Numerical Aerodynamics Research Articles

Numerical modeling of the wind regime on the beaches of the wash of the artificial storage facilities for mineral processing waste

A 2D numerical model has been developed to estimate the airflow velocity field when flowing around the dam of an artificial storage facility for mineral processing waste. To solve the aerodynamic problem of determining the air flow velocity field when flowing around such hydraulic structures with a complex geometric shape, a potential motion model was applied. The numerical integration of the equation for the velocity potential is carried out using the Liebman method. The geometric shape of the tailings storage facility is formed in a discrete model using the marking method. A computer program was created to implement the developed numerical aerodynamics model. Based on the processing of the results of computational experiments, coefficients were obtained that allow us to quickly determine the value of the air flow velocity at the beginning and end of the tailing pond beach, i.e. in the area of the most intense dust emission. This allows for a quick prediction of the risk of dust air pollution at different tailing pile heights.

Comparative Numerical Aerodynamics Performance Analysis of NACA0015 and NACA4415 Airfoils

The climate crisis caused by global greenhouse gas emissions has led to many disasters around the world in recent years. Some of these disasters are floods in various parts of Europe, melting of Arctic glaciers, and rising water levels in the oceans. People living on islands in Southeast Asian countries are forced to migrate due to rising water levels. With the increase in the frequency of such situations, life on earth is at risk. Greenhouse gas emissions harm not only humans but also animals and plants. The most effective measure that can be taken against this is to stay away from fossil fuels. With the use of fossil fuels, the carbon ratio in the atmosphere increases, and climatic imbalances occur. For this reason, the interest in alternative energy sources is increasing. Wind energy is one of the most widely used renewable energy sources. This is due to the low cost of installation and ease of use. The most important factor affecting the aerodynamic efficiency of wind turbines is the blade profiles. Numerous types of wing profiles have been designed and put into use. In this study, numerical analyzes of NACA 0015 and NACA 4415 airfoils at various angles of attack were performed by determining forces every five degrees between 0 and 20 degrees using ANSYS Fluent commercial software. Lift coefficients and drag coefficients were also calculated for the angles of attack used. According to the analysis results obtained, optimum attack angles were found for each airfoil. As a result, NACA0015 and NACA4415 airfoils were compared in terms of their performance.

A Nonlinear CFD/Multibody Incremental-Dynamic Model for A Constrained Mechanism

Numerical analysis of a multibody mechanism moving in the air is a complicated problem in computational fluid dynamics (CFD). Analyzing the motion of a multibody mechanism in a commercial CFD software, i.e., ANSYS Fluent®, is a challenging issue. This is because the components of a mechanism have to be constrained next to each other during the movement in the air to have a reliable numerical aerodynamics simulation. However, such constraints cannot be numerically modeled in a commercial CFD software, and needs to be separately incorporated into models through the programming environment, such as user-defined functions (UDF). This study proposes a nonlinear-incremental dynamic CFD/multibody method to simulate constrained multibody mechanisms in the air using UDF of ANSYS Fluent®. To testify the accuracy of the proposed method, Newton–Euler dynamic equations for a two-link mechanism are solved using Matlab® ordinary differential equations (ODEs), and the numerical results for the constrained mechanisms are compared. The UDF results of ANSYS Fluent® shows good agreement with Matlab®, and can be applied to constrained multibody mechanisms moving in the air. The proposed UDF of ANSYS Fluent® calculates the aerodynamic forces of a flying multibody mechanism in the air for a low simulation cost than the constraint force equation (CFE) method. The results could have implications in designing and analyzing flying robots to help human rescue teams, and nonlinear dynamic analyses of the aerodynamic forces applying on a moving object in the air, such as airplanes, birds, flies, etc.

A general numerical model for rotor aerodynamics based on added mass force

When wind turbines operate in complex atmospheric environments, the flow fields around their blades are complex and unsteady. To capture the lag characteristics of induced velocity when the dynamic environment of a rotor changes, this study further modified the equilibrium wake model using the blade element momentum and acceleration potential theories. In addition, a novel expression for the added mass force mA=128/75ρR3 was derived. Consequently, a numerical aerodynamics model of a rotor with an added mass force was developed. The model was used to calculate the aerodynamic load of a 5 MW wind turbine under steady wind, turbulence, gust, wind direction change, and rapid pitching. The results demonstrated that the numerical model with added mass force could reflect the rotor aerodynamic performance more accurately than its counterpart. The fluctuation amplitudes of the flapwise and edgewise bending moments of the blade root were smaller than those from the equilibrium wake model. The overshoot in loading, which was caused by the added mass force during pitching, could not be ignored. The research results were compared with experimental data from the National Renewable Energy Laboratory. It was found that the proposed model provided a new strategy for calculating the added mass force and predicted rotor aerodynamic loads more accurately than the model without added mass force.

Precomputed Panel Solver for Aerodynamics Simulation

In this article, we introduce an efficient and versatile numerical aerodynamics model for general three-dimensional geometry shapes in potential flow. The proposed model has low computational cost and achieves an accuracy of moderate fidelity for the aerodynamic loads for a given glider shape. In the geometry preprocessing steps of our model, lifting-wing surfaces are recognized, and wake panels are generated automatically along the trailing edges. The proposed aerodynamics model improves the potential theory-based panel method. Furthermore, a new quadratic expression for aerodynamic forces and moments is proposed. It consists of geometry-dependent aerodynamic coefficient matrices and has a continuous representation for the drag/lift-force coefficients. Our model enables natural and real-time aerodynamics simulations combined with general rigid-body simulators for interactive animation. We also present a design system for original gliders. It uses an assembly-based modeling interface and achieves interactive feedback by leveraging the partwise precomputation enabled by our method. We illustrate that one can easily design various flyable gliders using our system.

ДЕЯКІ РЕЗУЛЬТАТИ ЕКСПЕРИМЕНТАЛЬНИХ ДОСЛІДЖЕНЬ АЕРОДИНАМІЧНИХ ХАРАКТЕРИСТИК ЕЛЕМЕНТІВ НЕСУЧИХ СИСТЕМ ЛІТАЛЬНИХ АПАРАТІВ

Despite active development of methods of theoretical aerohydrodynamics, construction of the increasingly sophisticated mathematical models, and construction of correct methods for their numerical aerodynamics, the creators of new aircraft models still in many cases prefer reliable results of experimental research, despite the high cost and laboriousness. Exactly because the most perfect modern mathematical models describing the multivariable processes of co-operation of the real environment with the streamlined object, not to a full degree able to describe all concomitant effects. The results of systematic experimental researches of major aerodynamic descriptions of the elements of the bearing systems are presented such as a carrying capacity, force of resistance, and also moments of corporal profiles and wings of eventual scope of free-form in a plan and spatial configuration. Experimental researches were conducted in the attested wind-channels of the National aerospace university the name of N. Ye. Zhukovski " KHAI" at the parameters of similarity: degree of turbulence and number of Reynolds., corresponding to the external of a transport aviation environments. Weighing tests were carried out using the tested sixcomponent aerodynamic weights Substantial influence of form of wing is shown in a plan, his spatial configuration, and presence of mechanization both mechanical and power on basic aerodynamic descriptions of the bearing systems. The results of these experimental researches widely are highly sought in the processes of planning of wide spectrum of aircrafts, using the effect of carrying capacity both at the cruiser mode of flight and at maneuverings with the assured safe external environments. There is present experimental equipment, and also treatment of results of tests software real-time, not only total aerodynamic descriptions allow to get but, for example, such as hydrostatical pressure, also up-diffused, especially highly sought in the processes of прочностных calculations of elements of the bearing systems. Job performances can be used in the educational process of preparation of specialists of industry of higher qualification.

QUALITY RESEARCH OF BOUNDARY LAYER MODELING IN PERFORMING CFD-CALCULATION OF AERODYNAMIC CHARACTERISTICS OF THE CLOSED WING AIRCRAFT USING ANSYS FLUENT

Value to determine the parameters of the boundary layer is the basis of the numerical aerodynamics software ANSYS FLUENT. That is, nowadays, with the appearance of modern computational packages boundary layer simulation is not a big problem. The problem is the quality of the boundary layer modeling and computational grid and as a result – error in getting pressure distribution over the surface of the aircraft and the aerodynamic characteristics. Therefore, to study the aerodynamics of the aircraft it is necessary to obtain quality modeling computational grid (the number of final volume) and modeling of the boundary layer (the number of layers).In this work the influence of the boundary layer modeling in performing CFD-calculation of aerodynamic characteristics of the closed wing aircraft using ANSYS FLUENT is investigated. Rational partition of wall shelving final volume in layers for further boundary layer modeling is found.It was determined that the quality of the boundary layer simulation in ANSYS FLUENT significantly affects the coefficient of aerodynamic drag and hardly affects the coefficient of lift force. It is shown that the aerodynamic characteristics with some modeling of wall layers are stabilized and are not dependent upon further wall layers modeling. This phenomenon is similar to grid independence, when some calculation grid characteristics do not depend on further increasing the final volume mesh aircraft.

Uncertainties Quantification and Data Compression in numerical Aerodynamics

AbstractWe research how uncertainties in the angle of attack, in the Mach number and in the geometry of the airfoil propagate in the solution (pressure, density, velocity etc). To compute different statistical functionals of the solution we build a low‐rank response surface. The building algorithm is working on the fly, is based on the QR‐decomposition, has drastically reduced memory requirements and linear complexity. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Numerical Aerodynamics at DLR

Some years ago the national CFD project MEGAFLOW was initiated in Germany to combine many of the CFD development activities from DLR, universities and aircraft industry. Its goal was the development and validation of a dependable and efficient numerical tool for the aerodynamic simulation of complete aircraft which met the requirements of industrial implementations. The MEGAFLOW software system includes the block-structured Navier-Stokes code FLOWer and the unstructured Navier-Stokes code TAU. Both codes have reached a high level of maturity and they are intensively used by DLR and the German aerospace industry in the design process of new aircraft. Recently, the follow-on project MEGADESIGN and MEGAOPT were set up which focus on the development and enhancement of efficient numerical methods for shape design and optimization. This article highlights recent improvements of the software and its capability to predict viscous flows for complex industrial aircraft applications.

Advances in Numerical Bridge Aerodynamics and Recent Applications

Aerodynamic aspects are a major design factor in bridge engineering today. Whilst wind tunnel testing is the standard procedure for the assessment of the aerodynamic behaviour of bridge decks, numerical methods can provide a suitable supplement and offer further insight into flow properties. Here the two-dimensional Vortex Particle Method is discussed as a means to solve the underlying Navier-Stokes equations numerically. This well-known technique, which has been extensively used for the study of aeroelastic phenomena due to its flexibility and speed, has been extended to allow further improvements.A novel hybrid Particle-Mesh algorithm is developed which achieves a highly efficient particle velocity computation. This allows for a large number of computational elements and thus high-resolution simulations at modest computational cost. Applications of the computer code to problems in the field of wind engineering of structures are presented. Projects briefly described are: the Millau Viaduct, River Neath Bridge and a Savonius turbine. A high level of spatial and temporal resolution is used. It is concluded that such computations can provide important design guidance through fast-track aerodynamic testing.

The three-dimensional numerical aerodynamics of a movable block burner

Computational fluid-dynamics techniques were employed to study the aerodynamics of a movable block swirl burner, developed by the International Flame Research Foundation, IFRF, which is characterized by the ability to adjust continuously and dynamically the intensity of the swirl by means of the simultaneous rotation of eight movable blocks, inserted between eight fixed blocks. Five three-dimensional grids were constructed for the burner, corresponding to five positions of the movable blocks. Both the k-e and RNG k-e isotropic turbulence models were applied. Only the latter described the existence of a central reverse flow along the annular duct. The employment of first-order and second-order interpolation schemes provided distinct results. The later provided results closer to the experimental tests. The swirl number decayed in the annular duct. The predicted swirl numbers for this movable block swirl burner were lower than the corresponding IFRF's experimental data, as was also observed by other researchers. This gave rise to the suspicion of some possible measurement error in the IFRF's experiments. On the other hand, the lack of agreement between the experimental data and the predictions regarding swirling flows could be attributed to the possible inadequate performance of the k-e model, as a consequence of its isotropic approximation. Still another possible explanation could be a phenomenon called bifurcation, in which one given swirl number can be associated with two distinct conditions of steady state flow. In addition, this complex flows requires a scrupulous development of the grids for the boundary condition and the employment of adequate interpolation schemes.

Detailed study of complex flow fields of aerodynamical configurations by using numerical methods

The mathematical physics of fluid flow in a compressible medium, leads to nonlinear partial differential equations or their equivalent integral versions. For the solution of these equations one has generally to resort to numerical methods using mostly finite difference or finite volume schemes, which are well established now. These field methods are very suitable for studying the physical features of complex flows. The present paper gives at first a short sketch of the numerical procedure and thereafter goes into the detailed analysis of the flow fields of delta wings, double-delta wings, delta shaped wing-canard combinations and space vehicles. Further examples include long span wings and wing-bodies at supercritical onflows, flows around propellers and rotors and finally some unsteady flows. The examples cited are selected topics from the extensive studies undertaken in the department of numerical aerodynamics of thedlr in Braunschweig in the course of the last few years.

The Change in Critical Technologies for Computational Physics

It is noted that the types of technology required for computational physics are changing as the field matures. Emphasis has shifted from computer technology to algorithm technology and, finally, to visual analysis technology as areas of critical research for this field. High-performance graphical workstations tied to a supercommunicator with high-speed communications along with the development of especially tailored visualization software has enabled analysis of highly complex fluid-dynamics simulations. Particular reference is made here to the development of visual analysis tools at NASA's Numerical Aerodynamics Simulation Facility. The next technology which this field requires is one that would eliminate visual clutter by extracting key features of simulations of physics and technology in order to create displays that clearly portray these key features. Research in the tuning of visual displays to human cognitive abilities is proposed. The immediate transfer of technology to all levels of computers, specifically the inclusion of visualization primitives in basic software developments for all work stations and PCs, is recommended.

A Split-Matrix Method for the Numerical Solution of Two-Phase Flow Equations

A solution method for two-phase flow problems is presented that is very well established in numerical aerodynamics. The set of two-phase flow equations is presumed to be hyperbolic. The method solves the flow equation in its characteristic form (compatibility conditions) on a rectangular mesh. It uses the characteristic directions only to determine how the numerical solution depends on the upstream and downstream fluid flow states, in contrast to the method of characteristics. This results in a particular choice of backward and forward differences to approximate the spatial derivatives and yields a stable numerical scheme. The method works on a simple discrete mesh and does not need a staggered mesh for stability, as is widely used for two-phase flow calculations.

空気力学数値シミュレーション技術の現状と課題

空気力学数値シミュレーション技術の現状と課題

Recent advances in spark-ignition engine combustion research.

This paper presents an overview of the current trend of combustion research in spark-ignition engines. The subject of greatest and continuing interest is the elucidation of the mechanism of turbulent flame propagation and/or the flame structure. Although there remain some problems as yet, the goal may not necessarily be so far away, considering the remarkable progress in diagnostic techniques during the last decade. Advances in numerical aerodynamics have made it possible to simulate the flow phenomena in an engine. The field of numerical aero-thermo-chemistry, however, is still immature. Also, the investigation into knock has recently become a subject of growing interest. This review covers the above subjects, in some depth.