scholarly journals Erratum: Shock Waves from Line Sources. Numerical Solutions and Experimental Measurements

1971 ◽  
Vol 14 (10) ◽  
pp. 2248 ◽  
Author(s):  
Myron N. Plooster
Keyword(s):  
Shock Waves ◽  
Numerical Solutions ◽  
Experimental Measurements

scholarly journals Nematic Dispersive Shock Waves from Nonlocal to Local

2021 ◽  
Vol 11 (11) ◽  
pp. 4736
Author(s):  
Saleh Baqer ◽  
Dimitrios J. Frantzeskakis ◽  
Theodoros P. Horikis ◽  
Côme Houdeville ◽  
Timothy R. Marchant ◽  
...  
Keyword(s):  
Shock Wave ◽  
Liquid Crystals ◽  
Shock Waves ◽  
Numerical Solutions ◽  
Wave Structure ◽  
Beam Power ◽  
Input Beam ◽  
Shock Wave Structure ◽  
Wave Solutions ◽  
Modulation Theory

The structure of optical dispersive shock waves in nematic liquid crystals is investigated as the power of the optical beam is varied, with six regimes identified, which complements previous work pertinent to low power beams only. It is found that the dispersive shock wave structure depends critically on the input beam power. In addition, it is known that nematic dispersive shock waves are resonant and the structure of this resonance is also critically dependent on the beam power. Whitham modulation theory is used to find solutions for the six regimes with the existence intervals for each identified. These dispersive shock wave solutions are compared with full numerical solutions of the nematic equations, and excellent agreement is found.

On the Application of a Linearized Unsteady Potential-Flow Analysis to Fan-Tip Cascades

1986 ◽  
Vol 108 (1) ◽  
pp. 59-67
Author(s):  
W. J. Usab ◽  
J. M. Verdon
Keyword(s):  
Potential Flow ◽  
Vibrational Frequency ◽  
Numerical Solutions ◽  
Flow Analysis ◽  
Experimental Measurements ◽  
Two Dimensional ◽  
Good Qualitative Agreement ◽  
Blade Loading ◽  
Unsteady Aerodynamic ◽  
Flow Phenomena

A linearized potential flow analysis, which accounts for the effects of nonuniform steady flow phenomena on the unsteady response to prescribed blade motions, has been applied to five two-dimensional cascade configurations. These include a flat-plate cascade and three cascades which are representative of the tip sections of current fan designs. Here the blades are closely spaced, highly staggered, and operate at low mean incidence. The fifth configuration is a NASA Lewis cascade of symmetric biconvex airfoils for which experimental measurements are available. Numerical solutions are presented that clearly illustrate the effects and importance of blade geometry and mean blade loading on the linearized unsteady response at high subsonic inlet Mach number and high blade-vibrational frequency. In addition, a good qualitative agreement is shown between the analytical predictions and experimental measurements for the cascade of symmetric biconvex airfoils. Finally, recommendations on the research needed to extend the range of application of linearized unsteady aerodynamic analyses are provided.

On the population of the metastable states behind unstable shock waves in ionizing argon

1986 ◽  
Vol 170 ◽  
pp. 319-337 ◽  
Author(s):  
A. F. P. Houwing ◽  
T. J. Mcintyre ◽  
P. A. Taloni ◽  
R. J. Sandeman
Keyword(s):  
Shock Waves ◽  
Present Model ◽  
Dominant Role ◽  
Metastable States ◽  
Flow Instabilities ◽  
Experimental Measurements ◽  
Excitation Process ◽  
Electron Atom ◽  
Spatially Resolved

Experiments are described in which the populations of metastable levels in ionizing argon are measured through spatially resolved hook interferometry. The results are compared with the present model for shock-induced ionization and a recently proposed mechanism to explain observed flow instabilities. It is found that the experimental measurements support the presently accepted model, which states that electron–atom collisions play the dominant role in the excitation process, but contradicts recent proposals which predict a rapid build-up of anomalously high metastable populations through atom–atom collisions.

Expansion shock waves in numerical solutions of gasdynamic problems

2009 ◽  
Vol 1 (1) ◽  
pp. 21-30 ◽  
Author(s):  
M. V. Abakumov ◽  
S. I. Mukhin ◽  
Yu. P. Popov ◽  
D. V. Rogozhkin
Keyword(s):  
Shock Waves ◽  
Numerical Solutions ◽  
Gasdynamic Problems

scholarly journals On the Effects of Viscosity on the Shock Waves for a Hydrodynamical Case—Part I: Basic Mechanism

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Huseyin Cavus
Keyword(s):  
Shock Wave ◽  
Shock Waves ◽  
Numerical Solutions ◽  
Entropy Change ◽  
Basic Mechanism ◽  
Viscous Stress ◽  
Viscous Stress Tensor ◽  
Supersonic Regime ◽  
Interaction Of Shock Waves ◽  
Case Part

The interaction of shock waves with viscosity is one of the central problems in the supersonic regime of compressible fluid flow. In this work, numerical solutions of unmagnetised fluid equations, with the viscous stress tensor, are investigated for a one-dimensional shock wave. In the algorithm developed the viscous stress terms are expressed in terms of the relevant Reynolds number. The algorithm concentrated on the compression rate, the entropy change, pressures, and Mach number ratios across the shock wave. The behaviour of solutions is obtained for the Reynolds and Mach numbers defining the medium and shock wave in the supersonic limits.

CFD modelling of air and oxy-coal combustion

2014 ◽  
Vol 24 (4) ◽  
pp. 825-844 ◽  
Author(s):  
Katarzyna Stęchły ◽  
Gabriel Wecel ◽  
Derek B. Ingham
Keyword(s):  
Experimental Data ◽  
Combustion Chamber ◽  
Coal Combustion ◽  
Numerical Solutions ◽  
Numerical Prediction ◽  
Radiative Properties ◽  
Experimental Measurements ◽  
Ansys Fluent ◽  
Content Type ◽  
Combustion Environment

Purpose – The main goal of this work was the CFD analysis of air and oxy-coal combustion, in order to develop a validated with experimental measurements model of the combustion chamber. Moreover, the purpose of this paper is to provide information about limitations of the sub-models implemented in commercial CFD code ANSYS Fluent version 13.0 for the oxy-coal combustion simulations. The influence of implementation of the weighted sum of gray gas model (WSGGM) with coefficients updated to oxy-coal combustion environment has been investigated. Design/methodology/approach – The sub-models validated with experimental measurements model for the air combustion has been used to predict the oxy-coal combustion case and subsequently the numerical solutions have been compared with the experimental data, which enclose the surface incident radiation (SIR) and the flue gas temperature. To improve the numerical prediction of the oxy-coal combustion process the own routine for calculating properties of the oxy-combustion product has been implemented. Findings – The results of numerical simulation of combustion in the air environment fitted within the experimental measurements accuracy. However, the air combustion sub-models implemented for the oxy-coal combustion simulations does not predict the SIR within the experimental data accuracy. The implementation of own routine, which uses the coefficients calculated for oxy-coal combustion environment shows improvement in numerical prediction of oxy-coal combustion. Originality/value – The radiative properties of gases in the combustion chamber during oxy-coal combustion calculated using the WSGGM implemented in ANSYS Fluent 13.0 do not predict the SIR within experimental measurement accuracy, however, implementation of WSGGM with updated coefficients provide a reasonable improvement in numerical prediction of SIR in the oxy-coal combustion.

Hypersonic Flow with Attached Shock Waves over Delta Wings

1970 ◽  
Vol 21 (4) ◽  
pp. 379-399 ◽  
Author(s):  
B. A. Woods
Keyword(s):  
Shock Waves ◽  
Hypersonic Flow ◽  
Shock Layer ◽  
Numerical Solutions ◽  
Delta Wing ◽  
Simple Wave ◽  
Delta Wings ◽  
Conical Flows ◽  
Thin Shock Layer ◽  
Flow Variables

SummaryHypersonic conical flows over delta wings are treated in the thin-shock-layer approximation due to Messiter. The equations are hyperbolic throughout, even in regions where the full equations are elliptic, and have not hitherto been solved for flows with attached shock waves. The concept of the simple wave has been used to construct a class of solutions for such flows; they contain discontinuities in flow variables and shock slope but, for the case of flow over a delta wing with lateral symmetry, agreement with results of numerical solutions of the full equations is good. The method is applied to plane delta wings at yaw, and to wings with anhedral and dihedral. For the flow at the tip of a rectangular wing, it is shown that two distinct solutions may be constructed.

scholarly journals An adaptive approach to duct optimization of an industrial boiler air supply system using airfoils

2021 ◽  
pp. 157-157
Author(s):  
Branimir Stojiljkovic ◽  
Marta Trninic
Keyword(s):  
Numerical Solutions ◽  
Measured Data ◽  
Supply System ◽  
Experimental Measurements ◽  
Cfd Simulations ◽  
Air Supply ◽  
Industrial Boiler ◽  
Industrial Boilers ◽  
Volume Method ◽  
Level Of Agreement

The purpose of this paper is to examine the pressure drop caused by placing an airfoil at different angles of attack in the straight part of the rectangular air duct, as the first step of investigating the possibility of using a staggered cascade of airfoils for gradual deflection of the airflow in radial elbows of an air supply system used in industrial boilers. The initial problem was approached by using the commercial CFD code based on the Finite Volume Method (FVM) to numerically simulate a 2D incompressible turbulent flow and by conducting direct experimental measurements in the wind tunnel. The results of CFD simulations have been compared to experimentally measured data for two considered cases of inlet velocities and five different angles of attack. Numerical solutions show an adequate level of agreement with experimental measurements. The obtained results indicate the possibility of using a staggered cascade of airfoils for gradual deflection of the airflow.

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