image as of 2010

• Industrial Placement Tutor - Mechanical

Thermofluids Research Group

BEng Aeronautical Engineering (City), PhD (Southampton), CEng, MRAeS, MAIAA
T: +44 (0)116 252 2510
F: +44 (0)116 252 2525
E: ar45@le.ac.uk

Location: Room 139, Michael Atiyah Building

Brief Biography:

Born in Italy in 1972, 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 was appointed Lecturer in Thermofluids at the Department of Engineering, University of Leicester.

Research Interests:

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 turbulence modelled. 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.

Dr Rona continued this research as EU TMR fellow and then as lecturer, assessing flow instability control methods by the numerical model approach. These methods included geometry modifications, such as curved and straight ramps at the rectangular cutout leading and trailing edges, and mass injection. The analysis of the altered unsteady flow physics lead to a preliminary optimisation of such flow control methods. The amplitude of the predicted pressure oscillations was reduced by about 12 dB at selected locations and the form drag was reduced by five folds.

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.

Following a similar numerical approach, Dr Rona investigated the physics of unsteady subsonic coaxial cold jet flow and noise. An upgrade of an explicit in-house Navier Stokes numerical method was performed towards obtaining a validated higher order time accurate coaxial jet model with optimised dispersion relation preserving characteristics. This research started in January 1998 under an EU TMR sponsorship. It has generated a good internal and external interest (EOARD), due to its relevance to the aircraft engine community. The research has since expanded to study the role of jet temperature in screech for a supersonic round nozzle.

Since 2002, Dr Rona has 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 wellestablished 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.

Between 2003 and 2004, Dr. Rona completed a 12 months part-time Industrial Secondment at Alstom UK, sponsored by the Royal Academy of Engineering. The secondment reinforced the long-term industrial collaboration with Alstom and improved the thermofluids teaching syllabus by including industrially relevant examples and exercises. The main research activity has been to combine mesh adaptivity and multi-grid acceleration in an extension of the in-house open CFD software suite GENESIS. The work improved the spatial definition of the flow predictions for selected time-averaged CFD assessments of Alstom turbine blades. The Thermofluids and Environmental Engineering research group has an active internal collaboration which Dr Rona supports. In particular, he implemented surface flow visualisation methods for the low speed transition research by Prof. J.P. Gostelow. In 2002, the technique was adapted to the 20m/s - 40m/s tests on flow separation and wake analysis led by Dr. C. M. Coats.

Research Projects:
Dr Rona has active research is in unsteady aerodynamics and flows exhibiting a self-sustained instability and generating noise. He develops CFD software for complex compressible 3D flows using body-fitted curvilinear multi-block meshes, adaptive mesh refinement, and a third-order accurate finitevolume upwind method. Noisy flows past aircraft pressure relief valves and car door seals are modelled within a €3.2M EU FP6-2004-Mobility-2 grant, which Dr Rona coordinates. Involving collaboration with one French and two Italian universities  and Airbus France, Alstom UK, Fiat and Renault, this supports a team of 13 Marie Curie Fellows.

Recent Publications:

• Ackerman, J.R., Gostelow, J.P., Rona, A., Carscallen, W.E.: Measurements of fluctuating pressures on a circular cylinder in subsonic cross flow, AIAA Journal, Vol. 47, No. 9, September 2009, pp. 2121-2131, doi: 10.2514/1.40954.
• Rona, A.: The acoustic resonance of rectangular and cylindrical cavities, Journal of Algorithms & Computational Technology, Vol. 1, No. 3, November 2007, pp. 329-355, doi:10.1260/174830107782424110.
• El-Dosoky, M.F., Rona, A., Gostelow, J.P.: An analytical model for over-shroud leakage losses in a shrouded turbine stage, ASME Paper GT2007-27786, ASME Turbo-Expo 2007, Montreal, Canada, 14-17 May 2007.
• Rona, A.: Self-excited supersonic cavity flow instabilities as aerodynamic noise sources, International Journal of Aeroacoustics, Vol. 5, No. 4, December 2006, pp. 335-360, doi:10.1260/147547206779379921.
• Rona, A., Paciorri, R., Geron, M.: Design and testing of a transonic linear cascade tunnel with optimized slotted walls, ASME Journal of Turbomachinery, Vol. 128, January 2006, pp. 23-34, doi:10.1115/1.2101856.
• Rona, A., Zhang, X.: Time accurate numerical study of turbulent supersonic jets, Journal Sound and Vibration, Vol. 270, No. 1-2, February 2004, pp. 297-321, doi:10.1016/S0022-460X(03)00537-6.