated electronic instruments, flow measurement systems, and peripheral products.
Representative Jun Tanimoto, President
Number of employees 665 (consolidated)
Capital 2.2 billion JPY
(issued stock: 26.18 million)
Head office Shinjuku-ku, Tokyo, Japan

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