Sanjay Jayaram, Ph.D.
Associate Professor of Aerospace and Mechanical Engineering
Ph.D. Mechanical Engineering, University of Central Florida
M.S. Mechanical Engineering, University of Central Florida
B.S. Mechanical Engineering, R.V. College of Engineering, Bangalore, India
Dr. Jayaram’s research interests include bio-inspired aerodynamics, fluid-structure-controls interaction problems, advanced control systems design (adaptive and learning control, fault tolerant robust control) of multi-vehicle coordination, small spacecraft design, and dynamic systems and control of space vehicles. Below are some of the research topics he is currently working on.
(Though some of the topics mentioned above are not specifically listed below, interested students are encourage to contact and discuss potential research topics to explore)
Research Topic 1: Bio-inspired Aerospace Innovative Morphing Structures (Bio-AIMS) (Fluids-Structure-Controls Interaction Problems)
The primary goal of this research is to investigate the applications of biomimetic morphing and aerodynamic shape control based on shape memory alloys. The aerodynamic morphing of the trailing edge and tubercles on the leading edge will provide excellent aerodynamic as well as control characteristics systems for the aerospace engineering industry. Aerodynamics and Control system synthesis for aeroelastic systems incorporating morphing structures have shown the potential to design morphing wing sections which can be useful in improving the mission requirements of an aircraft flying through different flight regimes including transonic flow.
Important research topics to be explored:
- Unsteady aerodynamic modelling leading to aerodynamic and flow control using morphing structures. The applications of this work will be in the areas of flow control over wings and airfoils, the control of biomimetic aerodynamic flows.
- Leads to novel designs of unmanned aerial vehicles, by increasing the lift capabilities and reducing drag at the same time. Applications are to drag reduction in commercial aircraft and to develop energy efficient flow control schemes for future aircraft.
This research involves Computational Fluid Dynamics, Experimental Work (wind tunnel) and some aspects of fluid-structure interactions (Flutter and Aeroelasticity) and how to design control system to minimize aeroelastic effects.
Research Topic 2: Tubercles inspired Vertical Tail drag reduction
One of the top priorities for future aircraft designs (commercial, military or general aviation) is to increase the efficiency by reducing the fuel burn by developing technologies for drag reduction. Literature and experimental analysis indicates that viscous drag (which comes from skin friction) contributes close to 50% of the total drag experienced by an aircraft. Reduction in viscous drag directly translates to increasing range for the same fuel or increasing payload for the same range. This would also contribute to sustainable environment with lower engine emissions.
It may not be possible to decrease drag substantially (to make an impact) from every aspect of the aircraft structure, but drag reduction from wings, vertical and horizontal tails are currently being explored.
Vertical tail on an aircraft is sized to compensate instances of engine failures during takeoffs and low speed climb which includes crosswind conditions. The vertical tail is sufficiently sized to generate enough side force to counter the asymmetric thrust generated from the operating engine and overcome the drag from the failed engine (process known as “Windmilling”).
NASA, with several aircraft design industry is currently investigating one of the innovative approaches that uses Active Flow Control (AFC) technology to reduce the size (i.e., wetted area) of the vertical tail, directly leading to a decrease in drag, as well as a reduction in fuel consumption and greenhouse gas emissions.
While AFC has been proven to be an effective solution through numerical analysis and wind-tunnel testing, it is also complicated in terms of design and systems engineering as it involves installing several sweeping jet actuators on the vertical tail, with the nozzle exits located along the trailing edge of the vertical fin and pointing downstream to decrease the side force, thus reducing drag.
This research involves inducing tubercles on the leading edge of the vertical tail and investigating its effects on side force reduction and drag reduction. Various biomimetic technologies will be evaluated, both at leading edge and trailing edge to investigate the effects. This work involves both numerical analysis (CFD) and wind tunnel experiments.
Research Topic 3: Aerodynamic Control system for morphing structures using Intelligent Learning Control (ILC)
Active feedback control design to morph wings given a requirement of lift force is quite challenging. This involves sensing various measurements and provide an input to the control system which in turn generates commands for the Shape Memory Alloy (SMA) actuator to morph the wing to make a delta change in the lift characteristics.
This research involves developing feedback control laws and ultimately utilize the “intelligent learning control” methods using artificial intelligence and/or machine learning to perform these aerodynamic and stability maneuvers autonomously given varied flight regime conditions.
Research Topic 4: Multirotor Drones Turbulence Ground Effect – Noise and Stability
Topic 4.1 - Noise Reduction for UAM System Applications
Urban Air Mobility (UAM) systems are gaining in popularity across the world as a solution to a unique problem of traffic congestions in urban areas. Due to urban applications, UAM’s are envisioned to be VTOL aircraft systems. Though the market research and survey indicates widespread use of such systems, there are unique technical challenges as well as safety challenges these systems have to overcome for widespread use in cities. Some of the technical challenges is the area of improving aerodynamic efficiency, reduce noise and increase stability and control during takeoff and landing.
Currently, several technical areas are being looked into as “Technical Gaps” (reference NASA TP 2020-5007433) where technologies like increasing the number of blades, optimizing the blade airfoil shapes, optimizing the blade planform shape, avoiding blunt trailing edges, etc for improving aerodynamic characteristics.
Similarly, to reduce noise in urban environment, some of the areas being researched. Some of the potential areas are:
- Irregular rotor blade spacing could be used to modify the interactional aerodynamics. Irregular rotor blade spacing appears unexplored
- Exploring and understanding the effects of uneven blade lengths - each opposing blade could be the same length, but each opposing blade set could be a different length.
- Exploring biomimetic technologies for noise reduction – Inspiration from owl wing morphology. Explore the unique wing shapes of owl or blade morphing for potential reduction in noise (explore bio adaptations at leading edge and leading edge of the blade)
Topic 4.2 - Reducing Effect of Turbulence from Ground Effects for Multirotor VTOL Vehicles
Landing and takeoff of multi-rotor drones (VTOL) is quite difficult, while among the two, landing is the most challenging and complex. As the vehicle gets closer to the ground, the airflow bouncing of the ground is complicated and is not well studied or understood. Not enough solutions have been explored to compensate for this complex turbulence characteristics, particularly for autonomous drones. Likewise, this complex turbulence creates stability and control challenges in presence of ground effects, an area that has not been fully explored.
The purpose of this research is to find solutions to these complex problems.
- Understand the turbulence effects near ground (numerical methods using CFD)
- Investigate mitigation and/or compensation schemes (rotor blade morphing, counter-rotating strategies etc.)
- How the results of the study can be utilized to develop stability and control laws for smooth landing and takeoff (use of advanced control technologies like combined system of adaptive and learning control)
- Explore utilization of AI/ML strategies to reconfigure rotor blade shapes and control systems to demanding changes in environmental effects or aerodynamic changes.
Research Topic 5: Distributed Multivehicle Architecture
- Guidance, Navigation and Control of modern aerospace systems (cooperative teams of unmanned aerial vehicles)
- Increase the level of autonomy incorporating higher level decision making under uncertainties (prognostic health monitoring, collision avoidance etc. using AI/ML techniques)
- Optimal Estimation techniques, model-predictive control
Professional Organizations and Associations
He is a member to many professional societies, including AIAA, and the American Society for Engineering Education. He is currently serving as Treasurer for the Aerospace Division of ASEE and also as Committee Chair for AIAA/ASEE Leland Atwood Awards Committee.
Community Work and Service
Sanjay Jayaram joined Saint Louis University in 2005 as an Assistant Professor in the Department of Aerospace & Mechanical Engineering at Parks and became Coordinator of Aerospace Engineering in August 2013. He worked as a research associate at Florida Space Institute for one year from 1998 to 1999. He has peer reviewed journal and conference publications in many sources with a focus on advanced control systems design and spacecraft engineering. Jayaram heads/mentors several student-design spacecraft at Saint Louis University.