scholarly journals Aeroelastic simulations of a delta wing with a Chimera approach for deflected control surfaces

2021 ◽  
Author(s):  
Christopher Reinbold ◽  
Kaare Sørensen ◽  
Christian Breitsamter
Keyword(s):  
Flow Field ◽  
Delta Wing ◽  
Dynamic Pressure ◽  
Computational Effort ◽  
Control Surface ◽  
Navier Stokes ◽  
Moment Coefficient ◽  
Computational Structural Mechanics ◽  
Aeroelastic Simulations ◽  
Control Surfaces

AbstractA numerical tool for the computation of aircraft control surface aerodynamics with flexibility effects is presented. The solution is based on coupled Computational Fluid Dynamics (CFD) and Computational Structural Mechanics (CSM) simulations embedded in the multidisciplinary simulation environment SimServer. In SimServer, the DLR-TAU Code is utilized to obtain the CFD solution by solving the Reynolds-Averaged Navier–Stokes (RANS) equations. Structural displacements are computed with a modal solver. The Chimera implementation of SimServer, suited for hybrid grids, is applied to model the control surfaces. Numerical simulations with the flexible Chimera method are performed for the Model53 wing configuration, which is a generic delta wing with a deployed slat as well as an inboard and outboard trailing edge flap. Aerodynamic and aeroelastic simulations at high dynamic pressure $$q=45$$ q = 45  kPa and transonic speed $${\text {Ma}} = 0.8$$ Ma = 0.8 are performed for several angles of attack $$10^\circ \le \alpha \le 25^\circ$$ 10 ∘ ≤ α ≤ 25 ∘ and flap deflection angles $$-30^\circ \le \delta \le 30^\circ$$ - 30 ∘ ≤ δ ≤ 30 ∘ . The effect of structural deformations on the flow field and control surface effectiveness are analyzed and compared to computations of components treated fully rigid. At the targeted freestream condition $$M=0.8$$ M = 0.8 and $${\text {Re}}=15.1 \times 10^7$$ Re = 15.1 × 10 7 , the flow field around the Model53 configuration is characterized by the interaction of vortices and shock waves. The results of the lift and pitching moment coefficient for the rigid and flexible configuration revealed the importance of taking the structural flexibility into account in order to obtain more accurate results for the considered range of flap deflections. Furthermore, the computational effort of the aerodynamic and aeroelastic simulations are evaluated. The increase in computational effort is shown to be adequate for the given increase in accuracy.

scholarly journals Numerical investigations of vortex formation on a generic multiple-swept-wing configuration

2021 ◽  
Author(s):  
D. Sedlacek ◽  
S. Biechele ◽  
C. Breitsamter
Keyword(s):  
Flow Field ◽  
Delta Wing ◽  
Vortex Formation ◽  
Navier Stokes ◽  
Swept Wing ◽  
Field Development ◽  
Numerical Investigations ◽  
Moment Coefficient ◽  
Wind Tunnel Data ◽  
Double Delta Wing

AbstractFor an improvement of the flight stability characteristics of high-agility aircraft, the comprehension of the vortex development, behavior and break down is important. Therefore, numerical investigations on low aspect ratio, multiple-swept-wing configurations are performed in this study to analyze the influence of the numerical method on the vortex formation. The discussed configurations are based on a triple- and double-delta wing planform. Unsteady Reynolds-averaged Navier–Stokes (URANS) simulations and delayed detached eddy simulations (DDES) are performed for both configurations. The simulations are executed at Re $$= 3.0\times 10^6$$ = 3.0 × 10 6 , symmetric freestream conditions, and an angle of attack of $$\alpha = 16^\circ$$ α = 16 ∘ , for consistency with reference wind tunnel data. For the triple-delta-wing configuration, the results of the DDES show a satisfying accordance to the experiments compared to URANS, especially for the flow field and the pitching moment coefficient. For the double-delta-wing configuration, the URANS simulation provides reliable results with low deviation of the aerodynamic coefficients and high precision for the flow field development with respect to the experimental data.

Numerical analysis of exhaust jet secondary combustion in hypersonic flow field

2018 ◽  
Vol 32 (12n13) ◽  
pp. 1840045
Author(s):  
Tian-Peng Yang ◽  
Jiang-Feng Wang ◽  
Fa-Ming Zhao ◽  
Xiao-Feng Fan ◽  
Yu-Han Wang
Keyword(s):  
Flow Field ◽  
Hypersonic Flow ◽  
Flight Control ◽  
Stokes Equations ◽  
Field Structure ◽  
Control Surface ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Secondary Combustion ◽  
Exhaust Jet

The interaction effect between jet and control surface in supersonic and hypersonic flow is one of the key problems for advanced flight control system. The flow properties of exhaust jet secondary combustion in a hypersonic compression ramp flow field were studied numerically by solving the Navier–Stokes equations with multi-species and combustion reaction effects. The analysis was focused on the flow field structure and the force amplification factor under different jet conditions. Numerical results show that a series of different secondary combustion makes the flow field structure change regularly, and the temperature increases rapidly near the jet exit.

On the maximisation of control power in low-speed flight

2019 ◽  
Vol 123 (1266) ◽  
pp. 1099-1121
Author(s):  
L. M. B. C. Campos ◽  
J. M. G. Marques
Keyword(s):  
Control Surface ◽  
Pitching Moment ◽  
Multiple Control ◽  
Rolling Moment ◽  
Yaw Control ◽  
Control Power ◽  
Moment Coefficient ◽  
Engine Failure ◽  
Surface Deflections ◽  
Control Surfaces

ABSTRACTThe maximisation of control power is considered for an aircraft with multiple control surfaces, with the force and moment coefficients specified by polynomials of the control surface deflections of degree two. The optimal deflections, which maximise and minimise any force or moment coefficient, are determined subject to constraints on the range of deflection of each control surface. The results are applied to a flying wing configuration to determine: (i/ii) the pitch trim, at the lowest drag for the fastest climb, and at the highest drag for the steepest descent; (iii) the maximum and minimum pitching moment; (iv) the maximum and minimum yaw control power and the fraction needed to compensate an outboard engine failure for several propulsion configurations; (v) the maximum and minimum rolling moment. The optimal use of all control surfaces has significant advantages over using just one, e.g. the range of drag modulation with pitch trim is much wider and the maximum and minimum available control moments larger.

Modeling of Oscillating Control Surfaces Using Overset-Grid-Based Navier–Stokes Equations Solver

2017 ◽  
Vol 139 (3) ◽  
Author(s):  
Guru P. Guruswamy
Keyword(s):  
Stokes Equations ◽  
Control Surface ◽  
Navier Stokes ◽  
Test Case ◽  
Overset Grid ◽  
Navier Stokes Equations ◽  
Sensitivity Studies ◽  
Wind Tunnel Data ◽  
First Time ◽  
Control Surfaces

A modular procedure is presented to simulate moving control surfaces within an overset grid environment using the Navier–Stokes equations. Gaps are modeled by locally shearing the wing grids instead of using separate grids to model gaps. Grid movements for control surfaces are defined through a separate module, which is driven by an external grid generation tool. Results are demonstrated for a wing with a part-span control surface. Grids for the test case are determined from detailed grid sensitivity studies based on both nonoscillating and oscillating cases. Steady and, for the first time, unsteady pressures from overset grid computations are validated with wind tunnel data. This paper addresses the current needs of high-fidelity flow modeling to design advanced active-controls.

scholarly journals Numerical Simulation of the Aerodynamic Influence of Aircrafts During Aerial Refueling with Engine Jet

2019 ◽  
Vol 21 (1) ◽  
pp. 15-24 ◽  
Author(s):  
Yi Li ◽  
Yang Zhang ◽  
Junqiang Bai
Keyword(s):  
Stokes Equations ◽  
Dynamic Pressure ◽  
Lift Coefficient ◽  
Jet Flow ◽  
Aerodynamic Characteristics ◽  
Navier Stokes ◽  
Pitching Moment ◽  
Aerial Refueling ◽  
Rolling Moment ◽  
Moment Coefficient

Abstract Aerial refueling technology has been widely applied in various fields and it is one of the hotspots but difficulties for the aeronautical technologies. DLR-F6 WBNP model is used as a tanker and a fighter model is used as a receiver. The flow field of Probe–Drogue refueling and Flying Boom refueling is numerically simulated using the Reynolds-averaged Navier–Stokes equations, and the effects of the jet flow and the aerodynamic characteristics of the receiver are taken into consideration. The results indicate that the effect of downwash of the tanker reduces the lift coefficient and decreases the pitching moment coefficient of the receiver. The jet flow of tanker increases the dynamic pressure while decreases the local angle of attack, which increases the pressure difference between the upper and lower surfaces of receiver. Compared with the results without jet, the jet flow can increase the lift and the drag of the receiver and reduces the pitching moment, and even cause the change of rolling moment direction. Therefore, engine jet is an important factor when simulating aerial refueling.

Flow Structures and Pressure Fluctuations in a Centrifugal Pump at Design and Off-Design Conditions

2009 ◽  
Author(s):  
Zhongyong Pan ◽  
Yongyan Ni ◽  
Jinyama Ho ◽  
Shouqi Yuan
Keyword(s):  
Flow Field ◽  
Centrifugal Pump ◽  
High Frequency ◽  
Stokes Equations ◽  
Dynamic Pressure ◽  
Pressure Fluctuations ◽  
Navier Stokes ◽  
Flow Structures ◽  
Mean Velocity ◽  
Flow Field Characteristics

The flow structures and the pressure fluctuations in a centrifugal pump at both design and off-design points are presented in this paper. The flow structures are numerically obtained by solving the viscous incompressible Navier-Stokes equations with a 3D unsteady flow model. A sliding mesh technique is applied to take into account the impeller-volute interaction. The pressure fluctuations are obtained by both numerical simulations and experimental measurements. The former data denote all the flow field characteristics including those in the impeller, the interface, the volute and the diffuser, while the latter ones that acquisitioned by a high-frequency pressure sensor show only one position at the outlet flange. The FFT technology is adopted to process those dynamic pressure data to reveal the frequency features. All the power spectrum results present that the dominant frequencies are the blade passing ones, while the subdominant ones are varied depending on the flow rates and the positions. At design condition, the mean velocity field in both impeller and volute show well behaved flow with no separation, while subtle separation is found along the tongue side in the diffuser. Some unknown high-frequency contents are discovered in the flow field.

scholarly journals Manifold reduction techniques for the comparison of crank angle-resolved particle image velocimetry (PIV) data and Reynolds-averaged Navier-Stokes (RANS) simulations in a spark ignition direct injection (SIDI) engine

2021 ◽  
pp. 146808742110131
Author(s):  
Xiaohang Fang ◽  
Li Shen ◽  
Christopher Willman ◽  
Rachel Magnanon ◽  
Giuseppe Virelli ◽  
...  
Keyword(s):  
Flow Field ◽  
Particle Image ◽  
Direct Injection ◽  
Linear Manifold ◽  
Main Flow ◽  
Navier Stokes ◽  
Reduction Techniques ◽  
Image Velocimetry ◽  
Manifold Reduction ◽  
Relevance Index

In this article, different manifold reduction techniques are implemented for the post-processing of Particle Image Velocimetry (PIV) images from a Spark Ignition Direct Injection (SIDI) engine. The methods are proposed to help make a more objective comparison between Reynolds-averaged Navier-Stokes (RANS) simulations and PIV experiments when Cycle-to-Cycle Variations (CCV) are present in the flow field. The two different methods used here are based on Singular Value Decomposition (SVD) principles where Proper Orthogonal Decomposition (POD) and Kernel Principal Component Analysis (KPCA) are used for representing linear and non-linear manifold reduction techniques. To the authors’ best knowledge, this is the first time a non-linear manifold reduction technique, such as KPCA, has ever been used in the study of in-cylinder flow fields. Both qualitative and quantitative studies are given to show the capability of each method in validating the simulation and incorporating CCV for each engine cycle. Traditional Relevance Index (RI) and two other previously developed novel indexes: the Weighted Relevance Index (WRI) and the Weighted Magnitude Index (WMI), are used for the quantitative study. The results indicate that both POD and KPCA show improvements in capturing the main flow field features compared to ensemble-averaged PIV experimental data and single cycle experimental flow fields while capturing CCV. Both methods present similar quantitative accuracy when using the three indexes. However, challenges were highlighted in the POD method for the selection of the number of POD modes needed for a representative reconstruction. When the flow field region presents a Gaussian distribution, the KPCA method is seen to provide a more objective numerical process as the reconstructed flow field will see convergence with an increasing number of modes due to its usage of Gaussian properties. No additional criterion is needed to determine how to reconstruct the main flow field feature. Using KPCA can, therefore, reduce the amount of analysis needed in the process of extracting the main flow field while incorporating CCV.

On the Flow Fields of Inertial Impactors

1974 ◽  
Vol 96 (4) ◽  
pp. 394-400 ◽  
Author(s):  
V. A. Marple ◽  
B. Y. H. Liu ◽  
K. T. Whitby
Keyword(s):  
Flow Field ◽  
Stokes Equations ◽  
Relaxation Method ◽  
Water Model ◽  
Navier Stokes ◽  
Visualization Technique ◽  
Navier Stokes Equations ◽  
Theoretical Results ◽  
Plate Distance ◽  
Good Agreement

The flow field in an inertial impactor was studied experimentally with a water model by means of a flow visualization technique. The influence of such parameters as Reynolds number and jet-to-plate distance on the flow field was determined. The Navier-Stokes equations describing the laminar flow field in the impactor were solved numerically by means of a finite difference relaxation method. The theoretical results were found to be in good agreement with the empirical observations made with the water model.

Numerical Simulation of Muzzle Flow Field of Gun Based on CFD

2013 ◽  
Vol 291-294 ◽  
pp. 1981-1984
Author(s):  
Zhang Xia Guo ◽  
Yu Tian Pan ◽  
Yong Cun Wang ◽  
Hai Yan Zhang
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Stokes Equation ◽  
Wave Structure ◽  
Flow Fields ◽  
Single Equation ◽  
Navier Stokes ◽  
Turbulent Model ◽  
Navier Stokes Equation ◽  
Numerical Simulation Result

Gunpowder was released in an instant when the pill fly out of the shell during the firing, and then formed a complicated flow fields about the muzzle when the gas expanded sharply. Using the 2 d axisymmetric Navier-Stokes equation combined with single equation turbulent model to conduct the numerical simulation of the process of gunpowder gass evacuating out of the shell without muzzle regardless of the pill’s movement. The numerical simulation result was identical with the experimental. Then simulated the evacuating process of gunpowder gass of an artillery with muzzle brake. The result showed complicated wave structure of the flow fields with the muzzle brake and analysed the influence of muzzle brake to the gass flow field distribution.

Fluid flow over and through a regular bundle of rigid fibres

2016 ◽  
Vol 792 ◽  
pp. 5-35 ◽  
Author(s):  
Giuseppe A. Zampogna ◽  
Alessandro Bottaro
Keyword(s):  
Porous Medium ◽  
Fluid Flow ◽  
Flow Field ◽  
Stokes Equations ◽  
Transversely Isotropic ◽  
Navier Stokes ◽  
Leading Order ◽  
Macroscopic Scale ◽  
Navier Stokes Equations ◽  
Homogenized Model

The interaction between a fluid flow and a transversely isotropic porous medium is described. A homogenized model is used to treat the flow field in the porous region, and different interface conditions, needed to match solutions at the boundary between the pure fluid and the porous regions, are evaluated. Two problems in different flow regimes (laminar and turbulent) are considered to validate the system, which includes inertia in the leading-order equations for the permeability tensor through a Oseen approximation. The components of the permeability, which characterize microscopically the porous medium and determine the flow field at the macroscopic scale, are reasonably well estimated by the theory, both in the laminar and the turbulent case. This is demonstrated by comparing the model’s results to both experimental measurements and direct numerical simulations of the Navier–Stokes equations which resolve the flow also through the pores of the medium.

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