Surrogate-based optimization of nacelle intake with fan-intake interaction: Mitigating flow separation under crosswind

Abstract

Intake separation is a primary cause of distortion at the fan entrance, and crosswinds are a leading contributor to intake flow separation. Thus, improving the intake geometry to lower the distortion level during crosswind conditions is very important in engineering. As intake performance can be influenced by fan-intake interaction, in this paper, we conducted a comparative study of intake shape optimization design at a crosswind in the presence and absence of a fan stage. And a critical design point of 30-kts crosswind was considered to meet airworthiness standards. The analysis of flow mechanism inside intakes was conducted, and indicated the prominent difference of intake separation flow between fan-intake coupled simulations and intake only simulations under crosswind conditions. A POD-based CST method was conducted to obtain much fewer three-dimension nacelle parameters than the classical CST method. A Kriging-DE design model was adopted to replace the high-cost CFD simulations and searched for an optimal result. The results demonstrated that the optimization based on the fan-intake coupled simulation presented a lower intake distortion level and higher isentropic efficiency of the fan stage, highlighting the advantage of this optimization routine.