S V Krishna Chaitanya By

CHENNAI: A group of engineers at the Indian Institute of Technology Madras (IIT-M) has cracked the elusive secret code of thermoacoustic instability, a problem that gas turbine and aerospace industry has been grappling with for decades, incurring losses to the tune of $1 billion annually. The team has developed a host of precursors, dubbed as the world’s first early warning system for gas turbine power plants and jet engines.

The technology has found interest among some of the major players in the sector, including the National Aeronautics and Space Administration (NASA) and our own Indian Space Research Organisation (ISRO).

“We are exploring the process of working together with the ISRO. However, before we test the technology in aerospace sector, it will be tried first with ground-based engines like gas turbine power plants. We are now in talks with major gas turbine companies such as Ansaldo Energia, General Electric and Siemens to test the technology with real data. It needs lots of testing to root out any lacuna such as triggering of false alarms,” Prof R I Sujith of the Department of Aerospace Engineering in IIT-M told Express. A key person behind the project, he recently visited NASA in this regard.

Prof Sujith said no technology is available at present to help predict an impending instability in turbines.

The companies use pressure transducers to measure pressure fluctuations. After reaching the threshold point, the automatic controllers kick-in and shut down the engines. Once the turbines are shut, it takes at least an hour to restart - a situation that is cumbersome and costly.

C ontracts between the turbine manufacturers and power companies often require the manufacturers to bear the cost of such shutdowns and penalties incurred.

The situation is more critical when such instabilities arise in the engine of an aircraft or rocket, where the option to shut down the engine mid-air does not exist and severe vibrations or breakage of the engine can prove to be fatal. For such engines, extensive tests have to be run on-ground. However, a substantial number of these engines, especially for rockets, are destroyed while testing. “This is where our technology brings the radical change that industry has been craving for years. We can give several minutes of warning time, may be up to 20 minutes, for a power plant to take evasive action. For liquid rocket engines, it would probably be a few seconds, enough to stabilise the engine,” he said.

However, Prof Sujith said it would take at least two to three years for the technology to develop into a full-fledged early warning system and for industrial consumption. The technology’s robustness and protocols have to be established in the real scenario, which will take some time. “The companies will first provide historical data of thermoacoustic instabilities. Using the technology, we will try and predict the impending instabilities. This will give a tight understanding of the warning time and threshold limits,” he said.

“We can also customise the system, according to the industry specifications. But we have not reached that stage yet,” he said.