Results 81 to 90 of about 178 (131)

Pressure distributions on a cube in a simulated thunderstorm downburst. Part B: moving downburst observations

Journal of Wind Engineering and Industrial Aerodynamics, 2002
C W Letchford
exaly   +2 more sources

Control of an aircraft in downbursts

Journal of Guidance, Control, and Dynamics, 1990
Guidance schemes are designed to approximate the optimal survival and optimal performance paths through downbursts, which were determined in the previous paper. Specifically, climb-rate command following is used to achieve performance, and altitude command following is used to enhance survivability.
Yiyuan Zhao, A. E. Bryson
openaire   +1 more source

Approach guidance in a downburst

Journal of Guidance, Control, and Dynamics, 1992
We present a nonlinear feedback law for safe aircraft penetration through downbursts on landing approach. It is based on following a nominal approach path relative to the ground, subject to a minimum airspeed constraint. The guidance design uses a point-mass aircraft model and considers the flight path to be in the vertical plane.
Yiyuan Zhao, A. E. Bryson
openaire   +1 more source

Pressure distributions on a cube in a simulated thunderstorm downburst—Part A: stationary downburst observations

Journal of Wind Engineering and Industrial Aerodynamics, 2002
Abstract Thunderstorms are responsible for a large amount of wind-induced damage around the world. It is known that the wind characteristics in thunderstorms, particularly downbursts, differ significantly from those of synoptic scale boundary layer winds. This paper describes a study aimed at simulating the flow structure in a downburst and obtaining
M.T Chay, C.W Letchford
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Grid Validations for Downburst Simulations

Applied Mechanics and Materials, 2012
Downbursts, which resulted from the flow downdraft in thunderstorms, have become one of the most destructive disasters to buildings including transmission towers, etc. This disaster has drawn researchers’ interests and progresses have been continuously made by employing test and numerical tools.
Hui Xue Dang, Feng Li Yang, Jing Bo Yang
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Forecasting of Tornadoes and Downbursts

2020
Abstract Tornadoes and downbursts cause extreme wind speeds that often present a threat to human safety, structures, and the environment. While the accuracy of weather forecasts has increased manifold over the past several decades, the current numerical weather prediction models are still not capable of explicitly resolving tornadoes and
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Model of the wind field in a downburst

Journal of Aircraft, 1985
The downburst weather phenomenon produces a flow like that of a jet directed vertically downward at the ground. The resulting velocity field near the ground has been modeled as a classical ideal fluid flow generated by a suitable singularity distribution. The resulting model of horizontal, lateral, and vertical winds near the ground is quite realistic,
Shangxiang Zhu, Bernard Etkin
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Takeoff and landing in a downburst

Journal of Aircraft, 1987
Investigations into landing and takeoff in a downburst are made with a simple wind model based on the flow toward a flat plate. Approaches along a given nominal glide path are analyzed. The influence of the changing wind on the aircraft's demand for energy is calculated. The results are given in energy height errors. Computer simulations of an aircraft
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Optimal paths through downbursts

Guidance, Navigation and Control Conference, 1989
The control of an aircraft's takeoff path through a downburst is presently formulated as a dynamic optimization problem with minimum-altitude constraint and two different performance measures; a landing path through a downburst is also discussed. Paths are determined which, in addition to maximizing an airspeed/altitude combination immediately after ...
Yiyuan Zhao, A. E. Bryson
openaire   +1 more source

The Simulation of Downbursts and its Challenges

Structures 2004, 2004
Numerical simulations are employed to investigate the scale (Reynolds number) dependency and macro-flow dynamics of impinging jets with applications to downburst simulations. It is found that the flow is Reynolds number dependent most probably due to an unstable separation-reattachment near to the wall.
H. Hangan, J.-D. Kim, Z. Xu
openaire   +1 more source