Control-oriented low-speed dynamic modeling and trade-off analysis of air-breathing aerospace vehicles

2019 ◽  
Vol 20 (12) ◽  
pp. 893-907
Author(s):  
Hai-dong Shen ◽  
Rui Cao ◽  
Yan-bin Liu ◽  
Fei-teng Jin ◽  
Yu-ping Lu
Keyword(s):  
Dynamic Modeling ◽  
Aerospace Vehicles ◽  
Trade Off ◽  
Air Breathing ◽  
Low Speed

scholarly journals Exterior Noise Due to Interaction of Tyre-Thermoplastic Transverse Rumble Strips

2017 ◽  
Vol 42 (3) ◽  
pp. 449-457 ◽  
Author(s):  
Zaiton Haron ◽  
Mohd Hanifi Othman ◽  
Lim Meng Hee ◽  
Khairulzan Yahya ◽  
Mohd Rosli Hainin ◽  
...  
Keyword(s):  
Spectral Analysis ◽  
Surface Texture ◽  
Sound Level ◽  
Vehicle Speed ◽  
Noise Generation ◽  
Octave Band ◽  
Trade Off ◽  
Low Speed ◽  
The Public ◽  
Generation Mechanisms

AbstractTransverse rumble strips (TRS) are a common choice to reduce vehicle speed and increase driver alertness on roadways. However, there is a potential trade-off using them on rural roadway due to the noise problem created when vehicles go over the strips. The present study investigated the noise level, spectral analysis, and the possible noise generation mechanism when the TRS is hit by a vehicle. Tenraised- rumbler (RR) and three-layer-overlapped (TLO) TRS were selected in this study as they have received complaints from the public. Results showed that RR generated a relatively higher noise and impulse at a low speed, and increased sound level in each octave band. Based on these results, RR may irritate human ears even when the vehicle travels at a low speed. It was found that RR increased all noise generation mechanisms of tyre-pavement interaction whilst TLO increased structural resonance, sidewall and surface texture vibration.

scholarly journals Flight in slow motion: aerodynamics of the pterosaur wing

2010 ◽  
Vol 278 (1713) ◽  
pp. 1881-1885 ◽  
Author(s):  
Colin Palmer
Keyword(s):  
Wind Tunnel ◽  
Impact Damage ◽  
Slow Motion ◽  
Trade Off ◽  
Wind Tunnel Tests ◽  
Low Speed ◽  
Dynamic Soaring ◽  
Thin Walled ◽  
First Time

The flight of pterosaurs and the extreme sizes of some taxa have long perplexed evolutionary biologists. Past reconstructions of flight capability were handicapped by the available aerodynamic data, which was unrepresentative of possible pterosaur wing profiles. I report wind tunnel tests on a range of possible pterosaur wing sections and quantify the likely performance for the first time. These sections have substantially higher profile drag and maximum lift coefficients than those assumed before, suggesting that large pterosaurs were aerodynamically less efficient and could fly more slowly than previously estimated. In order to achieve higher efficiency, the wing bones must be faired, which implies extensive regions of pneumatized tissue. Whether faired or not, the pterosaur wings were adapted to low-speed flight, unsuited to marine style dynamic soaring but adapted for thermal/slope soaring and controlled, low-speed landing. Because their thin-walled bones were susceptible to impact damage, slow flight would have helped to avoid injury and may have contributed to their attaining much larger sizes than fossil or extant birds. The trade-off would have been an extreme vulnerability to strong or turbulent winds both in flight and on the ground, akin to modern-day paragliders.

scholarly journals Trade‐off between cost and accuracy in large‐scale surface water dynamic modeling

2017 ◽  
Vol 53 (6) ◽  
pp. 4942-4955 ◽  
Author(s):  
Augusto Getirana ◽  
Christa Peters‐Lidard ◽  
Matthew Rodell ◽  
Paul D. Bates
Keyword(s):  
Surface Water ◽  
Dynamic Modeling ◽  
Large Scale ◽  
Trade Off ◽  
Scale Surface

Investigation of all-speed schemes for turbulent simulations with low-speed features

2017 ◽  
Vol 232 (4) ◽  
pp. 757-770
Author(s):  
Ruofan Du ◽  
Chao Yan ◽  
Feng Qu ◽  
Ling Zhou
Keyword(s):  
Turbulent Flows ◽  
Compressible Flows ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Test Cases ◽  
Aerospace Vehicles ◽  
Low Speed ◽  
Upwind Schemes ◽  
Speed Flow ◽  
Dependent Parameter

Turbulence plays a key role in the aerospace design process. It is common that incompressible and compressible flows coexist in turbulent flows around aerospace vehicles. However, most upwind schemes in compressible solvers were designed to capture shock waves and have been proved to have difficulties in predicting low-speed flow regions. In order to overcome this defect, many all-speed schemes have been proposed. This paper investigates the properties of the all-speed schemes when applying to Reynolds averaged Navier–Stokes simulations with important low-speed features. First, the correctness of our code is validated. Then four test cases are adopted to evaluate the scheme performance, including a Mach 2.85 compression ramp, the NACA 4412 airfoil, a Mach 2.92 ramped cavity and a three-dimensional surface-mounted cube. Grid-converged results from the all-speed schemes show good agreement with the experimental data and remarkable improvement when compared to standard upwind schemes. Moreover, different from the traditional preconditioning methods, the all-speed schemes are simple to realize and free from the cut-off strategy or any problem-dependent parameter. Therefore, they are expected to be widely implemented into compressible solvers and applied to all-speed turbulent flow simulations.

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