Research Projects

Rotorcraft such as helicopters, multicopters, and VTOL platforms operate in complex aerodynamic environments characterized by nonlinear, unsteady, and strongly coupled flow phenomena. These effects become particularly critical during regimes such as hover near the ground, rapid descent, and yaw maneuvers, where vortex ring state (VRS), ground effect, and loss of tail rotor effectiveness (LTE) can occur. Accurate modelling of these conditions is essential for flight safety, control law development, performance prediction, and effective simulator-based pilot training. However, current aerodynamic models used in simulation frameworks often employ overly simplified approaches such as blade element momentum theory (BEMT), which do not capture these nonlinearities, or rely on high-fidelity CFD methods that are computationally too expensive for real-time use. As a result, most flight simulators lack sufficient fidelity in safety-critical regimes, limiting their effectiveness for both design and training. The proposed research addresses this long-standing gap by developing a suite of mid-fidelity, physics-based aerodynamic models and reduced-order models (ROMs) specifically tailored for integration into real-time rotorcraft flight dynamics simulators. These models will be validated through targeted wind tunnel experiments and flow diagnostics, ensuring both physical accuracy and computational tractability. The central hypothesis is that mid-fidelity vortex-particle-based simulation methods, when calibrated and validated using experimental data, can provide accurate representations of rotor–wake interactions, inflow dynamics, and aerodynamic loading in complex flight scenarios. These models, once reduced into ROMs, can be readily deployed in simulation environments such as the modular rotorcraft flight dynamics framework under development at the National Aerospace Laboratories (NAL). The research will begin with a detailed literature survey with a focus on VRS, LTE, and ground effect. A theoretical model based on an enhanced BEMT framework will be developed to serve as a benchmark. A modular rotor test rig will then be fabricated to simulate various rotor configurations and flight regimes. Force and moment measurements will be captured using a 6-DOF sensor, while high-resolution Particle Image Velocimetry (PIV) will be used to visualize wake and inflow structures. In parallel, simulations using open-source vortex-particle method codes will be conducted, matching experimental conditions and extending into broader parameter spaces. The validated datasets will then be used to construct ROMs using a combination of physics-based modelling and data-driven techniques. These ROMs will be formatted for direct integration into NAL’s SimCopter and other high-fidelity flight dynamics tools. This project is highly relevant to India’s evolving aerospace and defense ecosystem. The Indian Ministry of Defense has identified the need for heavy-payload logistic drones suitable for high-altitude operations, for which reliable aerodynamic modelling and simulation capabilities are essential. The proposed work complements ongoing initiatives at NAL, such as the High Fidelity Rotorcraft Flight Dynamic Modelling and Control Framework led by honorary co-PI Dr. Omkar Halbe. It also lays the foundation for potential commercialization through startup ventures focused on rotorcraft performance and simulation technologies. If successful, the project will result in a validated, scalable aerodynamic modelling toolchain that bridges the fidelity gap between CFD and low-order methods, enabling safer and more accurate simulation, design, and training across civilian and defense rotorcraft platforms. Beyond academic contributions, the outcomes are expected to improve aviation safety, reduce development risks, and support indigenous innovation in India’s growing rotorcraft sector.