Research Projects

The proposal has been developed to address one of the key areas of focus of the Bharatiya Vayuyan Adhiniyam, 2024, also known as the Indian Aircraft Act, 2024, which is the indigenous design and development of aircraft. The future of civil aviation is blended wing body (BWB) aircraft with Boundary layer ingestion (BLI)-based distributed propulsion, as shown in Fig. 1a (in full proposal). This technology is also being developed for military aviation, particularly for military transport aircraft and blended wing UAVs, such as the DRDO-SWiFT (Stealth Wing Flying Testbed). Several international companies are working towards various BWB designs with full-scale demonstrations aimed for within this decade. A BWB design provides several benefits, such as higher aerodynamic efficiency, lower fuel consumption, lower aerodynamic noise, and higher cargo space. Typically, BWBs have a distributed propulsion system, which offers benefits such as a reduction in ram drag, short take-off and landing, higher redundancy and safety, and lower aerodynamic noise. The reduction in ram drag is caused by boundary layer ingestion (BLI) by surface-mounted embedded engines. BLI-based engines create suction, which can potentially delay stall and improve the lift-to-drag (L/D) characteristics of both the fuselage and the wings. Several studies have focused on the effect of BLI on propulsion efficiency [Liebeck et al. 2004-Boeing]. However, very few studies have investigated the effect of the suction on the boundary layer, that is the flow-control aspect. The designs of the BWB and several other aerodynamic vehicles, which employ distributed propulsion systems, offer the unique opportunity of improvement in aerodynamic performance using trailing-edge suction-based flow control. This research proposal aims to conduct a fundamental investigation of this flow control opportunity, which will be one of the first of its kind. It will study how the characteristics of the boundary layer are affected by the suction created by a propeller, similar to a fan in a turbofan engine, Fig. 1b (in full proposal). The research will form the foundation for the development of flow control systems for next-generation aircraft and drones. Objectives: The objective of the proposed study is to experimentally (PI) and numerically (Co-PI) characterise the effects of suction by a propeller and a ducted propeller on the boundary layer over a flat plate and a wing, Fig. 1b (in full proposal). The study will include characterisation of the propeller and its interaction with a flat plate boundary layer having zero pressure gradient (Year 1). Propeller interaction with a NACA 0012 two-dimensional wing section having a boundary layer with an adverse pressure gradient (Year 2). Interaction of ducted propeller with flat plate and wing boundary layers (Year 3). Parameters varied will be the number of rotor blades (2 and 4), rotor advance ratio (0.4-0.8) and rotor tip clearance. Novelty: Investigation of the flow control aspect of a BLI-based engine, an important but overlooked aspect of next-generation aviation designs. Impact: Development of more efficient aircraft configurations (BWB, pusher, drone) with higher fuel efficiency and lower aerodynamic noise. Note: PI’s doctoral student has already started working on the project. Experimental design has been completed after a thorough literature review. The first set of experiments over the flat plate is scheduled to begin by the end of July 2025. The project is currently funded by PI, support through ARG will be very helpful in developing this initiative.