Parametric Study of Boundary-Layer Receptivity to Freestream Hot-Spot Perturbation over a Blunt Compression Cone

2014 ◽  
Author(s):  
Yuet Huang ◽  
Xiaolin Zhong
Keyword(s):  
Boundary Layer ◽  
Parametric Study ◽  
Hot Spot

Parametric Study of the Discharge Coefficient on Critical Sonic Nozzles ISO-9300 With Turbulent Boundary Layer

2002 ◽  
Author(s):  
F. Sa´nchez Silva ◽  
J. A. Cruz Maya ◽  
A. Go´mez Mercado ◽  
G. Tolentino Eslava
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Analytical Model ◽  
Parametric Study ◽  
Discharge Coefficient ◽  
Numerical Data ◽  
Starting Point ◽  
Two Dimensional Flow ◽  
Viscous Stresses ◽  
Good Agreement

A parametric study on determining discharge coefficient in ISO 9300 [1] toroidal sonic nozzles have been developed. The focus of this paper is to obtain the an analytical model for the calculus of this discharge coefficient on turbulent boundary layer conditions for gases at Pr = 0.7. The problem is divided in two sections: one in which the viscous stresses are taking in to account at boundary layer zone, based on turbulent boundary layer theory and taking as starting point the work carried out by Stratford [2]. Then, curvature of flow field is studied at the nucleus of the nozzle, obtaining discharge coefficient values using numerical simulation for a two-dimensional flow. The results have a good agreement with correlations of ISO-9300 [1], experimental and numerical data of Wu-Yan [3] and the analytical model from Stratford [2].

Combined Effects of Surface Trips and Unsteady Wakes on the Boundary Layer Development of an Ultra-High-Lift LP Turbine Blade

2004 ◽  
Vol 127 (3) ◽  
pp. 479-488 ◽  
Author(s):  
Xue Feng Zhang ◽  
Howard Hodson
Keyword(s):  
Boundary Layer ◽  
Turbine Blade ◽  
Parametric Study ◽  
Combined Effects ◽  
Suction Surface ◽  
High Lift ◽  
Boundary Layer Development ◽  
Wide Range ◽  
Profile Losses ◽  
Layer Development

An experimental investigation of the combined effects of upstream unsteady wakes and surface trips on the boundary layer development on an ultra-high-lift low-pressure turbine blade, known as T106C, is described. Due to the large adverse pressure gradient, the incoming wakes are not strong enough to periodically suppress the large separation bubble on the smooth suction surface of the T106C blade. Therefore, the profile loss is not reduced as much as might be possible. The first part of this paper concerns the parametric study of the effect of surface trips on the profile losses to optimize the surface trip parameters. The parametric study included the effects of size, type, and location of the surface trips under unsteady flow conditions. The surface trips were straight cylindrical wires, straight rectangular steps, wavy rectangular steps, or wavy cylindrical wires. The second part studies the boundary layer development on the suction surface of the T106C linear cascade blade with and without the recommended surface trips to investigate the loss reduction mechanism. It is found that the selected surface trip does not induce transition immediately, but hastens the transition process in the separated shear layer underneath the wakes and between them. In this way, the combined effects of the surface trip and unsteady wakes further reduce the profile losses. This passive flow control method can be used over a relatively wide range of Reynolds numbers.

scholarly journals Parametric study of multiple shock-wave/turbulent-boundary-layer interactions with a Reynolds stress model

Shock Waves ◽  
2021 ◽  
Author(s):  
K. Boychev ◽  
G. N. Barakos ◽  
R. Steijl ◽  
S. Shaw
Keyword(s):  
Boundary Layer ◽  
Shock Wave ◽  
Reynolds Stress ◽  
Parametric Study ◽  
High Speed ◽  
Computational Study ◽  
Numerical Approach ◽  
Wave Boundary Layer ◽  
Wave Boundary ◽  
Multiple Shock

AbstractThe flow of high-speed air in ducts may result in the occurrence of multiple shock-wave/boundary-layer interactions. Understanding the consequences of such interactions, which may include distortion of the velocity field, enhanced turbulence production, and flow separation, is of great importance in understanding the operating limits and performance of a number of systems, for example, the high-speed intake of an air-breathing missile. In this paper, the results of a computational study of multiple shock-wave/boundary-layer interactions occurring within a high-speed intake are presented. All of the results were obtained using the in-house computational fluid dynamics solver of Glasgow University, HMB3. First simulations of a Mach $$M=1.61$$ M = 1.61 multiple shock-wave/boundary-layer interaction in a rectangular duct were performed. The $$M=1.61$$ M = 1.61 case, for which experimental data is available, was used to establish a robust numerical approach, particularly with respect to initial and boundary conditions. A number of turbulence modelling strategies were also investigated. The results suggest that Reynolds-stress-based turbulence models are better suited than linear eddy-viscosity models. This is attributed to better handling of complex strain, in particular modelling of the corner separation. The corner separations affect the separation at the centre of the domain which in turn alters the structure of the initial shock and the subsequent interaction. Having established a robust numerical approach, the results of a parametric study investigating the effect of Mach number, Reynolds number, and confinement on the baseline solution are then presented. Performance metrics are defined to help characterize the effect of the interactions. The results suggest that reduced flow confinement is beneficial for higher-pressure recovery.

Turbulent Boundary Layer Separation Control by Using DBD Plasma Actuators: Part II—Numerical Model Validation and Parametric Study

2010 ◽  
Author(s):  
Xiaofei Xu ◽  
Huu Duc Vo ◽  
Njuki Mureithi ◽  
Xue Feng Zhang
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Parametric Study ◽  
Boundary Layer Separation ◽  
Plasma Actuator ◽  
Plasma Actuators ◽  
Low Flow ◽  
Dbd Plasma ◽  
Layer Separation ◽  
Flow Velocities

Following an experimental investigation into suppression of a 2-D turbulent boundary layer separation with dielectric barrier discharge (DBD) plasma actuators, the present work investigates the concept numerically. The purpose is to develop and validate a simulation tool that captures the flow physics and carry out a parametric study of the concept at flow regimes beyond the current flow control capability of plasma actuators of conventional strength. First, a plasma actuator model is integrated into the commercial computational fluid dynamics (CFD) code ANSYS CFX to simulate the effects of plasma actuation. This computational tool is validated through comparison of results with the experimental results for pulsed actuation in quiescent air and for the control of a turbulent boundary layer separation at low flow velocities. It is shown that CFX with an integrated plasma model can capture the main experimentally observed effects of DBD actuators on turbulent boundary layer separation. Subsequently, this numerical approach is used, with increased plasma actuator strength, to study the influence of different actuation parameters (e.g., actuation location, direction and frequency) on suppression of turbulent boundary layer separation at higher flow velocities.

Frozen Plasma Boundary-Layer Flows over Isothermal Flat Plates-Parametric Study

AIAA Journal ◽  
1984 ◽  
Vol 22 (2) ◽  
pp. 299-301 ◽  
Author(s):  
G. Ben-Dor ◽  
Z. Rakib ◽  
O. Igra
Keyword(s):  
Boundary Layer ◽  
Parametric Study ◽  
Plasma Boundary ◽  
Boundary Layer Flows ◽  
Flat Plates ◽  
Frozen Plasma

Effects of Boundary Layer Ingestion on the Aero-Acoustics of Transonic Fan Rotors

2012 ◽  
Author(s):  
J. J. Defoe ◽  
Z. S. Spakovszky
Keyword(s):  
Boundary Layer ◽  
Parametric Study ◽  
Power Level ◽  
Sound Power ◽  
Far Field ◽  
Noise Generation ◽  
Streamwise Vortices ◽  
Streamwise Vorticity ◽  
Flow Distortion ◽  
Swirling Vortex

The use of boundary-layer-ingesting, embedded propulsion systems can result in inlet flow distortions where the interaction of the boundary layer vorticity and the inlet lip causes horseshoe vortex formation and the ingestion of streamwise vortices into the inlet. A previously-developed body-force-based fan modeling approach was used to assess the change in fan rotor shock noise generation and propagation in a boundary-layer-ingesting, serpentine inlet. This approach is employed here in a parametric study to assess the effects of inlet geometry parameters (offset-to-diameter ratio and downstream-to-upstream area ratio) on flow distortion and rotor shock noise. Mechanisms related to the vortical inlet structures were found to govern changes in the rotor shock noise generation and propagation. The vortex whose circulation is in the opposite direction to the fan rotation (counter-swirling vortex) increases incidence angles on the fan blades near the tip, enhancing noise generation. The vortex with circulation in the direction of fan rotation (co-swirling vortex) creates a region of subsonic relative flow near the blade tip radius which decreases the sound power propagated to the far-field. The parametric study revealed that the overall sound power level at the fan leading edge is set by the ingested streamwise circulation, and that for inlet designs in which the streamwise vortices are displaced away from the duct wall, the sound power at the upstream inlet plane increased by as much as 9 dB. By comparing the far-field noise results obtained to those for a conventional inlet, it is deduced that the changes in rotor shock noise are predominantly due to the ingestion of streamwise vorticity.

Sign in / Sign up

Export Citation Format

Share Document