| 1. |
- Görtz, Stefan, et al.
(författare)
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Numerical Solutions for the Cawapi Configuration on Unstructured Grids at KTH/FOI, Sweden : Part I
- 2009
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Ingår i: Understanding and Modeling Vortical Flows to Improve the Technology Readiness Level for Military Aircraft.
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Steady and unsteady viscous simulations of a full-scale, semi-span and full-span model of the F-16XL-1 aircraft at seven different flight Reynolds/Mach number combinations have been performed with an unstructured CFD code. The steady-state simulations are with several turbulence models of different complexity. Detached-Eddy Simulation (DES) has been used to compute the unsteady flow. The computed results are compared with public domain flight-test data. Very good agreement is demonstrated for surface pressure distribution, local skin friction and boundary velocity profiles. The different turbulence models performed almost equally well, except the Spalart-Allmaras model, which failed to predict the flow qualitatively and quantitatively. The Differential Reynolds Stress Model (DRSM) outperformed all other models when it comes to local span-wise skin friction. DES was superior over RANS modeling at the highest angle of attack, where the flow over the outer wing is separated and partly unsteady.
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| 2. |
- Jirásek, Adam
(författare)
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Developement and application in design strategy for design of vortex generator flow control in inlets
- 2006
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Ingår i: 44th AIAA Aerospace Sciences Meeting and Exhibit9 - 12 January 2006, Reno, Nevada. ; , s. 1-14
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Konferensbidrag (refereegranskat)abstract
- This article summarizes the results of an optimization study of a micro-vortex generatorflow control in an inlet. Five parametric optimization was carried out using the classicalDesign of Experiment DOE method. Two main objectives were in focus. First, to developthe methodology and skills necessary to conduct a DOE optimization study in relativelynew area of the flow control. Second, to develop the procedures which would be used asa lead during design of flow control in inlets. New information about the behavior of thechannel with flow control were obtained during tests and analyzed. Several interestingconfigurations were located. The parameters of optimal settings were then used to set upthe vortex generator installation in a generic inlet.
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| 3. |
- Jirásek, Adam
(författare)
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Evaluation of the vortex generator flow control in the FOI-EIC-01 inlet at different flight conditions
- 2007
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Ingår i: Collection of Technical Papers - 43rd AIAA/ASME/SAE/ASEE Joint Propulsion Conference. - 9781563479038 ; , s. 687-701
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Konferensbidrag (refereegranskat)abstract
- The main goal of this work is to test the vortex generator flow control in the FOI-EIC-01 inlet at different flight conditions. The study has two phases. In the first, the entire flow around the UAV with inlet was calculated. Since it is not realistic to run RANS calculations of such a complicated configuration at a large number of flow conditions, the flow around the airframe-propulsion unit system was calculated as inviscid. The data on the boundaries of the inlet are collected and used in the second phase during tests of flow control.
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| 4. |
- Jiràsek, Adam, et al.
(författare)
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Libm3l and lsipdx - Utilities for inter-process data transfer and synchronization
- 2014
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Ingår i: 52nd AIAA Aerospace Sciences Meeting - AIAA Science and Technology Forum and Exposition, SciTech 2014. - Reston, Virginia : American Institute of Aeronautics and Astronautics Inc..
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Konferensbidrag (refereegranskat)abstract
- This paper describes two Open Source Software libraries which are currently under development - libm3l and lsipdx. The libm3l library is a utility enabling storage of the basic data types in a linked list and their transfer through the TCP/IP socket. The linked list can be transferred as a whole or just its part. The second utility, the lsipdx library, is a utility which enables transfer of the data among a number of processes and their synchronization. The libraries are therefore suitable candidate for data exchange and synchronization of a number of solvers in the multidisciplinary analysis. Both libraries are written in the ANSI-C programming language and are available to the public under GNU Lesser GPL, LGPL, license through the github site.
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| 5. |
- Jirásek, Adam
(författare)
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Mass flow boundary conditions for subsonic inflow and outflow boundary
- 2006
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Ingår i: AIAA Journal. - : American Institute of Aeronautics and Astronautics (AIAA). - 0001-1452 .- 1533-385X. ; 44:5, s. 939-947
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Tidskriftsartikel (refereegranskat)abstract
- The development and verification of an inflow and outflow mass flow boundary condition are described. In addition, an outflow Mach number boundary condition was implemented and tested. The main motivation behind the development of a mass flow boundary condition is a need to bridge the gap between the requirement of direct setting of mass flow as one of the most important parameters, and the difficulty of indirect control of mass flow using static pressure outflow and total states inflow boundary conditions. The mass flow and Mach number boundary conditions were verified in low-speed flow through a two-dimensional channel with constant area and in high-speed flow through the Royal Airforce Establishment M2129 S-duct with large separation. Special attention was paid to the behavior of the mass flow boundary conditions in choked flow.
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| 6. |
- Jirásek, Adam, et al.
(författare)
-
Numerical Solutions for the Cawapi Configuration on Unstructured Grids at KTH/FOI, Sweden : Part II
- 2009
-
Ingår i: Understanding and Modeling Vortical Flows to Improve the Technology Readiness Level for Military Aircraft.
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- This article represents a second contribution of the Swedish Defence Research Agency, FOI, and the Royal Institute of Technology, KTH, to the Cranked-Arrow Wing Aerodynamics Project International, CAWAPI. The main focus of this article is on evaluation of the effect of different formulation of boundary conditions on the engine mass flow and resulting wing upper surface pressures.
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| 7. |
- Jirásek, Adam
(författare)
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Vortex-generator model and its application to flow control
- 2005
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Ingår i: Journal of Aircraft. - : American Institute of Aeronautics and Astronautics (AIAA). - 0021-8669 .- 1533-3868. ; 42:6, s. 1486-1491
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Tidskriftsartikel (refereegranskat)abstract
- A new vortex-generator model is introduced, the jBAY model, which provides an efficient method for computational-fluid-dynamics (CFD) simulation of flow systems with vortex-generator arrays. The jBAY model is based on the lifting force theory of Bender, Anderson, and Yagle (Bender, E. E., Anderson, B. H., and Yagle, P. J., "Vortex Generator Modelling for Navier-Stokes Codes," American Society of Mechanical Engineers, FEDSM 996919, New York, July 1999) but uses a novel technique for defining the model control points. This greatly simplifies usage of the model as well as improving its performance and accuracy. The jBAY model is described in the context of its implementation in the CFD code Edge, an unstructured Reynolds-averaged Navier-Stokes solver. Results are presented for a single vortex generator on a flat plate and two flow control cases: an S-duct air intake and a high-lift wing configuration. The model is shown to give good agreement with both experimental results and with CFD computations where the vortex generator is fully gridded. It is demonstrated that the jBAY model is simple to apply and efficiently captures the effect of vortex generator arrays for both internal and external flows.
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| 8. |
- Jirásek, Adam
(författare)
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Vortex generator modeling and its application to optimal control of airflow in inlet
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This dissertation deals with the development of the vortex generator model and its use for the optimization study of vortex generator flow control in high-offset-ed inlets. In the first part, the overview of use of vortex generators and their mechanism is outlined. Both the application form the existing aircraft as well as laboratory studies are reviewed. The second part contains four papers. The first paper deals with the development, verification and validation of the vortex generator model in Navier-Stokes code. Although primarily meant to be used in inlets, the validation of the model was carried out in case of high-lift system by comparing pressure coefficient to the experimental data. Second paper deals with development of the inflow and outflow mass flow boundary conditions for Navier-Stokes codes. Newly designed mass flow boundary conditions were compared to existing mass flow boundary conditions. Special attention was paid to flows under condition of choking. Third paper deals with the Design of Experiment optimization study of the vortex generator flow control in the RAE M2129 inlet with two sets of five geometrical parameters. The aim is to reduce the inlet flow distortion and increase pressure recovery. The parameters of optimal vortex generator setup were then used to design a vortex generator flow control in more realistic inlet for a UAV. Fourth paper deals with testing of vortex generator flow control in the UAV inlet under different flight conditions. In order to be able to find appropriate parameters of flow in inlet, entire UAV with prescribed value of the mass flow was calculated. It was found that the proposed vortex generator installation malfunctioned when at conditions corresponding to the high altitude flight conditions. A new configuration with double number of vortex generators was then tested and at proven being stable. Triangular vortex generators were tested also.
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| 9. |
- Luckring, James M., et al.
(författare)
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Synthesis of Hybrid Computational Fluid Dynamics Results for F-16XL Aircraft Aerodynamics
- 2017
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Ingår i: Journal of Aircraft. - 0021-8669 .- 1533-3868. ; 54:6, s. 2100-2114
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Tidskriftsartikel (refereegranskat)abstract
- A synthesis is presented of recent numerical predictions for the F-16XL aircraft flowfields and aerodynamics. The computational analyses were all performed with hybrid Reynolds-averaged Navier-Stokes/large-eddy simulation formulations, with an emphasis on unsteady flows and associated aerodynamics, and results from five computational methods are included. The work focused on one particular low-speed high angle-of-attack flight-test condition, and comparisons against flight-test data are included. This work represents the third coordinated effort using the F-16XL aircraft, and a unique flight-test dataset, to advance the knowledge of slender airframe aerodynamics as well as the capability for predicting these aerodynamics with advanced computational fluid dynamics formulations. The prior efforts were identified as the Cranked-Arrow Wing Aerodynamics Project International.
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| 10. |
- Rizzi, Arthur, et al.
(författare)
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Computation of Aeroelastic Effects on F-16XL at Flight Conditions FC70 and FC25
- 2017
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Ingår i: Journal of Aircraft. - : AMER INST AERONAUTICS ASTRONAUTICS. - 0021-8669 .- 1533-3868. ; 54:2, s. 409-416
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Tidskriftsartikel (refereegranskat)abstract
- This article presents an aeroelastic study of CAWAPI F-16XL aircraft. The structural model of this aircraft is not publicly available and is therefore replaced by a structural model estimate that is constructed based on data available in public literature. The aeroelastic solution is done using solution for two flight conditions-FC70 and FC25. The primary task is to assess the importance of the aeroelastic effects on the FC70 solution and to assess whether large discrepancies are observed at flight condition FC70 between the computational and experimental data.
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