Dr Aldo Rona
Thermofluids Research Group
Location: Room 139, Michael Atiyah Building
|Research||Honours and Awards||Publications||Teaching|
|Journals and peer-reviewed papers
Aldo Rona received a B.Eng.(Hons) from the Department of Aeronautics, City University, London, in 1993 and a Ph.D. from the University of Southampton, U.K., in 1997. As EPSRC Research Fellow at the Department of Aeronautics and Astronautics, University of Southampton (1996-1997) he studied vortex boundary layer interactions by laser velocimerty. He then joined the Department of Aeronautics and Aerospace at the von Karman Institute for Fluid Dynamics, Belgium, as EU Marie Curie Fellow (1998). At the end of 1998, he joined the Department of Engineering, University of Leicester, as Lecturer in Thermofluids (1998-2010), where he currently works as Senior Lecturer in Thermofluids.
- Unsteady compressible flows.
- Finite-volume, shock-capturing, mesh-adaptive schemes.
- Large Eddy Simulations of unsteady acoustically active flows.
- Finite-difference pre-factored compact schemes for computational aero-acoustics.
- CFD methods for turbomachinery aerodynamics.
- Vortex flows.
- Application of experimental techniques complementary to CFD, such as surface visualisation, schlieren, and time-resolved PIV.
Dr Rona’s main interest is in unsteady compressible flow. This led him to a three-year doctoral study on supersonic flows over rectangular cutouts and screeching jets, at the University of Southampton, from 1993 to 1997. Time accurate numerical models were obtained solving the short-time averaged Navier-Stokes equations with the k-ω SST turbulence model. Aerodynamic noise was also predicted by the Ffowcs Williams and Hawkings application of the Lighthill acoustic analogy. The focus has been to address the aerodynamic unsteadiness and noise as two aspects of the same physical phenomenon.
Further developments, including active mass injection/suction techniques, were pursued between 2000 and 2002 with the support of EPSRC. A parametrical study identified the most effective mass flow injection configuration to suppress the instability in a Mach 1.5 turbulent cavity flow. A reduced order model of the unsteady baseline flow was developed towards designing a model-based control system for closed-loop control. The model was obtained by performing Proper Orthogonal Decomposition of the time-dependent flow predictions.
Between 2002 and 2008, Dr Rona collaborated with the University of Rome “La Sapienza” on a joint experimental and theoretical investigation of slotted tailboards for cascade wind tunnels. In 2003, the ALSTOM Power Technology Centre joined this team. The research improved the flow quality in the test section of the high-speed research tunnel at the University of Leicester. Experimental work at the University of Leicester has seen the implementation of a split beam double edge schlieren flow visualisation technique. While the schlieren technique is a well-established baseline method, the beam splitting is an innovative aspect that allows simultaneous records of orthogonal density gradients. The technique has the potential to allow the reconstruction of the density field, a result that is commonly obtained from more expensive laser based flow visualisations.
|Figure 1: Subsonic flow past a cylindrical cavity. Colour iso-levels of acoustic density perturbation and streaklines.|
Between 2006 and 2010, Dr Rona was Coordinator of the "unsteady aerodynamics training network in airframe components for competitive and environmentally friendly civil aircraft” (AeroTraNet). This €3.2M EU FP6-2004-Mobility-2 project was part of the Marie Curie Actions of the sixth Framework Programme. It provided multi-host Early Stage Training to 13 Marie Curie fellows in unsteady aerodynamics at Leicester, Roma Tre, Politecnico di Torino, and at the Institut de Mechanique des Fluides de Toulouse. At Leicester, Dr Rona developed CFD software for complex compressible 3D flows using body-fitted curvilinear multi-block meshes, adaptive mesh refinement, and a third-order accurate finite-volume upwind method. Figure 1 shows an instantaneous numerical snapshot of the flow over a cylindrical cavity, representing a wide-body civil aircraft fuel vent. The density perturbation iso-levels indicate the aerodynamically generated fuel vent noise. The tonal noise characteristics of this flow were studied in collaboration with the University of Rome "Roma Tre", by wind tunnel tests at ENEA.
Within the 2006-2010 AeroTraNet project, a collaboration with DIASP, Politecnico di Torino, explored the the different broad-band flow dynamics that develops past a rectangular cavity with a thick inflow boundary layer, representative of an automobile bodywork recess. The geometry and flow parameters were selected in consultation with the Fiat Research Center. Large Eddy Simulations with a synthetic-stochastic boundary layer inflow generator predicted the break-down of the inflow streak spacing over the enclosure and the onset of a new spanwise flow matrix, which was confirmed by water-tunnel Particle Image Velocimetry measurements at DIASP.
In 2010-2013, Dr Rona and Dr Adabayo, Honorary Visiting Fellow, University of Leicester, explored by PIV the Taylor instability developing between concentric cylinders at a Taylor number representative of oil bearing chambers in turbomachines. The work detailed the changes in the flow regime that the presence of a probe inserted in the flow causes to the Taylor vortex pattern.