Altitude Wind Research Articles

Design Assistant Decision Model for Parafoil Precise Airdrop

Decision capacity and command level is essential for accurate aerial delivery of parafoil. In this paper, we according to the system theory and the modular scheme, put forward the parafoil precision airdrop aided decision model consist ofaircraft flight route model,parafoil maneuvering performance model,high altitude wind field characteristic model, landing terrain environment model, the enemy threat situation model, complex electromagnetic environment simulation mode. Andwe focuses on the aircraft flight route model, landing terrain environment model and the simulation model of high altitude wind. The model can providecertain auxiliary decision information to airdrop commander; can also be used to other specific precision airdrop work.

Predictive Controller for Aircraft Landing under Wind Shear

Low altitude wind shear badly threatens aircrafts’ flight safety. Since flight states change rapidly during flying through wind shear, it is deficient to design an optimization controller by off-line analyse. A ring-vortex microburst wind shear model and B747 aircraft flight dynamics model were built. For glide slope tracking under wind shear, an off-line controller was designed by linear quadratic method. Furthermore, a model predictive controller with sequential optimization was designed. Simulation results show the on-line sequential optimization controller possess better tracking performance.

Multi-mass dynamic model of a variable-length tether used in a high altitude wind energy system

This paper presents a multibody approach to dynamics modelling of a variable-length tether moving through air, in a system where an airborne module generates aerodynamic lift and uses the tether to cyclically drive the winch-generator unit fixed on the ground. The rope is modelled as a series of straight, massless, elastic segments with the rope mass fragments lumped to the segment joints. Individual segment length is constant, with the exception of segment being wound out from the winch, while the number of segments is variable. For the segment being wound out, a special modelling approach is derived. The forces acting on the rope are also concentrated at the joints, thus simplifying computations and facilitating rope aerodynamic drag modelling. The proposed tether dynamics model is integrated into the overall model of controlled power production system and verified by computer simulation. The model is compared with two simpler tether dynamics models also proposed in the paper.

Developments in aviation meteorology

Developments in aviation meteorology

Noise spectra from wind turbines

This paper presents observations of audio noise in frequency range 20–20 000 Hz from wind turbines. The observations were performed around the theoretically calculated 40 dBA noise perimeter around the wind turbine farm at Oxhult, Sweden. This paper describes a newly designed and constructed a field qualified data acquisition system to measure spectra and total noise level of sound from wind turbines. The system has been calibrated at SP Borås. It is shown that it has a flat frequency response and is linear with amplitude and time.The total noise level (as integrated 20–20 000 Hz) is shown to be below 35 dBA (below the reference background noise at 36 dBA) at a 10 m altitude wind speed of 4–5 m/s. The measurements were made along the theoretical 40 dBA border at 8 m/s.It is concluded that the theoretical 40 dBA border seems reasonable calculated if the manufacturer specifications are used to extrapolate the sound level to correspond to 8 m/s at 10 m. Our data indicate that a simple sound propagation model is sufficient since the sound level is more affected by the nearby environment than the large scale forest structure. Also, the large scale forestry structure is bound to change with time and the error bars of measurements on total sound level are about 1 dBA, which is larger than any fine tuning with a more sophisticated model. More care should be taken to model the reflections from walls and other obstacles close to the microphones.The distribution of the spectral noise level around the turbine farm suggests that the noise originates from individual wind turbines closest to the measurement location rather than from the wind turbine farm as a whole. The spectra show narrow band spectral line features which do not contribute significantly to the total noise at this level. The narrow band features are only detectable at very long integration time and at 1 Hz spectral resolution. The spectral features are typical to originate from mechanical noise.The spectral acquisition method described in this paper can be used as a field qualified system for sound measurements in forest areas. The high spectral resolution is a viable remote diagnostic method for mechanical faults in the turbine machinery. Future work will concentrate on these two areas.

Special Issue on Seventy Years of Aerospace Research and Technology Excellence at NASA Glenn Research Center

Special Issue on Seventy Years of Aerospace Research and Technology Excellence at NASA Glenn Research Center

Estimating the spatial distribution of high altitude wind energy potential in Southeast Europe

High altitude winds are considered to be, together with solar energy, the most promising renewable energy source in the future. Till date, there are no yet solutions available on the market but various concepts for utilizing high altitude winds are under research and are expected to be fully operational within next few years.In this paper, the potential of high altitude wind energy will be investigated for the SEE (Southeast Europe) region and mapped using available data and technologies. The data available from NCEP/DOE analysis will be used in terms of obtaining the high altitude wind speeds for the span of 30 years, from 1980 to 2010, which are then processed for easier visualization. The obtained data is plotted against the available geographic data which could limit the positioning of the system (settlements, traffic…). The result of this work will display the “optimal” locations for these kinds of facilities for the Southeast Europe region. Such map could be beneficial for all future plans of utilizing this high altitude winds as a power source.

High Altitude Bird Migration at Temperate Latitudes: A Synoptic Perspective on Wind Assistance

At temperate latitudes the synoptic patterns of bird migration are strongly structured by the presence of cyclones and anticyclones, both in the horizontal and altitudinal dimensions. In certain synoptic conditions, birds may efficiently cross regions with opposing surface wind by choosing a higher flight altitude with more favourable wind. We observed migratory passerines at mid-latitudes that selected high altitude wind optima on particular nights, leading to the formation of structured migration layers at varying altitude up to 3 km. Using long-term vertical profiling of bird migration by C-band Doppler radar in the Netherlands, we find that such migration layers occur nearly exclusively during spring migration in the presence of a high-pressure system. A conceptual analytic framework providing insight into the synoptic patterns of wind assistance for migrants that includes the altitudinal dimension has so far been lacking. We present a simple model for a baroclinic atmosphere that relates vertical profiles of wind assistance to the pressure and temperature patterns occurring at temperate latitudes. We show how the magnitude and direction of the large scale horizontal temperature gradient affects the relative gain in wind assistance that migrants obtain through ascending. Temperature gradients typical for northerly high-pressure systems in spring are shown to cause high altitude wind optima in the easterly sectors of anticyclones, thereby explaining the frequent observations of high altitude migration in these synoptic conditions. Given the recurring synoptic arrangements of pressure systems across temperate continents, the opportunities for exploiting high altitude wind will differ between flyways, for example between easterly and westerly oceanic coasts.

濒危高原植物羌活化学成分与生态因子的相关性

Notopterygii Rhizoma Et Radix,a plateau endangered medicinal herbs,is the rhizoma of umbelliferous plant N. incisum and N. franchetii. This paper aim to investigate the correlation between ecological factors of production area of Notopterygii Rhizoma Et Radix,and the major active components contents. HPLC was established to analyze the contents of two chemicals( Notopterol,Isoimperatorin). Data of 9 ecological factors,including air pressure,annual average temperature, maximum annual temperature,minimum annual temperature,annual precipitation,average wind speed,sunshine duration, and relative humidity,were obtained from the China Meteorological Data Service Network. And then,the relationship of chemical compounds and ecological factors were analyzed Partial Least Squares( PLS) and Redundancy Analysis( RDA) methods. Chemical determination shows the content of Notopterol are higer than Isoimperatorin in N. incisum,but the content of Notopterol are belower than Isoimperatorin in N. franchetii.. Analyses by PLS and RDA,sunshine duration is the most important eco-factor and is positive correlation with Notopterol in N. incisum. And the second and third is annual precipitation and elevation. Annual precipitation is the biggest eco-factor and is negative correlation with Isoimperatorin in N. incisum,Second one is temperature. However,in N. franchetii,altitude,annual precipitation and average wind speed are principal factors that influencing on Notopterol and positively correlation with it. Meanwhile these three main influence factors have significant negative correlation with Isoimperatorin. The result indicated that sunshine duration altitude and annual precipitation are primary factors influencing accumulation of chemical compounds in Notopterygii Rhizoma Et Radix, sunshine duration enhance the accumulation of chemical compounds in Notopterygii Rhizoma Et Radix,the higher altitude, and more annual precipitation means better accumulation of the Notopterol,On the contrary,Isoimperatorin is negative with these two eco-factors. Producing regionalization based on chemical contents by principal component analysis displayed that Sichuan was the best optimal area for N. incisum and N. franchetii. Our data provide scientific proof for protection and cultivation of endangered plateau Notopterygii Rhizoma Et Radix.

Kite Modeling for Higher Altitude Wind Energy

Among the renewable energy sources, high altitude wind power is gaining increased attention for its better strength, steadiness, and coverage compared to the traditional ground-based wind power with wind turbines. However, unlike the latter, the technology for high altitude wind is still immature and the works on the field are mostly empirical. In our research, we try to set up a framework about force analysis and provide a stepping stone for other kite energy researchers and engineers to develop more efficient systems. In this paper, we analyzed and experimentally verified the effects of acting aerodynamic forces at different angles of attack ranging from 0° to 90°. We also studied the power potentials of a kite corresponding to these varying forces. The work will enable a researcher or engineer to design a more feasible and more efficient kite power system with better understanding of the kite dynamics.

High Altitude Cycloidal Wind Turbine System Design

As a novel high altitude wind power system, this paper describes a cycloidal wind turbine mounted on a tethered balloon or parafoil. The rotor system was designed conceptually and the performance was estimated. The rotor blade span length is 10 meters and its diameter is 10 meters. When the rotor operates at 1,500 meters above ground, it produces 4.6 times more energy by the balloon tethered model. The parafoil tethered rotor power generation becomes 4.1 times at the same condition, which is a little smaller comparing with the balloon tethered model. The reason is its energy consumption at low wind speed condition to produce supplementary lifting force through mode conversion.

Cost analysis of stratospheric albedo modification delivery systems

We perform engineering cost analyses of systems capable of delivering 1–5 million metric tonnes (Mt) of albedo modification material to altitudes of 18–30 km. The goal is to compare a range of delivery systems evaluated on a consistent cost basis. Cost estimates are developed with statistical cost estimating relationships based on historical costs of aerospace development programs and operations concepts using labor rates appropriate to the operations. We evaluate existing aircraft cost of acquisition and operations, perform in-depth new aircraft and airship design studies and cost analyses, and survey rockets, guns, and suspended gas and slurry pipes, comparing their costs to those of aircraft and airships. Annual costs for delivery systems based on new aircraft designs are estimated to be $1–3B to deliver 1 Mt to 20–30 km or $2–8B to deliver 5 Mt to the same altitude range. Costs for hybrid airships may be competitive, but their large surface area complicates operations in high altitude wind shear, and development costs are more uncertain than those for airplanes. Pipes suspended by floating platforms provide low recurring costs to pump a liquid or gas to altitudes as high as ∼ 20 km, but the research, development, testing and evaluation costs of these systems are high and carry a large uncertainty; the pipe system’s high operating pressures and tensile strength requirements bring the feasibility of this system into question. The costs for rockets and guns are significantly higher than those for other systems. We conclude that (a) the basic technological capability to deliver material to the stratosphere at million tonne per year rates exists today, (b) based on prior literature, a few million tonnes per year would be sufficient to alter radiative forcing by an amount roughly equivalent to the growth of anticipated greenhouse gas forcing over the next half century, and that (c) several different methods could possibly deliver this quantity for less than $8B per year. We do not address here the science of aerosols in the stratosphere, nor issues of risk, effectiveness or governance that will add to the costs of solar geoengineering.

Harvesting high altitude wind energy for power production: The concept based on Magnus’ effect

High altitude winds are considered to be, together with solar energy, the most promising renewable energy source in the future. The concepts based on kites or airfoils are already under development. In this paper the concept of transforming kinetic energy of high altitude winds to mechanical energy by exploiting Magnus effect on airborne rotating cylinders is presented, together with corresponding two-dimensional per-module aerodynamic and process dynamics analysis. The concept is based on a rotating airborne cylinder connected to the ground station with a tether cable which is used for mechanical energy transfer. Performed studies have shown the positive correlation between the wind speed and mechanical energy output. The main conclusion of this work is that the presented concept is feasible for power production.

Analysis on lightning triggering possibility along transmission tethers of high altitude wind energy exploitation system

Recently a new concept of umbrella–ladder combination system to exploit the high altitude wind energy has been proposed. In this system the polyethylene polymer transmission tether plays an important role as the connection between the high altitude wind power absorber and the ground station. To make the concept practical, whether the tether would lead lightning to the ground station is one of the key issues. In this paper, the possibility of the polyethylene polymer transmission tether triggering lightning is studied. Firstly, the lightning environment characteristics are summarized, especially the possible potential distribution and electric field distribution. The charge structure of the thundercloud and the lightning activities which may affect the high altitude wind energy absorber are described. Secondly, the ways of the tether triggering lightning under thunderstorm in static electric field produced by charge accumulated in thundercloud and in impulsive electric field produced by lightning are analyzed. The lightning impulse characteristic of the tether and the influence factors on it are obtained through experiment and the result shows that the critical lightning impulsive breakdown electric field is about 300kV/m. Therefore there is a great possibility that the tether triggering lightning. Finally the simple lightning protection for the system is discussed.

Development of a Robotic Kite to Generate Electricity from Wind

In the pursuit of renewable energy, high altitude wind is gaining increased attention for its better strength, steadiness, and coverage over the ground wind. In this paper, we will describe our development on EHAWK (Electric from High Altitude Wind with Kite), a robotic kite system to generate electricity from wind. So far we have designed and tested several generations of EHAWK systems and gained experiences on harnessing the high altitude wind on both experimental and theoretical fronts.

Role of circulation parameters in long range aerosol transport: Evidence from Winter-ICARB

This study explores the inevitable role of wind parameters such as wind speed, wind convergence and wind vorticity in the long range transport and distribution of aerosols in the winter time atmosphere over the Bay of Bengal (BoB) during the campaign Winter ICARB. MODIS observed aerosol optical depth (AOD), with an excellent agreement with ship borne Microtops AOD, was found to increase over the BoB particularly, in the eastern parts during the course of the campaign. The influence of atmospheric circulation on this increase is examined using the wind field from NCEP reanalysis and computed wind convergence and vorticity for first and second halves (FH and SH) of the campaign along with a back trajectory analysis using HYSPLIT transport and dispersion model. While surface winds over the BoB remained nearly the same throughout the campaign denying the possibility of enhancement in marine aerosol generation, the higher altitude winds altered significantly in SH providing a channel for aerosol transport from the Indian landmass to the BoB in addition to the increased forest fire contribution from south Asia. This suggested mechanism is supported by CALIPSO aerosol extinction profiles over the eastern BoB and the surrounding land masses. Fine particle dominance in MODIS AOD and diminished correlation between ship borne AOD and surface aerosol mass measurements during SH corroborate this inference by indicating the presence of elevated aerosol layers, which can contribute substantially to the radiative effects of the earth–atmosphere system. This study throws light on the importance of wind convergence and vorticity in the investigations on the long range transport and spatial distribution of aerosols.

Robert S. Arrighi. Revolutionary Atmosphere: The Story of the Altitude Wind Tunnel and the Space Power Chambers. xviii + 392 pp., illus., bibl., index. Washington, D.C.: National Aeronautics and Space Administration, 2010. $25 (cloth).

Previous articleNext article No AccessBook ReviewsRobert S. Arrighi. Revolutionary Atmosphere: The Story of the Altitude Wind Tunnel and the Space Power Chambers. xviii + 392 pp., illus., bibl., index. Washington, D.C.: National Aeronautics and Space Administration, 2010. $25 (cloth).Erik M. ConwayErik M. Conway Search for more articles by this author PDFPDF PLUSFull Text Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by Isis Volume 102, Number 4December 2011 Publication of the History of Science Society Article DOIhttps://doi.org/10.1086/664888 Views: 2Total views on this site © 2011 by The History of Science Society. All rights reserved.PDF download Crossref reports no articles citing this article.

Numerical Simulation for Part Effect of Ventilation of Extra-Long Road Tunnel

Er Lang Shan tunnel is the most absolute altitude constructed highway tunnel in china, which is firstly used the semi-transverse ventilation system, is characteristic of extensive length, higher absolute altitude, multivariate climate, two-way traffic and complex wind stream. Based on FEM software CFDesign, the distributed losses, the conflux losses and the shoot of jet fans in the semi-transverse ventilation system of Er Lang Shan highway tunnel are studied by numerical simulation. Part resistance coefficients that numerical simulation of the semi-transverse Ventilation under various work condition needs are obtained.

Design of Probabilistic Pilot Model with Fuzzy Controller for Microburst Escape

Pilot should control the aircraft manually when encountering low altitude wind shear during takeoff and landing. For wind shear escape and flight safety research, an effective human pilot model together with wind shear and flight dynamics model should be built with high fidelity. A skill-based human pilot model was built which can describe pilots’ characteristics such as experiences, skills, emotions, reaction abilities, etc. A fuzzy controller was designed for lateral and longitudinal escape control in pilot model. Since single pilot could not represent a group of pilots’ control behavior, some of the model parameters were set to be stochastic, then the Monte Carlo method was adopted to obtain a numerical approximation of safety analysis results. With the probabilistic pilot model, escape strategies and safety analysis can be studied by simulation with high fidelity.

Safety Analysis of Aircraft Flying through Low Altitude Wind Shear

Low altitude microburst wind shear would do harm to aircrafts’ takeoff and landing. In order to analyze flight safety and advise better escape strategies, a mathematical model was built with high fidelity by a vortex ring based microburst model and a flight dynamics model with wind effects. A human pilot model which can describe characteristics of pilots such as skills, experiences, emotion, etc was embedded into the dynamics model. Since the key parameters of the microburst wind shear model and pilot model were set to be stochastic, the Monte Carlo method was adopted to obtain a numerical approximation of the probability density function of the minimum altitude and the F-factors for flight safety analysis.