Wind tunnel measurements of crown streamlining and drag relationships for several hardwood species

2005 ◽  
Vol 35 (5) ◽  
pp. 1238-1249 ◽  
Author(s):  
Stephan Vollsinger ◽  
Stephen J Mitchell ◽  
Kenneth E Byrne ◽  
Michael D Novak ◽  
Mark Rudnicki
Keyword(s):  
Wind Speed ◽  
Wind Tunnel ◽  
Populus Tremuloides ◽  
Leaf Size ◽  
Frontal Area ◽  
Black Cottonwood ◽  
Red Alder ◽  
Drag Coefficients ◽  
Hardwood Species ◽  
Paper Birch

Understanding tree susceptibility to wind damage is central to natural disturbance and succession studies. Susceptibility depends on the wind loads experienced by trees and their ability to resist these loads. In this study, we investigated the wind force or "drag" acting on the crowns of juvenile specimens of three hardwood species common to northwestern North America, black cottonwood (Populus trichocarpa Torr. & A. Gray), red alder (Alnus rubra Bong.), and paper birch (Betula papyrifera Marsh.). Ten freshly cut crowns of each species were exposed to wind speeds from 4 to 20 m/s in a wind tunnel. At 20 m/s, streamlining reduced the frontal area to 28% of its initial value for black cottonwood, 37% for red alder, and 20% for paper birch. Crown drag coefficients calculated using frontal area in still air varied with wind speed. At 20 m/s they ranged from 0.15 to 0.22 for these species. Drag was proportional to the product of mass and wind speed, and to the product of wind speed squared and wind-speed-specific frontal area. Removing branches by whole-branch pruning had little effect on drag per unit branch mass. To further investigate the effect of leaf size, we also used smaller samples of bigleaf maple (Acer macrophyllum Pursh) and trembling aspen (Populus tremuloides Michx.). Whole-crown drag coefficients did not vary systematically with leaf size, but drag per unit of crown mass increased with leaf size. Bigleaf maple had a higher drag per unit of crown mass than other species.

Olfactory and feeding preferences of Cryptorhynchus lapathi among hosts and nonhosts

2006 ◽  
Vol 138 (3) ◽  
pp. 357-366 ◽  
Author(s):  
Cynthia L. Broberg ◽  
John H. Borden ◽  
Regine Gries
Keyword(s):  
Populus Tremuloides ◽  
Populus Trichocarpa ◽  
Alnus Rubra ◽  
Trembling Aspen ◽  
Feeding Preferences ◽  
Black Cottonwood ◽  
Successful Development ◽  
Red Alder ◽  
Acer Macrophyllum ◽  
Frequent Attack

AbstractIn British Columbia, native willows (Salix spp.) (Salicaceae) and, to a lesser extent, black cottonwood (Populus trichocarpa Torr. & Gray) (Salicaceae) are frequently attacked by the poplar and willow borer, Cryptorhynchus lapathi (L.) (Coleoptera: Curculionidae). Red alder (Alnus rubra Bong.) (Betulaceae), trembling aspen (Populus tremuloides Michx.), and bigleaf maple (Acer macrophyllum Pursh) (Aceraceae) are not attacked. We studied olfaction and feeding preferences in the laboratory and feeding, oviposition, and emergence in the field. Female C. lapathi preferred Scouler's willow (Salix scouleriana Barratt ex Hook.) over all other species by olfaction, but males did not discriminate between Scouler's willow and black cottonwood or trembling aspen. All species elicited at least some attraction in no-choice situations. Willow was generally preferred for feeding, but black cottonwood and red alder were also acceptable, unlike trembling aspen or bigleaf maple. In field caging experiments, adult weevils emerged from willow, black cottonwood, and red alder. We conclude that olfaction and feeding preferences are sufficiently powerful to mediate the frequent attack observed on native willows, the intermediate levels of attack on cottonwood, and the absence of attack on red alder. Successful development on red alder suggests that C. lapathi could expand its host range to include this species.

Wind tunnel measurements of crown streamlining and drag relationships for three conifer species

2004 ◽  
Vol 34 (3) ◽  
pp. 666-676 ◽  
Author(s):  
Mark Rudnicki ◽  
Stephen J Mitchell ◽  
Michael D Novak
Keyword(s):  
Wind Speed ◽  
Wind Tunnel ◽  
Pinus Contorta ◽  
Prediction Models ◽  
Lodgepole Pine ◽  
Tsuga Heterophylla ◽  
Frontal Area ◽  
Thuja Plicata ◽  
Tree Crowns ◽  
Wind Speeds

Estimating the wind force or drag acting on tree crowns is central to understanding both the chronic effects of wind and the calculation of critical wind speed in windthrow prediction models. The classical drag equation is problematic for porous, flexible tree crowns whose frontal area declines as wind speeds increase and branches streamline. Juvenile crowns of three morphologically different conifers, western redcedar (Thuja plicata Donn ex D. Don), western hemlock (Tsuga heterophylla (Raf.) Sarg.), and lodgepole pine (Pinus contorta Dougl. ex Loud.), were exposed to wind speeds from 4 to 20 m/s in a wind tunnel. At 20 m/s, streamlining reduced the frontal area by 54% for redcedar, 39% for hemlock, and 36% for lodgepole pine. Crown drag coefficients calculated using frontal area in still air varied with wind speed. At 20 m/s, they were 0.22, 0.47, and 0.47 for these species, respectively. Drag was proportional to the product of mass and wind speed and also to the product of wind speed squared and wind speed specific frontal area. Lodgepole pine and redcedar had lower drag per unit of branch mass than did hemlock. Removing branches by pruning had little effect on drag per unit branch mass.

Cydia strobilella (Lepidoptera: Tortricidae): antennal and behavioral responses to host and nonhost volatiles

2002 ◽  
Vol 134 (6) ◽  
pp. 793-804 ◽  
Author(s):  
C. Bédard ◽  
R. Gries ◽  
G. Gries ◽  
R. Bennett
Keyword(s):  
Populus Tremuloides ◽  
Betula Papyrifera ◽  
Populus Balsamifera ◽  
Black Cottonwood ◽  
Acer Macrophyllum ◽  
Host Seeking ◽  
Baited Traps ◽  
Seed Cone ◽  
Electroantennographic Detection ◽  
Paper Birch

AbstractFemale spruce seed moths, Cydia strobilella (L.) (Lepidoptera: Tortricidae), oviposit on seed cones of most North American spruces (Picea spp.) (Pinaceae) at the time of pollination, and larvae feed on seeds in the maturing cones. We tested the hypothesis that host-seeking moths respond to volatiles from both host and nonhost trees. In coupled gas chromatographic – electroantennographic detection (GC–EAD) analyses of extracts of spruce seed cone volatiles, > 17 compounds elicited antennal responses from male and female C. strobilella. A blend of seven compounds, including (−)-α-pinene and (−)-β-pinene, α-longipinene and α-humulene, Z3-hexenol, methyl eugenol, and cymen-8-ol, was more attractive to female C. strobilella in laboratory bioassay experiments than the complete seed cone volatile blend, containing these compounds at equivalent quantities and ratios. In GC–EAD analyses of volatile extracts from nonhost angiosperm trees, EAD-activity was associated with compounds present in (almost) every volatile source, including trembling aspen, Populus tremuloides (Michx.) (Salicaceae), paper birch, Betula papyrifera (Marsh.) (Betulaceae), black Cottonwood, Populus balsamifera trichocarpa (Torr. and Gray) (Salicaceae), and bigleaf maple, Acer macrophyllum (Pursh.) (Aceraceae). In a field experiment in the interior of British Columbia, the antennally active nonhost aldehydes, alcohols, and (±)-conophthorin all reduced captures of male C. strobilella in pheromone-baited traps. Collectively, our data suggest that host selection by C. strobilella is mediated, in part, by semiochemicals from both host and nonhost trees.

Extremely Gusty Winds from a Viewpoint of Aerodynamic Force

2020 ◽  
Author(s):  
Junji Maeda ◽  
Takashi Takeuchi ◽  
Eriko Tomokiyo ◽  
Yukio Tamura
Keyword(s):  
Wind Speed ◽  
Wind Tunnel ◽  
Rise Time ◽  
Aerodynamic Force ◽  
Step Function ◽  
Object Size ◽  
Aerodynamic Forces ◽  
Wind Force ◽  
Wind Observation

To quantitatively investigate a gusty wind from the viewpoint of aerodynamic forces, a wind tunnel that can control the rise time of a step-function-like gust was devised and utilized. When the non-dimensional rise time, which is calculated using the rise time of the gusty wind, the wind speed, and the size of an object, is less than a certain value, the wind force is greater than under the corresponding steady wind. Therefore, this wind force is called the “overshoot wind force” for objects the size of orbital vehicles in an actual wind observation. The finding of the overshoot wind force requires a condition of the wind speed recording specification and depends on the object size and the gusty wind speed.

Aerodynamics of Cyclist Posture, Bicycle and Helmet Characteristics in Time Trial Stage

2012 ◽  
Vol 28 (3) ◽  
pp. 317-323 ◽  
Author(s):  
Vincent Chabroux ◽  
Caroline Barelle ◽  
Daniel Favier
Keyword(s):  
Statistical Analysis ◽  
Wind Tunnel ◽  
Drag Coefficient ◽  
Drag Force ◽  
Time Trial ◽  
Frontal Area ◽  
Significant Gain ◽  
Upper Limbs ◽  
Force Coefficient ◽  
Coefficient Reduction

The present work is focused on the aerodynamic study of different parameters, including both the posture of a cyclist’s upper limbs and the saddle position, in time trial (TT) stages. The aerodynamic influence of a TT helmet large visor is also quantified as a function of the helmet inclination. Experiments conducted in a wind tunnel on nine professional cyclists provided drag force and frontal area measurements to determine the drag force coefficient. Data statistical analysis clearly shows that the hands positioning on shifters and the elbows joined together are significantly reducing the cyclist drag force. Concerning the saddle position, the drag force is shown to be significantly increased (about 3%) when the saddle is raised. The usual helmet inclination appears to be the inclination value minimizing the drag force. Moreover, the addition of a large visor on the helmet is shown to provide a drag coefficient reduction as a function of the helmet inclination. Present results indicate that variations in the TT cyclist posture, the saddle position and the helmet visor can produce a significant gain in time (up to 2.2%) during stages.

Aerodynamics of Gliding Flight of a Black Vulture Coragyps Atratus

1970 ◽  
Vol 53 (2) ◽  
pp. 363-374 ◽  
Author(s):  
G. CHRISTIAN PARROTT
Keyword(s):  
Wind Tunnel ◽  
Wing Area ◽  
Drag Coefficients ◽  
Wing Span ◽  
Drag Forces ◽  
Gliding Flight ◽  
Black Vulture ◽  
Air Speed

1. A black vulture (mass = 1.79 kg) gliding freely in a wind tunnel adjusted its wing span and wing area as its air speed and glide angle changed from 9.9 to 16.8 m/s and from 4.8° to 7.9°, respectively. 2. The minimum sinking speed was 1.09 m/s at an air speed of 11.3 m/s. 3. The maximum ratio of lift to drag forces was 11.6 at an air speed of 13.9 m/s. 4. Parasite drag coefficients for the vulture are similar to those for conventional airfoils and do not support the contention that black vultures have unusually low values of parasite drag.

Study on the Relation Between Side Ratios of Rectangular Cross Sections and Secondary Vortices at Trailing Edge in Motion-Induced Vortex Excitation

2017 ◽  
Author(s):  
Kazutoshi Matsuda ◽  
Kusuo Kato ◽  
Kouki Arise ◽  
Hajime Ishii
Keyword(s):  
Wind Speed ◽  
Wind Tunnel ◽  
Cross Sections ◽  
Leading Edge ◽  
Trailing Edge ◽  
Wind Speeds ◽  
Smoke Flow ◽  
Flow Visualizations ◽  
Institute Of Technology ◽  
Secondary Vortices

According to the results of conventional wind tunnel tests on rectangular cross sections with side ratios of B/D = 2–8 (B: along-wind length (m), D: cross-wind length (m)), motion-induced vortex excitation was confirmed. The generation of motion-induced vortex excitation is considered to be caused by the unification of separated vortices from the leading edge and secondary vortices at the trailing edge [1]. Spring-supported test for B/D = 1.18 was conducted in a closed circuit wind tunnel (cross section: 1.8 m high×0.9 m wide) at Kyushu Institute of Technology. Vibrations were confirmed in the neighborhoods of reduced wind speeds Vr = V/fD = 2 and Vr = 8 (V: wind speed (m/s), f: natural frequency (Hz)). Because the reduced wind speed in motion-induced vortex excitation is calculated as Vr = 1.67×B/D = 1.67×1.18 = 2.0 [1], vibrations around Vr = 2 were considered to be motion-induced vortex excitation. According to the smoke flow visualization result for B/D = 1.18 which was carried out by the authors, no secondary vortices at the trailing edge were formed, although separated vortices from the leading edge were formed at the time of oscillation at the onset wind speed of motion-induced vortex excitation, where aerodynamic vibrations considered to be motion-induced vortex excitation were confirmed. It was suggested that motion-induced vortex excitation might possibly occur in the range of low wind speeds, even in the case of side ratios where secondary vortices at trailing edge were not confirmed. In this study, smoke flow visualizations were performed for ratios of B/D = 0.5–2.0 in order to find out the relation between side ratios of rectangular cross sections and secondary vortices at trailing edge in motion-induced vortex excitation. The smoke flow visualizations around the model during oscillating condition were conducted in a small-sized wind tunnel at Kyushu Institute of Technology. Experimental Reynolds number was Re = VD/v = 1.6×103. For the forced-oscillating amplitude η, the non-dimensional double amplitudes were set as 2η/D = 0.02–0.15. Spring-supported tests were also carried out in order to obtain the response characteristics of the models.

scholarly journals Design and installation of vibration testing system for spring mounted model of wing

2015 ◽  
Vol 18 (4) ◽  
pp. 179-187
Author(s):  
Anh Tien Tran ◽  
Nam Ngoc Linh Hoang
Keyword(s):  
Wind Speed ◽  
Wind Tunnel ◽  
Theoretical Analysis ◽  
Testing System ◽  
Vibration System ◽  
Ultrasonic Sensors ◽  
Wing Model ◽  
Suitable Area ◽  
Naca 0015 ◽  
Theoretical Dynamics

This paper presents the design and installation of measuring vibration system in wind tunnel area 1m x 1m. The theoretical analysis of the spring structure in this model help we possible to design a system for wind tunnel by yourself with suitable area, wind speed as well as survey wing model to obtain results desire. This system helps us to observe the oscillation of wing survey by eyes, but to know exactly how wing fluctuates, also the pitching angle of wing, we use ultrasonic sensors to measure the distance variation, will be presented in more detail in the text. At the same time, the article also shows how to make a simple and durable wing model with NACA 0015 airfoil - wing model will be surveyed ranged in system above. The aerodynamic phenomena affect to the vibration of the wing are also mentioned and overcome in the design of the wing. Finally we process the data after measured to see the similarities between the experiment and the theoretical dynamics of aviation.

scholarly journals PENELITIAN MEKANISME STALL AKIBAT PERKEMBANGAN GELEMBUNG SEPARASI PADA SAYAP NACA 0017 SECARA EKSPERIMEN DI TEROWONGAN ANGIN SUBSONIK

2010 ◽  
Vol 2 (2) ◽  
Author(s):  
Agus Aribowo
Keyword(s):  
Reynolds Number ◽  
Wind Speed ◽  
Wind Tunnel ◽  
Wind Tunnel Experiment ◽  
Effect Mechanism ◽  
Subsonic Wind Tunnel

This paper presents the results of investigation the separation buble which growing and burst on aerofoil NACA 0017 with effect mechanism of stall in the subsonic wind tunnel. Experiment have done on wind speed 20 m per s and 30 m per s. The data pecked from the orifice of pressure with interval 2 degree until stall position. The result was separation buble which growing on the airfoil, going to ahead of airfoil together with increasing the Reynolds number. After touching, the flow appeared to separate from the upper airfoil without reattachment.

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