Numerical Simulation of the Supersonic Disk-Gap-Band Parachute by Using Implicit Coupling Method

2017 ◽  
Vol 18 (5) ◽  
pp. 343-349
Author(s):  
Xue Yang ◽  
Li Yu ◽  
Cheng Shen ◽  
Xiao Shun Zhao
Keyword(s):  
Wind Tunnel Test ◽  
Numerical Results ◽  
Coupling Method ◽  
Test Results ◽  
Governing Equations ◽  
Time Step ◽  
Projected Area ◽  
Newmark Scheme ◽  
Canopy Area ◽  
Shock Oscillation

AbstractThe implicit coupling method is applied to model the 0.8 m disk-band-gap parachute at Mach 2.0. The fluid and structure governing equations are solved by the Lower-Upper Symmetric Gauss-Seidel (LU-SGS) algorithm and Newmark scheme, respectively. By exchanging the numerical results of the coupling surface with Gauss-Seidel algorithm, high accuracy solutions at every physical time step are obtained. The numerical results of the canopy drag coefficient and projected area fit well with the wind tunnel test results. The simulation reproduces the shock oscillation and breathing phenomenon of the canopy that are usually observed in these systems at Mach 2.0. Furthermore, it is found that the unstable saddle point is the main reason for the shock oscillation of the canopy. And the unsynchronized phases of the canopy area and shock oscillation curves lead to the drag of the canopy oscillate in irregular state.

Design and experimental validation of a specialized pressure-measuring rake for blended wing body aircraft’s unconventional inner flow channel

2020 ◽  
Vol 234 (15) ◽  
pp. 2186-2196
Author(s):  
Xin Xu ◽  
Dawei Liu ◽  
Keming Cheng ◽  
Dehua Chen
Keyword(s):  
Wind Tunnel ◽  
Design Method ◽  
Wind Tunnel Test ◽  
Numerical Results ◽  
Flow Channel ◽  
Test Results ◽  
Complex Flow ◽  
Air Intake ◽  
Blended Wing Body ◽  
External Flows

The internal drag of the unconventional inner flow channel of blended wing body aircraft must be measured accurately to correct the air intake effect of the blended wing body flow-through model in wind tunnel tests. In this study, the pressure distribution of the inner flow channel under the interaction of internal and external flows was obtained through numerical simulation. A specialized pressure-measuring rake was designed based on the numerical results, and a validation test was conducted in a 2.4 m × 2.4 m transonic wind tunnel. Compared with the flow in traditional inlets/nozzles, the flow in the unconventional inner channel in the current research is asymmetric, the distortion index is higher, and the internal drag is more sensitive to flow changes. The wind tunnel test results have a good correlation with the numerical results, and the repeatability of the test results is satisfactory, indicating that the measurement accuracy and precision of the pressure-measuring rake are acceptable. The design method of the specialized rake is feasible, and it can be used to guide the measurement of complex flow in unconventional inner flow channels of blended wing body aircraft.

Rancang Bangun Piranti Lunak Pengolah Data Pasca Pengujian Terowongan Angin Kecepatan Rendah Indonesia

2016 ◽  
Vol 7 (2) ◽  
pp. 131-138
Author(s):  
Ivransa Zuhdi Pane
Keyword(s):  
Wind Tunnel ◽  
Wind Tunnel Test ◽  
Test Results ◽  
Effective Solution ◽  
Post Processing ◽  
Prototype Development ◽  
Design Activities ◽  
Index Terms ◽  
Test Objects ◽  
Processing Requirement

Data post-processing plays important roles in a wind tunnel test, especially in supporting the validation of the test results and further data analysis related to the design activities of the test objects. One effective solution to carry out the data post-processing in an automated productive manner, and thus eliminate the cumbersome conventional manual way, is building a software which is able to execute calculations and have abilities in presenting and analyzing the data in accordance with the post-processing requirement. Through several prototype development cycles, this work attempts to engineer and realize such software to enhance the overall wind tunnel test activities. Index Terms—software engineering, wind tunnel test, data post-processing, prototype, pseudocode

scholarly journals Investigation of the Time Dependence of Wind-Induced Aeroelastic Response on a Scale Model of a High-Rise Building

2021 ◽  
Vol 11 (8) ◽  
pp. 3315
Author(s):  
Fabio Rizzo
Keyword(s):  
Wind Tunnel ◽  
Time Dependence ◽  
Wind Tunnel Test ◽  
Structural Response ◽  
Cumulative Distribution ◽  
Scale Model ◽  
Acquisition Time ◽  
Test Results ◽  
High Rise ◽  
High Rise Building

Experimental wind tunnel test results are affected by acquisition times because extreme pressure peak statistics depend on the length of acquisition records. This is also true for dynamic tests on aeroelastic models where the structural response of the scale model is affected by aerodynamic damping and by random vortex shedding. This paper investigates the acquisition time dependence of linear transformation through singular value decomposition (SVD) and its correlation with floor accelerometric signals acquired during wind tunnel aeroelastic testing of a scale model high-rise building. Particular attention was given to the variability of eigenvectors, singular values and the correlation coefficient for two wind angles and thirteen different wind velocities. The cumulative distribution function of empirical magnitudes was fitted with numerical cumulative density function (CDF). Kolmogorov–Smirnov test results are also discussed.

scholarly journals Gust Alleviation Control using Prior Gust Information: Wind Tunnel Test Results

2019 ◽  
Vol 52 (12) ◽  
pp. 128-133
Author(s):  
Yoshiro Hamada ◽  
Kenichi Saitoh ◽  
Noboru Kobiki
Keyword(s):  
Wind Tunnel ◽  
Wind Tunnel Test ◽  
Test Results ◽  
Gust Alleviation

Analytical Study of the Convection Heat Transfer From an Isothermal Wedge Surface to Fluids

2012 ◽  
Vol 134 (6) ◽  
Author(s):  
M. Bachiri ◽  
A. Bouabdallah
Keyword(s):  
Heat Transfer ◽  
Prandtl Number ◽  
Ad Hoc ◽  
Convection Heat Transfer ◽  
Analytical Approximation ◽  
Numerical Results ◽  
Convection Heat ◽  
Governing Equations ◽  
Wedge Surface ◽  
Prandtl Numbers

In this work, we attempt to establish a general analytical approximation of the convection heat transfer from an isothermal wedge surface to fluids for all Prandtl numbers. The flow has been assumed to be laminar and steady state. The governing equations have been written in dimensionless form using a similarity method. A simple ad hoc technique is used to solve analytically the governing equations by proposing a general formula of the velocity profile. This formula verifies the boundary conditions and the equilibrium of the governing equations in the whole spatial region and permits us to obtain analytically the temperature profiles for all Prandtl numbers and for various configurations of the wedge surface. A comparison with the numerical results is given for all spatial regions and in wide Prandtl number values. A new Nusselt number expression is obtained for various configurations of the wedge surface and compared with the numerical results in wide Prandtl number values.

scholarly journals Observations on some transonic wind tunnel test results of a standard model with a T-tail

2016 ◽  
Vol 66 (4) ◽  
pp. 34-39 ◽  
Author(s):  
Dijana Damljanovic ◽  
Djordje Vukovic ◽  
Aleksandar Vitic ◽  
Jovan Isakovic ◽  
Goran Ocokoljic
Keyword(s):  
Wind Tunnel ◽  
Standard Model ◽  
Wind Tunnel Test ◽  
Test Results ◽  
Transonic Wind Tunnel

scholarly journals Lyapunov Based Estimation of Flight Stability Boundary under Icing Conditions

2017 ◽  
Vol 2017 ◽  
pp. 1-10 ◽  
Author(s):  
Binbin Pei ◽  
Haojun Xu ◽  
Yuan Xue
Keyword(s):  
Equilibrium Point ◽  
External Disturbance ◽  
Stability Boundary ◽  
Wind Tunnel Test ◽  
Test Results ◽  
Theoretical Support ◽  
Effect Model ◽  
Short Period ◽  
The Stability ◽  
Period Model

Current fight boundary of the envelope protection in icing conditions is usually defined by the critical values of state parameters; however, such method does not take the interrelationship of each parameter and the effect of the external disturbance into consideration. This paper proposes constructing the stability boundary of the aircraft in icing conditions through analyzing the region of attraction (ROA) around the equilibrium point. Nonlinear icing effect model is proposed according to existing wind tunnel test results. On this basis, the iced polynomial short period model can be deduced further to obtain the stability boundary under icing conditions using ROA analysis. Simulation results for a series of icing severity demonstrate that, regardless of the icing severity, the boundary of the calculated ROA can be treated as an estimation of the stability boundary around an equilibrium point. The proposed methodology is believed to be a promising way for ROA analysis and stability boundary construction of the aircraft in icing conditions, and it will provide theoretical support for multiple boundary protection of icing tolerant flight.

scholarly journals Thermal modeling of hydrogen storage by absorption in a magnesium hydrides tank

2014 ◽  
Vol 5 ◽  
pp. A21 ◽  
Author(s):  
Karim Lahmer ◽  
Rachid Bessaïh ◽  
Angel Scipioni ◽  
Mohammed El Ganaoui
Keyword(s):  
Hydrogen Absorption ◽  
Numerical Scheme ◽  
Computational Time ◽  
Governing Equations ◽  
Time Step ◽  
Kinetic Reaction ◽  
Fully Implicit ◽  
Temporal Profiles ◽  
Tank Geometry ◽  
Reaction Equations

This paper summarizes numerical results of hydrogen absorption simulated in an axisymmetric tank geometry containing magnesium hydride heated to 300 °C and at moderate storage pressure 1 MPa. The governing equations are solved with a fully implicit finite volume numerical scheme used by a commercial software FLUENT. The effect of the different kinetic reaction equations modeling hydrogen absorption was studied by the introduction of a specific subroutine at each time step in order to consider which one will provide results close to available experimental results. Spatial and temporal profiles of temperature and concentration in hydride bed are plotted. Results show that suitable method for our two-dimensional study is a CV-2D technique because it generates the smallest error especially during the beginning of the reaction. Also, its computational time is the shortest one compared to the other methods.

Galloping response of sector-shape iced eight bundle conductors

2020 ◽  
Vol 47 (10) ◽  
pp. 1201-1213
Author(s):  
Meng-qi Cai ◽  
Lin-shu Zhou ◽  
Qian Xu ◽  
Xiao-hui Yang ◽  
Xiao-hui Liu
Keyword(s):  
Transmission Lines ◽  
Theoretical Basis ◽  
Wind Tunnel Test ◽  
Dynamic Responses ◽  
Test Results ◽  
The Finite Element Method ◽  
Aerodynamic Coefficients ◽  
Aerodynamic Loads ◽  
Natural Modes ◽  
Wind Velocities

Wind tunnel test results of the aerodynamic coefficients of sector-shape iced eight bundle conductors varying with wind attack angles are presented. Then, by means of the user-defined cable elements, the aerodynamic loads are applied on the cable elements of each sub-conductor through the finite element method (FEM). In addition, the galloping responses of sector-shape iced eight bundle conductors are discussed. Finally, galloping responses, including dynamic responses (natural modes and frequencies), galloping orbits, and amplitudes of typical sector-shape iced eight bundle conductor transmission lines in the cases of different span lengths, wind velocities, and angles of wind attack are studied, respectively. These results provide useful references for a theoretical basis for the study of galloping and the technique of anti-galloping in cold regions.

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