Effects of Vane Sweep on Fan-Wake/Outlet-Guide-Vane Interaction Broadband Noise

Abstract

A method is developed for predicting broadband noise due to the fan-wake interacting with the downstream swept outlet-guide-vanes in turbofan jet engines. It is validated against the NASA Source Diagnostic Test data. Sweep effects on the source, on the response and on the unsteady lift coupling with the duct modes are discussed. The mechanisms of broadband noise reduction due to vane sweep are studied, and a simple model to account for sweep effects is proposed accordingly.

A Rapid RI-TP Model for Predicting Turbine Wake Interaction Broadband Noise

“…The blade is often split into segments (Strip Theory) and each segment is assumed to be a very thin flat plate with a local mean stagger angle and zero attacking angle (thin-flat-plate assumption). Based on above hypotheses, it is noted that the thin-flat-plate assumption of a fan blade is applicable, but the rationality of using it on a turbine blade is untraceable, let alone the prediction of turbine broadband noise using those broadband noise models [19,20].…”

“…Then, substituting Equations ( 15)~ (17) and Equation (20) into Equation ( 12) can result in the final expression of the sound power spectrum function. This formula is suitable for the broadband noise prediction of a turbine with high blending angle.…”

“…However, the turbulence information as input in most traditional analytical models is empirical. To resolve this issue, the RANS-informed analytical method [19][20][21][22][23] has been the focus of many studies. Its time-and-resourcesaving ability compared with numerical methods, and higher-robustness compared with traditional analytical models, improves the RANS-informed analytical method's prospects.…”

“…In 1973, Smith [33] proposed a fundamental and groundbreaking method called LINSUB to calculate unsteady blade lift, moment and acoustic waves for unsteady, subsonic flow through an infinite, two-dimensional cascade of flat plate blades at zero mean incidence. Many following works, like Hanson [37,38], Cheong [39], Ju [19,20] and Tong [23], were all built on the basis of LINSUB.…”