Day 2 :
Washington University in St. Louis
Keynote: Shape optimization of axisymmetric bodies in hypersonic reactive flow for minimizing drag and heat transfer
Time : 08:00-08:30
Ramesh K. Agarwal is the William Palm Professor of Engineering and the director of Aerospace Research and Education Center at Washington University in St. Louis. From 1994 to 2001, he was the Sam Bloomfield Distinguished Professor and Executive Director of the National Institute for Aviation Research at Wichita State University in Kansas. From 1978 to 1994, he worked in various scientific and managerial positions at McDonnell Douglas Research Laboratories in St. Louis. He became the Program Director and McDonnell Douglas Fellow in 1990. Dr. Agarwal received Ph.D in Aeronautical Sciences from Stanford University in 1975, M.S. in Aeronautical Engineering from the University of Minnesota in 1969 and B.S. in Mechanical Engineering from Indian Institute of Technology, Kharagpur, India in 1968. He is the author and coauthor of over 400 publications and serves on the editorial board of 20+ journals. He has given many plenary, keynote and invited lectures at various national and international conferences worldwide. Professor Agarwal continues to serve on many academic, government, and industrial advisory committees. Dr. Agarwal is a Fellow of sixteen societies including the Institute of Electrical and Electronics Engineers (IEEE), American Association for Advancement of Science (AAAS), American Institute of Aeronautics and Astronautics (AIAA), American Physical Society (APS), American Society of Mechanical Engineers (ASME), Royal Aeronautical Society and American society for Engineering Education (ASEE). He has received many prestigious honors and national/international awards from various professional societies and organizations for his research contributions.
A large design concern for high-speed vehicles such as next generation launch vehicles or reusable space vehicles is the drag and heat transfer experienced at hypersonic velocities. In this paper, the optimized shapes for minimum drag and heat transfer for axisymmetric bodies are developed using computational fluid dynamics (CFD) software in conjunction with a multi-objective genetic algorithm. For flow field calculations, the commercial flow solver ANSYS FLUENT is employed to solve the unsteady compressible Reynolds Averaged Navier-Stokes (RANS) equations using several turbulence models, namely the Spalart-Allmaras (SA) model, the SST k-ω model and the transitional flow model k-kl-ϵ. The results from these models are compared to determine their accuracy for drag and heat transfer predictions. The hypersonic body shapes are optimized for minimum drag and heat transfer using a multi-objective genetic algorithm. Both cases with air in equilibrium and thermochemical non-equilibrium are considered. For air in thermochemical non-equilibrium, a seven species (N, O, N2, O2, NO, NO+ and e-)chemical reaction model is considered. The shape optimization results for a blunt body with a spherical nose are presented.Nearly 25~30% reduction in drag and 18~20% reduction in heat transfer is obtained for the optimized shape compared to the original shape; slight variationsin reduction in drag and heat transfer are due to the fact whether the air is in equilibrium or in non-equilibrium.
University of California, Irvine
Time : 08:30 - 09:00
Yun Wang received his B.S. and M.S. degrees from Peking University in 1998 and 2001, respectively. In 2001, he went to the Pennsylvania State University where he obtained his Ph.D degree in Mechanical Engineering in 2006. Right after his PhD study, Wang joined the Mechanical and Aerospace Engineering faculty at the University of California, Irvine. In 2012, Wang was promoted as associated professor. He is currently the director of the Renewable Energy Resources Lab with research focuses on PEM fuel cell, new battery, microfluidics, and thermal transport.
Flow batteries are a rechargeable electrochemical energy system, in which electrolytes contain one or more dissolved electroactive species, and the chemical energy in electrolytes is reversibly converted to electricity. Flow battery technology offers advantages in energy storage and conversion, including: 1.) large capacity (determined by the external tank volume); 2.) negligible degradation when left completely discharged for long periods; 3.) charge/recharge through electrolyte replacement or external power source; and 4.) no permanent damage when electrolytes are accidentally mixed. Among the major types of flow batteries, the vanadium redox flow battery is a type of rechargeable flow battery that employs vanadium ions at different oxidation states to store chemical potential energy.rnrn In this talk, we introduce our ongoing research on Redox Flow Batteries (RFB), including analyses to evaluate dilute solution assumption, pore-level transport resistance, pumping power, and time constants. A model is developed to describe the dynamic system of a RFB and consists of a set of partial differential equations of mass, momentum, species, charges, and energy conservation, in conjunction with the electrode’s electrochemical reaction kinetics. The model, validated against experimental data, predicts fluid flow, concentration increase/decrease, temperature contours and local reaction rate. Experiment was also conducted to show the cyclability. Fig. 1 presents the validation of the model for flow battery at the stage of charge, idling, and discharge.