The Clean Sky Green Rotorcraft ITD focuses on innovative rotor blades and engine installation for noise reduction, lower airframe drag, diesel engine and electrical systems for fuel consumption reduction and environmentally friendly flight paths. In this framework the research consortium was aiming at the development of laminar blades (producing lower drag) to provide the greatest possible reduction in fuel consumption. This required the capability to model the underlying physics such as the unsteady laminar boundary layer and, further, transition from laminar to turbulent flow.
In this respect, the proposal answered topic JTI-CS-2009-2-GRC-01-002, dedicated to the development of the necessary numerical models to predict transition and compute the unsteady laminar base flow. More specifically it was proposed, as required by the GRC Consortium, to develop numerical tools able to:
- Compute the main boundary layer quantities for unsteady flow conditions
- Perform stability analysis using the multiple-scale technique and the ray theory for the evaluation of the laminar flow region on the blade.
- Take as input the three components of the velocity distribution on the blade surface provided by an external inviscid flow solver.
The Fluid Dynamics Group at the Department of Mechanical Engineering at the University of Salerno was especially suited for this task since it possesses the expertise and long experience in the field of transition prediction, especially involving ray theory.
The project was entirely dedicated to the development of the necessary theoretical and numerical models to both predict transition and compute the laminar base-flow quantities under unsteady conditions, like those occurring on blades of rotorcrafts undergoing hover and forward flight. The objective of the project, as required by the GRC consortium, was to develop theoretical and numerical tools able to:
- compute the main boundary layer quantities for unsteady flow conditions;
- perform stability analysis using the multiple-scale technique and the ray theory for the evaluation of the laminar flow region on the blade.
Both objectives have been attained, delivering computer codes that take as inputs the three components of the external velocity, to be provided by an inviscid flow solver that sits outside this project.