Academia Research Supports NDT Testing Specialists in Continuing to Promote Cutting Edge Engineering and Manufacturing in Wales
TWI Ltd. is a global company and one of the world’s foremost independent research and technology organisations, specialising in welding, joining and allied processes, including Non-Destructive Testing (NDT). Established in 1946, TWI currently operates from five UK and 13 overseas facilities. Their Welsh Technology Centre, based in Neath/Port Talbot, specialises in the development and application of state-of-the-art NDT testing methods. To enable and enhance their NDT capabilities,TWIi has developed a rapid NDT inspection system for complex, composite components, as part of the “IntACom” project.
TWI’s “IntACom” NDT system comprises of two, 6-axis robotic arms, carrying ultrasonic probes mounted on top of water jets. The system uses water jets to transmit ultrasonic signals to the surface of a composite test piece, with the reflected signal providing information about its condition. For the most effective delivery and accurate receipt of the ultrasonic signal, a “couplant” water jet is required to be issued from the nozzle in a stable, laminar flow condition.
In the current system, distortion of the ultrasonic signal was attributed to turbulent water jet behaviour. Consequently, TWI sought assistance from ASTUTE 2020 who were tasked with optimising the flow dynamics of the water jet through the application of their computational engineering modelling expertise, specifically Computational Fluids Dynamics (CFD). The resulting project was a collaboration between Swansea University, University of Wales Trinity Saint David (UWTSD) and TWI.
Challenges
TWI had established that the performance of their “IntACom” ultrasonic NDT device could be enhanced with an improvement in the transmission and receipt of the ultrasonic signal via the water couplant. The current water nozzle’s configuration comprises of a tangential inlet to a chamber from which the swirling flow passes through a flow straightener section and finally into a converged profile which feeds the flow to an outlet.
Solution
To tackle the challenge, a novel area of research was identified that would require the development of a computational model to assess and ultimately optimise the flow dynamics of the couplant water through the nozzle. Several aspects were identified as being required in the modelling process:
- A simulation of the flow within the original nozzle design to assess and visualise the flow’s behaviour prior to issuing from the nozzle;
- In addition to a model of the flow inside the nozzle, a modelling technique was required to capture the free surface behaviour of the flow on exiting the nozzle;
- Optimisation of the flow straightener section;
- An assessment of the inclusion of a sponge section into the device to aid in linearising the flow and,
- Optimisation of the outlet section’s nozzle shape in order to enhance the laminar flow condition.
Swansea University developed a Computational Fluid Dynamics (CFD) model of the flow region inside the nozzle. This allowed for the visualisation of streamlines and identified that there were aspects of the original nozzle’s configuration that were contributing to non-laminar flow features. To assess the behaviour of the flow on exiting the nozzle a Volume of Fluid (VoF) modelling approach was implemented that tracked the front of the water moving through the air and helped to assess the distance and stability of the travelling water jet. Several modifications to the orientation of the tubes in the flow straightener section were considered, as well as the inclusion of a layer of sponge, simulated by the application of a porous model. Additionally, a novel outlet nozzle shape was suggested and modelled and experimental work was validated by TWI & UWTSD. From the simulation results, it was possible to create an optimised nozzle that met TWI’s requirement of improved laminar behaviour.
Impact
TWI are fully committed to enhancing the performance of their IntACom NDT system and intend to undertake a full testing program with the new water nozzle configuration. The engagement of both TWI and the ASTUTE 2020 team has led to extensive, mutually beneficial knowledge exchange.
As a direct result of the collaboration, two new jobs have been created at the Port Talbot facility, allowing TWI to modify the current design of their ultrasonic water couplant delivery system in the IntACom device, which will result in:
- More accurate delivery of the ultrasonic signal and interpretation of results.
- An enhancement of the imaging capabilities and defect classification of TWI’s IntACom NDT system.
- The potential to generate system and software sales, in addition to increased consultancy profits for TWI from the IntACom system.
- The avoidance of unnecessary full repairs offers an environmental impact of reducing consumption of materials.
- With an improved, more stable water jet the distance between the nozzle and the test component can be increased, allowing examination of structures with more complex geometries and areas which were previously inaccessible.
The benefits of this collaborative project will ultimately allow TWI to remove significant barriers to the uptake of high value automated NDT inspection systems. Their application will benefit many industries as the use of composites is growing exponentially and the ability to reduce inspection/service times will be of great benefit. To have novel NDT technology of this type based in Wales will continue to promote cutting edge engineering and manufacturing within West Wales and the Valleys.
The IntACom project is part of TWI's Advanced Engineering Materials Research Institute (AEMRI), which is funded by the Welsh European Funding Office (WEFO) using European Regional Development Funds (ERDF).
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