Raffaele Donelli

Transonic High Reynolds Number Transition Experiments in the ETW Cryogenic Wind Tunnel

With the goal of studying Natural Laminar Flow (NLF) wings for future ‘green’ transport aircraft, the aim of the European Research Project TELFONA is to develop and demonstrate the possibility of testing full aircraft models at large Reynolds numbers in the cryogenic Wind Tunnel ETW, with direct measurements of total drag. Two main steps were defined, first the design and test of a ‘calibration’ model, to be followed by a realistic transport aircraft model. This paper is dedicated to the first one, which was especially designed in order to allow a calibration of the Wind Tunnel transition N-factors at large values of the chord Reynolds number typical of testing in ETW. In order to do so, the wing shape was optimized so that TS and CF N-factors would show a monotonous growth over the longest possible distance. Apart from classical aerodynamic forces, two lines of pressure taps, as well as four patches of a two components cryogenic Temperature- Sensitive Paint (cryoTSP), were installed on both sides of each wing. Model surface temperatures were recorded by several CCD cameras as the intensity of light emission from the TSP, which has to be excited by suitable light sources. After the tests, stability analysis was applied in order to ‘calibrate’ the various models currently used by research labs in Europe, involving a wide range of approaches, including simplified database, local linear and non local linear stability approaches. The paper will describe these different phases of the activities, from design, testing and numerical validation, with a focus on the validation and calibration of transition prediction tools. Examples of numerical results obtained by the project partners will be confronted to the experiments.

Design of a Supersonic Natural Laminar Flow Wing-Body

The present investigation has been carried out within the SUPERTRAC project funded by the European Community in the 6th Framework Programme and aimed at investigating various techniques within laminar flow technology applied to supersonic drag reduction. In particular, this work deals with natural laminar flow shape design of a supersonic high-sweep wing–body configuration. The reference geometry has been provided by Dassault Aviation, one of the two industrial partners together with Airbus. Two different design are presented, produced by the Italian Aerospace Research Center and ONERA, respectively, using numerical optimization procedures based on evolutionary computing techniques and robust aerodynamic analysis tools. Results show how shape optimization can be effective in changing the boundary-layer characteristics of a supersonic high-swept wing and enhancing natural laminar flow on the wing surface.

Design of a laminar-turbulent transition flight experiment

*† ‡ § ** Laminar-turbulent transition is commonly recognized as an important factor in the design of re-entry vehicles. In the framework of the European project EXPERT, organized by the European Space Agency (ESA), CIRA, ONERA and VKI are working together to design and implement on the EXPERT capsule an experiment on induced transition. The aim of the present work is to summarize and test the main correlations commonly used to estimate transition in hypersonic regime, applying them to the flight of the EXPERT capsule. An experimental test campaign has been also carried on in order to verify the reliability of such correlations in wind tunnel conditions representative of the EXPERT flight. Finally, the preliminary sensors layout proposed for the EXPERT capsule is shown for the flight is foreseen in 2007.

Computational Analysis of Shock Wave Boundary Layer Interactions in Non-equilibrium Hypersonic Flow

In this paper we report and discuss the results of the computational analysis of the flowfield past a double wedge model that has been used in a test campaign performed in the Hypervelocity Expansion Tube at the University of Illinois. Along with the center of the model 19 coaxial thermocouple gauges at 16 different streamwise locations are mounted to address heat flux measurements in several test campaigns performed in air and nitrogen flow at low and high enthalpy free-stream conditions. Therefore, in the present work, numericalto-experimental comparisons have been provided and discussed in order to address critical flowfield phenomena, such as the Shock Shock Interaction, Shock Wave Laminar Boundary Layer Interactions and the resulting heat transfer, that are common place in hypervelocity double wedge flow.

High Reynolds Number Transition Experiments in ETW (TELFONA project)

A wind–tunnel experiment on laminar-turbulent transition has been performed in ETW (the European Transonic Wind Tunnel in Koln) at high Reynolds number and cryogenic conditions. The studied geometry is a sting mounted full model in swept–wing configuration. The transition location was determined by means of Temperature Sensitive Paint (CryoTSP). The experimental observations were further analysed using different transition prediction tools, based on linear stability theory.

Transition Control Testing in the Supersonic S2MA Wind Tunnel (SUPERTRAC project)

This paper presents an attempt to control the laminar-turbulent transition on a swept wing in supersonic flow. The first part deals with the control of the transition due to crossflow (CF) instabilities present on a swept wing, by using Micron-Sized Roughness elements (MSR); the second one is focused on the prevention of the turbulent contamination along the Leading Edge (LE), using appropriate Anti-Contamination Devices (ACD). The work includes both numerical and experimental investigation.

CIRA Experiments and Payloads flying on EXPERT - The ESA Experimental Re-Entry Vehicle.

The ESA European Space Agency is currently developing the project EXPERT – Experimental Re-entry Vehicle Test-bed. The EXPERT capsule features a generic simple shape and will perform a sub-orbital ballistic hypersonic flight; with a selection of major shape parameters to avoid any surface active oxidation, degradation and flow contamination. In the frame of Expert Project, CIRA has covered a double role: Payloads Coordinator with the main objectives to supervise all scientific aspects of embarked experiments, to coordinate all main and critical mechanical tests, to harmonize and optimize their integration on the EXPERT vehicle and their interfaces from mechanical, electrical and software point of view: and as Principal Investigator of 3 Payloads corresponding to the following experiments: a) Natural LTT Laminar-To-Turbulent Transition, b) SWBLI Shock Layer – Boundary layer Interaction ahead the ceramic flaps, c) Flying Winglet – UHTC Sharp Hot Structure “SHS”. In this paper a detailed overview of the designed experiment, correlation with the theoretical aspects, results of the on-ground qualification activities and expected results from the data collected in the coming flying mission are reported and discussed.

Laminar-turbulent transition flight experiment on the EXPERT capsule

Laminar-turbulent transition is commonly recognized as an important factor in the design of re-entry vehicles. In the framework of the European project EXPERT, organized by the European Space Agency (ESA), CIRA and ONERA have worked together to design and implement on the EXPERT capsule an experiment on natural transition. The aim of the present work is to summarize the status of the Payload 04 showing all the activities performed up to the shipment phase.