Master thesis and internship[BR]- Master's thesis : Secondary flows in tandem blades[BR]- Integration Internship : Safran Group

Abstract

The design of an aircraft engine requires from the low pressure compressor (LPC) at every engine operating point (CRUISE, CLIMB, TAKE-OFF, etc): • A specific capacity in mass flow and compression ratio, • While maximising the efficiency. In order to achieve this, for a certain chosen architecture: • Rotors are designed to deliver a certain compression ratio by flow turning, • Stators are designed to diffuse the flow while counteracting the swirl created by the rotor. In certain engine designs, the amount of flow turning required is greater than what a single blade can provide. This results may create flow detachment and may compromise the LPC’s ability to ensure each engine operating point at a proper efficiency. A valid solution is to use tandem blades, meaning two blades within one row among which the flow turning is divided. that makes the flow more stable and attached. One of the main causes of loss is the presence of secondary flows, which are created by the low momentum zones due to the hub and shroud interacting with the blade geometry. The tandem configuration is a solution to improve the situation and reduce their negative impact. The interaction of these secondary flows with a tandem blade design is a relatively new challenge in the industrial and academic community. The aim of this project is to evaluate the secondary flows in tandem blades by developing an objective method to quantify and localise the losses and then to distinguish their main sources. A qualitative analysis of the flow along the two types of tandem blades designed by Safran AeroBooster(SAB) is carried out. The case study is the Outlet Guide Vane (OGV) geometry of the booster provided by SAB. A comparison of different tandem design philosophies is carried out. This is followed by a study of the effect of the slot geometry between the front and aft blade. Finally, an evaluation of the effect of the different turbulence models is evaluated.