Abhishek Saha: Driving Research Toward Cleaner Energy

In a world where climate change is a hot topic of discussion, Dr. Abhishek Saha is laying the groundwork for real-life solutions to the problem of greenhouse gas emissions. Saha, as he is known, is currently Associate Research Scholar at Princeton’s Department of Mechanical and Aerospace Engineering. However, his interest in how engines work began when he was growing up in his hometown of Kolkata, India, and continued as he attended Jadavpur University (also in Kolkata) to earn his bachelor’s in Mechanical Engineering.

            “I had a strong interest in cars, motorcycles, airplanes, rockets—basically all sorts of vehicles,” Saha recalls. “That interest became even stronger as I started learning the details of these incredible machines during undergrad. It amazed me how something as simple as liquid fuel can generate and channel the power to propel a vehicle at high speeds. I began to realize that every piece of the puzzle—from the engine to aerodynamics—is extremely important.”

            In his senior year at Jadavpur, Saha was recruited by Tata Motors, a large multinational automotive manufacturing company in India, and began working there following his graduation in 2006. After a year and a half of assessing car performance and planning new production lines, Saha realized that his true calling was in research. He applied to graduate schools in the U.S. and was accepted by the University of Central Florida (UCF) in Orlando, where he started in the spring of 2008. He completed his academic work in 2012, having earned his master’s and doctorate in Mechanical Engineering.

            For his PhD thesis, Saha studied evaporation, precipitation, and instabilities of functional droplets sprayed during thermal spray and spray-drying applications using an acoustic levitator for his experiments. He received the Outstanding Dissertation Award from UCF for this work.

Saha wanted to continue and extend his research through a postdoctoral opportunity and applied to a number of groups both in and outside the U.S. As fate would have it, Chung K. Law, PhD, Robert H. Goddard Professor of Mechanical and Aerospace Engineering, was looking for someone to add to his research team at Princeton. Saha was offered and accepted a position as Postdoctoral Research Associate in 2012 and became Associate Research Scholar in 2014.

“In academic research, especially at a major university, the research staff is essential to the total enterprise,” Prof. Law says. “Saha is my right hand person, an indispensable part of the group. He assists with all the day-to-day operations and carries out his responsibilities extremely well.”

At any given time, Saha conducts and supervises research activities, plans current and future research endeavors, and writes proposals to various agencies to seek funding. In collaboration with his colleagues, he has authored numerous articles published in such journals as Combustion and Flame, Journal of Fluid Mechanics, Physical Review Letters, and Soft Matter. He has presented his findings at various conferences in the U.S. and abroad.

His work in the area of combustion has focused on the propagation of laminar and turbulent flames in low- to high-pressure conditions, looking into the effects of flame-front instabilities, turbulence wrinkling, and differential diffusion. “We recently demonstrated that it is possible to burn a CO2 diluted fuel-lean hydrogen mixture with flame temperatures beyond the flammability limit in a turbulent environment, such as those found in car engines and gas turbines,” Saha explains. “If the engines are operated and designed carefully, our results can provide a major breakthrough, as lean and diluted burning would significantly reduce fuel consumption and emissions.” This work was presented at the Eastern States Section Meetings of Combustion Institute in April 2016, where it received the George H. Markstein Best Paper Award.

Saha is also studying the impact of droplet impact on liquid surfaces. For internal combustion engines, the fuel droplets impacting the previously deposited fuel layer on hot engine and piston surfaces result in vaporization patterns that can be significantly different from droplets vaporizing away from hot surfaces, he says.

“In car engines, we want the fuel spray droplets to evaporate and homogenously mix with air before they burn. However, part of the spray impacts the engine wall and creates a layer of liquid fuel, generating soot and NOx. We need to know how these fuel droplets either merge to increase the layer thickness or bounce off to vaporize following the ideal path of combustion.” Saha asserts that their experiments have the potential to aid in the development of sub-grid models that can be used in full-scale engine simulation. 

For the past two years, Saha has coordinated the annual Princeton-Combustion Institute Summer School on Combustion—a week-long program in existence since 2010 for graduate students and senior researchers in the field of combustion science. In this immersive experience, participants stay on campus and have the opportunity to meet and network with colleagues. Four to five courses taught by leading combustion scientists are offered, with topics ranging from the fundamentals in theory and chemistry to more advanced subjects, such as turbulent combustion, internal combustion engines, and novel combustion techniques. About 200 people from around the world attend each year.

“It is a joy to be part of this important event as it serves to nurture future generations in the combustion community,” Saha says. “Every now and then at conferences, we meet attendees from past sessions and they tell us how beneficial the summer school was for them.”

Saha, whose future aspirations are to continue a career in research and perhaps one day to secure a tenured faculty position, believes that the greenhouse effect and the associated climate change are major issues in today’s world. “If we do not accept and acknowledge the dire need for all of us to work together to protect our environment, a major climate shift may be inevitable,” he says.  “If we act together and plan our next steps with caution, keeping the best interest of the world in mind, we will be able to avoid this calamity.

“As combustion scientists, we need to continue our work on both the fundamental and applied aspects, with a goal to design engines with lean and clean burning strategies. It is possible to meet the world’s need for energy while greatly reducing greenhouse gas emission at the same time.” 

—Adriene Marshall