Model Problems Associated with the Prediction of Noise by High Speed Shear Layers

1993 ◽  
pp. 260-281 ◽  
Author(s):  
John M. Seiner ◽  
T. R. S. Bhat
Keyword(s):  
High Speed ◽  
Shear Layers

Mixing enhancement in high-speed turbulent shear layers using excited coherent modes

AIAA Journal ◽  
1998 ◽  
Vol 36 ◽  
pp. 2027-2035
Author(s):  
K. Lee ◽  
T. C. Liu
Keyword(s):  
High Speed ◽  
Shear Layers ◽  
Turbulent Shear ◽  
Mixing Enhancement

Mixing Enhancement in High-Speed Turbulent Shear Layers Using Excited Coherent Modes

AIAA Journal ◽  
10.2514/2.303 ◽  
1998 ◽  
Vol 36 (11) ◽  
pp. 2027-2035 ◽  
Author(s):  
K. Lee ◽  
J. T. C. Liu
Keyword(s):  
High Speed ◽  
Shear Layers ◽  
Turbulent Shear ◽  
Mixing Enhancement

Flame and Flow Topologies in an Annular Swirling Flow

2013 ◽  
Author(s):  
I. Chterev ◽  
C. W. Foley ◽  
S. Kostka ◽  
A. W. Caswell ◽  
N. Jiang ◽  
...  
Keyword(s):  
High Speed ◽  
Vortex Breakdown ◽  
Swirling Flow ◽  
Flow Fields ◽  
Shear Layers ◽  
Flame Stabilization ◽  
Preheat Temperature ◽  
Breakdown Region ◽  
Flame Shape ◽  
Annular Swirling Flow

A variety of different flame configurations and heat release distributions, with their associated flow fields, can exist in high swirl, annular flows. Each of these different configurations, in turn, has different thermoacoustic sensitivities and influences on combustor emissions, nozzle life, and liner heating. These different configurations arise because at least three flame stabilization locations are present, associated with the inner and outer shear layers of the annulus, and the stagnation point of the vortex breakdown region. This paper discusses the flame and flow topologies that exist in these flows. These results illustrate the importance of the sensitivity of flame configurations to geometric (such as centerbody size and shape, combustor diameter, exhaust contraction) and operational (e.g., bulkhead temperature, preheat temperature, fuel air ratio) parameters. We particularly emphasize the centerbody shape as differentiating between two different families of flame shapes. Results are shown illustrating the time averaged and instantaneous flame shape and flow fields, using high speed PIV, OH-PLIF, and luminosity imaging.

Shear/rotation competition during the roll-up of acoustically excited shear layers

2018 ◽  
Vol 844 ◽  
pp. 831-854 ◽  
Author(s):  
Abbas Ghasemi ◽  
Burak Ahmet Tuna ◽  
Xianguo Li
Keyword(s):  
High Speed ◽  
Amplification Factor ◽  
Reynolds Numbers ◽  
Shear Layers ◽  
Acoustic Excitation ◽  
Vortex Pairing ◽  
Time Space ◽  
Image Velocimetry ◽  
Velocity Spectra ◽  
Nonlinear State

Naturally developing and acoustically excited shear layers at the Reynolds numbers $Re_{\unicode[STIX]{x1D703}_{0}}=U\unicode[STIX]{x1D703}_{0}/\unicode[STIX]{x1D708}=85{-}945$ are studied using the hot-wire (HW) anemometry and particle image velocimetry (PIV), with a focus on the shear/rotation competition during the initial Kelvin–Helmholtz (KH) roll-up. Velocity spectra and the spatial linear stability (LST) analysis characterize the fundamental ($f_{n}$) and its subharmonic ($f_{n}/2$) mode interacting due to the vortex pairing. For $276\leqslant Re_{\unicode[STIX]{x1D703}_{0}}\leqslant 780$, the root-mean-square (r.m.s.) of the streamwise turbulence intensity shows a double-peaking phenomenon, i.e. major and minor peaks of the $u_{rms}$ coexist towards the high-speed (HS) and the low-speed (LS) sides, respectively. The single/double-peaked $u_{rms}$ profiles are found to be correlated with the scattered/organized distribution of the shear/rotation, demonstrating a transitioning character with the downstream distance, $Re_{\unicode[STIX]{x1D703}_{0}}$ and the upstream turbulence levels. The rotating vortex cores and the corresponding peripheral shear regions, demonstrate the phase reversal of the velocity fluctuations with respect to the HS and the LS sides. Excitation at $f_{n}$ increases the vortex count by 21 %, advances the location of the first KH roll-up and hence also the minor peak formation location. Due to the enhanced pairing at the $f_{n}/2$ forcing, the vortex count reduces by 23 %. Before merging into the downstream rotation core, the upstream vortex is shifted towards the HS side and the major peak is accordingly augmented. Actuation advances the transition to the nonlinear state, as well as the saturation of the amplification factor. The volumetric topologies of the shear/rotation loops tracked in consecutive phases during the period of the acoustic excitation, separate from the edge and grow in time–space due to the viscous diffusion. The shearing and rotating loops are found to be associated with the thinning (elongation) and expansion (accumulation) of the vorticity, respectively.

A gun tunnel investigation of hypersonic free shear layers in a planar duct

1995 ◽  
Vol 299 ◽  
pp. 133-152 ◽  
Author(s):  
D. R. Buttsworth ◽  
R. G. Morgan ◽  
T. V. Jones
Keyword(s):  
Mach Number ◽  
High Speed ◽  
Mixing Layer ◽  
Spreading Rate ◽  
Shear Layers ◽  
Pressure Measurements ◽  
Rate Asymmetry ◽  
Pitot Pressure ◽  
Free Shear Layers ◽  
Mach 3

An experimental investigation of high Mach number free shear layers has been undertaken. The experiments were performed using a Mach 7 gun tunnel facility and a planar duct with injection from the base of a central strut producing a Mach 3 flow parallel to the gun tunnel stream. This configuration is relevant to the development of efficient scramjet propulsion, and the gun tunnel Mach number is significantly higher than the majority of previous supersonic turbulent mixing layer investigations reported in the open literature. Schlieren images and Pitot pressure measurements were obtained at four different convective Mach numbers ranging from 0 to 1.8. Only small differences between the four cases were detected, and the relatively large high-speed boundary layers at the trailing edge of the struct injector appear to strongly influence the shear layer development in each case. The Pitot pressure measurements indicated that, on average, the free shear layers all spread into the Mach 3 stream at an angle of approximately 1.4°, while virtually no spreading into the Mach 7 stream was detected until all of the low-speed stream was entrained. The free shear layers were simulated using a PNS code; however, the experimentally observed degree of spreading rate asymmetry could not be fully predicted with the k−ε turbulence model, even when a recently proposed compressibility correction was applied.

Numerical simulation of high speed reacting shear layers using AUSM+- up scheme-based unstructured finite volume method solver

2017 ◽  
Vol 08 (03) ◽  
pp. 1750020 ◽  
Author(s):  
M. Deepu ◽  
M. P. Dhrishit ◽  
S. Shyji
Keyword(s):  
Finite Volume ◽  
High Speed ◽  
Splitting Method ◽  
Time Integration ◽  
Chemical Species ◽  
Shear Layers ◽  
Supersonic Stream ◽  
Reacting Flow ◽  
Two Dimensional ◽  
Flow Solver

Development of an Advection Upstream Splitting Method (AUSM[Formula: see text]-up) scheme-based Unstructured Finite Volume (UFVM) solver for the simulation of two-dimensional axisymmetric/planar high speed compressible turbulent reacting shear layers is presented. The inviscid numerical flux is evaluated using AUSM[Formula: see text]-up upwind scheme. An eight-step hydrogen–oxygen finite rate chemistry model is used to model the development of chemical species in a supersonic reacting flow field. The chemical species terms are alone solved implicitly in this explicit flow solver by rescaling the equation in time. The turbulence modeling has been done using RNG-based [Formula: see text]–[Formula: see text] model. Three-stage Runge–Kutta method has been used for explicit time integration. The nonreacting two-dimensional Cartesian version of the same solver has been successfully validated against experimental and numerical results reported for the wall static pressure data in sonic slot injection to supersonic stream. Detailed validation studies for reacting flow solver has been done using experimental results reported for a coaxial supersonic combustor, in which species profile at various axial locations has been compared. Present numerical solver is useful in simulating combustors of high speed air-breathing propulsion devices.

High-speed video recording of basal shear layers in snow chute flows

2010 ◽  
Vol 64 (2) ◽  
pp. 182-189 ◽  
Author(s):  
Marius Schaefer ◽  
Thomas Rösgen ◽  
Martin Kern
Keyword(s):  
High Speed ◽  
Video Recording ◽  
Shear Layers ◽  
High Speed Video ◽  
Basal Shear
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