Dr. Narasimalu Srikanth is Programme Director and Senior Scientist leading the offshore renewables in ERI@N (Programme Partner - EcoLabs COI). He leads industrial research projects on offshore turbine development as well as floating solar and hybrid renewable energy systems. He also leads a joint industry program on offshore renewables comprising MNCs and SMEs focusing on relevant applied research needs to promote ocean renewables towards remote coastal and islandic regions and in structural health monitoring of assets in marine environment. He has been conducting environmental impact, structural integrity and asset health monitoring studies towards energy system deployment in remote islands of Southeast Asia and tropical belt region.
Prior to joining NTU, he was Technical Director and Senior Specialist at Vestas Wind Energy Systems. He has more than 25 years of industrial experience leading research and development efforts in product and technology development at ASM Technology Singapore, Tata Engineering, etc. He has worked in a wide range of equipment and machinery building, product design for automotive, semiconductor packaging and in renewable energy industries. He has published more than 150 journal papers and 30 patents.
His areas of research interest are product development, renewable systems, floating systems, advanced composites, additive manufacturing, failure analysis, asset health monitoring, machine learning, IOT system and environmental degradation studies.
Southeast Asia has more than 25,000 islands, which individually have limited skilled resources, infrastructure and material handling. Traditionally, tidal turbines are mounted in seabed, however in Singapore, sea space is busy and hence sending deep divers needs permission and is costly.
In this product development effort, a tidal turbine was designed into a floating structure as per the naval architecture principle that could self-erect for scheduled maintenance against biofouling and corrosion strength. The floating tidal turbine can be towed and moored to any coastal location and can be brought back to main land for dry dock for major repair and maintenance. Thereby the overall and maintenance is low. As principal investigator of the project, a 62KW system was designed and fabricated in Singapore, and deployed in Sentosa waters. Presently it is being deployed in Philippines by the industry collaborator.
Philippines and Taiwan experience low wind speed but occasionally experience sudden gust wind loads such as typhoons. The company wanted wind turbine towards low wind flow condition but should overcome the gust wind. Hence, turbines with low wind flow aerofoil design and larger rotor diameter were designed. However, when the gust wind load occurs, it will experience high structural load. Hence this turbine was made to have a self-erecting design principle when the turbine owner obtains the weather forecast, he could self-descent and erect the turbine as needed.
The turbine was designed with necessary lightning protection and with a localized energy storage to power desalination type local loads. The turbine could be dismantled and packed into the containers for shipment. It also avoided exotic foundations as compared to conventional wind turbine, by utilizing the containers as the load spreaders and suited well to even reclaimed soil conditions such as Tuas and Semakau that has half the bearing strength compared to normal firm ground.
In wind turbines, the gearbox lubricants have to be cooled as it absorbs 2 to 3 percent of the energy through the friction in the drive train. This causes it to heat and exceed the flash point. Hence a cooler is used on the nacelle of the wind turbine to dissipate the heat. Due to this extra cooler system, the cost goes up by 5%. This project involved designing a system where the surface of the wind turbine nacelle could be modified as heat spreaders with integrated lubricant cooling coils to make use of the wind flow past the nacelle and thereby the gearbox oil could be cooled to required temperature. To spread the heat efficiently, the design incorporated heat pipes that enabled passive cooling more efficiently with low maintenance, since the wind turbines are installed in remote locations.
Traditionally the semiconductor IC packaging industry used gold wire for the interconnection of the chip to the leads. Due to increasing cost of gold, the industry was shrinking the gold wire diameter from 125 um to 15 um. Handling of the thin gold wire became more challenging for the wire bonding manufacturers, as the wire bonders had to operate at high speed of bonding 20 wires in one second. This project focused on replacing the gold wire by copper wire since it is a good electrical conductor. As copper is easily oxidised, an inert atmosphere kit was designed. It uses nitrogen with a dual flow design that achieved an inert atmosphere even in an open atmosphere and the wire bonding could be performed using copper wire without oxidation. The design was patented and today, the company sells such a wirebonder as "Copper Wire Bonder" especially for power devices.
Since customers in semiconductor packaging industry started using gold wire for costly IC packages and copper wires for power-IC packages, the company decided to develop a wire bonder capable of supporting both type of devices. This project involved the development of a dual frequency transducer by designing the piezoelectrics to have two frequencies. Today the transducer operates at 100KHz and suits well to copper bonding and 138 KHz towards gold wire bonding. The transducer was patented and paved way to be developed as a new product in the IC packaging market. This design was the international winner in the "No Boundaries Contest" conducted by Machine Design Journal, Compaq Computers and Ansys Corporation.
During the development of the first indigenous car in India, the design team chose a bronze type gears for the window riser which resulted in more than 80 dB of sound. To solve this issue, the vibration and acoustics were analysed through simulation, and a nylon based gear drive was developed to cut down the acoustic noise generated without compromising the power transmission of the gear train.
When designing a gear shaper, there was a need for torque transfer between two reciprocating kinematic pairs. An elastohydrodynamic bearing that had a spur type internal gear pair was designed to allow reciprocation while the external outer gear was designed to work as a worm gear pair to transfer torque. Presently this power transfer method enabled the company to have its own indigenous power transmission method.
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