Mn. Osullivan et al., COMPUTATIONAL STUDY OF VISCOUS EFFECTS ON LOBED MIXER FLOW FEATURES AND PERFORMANCE, Journal of propulsion and power, 12(3), 1996, pp. 449-456
This article describes a computational study of viscous effects on lob
ed mixer flowfields. The computations, which were carried out using a
compressible, three dimensional, unstructured-mesh Navier-Stokes solve
r, were aimed at assessing the impacts on mixer performance of inlet b
oundary-layer thickness and boundary-layer separation within the lobe.
The geometries analyzed represent a class of lobed mixer configuratio
ns used in turbofan engines. Parameters investigated included lobe pen
etration angles From 22 to 45 deg, stream-to stream velocity ratios fr
om 0.5 to 1.0, and two inlet boundary-layer displacement thicknesses.
The results show quantitatively the increasing influence of viscous ef
fects as lobe penetration angle is increased. It is shown that the sim
ple estimate of shed circulation given by Skebe et al. (Experimental I
nvestigation of Three-Dimensional Forced Mixer Lobe Flow Field, AIAA P
aper 88-3785, July, 1988) can be extended even to situations in which
the flow is separated, provided an effective mixer exit angle and heig
ht are defined. An examination of different loss sources is also carri
ed out to illustrate the relative contributions of mixing loss and of
boundary layer viscous effects in cases of practical interest.