Contra rotative propeller performance estimation

Abstract

Due to the continuous increase in the fuel price, the propeller engine solution (the most efficient in fuel saving terms) becomes very attractive to airlines and thus, to aircraft manufacturers. However, airlines aren’t ready to fly an aircraft at lower cruise Mach number than the traditional Mach 0,84, which jeopardizes the fuel efficiency of propellers. At this stage is where the contra-rotative concept appears, which let us to increase the cruise speed while reducing fuel consumption. Although this solution is not completely new, it is not mastered as others like simple turboprops, or turbofans. So, before being capable of using this innovative kind of technology, it’s completely necessary to overcome some of the unknowns existing around it. In this frame, Airbus is already working in a single aisle new generation airline, which has the possibility of taking thrust from a pair of contra-rotative propellers mounted in T-tail configuration. The project will enter soon in the conception phase, and so it’s time to start the design of the propellers to go further in the conception. In order to reach these objectives, the engineers have to dispose of the necessary tools to simulate the solution, and from all of them we make a zoom on the aerodynamics tools. The company already has CFD simulation software, such as Tau2D and elsA, which are used in this study. But, propeller design combines these elements with other such as performance estimation even more necessary than pure aerodynamic effect such as lift and drag. LPC2 (from French Ligne Portante Courbe 2, Curved Lifting Line 2) is the chosen tool for this purpose. The tool was conceived by ONERA in 1989, and with the success of turbofans it has been somehow forgotten for almost twenty years. So, the main goal of the internship is to validate its performance and tune it to use it in further deeper studies. This is done in the first part of the project and one could say with good success