The Modane (France) center's S1 wind tunnel operates using two counter-rotating 15 meter diameter fans. Each rotor is driven by a Pelton turbine with a maximum power of 44 MW. This machine, unique in its type, has been in service for more than 50 years. It was initially designed to operate at high subsonic speeds but is now frequently used to test configurations at transonic speeds, at its maximum power. This has resulted in a large amount of fatigue to different parts, in particular the fans, which has led to a program of renovation of the installation. Several computing operations have been programmed at Onera to prepare for the replacement of the fans. Within this framework, the Turbomachinery team is responsible for carrying out a study of the aerodynamic behavior of the current blades.
Different numerical calculations have been performed in order to simulate the flow in the counter-rotating fans at Modane (fig. 1). The mechanisms involved when the machine is operating, in particular for off-design conditions, have been clearly identified (fig. 2). Even though it was designed more than 60 years ago, the study showed that the current fans behave very well.
Figure 1 : 3D CFD result: the flow around the blades of the fans in S1 Modane
Figure 2 : The mechanisms of the interactions
between the support masts
and the fans are emphasized here
