Dr. Krothapalli received his Ph.D. degree from Stanford University in 1979 under the guidance of Professors Krishnamurti Karamcheti and Donald Baganoff in the department of aeronautics and astronautics. The topic of his Ph.D. dissertation was on mixing of incompressible multiple turbulent jets. The problem was investigated in the context of multiple jet ejectors used in Short Take-off and Vertical Landing aircraft. While investigating this problem, he stumbled upon the effect of aspect ratio on the development of rectangular jets, especially, the phenomena of axis switching (JFM 107, 1981). Although, there is significant literature on turbulent jets, very little attention has been paid in the past to this aspect of the problem. The paper was widely referred due to growing interest in using rectangular nozzles in fighter aircraft (F117 and F22) and other applications. Dr. Krothapalli then turned his attention back to the multiple jet ejector problems, where the jets are typically operated at nozzle pressure ratios (stagnation pressure/ ambient pressure) of greater than about 3. The choked nozzles operating at these conditions generate intense discrete tones commonly referred to as screech, that help to increase mixing. As a result, the ejector performance improves. Next three years, working with a Ph.D. student Y.C. Hsia at Stanford, were occupied in developing a better understanding of screech and related phenomena. Salient results of this research were published in 1986 (JSV, 106) that is widely referred due to the interest in high speed mixing using non-axisymmetric nozzles. In an attempt to measure velocity field in high speed jet flows, Dr. Krothapalli’s attention has moved to the development of Particle Image Velocimetry in 1983 (Expt. Fluids, 5 & 18). A close cooperative effort with Dr. Lourenco has resulted in the development of a PIV system with the high-resolution digital recording of images in 1991. This development lead to the formation of two small companies that specialized in marketing the PIV systems. The assets of the first company were sold to TSI inc in 1993. The current company, Integrated Design Tools, Inc., started in 1997, has developed easy to use stereoscopic PIV systems (JFM, 2003) that are in use at NASA and many industrial and University laboratories in USA, ONERA- France, Japan, Israel, India, Portugal and Italy. Utilizing the stereoscopic PIV system, Dr. Krothapalli in collaboration with Professor Lourenco and a Ph.D. student Bahadir Alkislar, measured the unsteady characteristics of a screeching jet with the primary aim of providing an understanding of the role of large-scale coherent vortical structures on high-speed jet noise (JFM, 2003).

In the mid to late 1980’s Dr. Krothapalli spent considerable time in developing the understanding of the Dynamic stall process related to wings undergoing rapid pitch up (AIAA J., 30 & 33). In collaboration with Dr. Shih, more recently, a novel control method using microjet injection was used successfully to mitigate the dynamic stall occurring over an oscillating airfoil at M = 0.4 (ASME paper, 2003).

In collaboration with Prof. Strykowski of University of Minnesota, Dr Krothapalli in early 1990’s developed countercurrent nozzle for mixing enhancement of high-speed jets (JFM, 308). Based on this research they came up with a novel concept of fluidic thrust vectoring of supersonic jets (AIAA J. 34). This technique has been tested at China Lake under the simulated Ramjet operating conditions (JFE, 122).

During early 1990’s a decision was made by NASA administrators in Washington to close down a vigorous aerodynamic research activity at NASA Ames Research Center. In the process, a Vertical Take-off and Landing (VTOL) aircraft jet simulation facility was transferred to Florida State University. The development of Joint Strike Fighter required an understanding of high speed impinging jet flow fields. A program of research was initiated under the sponsorship of NASA Ames to study single and multiple supersonic impinging jets with particular attention to mitigate the noise and lift loss due to ground effect (JFM, 1999, AIAA J. 39, AIAA Paper, 2003). A cooperative effort with Dr. Farukh Alvi and Dr. Chang Shih led to the development of an effective control using microjets placed at the nozzle exit (AIAA J. 41) for noise suppression and lift loss recovery.

While on Sabbatical in 1995-1996 at NASA Ames Research Center, Dr. Krothapalli got interested in high-speed jet noise, especially its suppression. During this period, he recognized that forward flight could have very beneficial effects on noise suppression (AIAA J, 1997). Upon learning from Dr. Dennis Bushnell of NASA Langley that water injection could have beneficial effects on noise suppression, first recognized by Russian Scientists at SAGI, Dr. Krothapalli embarked on a research program to study this problem in detail (JFM, 2003). Around this time, US NAVY faced with a severe community noise problem, resulting F-18E/F fights, that needed to be dealt with in a short time. Under the sponsorship of ONR, Dr. Krothapalli initiated a relatively large research program in high-speed jet noise suppression. In collaboration with Professor Vijay Arakeri of Indian Institute of Science, and a Ph.D. student Brent Greska, a novel suppression technique using microjet air injection at the nozzle exit was discovered and successfully tested on a J97 jet engine. (AIAA Papers 2002,2003, JFM, 2003).

In collaboration with Prof. G.S. Bhat of Indian Institute of Science, a research activity to provide a better understanding of the cloud physics is being developed. Some early results of this work were published recently in Monthly Weather Review (2000) and Current Science (2003). An experimental facility was developed to study the effect of condensational heating in clouds.

With recent resurgence of interest in alternative energy technologies, Dr. Krothapalli started a new university wide center (Sustainable Energy Science & Engineering Center) to focus on sustainable energy systems using solar radiation. Initially, the focus of the research activity is on solar electricity generation, including electrolytic hydrogen production and storage and fuel cells. A 5kW solar-hydrogen production facility is currently being constructed. A two semester course sequence was developed and taught for the first time during the 2003-04 academic year to expose the senior undergraduate and graduate students to the field of energy conversion systems with particular attention to greenhouse gas emissions free energy production strategies. Teaching and research laboratories on photovoltaics, solar thermal systems and fuel cells are currently being developed.

Other Tidbits

Professor Krothapalli currently holds the Don Fuqua Eminent Scholar Chair of Engineering at the Florida State University in Tallahassee. He was appointed to this position in August 1993. For the period September 1987 – May 2002, he has served as chairman of the Mechanical Engineering Department at the FAMU-FSU College of Engineering. He was the founding member of the department that started in August 1983. Prior to coming to FSU, he was on the faculty of aeronautics and astronautics department at Stanford University as an acting assistant professor during January 1981 – July 1983. For a short period (August 1979 - December 2000), he was an assistant professor Aerospace and Mechanical Engineering at University of Oklahoma.

He earned his undergraduate degree in Aeronautical Engineering from the Madras Institute of Technology, India in 1973 and a Masters degree from the University of Tennessee @ Knoxville in 1975.

He was a National Research Council Senior Fellow at NASA Ames Research Center and is a Fellow of American Society of Mechanical Engineers. Professor Krothapalli is co-founder of Integrated Design Tools Inc., a leading provider of Particle Image Velocimetry systems and high-speed and high-resolution digital cameras.