Viscous effects far downstream in a slowly expanding hypersonic nozzle.

AIAA Journal ◽  
1966 ◽  
Vol 4 (5) ◽  
pp. 807-815 ◽  
Author(s):  
MAURICE L. RASMUSSEN ◽  
KRISHNAMURTY KARAMCHETI
Keyword(s):  
Viscous Effects ◽  
Hypersonic Nozzle

Airfoil Shape Optimization Using Sensitivity Analysis on Viscous Flow Equations

1993 ◽  
Vol 115 (1) ◽  
pp. 75-84 ◽  
Author(s):  
Mohamed E. Eleshaky ◽  
Oktay Baysal
Keyword(s):  
Shape Optimization ◽  
Stokes Equations ◽  
Prediction Method ◽  
Taylor Series Expansion ◽  
Optimization Method ◽  
Viscous Effects ◽  
Hypersonic Nozzle ◽  
Flow Equations ◽  
Flow Prediction ◽  
Highly Nonlinear

An aerodynamic shape optimization method has previously been developed by the authors using the Euler equations and has been applied to supersonic-hypersonic nozzle designs. This method has also included a flowfield extrapolation (or flow prediction) method based on the Taylor series expansion of an existing CFD solution. The present paper reports on the extension of this method to the thin-layer Navier-Stokes equations in order to account for the viscous effects. Also, to test the method under highly nonlinear conditions, it has been applied to the transonic flows. Initially, the success of the flow prediction method is tested. Then, the overall method is demonstrated by optimizing the shapes of two supercritical transonic airfoils at zero angle of attack. The first one is shape optimized to achieve a minimum drag while obtaining a lift above a specified value. Whereas, the second one is shape optimized for a maximum lift while attaining a drag below a specified value. The results of these two cases indicate that the present method can produce successfully optimized aerodynamic shapes.

Correction: Changes in Modern Lifting-Line Methods for Swept Wings and Viscous Effects

2018 ◽  
Author(s):  
Jose Rodolfo Chreim ◽  
Marcos Pimenta ◽  
Joao Lucas D. Dantas ◽  
Gustavo Assi
Keyword(s):  
Viscous Effects ◽  
Lifting Line ◽  
Swept Wings

Thermo-viscous Effects in Extrusion of Planar Jets with Solidification

1992 ◽  
Vol 7 (1) ◽  
pp. 32-37 ◽  
Author(s):  
A. N. Alexandrou ◽  
G. Torikoglu
Keyword(s):  
Viscous Effects

scholarly journals Large Eddy Simulations of Strongly Non-Ideal Compressible Flows through a Transonic Cascade

Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 772
Author(s):  
Jean-Christophe Hoarau ◽  
Paola Cinnella ◽  
Xavier Gloerfelt
Keyword(s):  
Compressible Flows ◽  
Flow Behavior ◽  
Pressure Ratio ◽  
Organic Rankine Cycle ◽  
Ideal Gas ◽  
Operating Conditions ◽  
Large Eddy Simulations ◽  
Working Fluid ◽  
Viscous Effects ◽  
Large Eddy

Transonic flows of a molecularly complex organic fluid through a stator cascade were investigated by means of large eddy simulations (LESs). The selected configuration was considered as representative of the high-pressure stages of high-temperature Organic Rankine Cycle (ORC) axial turbines, which may exhibit significant non-ideal gas effects. A heavy fluorocarbon, perhydrophenanthrene (PP11), was selected as the working fluid to exacerbate deviations from the ideal flow behavior. The LESs were carried out at various operating conditions (pressure ratio and total conditions at inlet), and their influence on compressibility and viscous effects is discussed. The complex thermodynamic behavior of the fluid generates highly non-ideal shock systems at the blade trailing edge. These are shown to undergo complex interactions with the transitional viscous boundary layers and wakes, with an impact on the loss mechanisms and predicted loss coefficients compared to lower-fidelity models relying on the Reynolds-averaged Navier–Stokes (RANS) equations.

scholarly journals Pulsed Flow Turbine Design Recommendations

2021 ◽  
Vol 6 (3) ◽  
pp. 24
Author(s):  
Florian Hermet ◽  
Nicolas Binder ◽  
Jérémie Gressier ◽  
Gonzalo Sáez-Mischlich
Keyword(s):  
Design Of Experiments ◽  
Performance Indicator ◽  
Influential Factors ◽  
Factor Level ◽  
Viscous Effects ◽  
Inviscid Flows ◽  
Screening Design ◽  
Pulsed Flow ◽  
Number Of Factors ◽  
Turbine Design

A preliminary analysis of turbine design, fit for pulsed flow, is proposed in this paper. It focuses on an academic 2D configuration using inviscid flows, since pressure loads due to wave propagation are several orders of magnitude higher than friction and viscous effects do not significantly impinge on the inviscid part, as previously shown by Hermet, 2021. As such, a large parametric study was carried out using the design of experiments methodology. A performance indicator adapted to unsteady environment is carefully defined before detailing the factors chosen for the design of experiments. Since the number of factors is substantial, a screening design to identify the factors influence on the output is first established. The non-influential factors are then omitted in a more quantitative study of the output law. The surface response calculation allows determining the factor level favouring the best output. Consequently, the main trends in the turbine design driven by a pulsed flow can be stated.

A WEAKLY NONLINEAR INSTABILITY OF MISCIBLE DISPLACEMENTS IN A RECTILINEAR POROUS MEDIA FLOW

1994 ◽  
Vol 04 (05) ◽  
pp. 1319-1328 ◽  
Author(s):  
WILLIAM B. ZIMMERMAN
Keyword(s):  
Linear Theory ◽  
Landau Equation ◽  
Separation Of Variables ◽  
Finite Amplitude ◽  
Linear Stability Theory ◽  
Porous Media Flow ◽  
Perturbation Scheme ◽  
Viscous Effects ◽  
Regular Perturbation ◽  
Displacement Front

The linear stability theory of Tan & Homsy [1986] is extended to include the effects of weak nonlinear coupling between mass flux and viscous effects when the viscous fingers grow from a slowly diffusing, nearly flat displacement front. A regular perturbation scheme combined with a similarity-separation of variables technique leads to a Landau equation for the amplitude of the disturbance. The Landau constant has a simple pole for a given wavenumber within the linear theory cutoff wavenumber for growth. An argument is given that this pole leads to pairing of fingers while the instability remains small. Comparison of the length scale of the pole of the Landau constant with experimental measurements of finger scale shows good agreement where plausibly finite-amplitude effects might come into play, but with the linear theory otherwise.

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