On the Interaction of a Boundary Layer with a Cross-flow Synthetic Jet

2002 ◽  
Author(s):  
Douglas Smith ◽  
Craig Schmidt
Keyword(s):  
Boundary Layer ◽  
Cross Flow ◽  
Synthetic Jet

scholarly journals Scalings for rectangular synthetic jet trajectory in a turbulent boundary layer

2021 ◽  
Vol 915 ◽  
Author(s):  
Girish K. Jankee ◽  
Bharathram Ganapathisubramani
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Synthetic Jet ◽  
Jet Trajectory

Abstract

Stationary cross-flow breakdown in a high-speed swept-wing boundary layer

2021 ◽  
Vol 33 (2) ◽  
pp. 024108
Author(s):  
Jianqiang Chen ◽  
Siwei Dong ◽  
Xi Chen ◽  
Xianxu Yuan ◽  
Guoliang Xu
Keyword(s):  
Boundary Layer ◽  
High Speed ◽  
Cross Flow ◽  
Swept Wing

Modelling Vortex Generating Jet-Induced Transition in Low-Pressure Turbines

2013 ◽  
Author(s):  
Florian Herbst ◽  
Andreas Fiala ◽  
Joerg R. Seume
Keyword(s):  
Boundary Layer ◽  
Cross Flow ◽  
Transition Process ◽  
Low Pressure ◽  
Boundary Layer Transition ◽  
Quantitative Prediction ◽  
Design Parameters ◽  
Transition Model ◽  
Layer Transition ◽  
Wall Flows

The current design of low-pressure turbines (LPTs) with steady-blowing vortex generating jets (VGJ) uses steady computational fluid dynamics (CFD). The present work aims to support this design approach by proposing a new semi-empirical transition model for injection-induced laminar-turbulent boundary layer transition. It is based on the detection of cross-flow vortices in the boundary layer which cause inflectional cross-flow velocity profiles. The model is implemented in the CFD code TRACE within the framework of the γ-Reθ transition model and is a reformulated, re-calibrated, and extended version of a previously presented model. It is extensively validated by means of VGJ as well as non-VGJ test cases capturing the local transition process in a physically reasonable way. Quantitative aerodynamic design parameters of several VGJ configurations including steady and periodic-unsteady inflow conditions are predicted in good accordance with experimental values. Furthermore, the quantitative prediction of end-wall flows of LPTs is improved by detecting typical secondary flow structures. For the first time, the newly derived model allows the quantitative design and optimization of LPTs with VGJs.

Streamwise evolution of longitudinal vortices in a turbulent boundary layer

2009 ◽  
Vol 623 ◽  
pp. 27-58 ◽  
Author(s):  
OLA LÖGDBERG ◽  
JENS H. M. FRANSSON ◽  
P. HENRIK ALFREDSSON
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Vortex Core ◽  
Cross Flow ◽  
General Point ◽  
Natural Setting ◽  
Viscous Effects ◽  
Array Configuration ◽  
The Cross ◽  
Flow Plane

In this experimental study both smoke visualization and three-component hot-wire measurements have been performed in order to characterize the streamwise evolution of longitudinal counter-rotating vortices in a turbulent boundary layer. The vortices were generated by means of vortex generators (VGs) in different configurations. Both single pairs and arrays in a natural setting as well as in yaw have been considered. Moreover three different vortex blade heights h, with the spacing d and the distance to the neighbouring vortex pair D for the array configuration, were studied keeping the same d/h and D/h ratios. It is shown that the vortex core paths scale with h in the streamwise direction and with D and h in the spanwise and wall-normal directions, respectively. A new peculiar ‘hooklike’ vortex core motion, seen in the cross-flow plane, has been identified in the far region, starting around 200h and 50h for the pair and the array configuration, respectively. This behaviour is explained in the paper. Furthermore the experimental data indicate that the vortex paths asymptote to a prescribed location in the cross-flow plane, which first was stated as a hypothesis and later verified. This observation goes against previously reported numerical results based on inviscid theory. An account for the important viscous effects is taken in a pseudo-viscous vortex model which is able to capture the streamwise core evolution throughout the measurement region down to 450h. Finally, the effect of yawing is reported, and it is shown that spanwise-averaged quantities such as the shape factor and the circulation are hardly perceptible. However, the evolution of the vortex cores are different both between the pair and the array configuration and in the natural setting versus the case with yaw. From a general point of view the present paper reports on fundamental results concerning the vortex evolution in a fully developed turbulent boundary layer.

Turbulent fluid and particle interaction in the boundary layer for cross flow over a tube

1998 ◽  
Vol 24 (2) ◽  
pp. 213-223 ◽  
Author(s):  
J.R. Fan ◽  
X.Y. Zhang ◽  
J. Jin ◽  
Y.Q. Zheng ◽  
K.F. Cen
Keyword(s):  
Boundary Layer ◽  
Particle Interaction ◽  
Cross Flow ◽  
Turbulent Fluid

scholarly journals Sound propagation in a lined nozzle with shear and bias flows

2018 ◽  
Vol 18 (1) ◽  
pp. 3-48
Author(s):  
LMBC Campos ◽  
C Legendre
Keyword(s):  
Boundary Layer ◽  
Mach Number ◽  
Boundary Layers ◽  
Lower Boundary ◽  
Cross Flow ◽  
Core Flow ◽  
The Core ◽  
Wide Range ◽  
Bias Flow ◽  
Number Formula

In this study, the propagation of waves in a two-dimensional parallel-sided nozzle is considered allowing for the combination of: (a) distinct impedances of the upper and lower walls; (b) upper and lower boundary layers with different thicknesses with linear shear velocity profiles matched to a uniform core flow; and (c) a uniform cross-flow as a bias flow out of one and into the other porous acoustic liner. The model involves an “acoustic triple deck” consisting of third-order non-sinusoidal non-plane acoustic-shear waves in the upper and lower boundary layers coupled to convected plane sinusoidal acoustic waves in the uniform core flow. The acoustic modes are determined from a dispersion relation corresponding to the vanishing of an 8 × 8 matrix determinant, and the waveforms are combinations of two acoustic and two sets of three acoustic-shear waves. The eigenvalues are calculated and the waveforms are plotted for a wide range of values of the four parameters of the problem, namely: (i/ii) the core and bias flow Mach numbers; (iii) the impedances at the two walls; and (iv) the thicknesses of the two boundary layers relative to each other and the core flow. It is shown that all three main physical phenomena considered in this model can have a significant effect on the wave field: (c) a bias or cross-flow even with small Mach number [Formula: see text] relative to the mean flow Mach number [Formula: see text] can modify the waveforms; (b) the possibly dissimilar impedances of the lined walls can absorb (or amplify) waves more or less depending on the reactance and inductance; (a) the exchange of the wave energy with the shear flow is also important, since for the same stream velocity, a thin boundary layer has higher vorticity, and lower vorticity corresponds to a thicker boundary layer. The combination of all these three effects (a–c) leads to a large set of different waveforms in the duct that are plotted for a wide range of the parameters (i–iv) of the problem.

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