September 24, 2019


According to the requirements of the topic JTI-CS2-2018-CFP08-REG-03-01, the proposal ESTRO will produce experimental and numerical data in low flow speed and in “cruise conditions” to validate the relevant aerodynamic performance of the Regional 90 seats turboprop A/C wing including laminar flow extension measurements and wing span load distribution.

In particular, the tests in wind tunnel conditions will be performed at Reynolds numbers expected to be around 11 millions , and at low and cruise Mach numbers. Accurate pressure distributions, infrared flow images, wing deformation, wall balance and load control and alleviation measurements are expected. The data will be the result of an experimental test campaign performed in a Laminar transonic Wind tunnel with the main objective to evaluate the laminar flow robustness, the aerodynamic performances and load control effectiveness of a turboprop A/C wing at high/medium speeds (Mach numbers up to 0.67) and wind tunnel Reynolds number around 10-11 million. Numerical simulations aim to first assess the wind tunnel experimental results and then to extrapolate the data to flight conditions. In addition, the effects of the propeller on the wing laminar flow extension will be evaluated through 3D boundary layer computations coupled to linear stability analyses based on ray theory and multiple scale technique.

As a first step, the consortium ESTRO will prepare the technical specification for the launch (according to the Italian regulations) of an European Call for tender for the assignment of the contract for the wind tunnel test campaign. The test matrix described in the topic JTI-CS2-2018-CFP08-REG- 03-01 will be reviewed, in cooperation with the TM, before publishing in the technical specification. A preliminary review of the existing European laminar wind tunnels has been carried out and the result will be described in the next section.

In parallel, the consortium ESTRO will perform the tuning of the numerical tools for the estimation of the laminar flow robustness and of all the procedure that will be used for the evaluation of the loads on the deformed wing. The tuning will be performed in wind tunnel flow conditions by comparing numerical results against experimental ones.

Successively, the assessed and validated tools will be applied in order to extrapolate the aerodynamics, the laminar flow performance and load control effectiveness in cruise conditions.
In detail, the proposal ESTRO can be broken down into the following four phases

1 Wind Tunnel Selection

  • Review of the test matrix (in agreement with the TM)
  • Draft of the preliminary technical specification
  • Test Matrix consolidation
  • Final technical specification
  • Call for tender

2. Numerical tools preparation phase

  • State of the art of the numerical tools for the evaluation of the laminar flow robustness
  • Tuning of methods and procedures
  • Numerical analyses focused on the computation of:
    • Aerodynamic wind tunnel performance (RANS Computations);
    • Non viscous Computations
  • Boundary Layer Computations
    • Conical laminar boundary layer
    • Full 3D laminar boundary layer
  • Linear Stability computations
    • Local and non-local stability analyses;
    • Linear stability analysis based on the ray theory
  • Loads distribution/ deformation calculations via CFD-CSM coupling. The objective is to estimate loads on the deformed wind tunnel model and the final deformed geometry
  • Euler and Potential Methods for propeller effect evaluation
    • Vorton Methods;
    • Euler and disk actuator approach

1.1.3. Wind Tunnel Testing phase

  • Aerodynamic wing performance (Lift, drag, moment);
  • Pressure distributions at several Mach and WT Reynolds Numbers
  • Laminar flow measurements
    • Infrared images
    • Pressure measurements
  • Measurements of the Wind Tunnel Model deformation;
  • Data Analysis.

4. Numerical Investigation in Flight conditions

  • Aerodynamic wing performance (Lift, drag, moment) in flight conditions;
  • Laminar flow robustness (effects of droop noose, morphing winglet, morphed trailing edge,..);
  • Receptivity analysis
  • Effectiveness of the LC&A devices
  • Operated propeller effects on laminar flow extension