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20 pages, 4500 KiB

Open AccessArticle

Application of the Moment Method for Numerical Simulation of Homogeneous-Heterogeneous Condensation

by Igor E. Ivanov, Vladislav S. Nazarov and Igor A. Kryukov

Fluids 2022, 7(2), 68; https://doi.org/10.3390/fluids7020068 - 7 Feb 2022

Cited by 3 | Viewed by 2474

The paper considers the numerical modeling of the processes of homogeneous and heterogeneous condensation and evaporation in multiphase flows using the method of moments. Nonstationary processes of gas dynamics and phase transitions in the two-dimensional plane and axisymmetric regions are described by a [...] Read more.

The paper considers the numerical modeling of the processes of homogeneous and heterogeneous condensation and evaporation in multiphase flows using the method of moments. Nonstationary processes of gas dynamics and phase transitions in the two-dimensional plane and axisymmetric regions are described by a general system of equations. The system of equations is expanded by adding two equations. One describes the evolution of the total mass fraction of the condensing substance; the other describes the evolution of the mass fraction of solid particles. An instant wetting model is used to model heterogeneous nucleation. The Gyarmathy model is used for the approximation of the average droplet growth rate. Heterogeneous condensation is modeled based on the distribution function of foreign impurities. An approach to calculating evaporation in the heterogeneous case is proposed. A comparison of the proposed models with a numerical experiment is given. Numerical simulation of homogeneous-heterogeneous condensation in a gas-dynamic ejector is carried out. Full article

(This article belongs to the Special Issue Applied Aerodynamics and Gas Dynamics in Memory of Prof. Isaak P. Ginzburg)

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15 pages, 1893 KiB

Open AccessArticle

Stationary Mach Configurations with Pulsed Energy Release on the Normal Shock

by Mikhail V. Chernyshov, Anna S. Kapralova, Stanislav A. Matveev and Karina E. Savelova

Fluids 2021, 6(12), 439; https://doi.org/10.3390/fluids6120439 - 5 Dec 2021

Cited by 4 | Viewed by 2306

Abstract

We obtained a theoretical analysis of stationary Mach configurations of shock waves with a pulsed energy release at the main (normal) shock and a corresponding change in gas thermodynamic properties. As formation of the stationary Mach configuration corresponds to one of two basic, [...] Read more.

We obtained a theoretical analysis of stationary Mach configurations of shock waves with a pulsed energy release at the main (normal) shock and a corresponding change in gas thermodynamic properties. As formation of the stationary Mach configuration corresponds to one of two basic, well-known criteria of regular/Mach shock reflection transition, we studied here how the possibility of pulsed energy release at the normal Mach stem shifts the von Neumann criterion, and how it correlates then with another transition criterion (the detachment one). The influence of a decrease in the “equilibrium” gas adiabatic index at the main shock on a shift of the solution domain was also investigated analytically and numerically. Using a standard detonation model for a normal shock in stationary Mach configuration, and ordinary Hugoniot relations for other oblique shocks, we estimated influence of pulsed energy release and real gas effects (expressed by decrease of gas adiabatic index) on shift of von Neumann criterion, and derived some analytical relations that describe those dependencies. Full article

(This article belongs to the Special Issue Applied Aerodynamics and Gas Dynamics in Memory of Prof. Isaak P. Ginzburg)

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11 pages, 2348 KiB

Open AccessArticle

Numerical Simulation of a Periodic Quasi-Switching Mode of Flow around a Conical Dimple with a Slope Angle of 10 Degrees on the Wall of a Narrow Channel Using URANS

by Sergey Isaev, Dmitry Nikushchenko, Alexandr Sudakov, Nikita Tryaskin, Ann Egorova, Leonid Iunakov, Alexandr Usachov and Valery Kharchenko

Fluids 2021, 6(11), 385; https://doi.org/10.3390/fluids6110385 - 26 Oct 2021

Cited by 1 | Viewed by 1725

Abstract

The applicability of the solution of the unsteady Reynolds-averaged Navier–Stokes equations (URANS) for the numerical simulation of the periodic quasi-switching regime of vortex generation and heat transfer in a deep conical dimple with a slope angle of

10^{\circ}

on the wall of [...] Read more.

The applicability of the solution of the unsteady Reynolds-averaged Navier–Stokes equations (URANS) for the numerical simulation of the periodic quasi-switching regime of vortex generation and heat transfer in a deep conical dimple with a slope angle of

10^{\circ}

on the wall of a narrow channel is substantiated. To calculate the turbulent regime, the model of shear stress transfer by Menter 2003, modified taking into account the influence of the curvature of streamlines within the framework of the Rodi-Leshziner-Isaev approach, is used. At Reynolds number

R e = 10^{4}

, the oscillation period of the transverse

R_{z}

and longitudinal forces

R_{x}

, as well as the total heat transfer

N u_{m m}

to the control section of the heated channel wall with a dimple, is set equal to 60, which corresponds to the Strouhal number

S t = 0.0167

. Computer visualization of swirling jet-vortex flows demonstrates focus-type sources on the side faces of the dimple. In the self-oscillating mode, a two-cell vortex system is formed with different intensities at the oscillation period

R_{z}

. Periodic changes in friction, Nusselt numbers and temperature are recorded in the longitudinal and transverse median sections of the dimple and reflect the oscillations of the vortex structure from left to right and from right to left. The formation of a fan jet is shown, which oscillates relative to the plane of longitudinal symmetry, causing a redistribution of power and thermal loads. Full article

(This article belongs to the Special Issue Applied Aerodynamics and Gas Dynamics in Memory of Prof. Isaak P. Ginzburg)

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14 pages, 12214 KiB

Open AccessArticle

Interaction between Shock Waves Travelling in the Same Direction

by Pavel Bulat, Konstantin Volkov and Igor Volobuev

Fluids 2021, 6(9), 315; https://doi.org/10.3390/fluids6090315 - 3 Sep 2021

Cited by 2 | Viewed by 3722

Abstract

In this paper, we study the intersection (interaction) between several steady shocks traveling in the same direction. The interaction between overtaking shocks may be regular or irregular. In the case of regular reflection, the intersection of overtaking shocks leads to the formation of [...] Read more.

In this paper, we study the intersection (interaction) between several steady shocks traveling in the same direction. The interaction between overtaking shocks may be regular or irregular. In the case of regular reflection, the intersection of overtaking shocks leads to the formation of a resulting shock, contact discontinuity, and some reflected discontinuities. The type of discontinuity depends on the parameters of incoming shocks. At the irregular reflection, a Mach shock forms between incoming overtaking shocks. Reflected discontinuities come from the points of intersection of the Mach stem with the incoming shocks. We also consider the possible types of shockwave configurations that form both at regular and irregular interactions of several overtaking shocks. The regions of existence of overtaking shock waves with different types of reflected shock and the intensity of reflected shocks are defined. The results obtained in the study can potentially be useful for designing supersonic intakes and advanced jet engines. Full article

(This article belongs to the Special Issue Applied Aerodynamics and Gas Dynamics in Memory of Prof. Isaak P. Ginzburg)

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17 pages, 1669 KiB

Open AccessArticle

Approximate Analytical Models of Shock-Wave Structure at Steady Mach Reflection

by Mikhail V. Chernyshov, Karina E. Savelova and Anna S. Kapralova

Fluids 2021, 6(9), 305; https://doi.org/10.3390/fluids6090305 - 28 Aug 2021

Cited by 4 | Viewed by 2757

Abstract

In this study, we obtain the comparative analysis of methods of quick approximate analytical prediction of Mach shock height in planar steady supersonic flows (for example, in supersonic jet flow and in narrowing channel between two wedges), that are developed since the 1980s [...] Read more.

In this study, we obtain the comparative analysis of methods of quick approximate analytical prediction of Mach shock height in planar steady supersonic flows (for example, in supersonic jet flow and in narrowing channel between two wedges), that are developed since the 1980s and being actively modernized now. A new analytical model based on flow averaging downstream curved Mach shock is proposed, which seems more accurate than preceding models, comparing with numerical and experimental data. Full article

(This article belongs to the Special Issue Applied Aerodynamics and Gas Dynamics in Memory of Prof. Isaak P. Ginzburg)

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24 pages, 7985 KiB

Open AccessArticle

Refraction of Oblique Shock Wave on a Tangential Discontinuity

by Pavel Bulat, Anzhelika Melnikova, Vladimir Upyrev and Konstantin Volkov

Fluids 2021, 6(9), 301; https://doi.org/10.3390/fluids6090301 - 24 Aug 2021

Cited by 2 | Viewed by 3029

Abstract

The refraction of an oblique shock wave on a tangential discontinuity dividing two gas flows with different properties is considered. It is shown that its partial reflection occurs with the exception of the geometrical diffraction of an oblique shock. Another oblique shock, expansion [...] Read more.

The refraction of an oblique shock wave on a tangential discontinuity dividing two gas flows with different properties is considered. It is shown that its partial reflection occurs with the exception of the geometrical diffraction of an oblique shock. Another oblique shock, expansion wave or weak discontinuity that coincides with the Mach line can act as a reflected disturbance. This study focuses on the relationships that define the type of reflected discontinuity and its parameters. The domains of shock wave configurations with various types of reflected discontinuities, including characteristic refraction and refraction patterns with a reflected shock and a reflected rarefaction wave, are analyzed. The domains of existence of various shock wave structures with two types of reflected disturbance, and the boundaries between them, are defined. The domains of parameters with one or two solutions exist for the characteristic refraction. Each domain is mapped by the type of refraction with regard to the Mach number, the ratio of the specific heat capacities of the two flows and the intensity of a refracted oblique shock wave. The conditions of the regular refraction and the Mach refraction are formulated, and the boundaries between the two refraction types are defined for various types of gases. Refraction phenomena in various engineering problems (hydrocarbon gaseous fuel and its combustion products, diatomic gas, fuel mixture of oxygen and hydrogen, etc.) are discussed. The result can be applied to the modeling of the shock wave processes that occur in supersonic intakes and in rotating and stationary detonation engines. The solutions derived can be used by other researchers to check the quality of numerical methods and the correctness of experimental results. Full article

(This article belongs to the Special Issue Applied Aerodynamics and Gas Dynamics in Memory of Prof. Isaak P. Ginzburg)

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17 pages, 4352 KiB

Open AccessArticle

Special Cases of Using Visualization Technology for Analyzing the Dynamics of Gaseous Environment

by Mikhail Sotskiy, Denis Levin and Victor Selivanov

Fluids 2021, 6(8), 290; https://doi.org/10.3390/fluids6080290 - 18 Aug 2021

Cited by 3 | Viewed by 1555

Abstract

A new visualization technology is presented, which was used in applied research when observing and modeling the dynamics of the flow of gaseous environments. In the process of developing and improving the technology, a set of experimental results was compiled to study the [...] Read more.

A new visualization technology is presented, which was used in applied research when observing and modeling the dynamics of the flow of gaseous environments. In the process of developing and improving the technology, a set of experimental results was compiled to study the phenomenon of combustion and detonation of a hydrogen-oxygen mixture, as well as the phenomena of propagation, action, and interaction of shock waves and gas-dynamic structures. On the example of analyzing data on the dynamics of the formation of a vortex ring, the possibilities of verifying the computational model of the implemented physical process are shown. The presented results reflect the level of information content when using technology to carry out tests. Full article

(This article belongs to the Special Issue Applied Aerodynamics and Gas Dynamics in Memory of Prof. Isaak P. Ginzburg)

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23 pages, 5011 KiB

Open AccessArticle

Fluid Dynamics of Thrust Vectorable Submerged Nozzle

by Sergey Denisikhin, Vladislav Emelyanov and Konstantin Volkov

Fluids 2021, 6(8), 278; https://doi.org/10.3390/fluids6080278 - 10 Aug 2021

Cited by 1 | Viewed by 2381

Abstract

A numerical simulation of the gas-dynamic processes in the thrust vectorable nozzle of the solid rocket motor is considered. Construction of a geometric model and a generation of computational mesh, and reconstruction of model and mesh at each time step are discussed. Calculations [...] Read more.

A numerical simulation of the gas-dynamic processes in the thrust vectorable nozzle of the solid rocket motor is considered. Construction of a geometric model and a generation of computational mesh, and reconstruction of model and mesh at each time step are discussed. Calculations of the flowfield of combustion products in the pre-nozzle chamber and nozzle block are carried out for various angles of nozzle rotation. The distributions of the gas dynamic quantities in the pre-nozzle volume corresponding to the outflow of the combustion products from the cylindrical channel and star-shaped channel are compared, as well as the solutions of the problem obtained with quasi-stationary and unsteady formulations. The effects of the channel shape on the distribution of flow quantities and formation of a vortical flow structure in the nozzle block are discussed. Full article

(This article belongs to the Special Issue Applied Aerodynamics and Gas Dynamics in Memory of Prof. Isaak P. Ginzburg)

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25 pages, 3435 KiB

Open AccessArticle

Aerodynamic Characteristics of a Single Airfoil for Vertical Axis Wind Turbine Blades and Performance Prediction of Wind Turbines

by Samuel Mitchell, Iheanyichukwu Ogbonna and Konstantin Volkov

Fluids 2021, 6(7), 257; https://doi.org/10.3390/fluids6070257 - 13 Jul 2021

Cited by 9 | Viewed by 6677

Abstract

The design of wind turbines requires a deep insight into their complex aerodynamics, such as dynamic stall of a single airfoil and flow vortices. The calculation of the aerodynamic forces on the wind turbine blade at different angles of attack (AOAs) is a [...] Read more.

The design of wind turbines requires a deep insight into their complex aerodynamics, such as dynamic stall of a single airfoil and flow vortices. The calculation of the aerodynamic forces on the wind turbine blade at different angles of attack (AOAs) is a fundamental task in the design of the blades. The accurate and efficient calculation of aerodynamic forces (lift and drag) and the prediction of stall of an airfoil are challenging tasks. Computational fluid dynamics (CFD) is able to provide a better understanding of complex flows induced by the rotation of wind turbine blades. A numerical simulation is carried out to determine the aerodynamic characteristics of a single airfoil in a wide range of conditions. Reynolds-averaged Navier–Stokes (RANS) equations and large-eddy simulation (LES) results of flow over a single NACA0012 airfoil are presented in a wide range of AOAs from low lift through stall. Due to the symmetrical nature of airfoils, and also to reduce computational cost, the RANS simulation is performed in the 2D domain. However, the 3D domain is used for the LES calculations with periodical boundary conditions in the spanwise direction. The results obtained are verified and validated against experimental and computational data from previous works. The comparisons of LES and RANS results demonstrate that the RANS model considerably overpredicts the lift and drag of the airfoil at post-stall AOAs because the RANS model is not able to reproduce vorticity diffusion and the formation of the vortex. LES calculations offer good agreement with the experimental measurements. Full article

(This article belongs to the Special Issue Applied Aerodynamics and Gas Dynamics in Memory of Prof. Isaak P. Ginzburg)

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