The VortexWell® and its Innovative Helical Strakes

At Okazaki we are very proud of our VortexWell® Thermowell. So I thought it would be good to discuss the Helical Strake design we have used and how it works to greatly reduce the formation of Vortices.

Why the VortexWell®?

When fluid flows around a blunt object in it’s path, such as a standard Thermowell, it forms vortices downstream of the object. This is commonly known as Vibration Induced Vortices. The implications of these vortices can have a huge impact, from inaccurate readings to complete failure of the thermowell.

After extensive R&D and independent evaluation, we have developed a unique design of thermowell which we call the VortexWell®. This doesn’t require a velocity collar and is cost effective for the end user in terms of purchase, installation and maintenance costs.

What is the VortexWell®?

The VortexWell® incorporates an innovative helical strake design, very similar to the helical strakes seen on columns and cooling towers. By using the latest CFD software to visualize the flow behaviour, we were able to accurately compare a standard tapered thermowell and the VortexWell®.

In the tests, the standard tapered thermowell showed classic shedding behaviour as expected, whereas the VortexWell® demonstrated no signs of natural flow behaviour. The VortexWell® helical strake design disturbed the flow sufficiently to interrupt the regular formation of vortices. Whilst a small vortex was observed in the wake of the VortexWell® this was a localized stagnation point and didn’t shed.

How the VortexWell® works?

As the vortex shedding frequency approaches the thermowell natural frequency, the tip displacement and stresses are greatly magnified and the thermowell can fail. Even when the thermowell has passed calculations to the ASME PTC 19.3 standard, failures are still known to have happened, Monju Power Plant being a prime example.

To solve this issue, we looked at several different ideas, from increasing damping to streamlined cross sections. It was found that the best solution was to incorporate a helical strake as a vortex suppression method which made our VortexWell the best performing and safest thermowell available.

More information.

If you’d like to learn more about our VortexWell® Thermowell you can view more information here https://www.okazaki-mfg.co.uk/products/sensors/vortexwell-thermowell.

Alternatively, you can all us on 029 2081 4333 or email the team on sales@okazaki-mfg.co.uk.

We will be exhibiting at the Farnborough Airshow between 22nd and 26th July.

We will advise more details of where to find us when we have them.

On November 8th and 9th we be hosting a Showroom at the Hydrogen Online Conference.

You will be able to view a short presentation, download information about our products and join in live chats.

If you'd like to attend the event registration is free at www.hydrogen-online-conference.com. You will have access to the Keynote Presentations, Showrooms and networking area.

The Power Generation sector, as with most of the sectors we work with, is one of the most demanding environments to work in. And it certainly requires outstanding levels of accuracy and reliability when it comes to the ability to measure temperature within its processes and applications.

Added to that, there are also challenges to be faced by the Power generation sector over the coming decades as the industry faces up to massive increases in usage, by 2030 electricity use will double globally and triple in developing countries.

With these massive demands facing the industry it is imperative that Power Generation facilities are more reliable than ever to enable them to create the electricity that will be required in the coming years. At Okazaki, our engineers have developed a range of products that are designed for long life as well as giving the highest level of accuracy in their results.

Our expertise in the Power Generation sector is Temperature and Pressure Measurement units, Cabling and Electric Heaters. And we can offer products for many applications whether that be in Coal, Gas, Nuclear, Hydro Power, Gas Turbine Plants and Thermal Power Stations to mention a few.

For the benefit of this article, I wanted to talk about two products, Thermocouple Assemblies and Resistance Temperature Detectors (RTD’s).

As with all our products our Thermocouples and RTD’s have been extensively and rigorously tested to ensure they can meet severe demands that will be placed on them. They also meet several safety standards around the world.

Thermocouples

A thermocouple connects both ends of two different types of metal wires. When a temperature difference occurs between the contacts at both ends, a thermoelectromotive force is generated in this closed circuit and current flows through the circuit. The magnitude of this thermoelectromotive force and its polarity are determined by the temperature at both ends and the combination of the two metal wires, and are not affected by the thickness or length of the metal wires. Therefore, it is possible to measure the temperature by knowing the thermoelectromotive force at each temperature of a specific thermocouple in advance.

Our range of Thermocouple Assemblies which include, Tubeskin Thermocouples (Fantype and Aeropad) and Multipoint Temperature Assemblies have been designed to eliminate temperature measurement problems that happen within the Power generation industry.

Any problems arising from flame impingement, heat sink effects and radiant heat can be dealt with as quickly and effectively as possible. Truly accurate and reliable temperature measurement will improve your furnace operation and consequently increasing your throughput.

Resistance Temperature Detectors (RTD)

Our RTD sensors are designed and manufactured to operate over the extreme temperature range of -260℃ to +930℃.

Compared to conventional resistance temperature detectors, the conductors and resistance elements of our sheath RTD’s are insulated with a chemically stable magnesium oxide to maintain airtightness, so they have a longer life against aging and disconnection. 

These sensors offer excellent performance across this wide temperature range giving High Accuracy with fast Thermal Response, with no effect from High Vibration, Mechanical shock, and adverse radiation levels.

If you’d like to discuss any of our products with our team you can call us on 029 2081 4333 or email on sales@okazaki-mfg.co.uk.