A Study on Aerodynamics and Stability Characteristics of a Bell-Shaped Span-Load Wing

The existence of the new bell-shaped span-load wing is said to has the best lift distribution especially comparing to the elliptical wing. Bell-shaped span-load wing is designed by configuring the twist of the wing. However, the information on the aerodynamic and stability characteristics of the bell-shaped span-load wing is limited. Thus, the main purpose of the research is to evaluate the aerodynamic and stability characteristic to strengthen the claim of the capability of bell-shaped span-load wing in producing minimum induced drag. As the research is expected to be beneficial to the aviation design team, detailed information regarding the lift distribution as well as the induced drag produced is analysed at the optimum angle of attack and the results is further explained in this research. The numerical method for the analysis is done by using Lifting Line Theory (LLT) in the XFLR5 software which can analyse the wings of aircraft in terms of its aerodynamic and stability characteristic. Then, the comparison of the aerodynamic characteristics for bell-shaped span-load, elliptical span-load and tapered wing done in this research is to strengthen the appeal made stating that the bell-shaped span-load wing is the best type of wing ever existed and may replace the elliptical wing as the best wing shape with aerodynamically most efficient. The research has proven that along the wingspan, the bell-shaped span-load wing produced the lowest and minimum induced drag when being compared. At the optimum angle of attack of bell-shaped span-load wing, though the lift produced is slightly lower than the elliptical and tapered wing, the difference in the induced drag is obvious as bell-shaped span-load wing produces induced drag that is lower than 0. In other words, starting from the semi span of the wing to the wingtip, the bell-shaped span-load wing managed to be the most aerodynamically efficient wing.

Recommended angle of a modular dynamic façade in hot-arid climate: daylighting and energy simulation

PurposeThe modular dynamic façade (MDF) concept could be an approach in a comfort-centric design through proper integration with energy-efficient buildings. This study focuses on obtaining and/or calculating an efficient angle of the MDF, which would lead to the optimum performance in daylight availability and energy consumption in a single south-faced official space located in the hot-arid climate of Yazd, Iran.Design/methodology/approachThe methodology consists of three fundamental parts: (1) based on previous related studies, a diamond-based dynamic skin façade was applied to a south-faced office building in a hot-arid climate; (2) the daylighting and energy performance of the model were simulated annually; and (3) the data obtained from the simulation were compared to reach the optimum angle of the MDF.FindingsThe results showed that when the angle of the MDF openings was set at 30°, it could decrease energy consumption by 41.32% annually, while daylight simulation pointed that the space experienced the minimum possible glare at this angle. Therefore, the angle of 30° was established as the optimum angle, which could be the basis for future investment in responsive building envelopes.Originality/valueThis angular study simultaneously assesses the daylight availability, visual comfort and energy consumption on a MDF in a hot-arid climate.

Direct design process of aerodynamic profiles using the Joukowsky transformation

This document shows the results of a part of the direct design process of airfoils. The research and design of these geometric shapes are of great relevance for their application in aerodynamic devices, since, if a wing profile with a great aerodynamic fineness is developed, the efficiency of the devices that have this geometric shape will be improved on its wings, propellers, etc. This project started from two analytical processes, the first was to obtain the shape of the wing profiles through the Joukowsky transformation, later the pressure distribution of each aerodynamic profile was obtained through the methodology developed by Theodorsen, the profiles that achieved optimal results were subjected to the third and last analysis in the Qblade software, this software allows to find the angle of attack that produces the maximum aerodynamic fineness, in addition to an approximation to the lift and drag coefficients, in this way several curved and aerodynamic profiles were obtained. Various thicknesses whose aerodynamic fines range between 100 and 250 at the optimum angle of attack.

Theoretical Deduction of the Optimum Tilt Angles for Small-Scale Linear Fresnel Reflectors

A theoretical justification and computation of the optimum values of the two longitudinal tilt angles of a small-scale linear Fresnel reflector is provided. The optimum angle of the mobile structure is proved to be half the latitude of the geographic location, while the optimum angle of the secondary reflector system is proved to be equal to that latitude. Brute-force verification is carried out for five EU cities, each in one of the five European climate zones.

Influence of the Welding Angle on the Mechanical Behavior of Plates obtained by the Tailor Welded Blank (TWB) Process

Tailor Welded Blank (TWB) is a top-welding technique (by unconventional processes) of sheets of different specifications (materials, thicknesses and/or coatings). Because it allows localised distribution of mechanical properties and mass, it can optimise the relationship between structural rigidity and total weight. The great challenge of this technique is to combine two processes with completely different demands, welding and mechanical forming. This work investigates the mechanical behavior of sheets obtained by the Tailor-blank process from the determination of the optimum angle. We performed tensile tests on sheets with different weld line inclinations, as the general objective is to consolidate knowledge about the process, characterise the conditions for sheet formation obtained by the technique, in a safe conformation range, with complex contours, dimensional qualities and free of catastrophic failure. Steel sheets, interstitial free (IF), of 1.10mm and 0.65mm thick were used. The TWB was applied with a welding line oriented from 0º to 90º (ranging from 15° to 15°). The optimum angle obtained was 30º, where there was a good relationship between the breaking load, purely tensile and shear stresses, and the total elongation. In relation to the angle of 0º, the optimum angle presented a superior elongation of approximately 40%. It was still possible to notice that the thickness of the plates influenced the optimum angle, even if the LSR (Limit Strength Ratio) is close.

Quality improvement of general anteroposterior radiographic image of vertebral body according to optimum angle of incidence

OBJECTIVE: In this study, we present an appropriate angle of incidence to reduce the distortions in images of L4 and L5 during a general anteroposterior radiograph examination. METHOD: We selected 170 patients who had normal radiological findings among those who underwent anteroposterior and lateral examination for lumbar vertebrae. An optimum angle of incidence wa suggested through the statistical analysis by measuring the lumbar lordosis angle and the intervertebral disc angle in these 170 patients. RESULT: We suggested the incident angle (10.28°) of L4 and the incident angle (23.49°) of L5. We compared the distorted area ratios when the incident angle was 0°, 10°, and 23.5° using the ATOM® phantom. The ratio for the L4 decreased from 14.90% to 12.11% and that of the L5 decreased from 15.25% to 13.72% after applying the angle of incidence. We determined the incident angle (9.34°) of L4 and (21.26°) of L5 below 30° of LLA. Thus, we determined the incident angle (11.21°) of L4 and (25.73°) of L5 above 30° of LLA. CONCLUSION: When you apply the optimum angle of incidence, the distortion of image was minimized and an image between the joints adjacent to the anteroposterior vertebral image with an accurate structure was obtained. As a result, we were able to improve the quality of the image and enhance diagnostic information.

Optimum Angle of Force Production Temporarily Changes Due to Growth in Male Adolescence

The peak increase in lean mass in adolescents is delayed from peak height velocity (PHV), and muscle flexibility temporarily decreases as bones grow. If the decrease in muscle flexibility is caused by muscle elongation, the relationship between the exerted torque and the joint angle could change in adolescents. The purpose of this study was to investigate the change in the optimum angle of force production due to growth. Eighty-eight healthy boys were recruited for this study. Isokinetic knee extension muscle strength of the dominant leg was recorded. The outcome variable was the knee flexion angle when maximal knee extension torque was produced (optimum angle). The age at which PHV occurred was estimated from subjects’ height history. We calculated the difference between the age at measurement and the expected age of PHV (growth age). A regression analysis was performed with the optimal angle of force exertion as the dependent variable and the growth age as the independent variable. Then, a polynomial formula with the lowest p-value was obtained. A significant cubic regression was obtained between optimum angle and growth age. The results suggest that the optimum angle of force production temporarily changes in male adolescence.

ИССЛЕДОВАНИЕ ЭКОЛОГИЧЕСКИХ ПОКАЗАТЕЛЕЙ АВТОТРАКТОРНОГО ДИЗЕЛЯ ПРИ РАБОТЕ НА ПРЕДЕЛЬНЫХ СОСТАВАХ ЭТЭ

Цель исследований экспериментальное определение токсических показателей дизельного двигателя Д-245.5S2 сельскохозяйственного трактора при его работе на этаноло-топливной эмульсии с предельным содержание этанола в смеси. Объект исследования: экспериментальная установка (двигатель Д-245.5S2, электротормозной стенд RAPIDO SAK N670 с балансирной маятниковой машиной). Испытания дизеля проводились в соответствии с ГОСТ 18509-88. Исследования проводились на дизельном топливе и этаноло-топливной эмульсии с содержанием этанола 20 и 50 в смеси. Во время проведения исследований снималась регулировочная характеристика для определения оптимального угла опережения впрыскивания (угол 22 до верхней мертвой точки (ВМТ)). Затем снимались нагрузочные характеристики при частоте вращения коленчатого вала 1800 мин-1 и 1400 мин-1 и скоростная характеристика. Во всех экспериментах производилась фиксация эффективных и экологических показателей. Опираясь на полученные в результате испытаний экспериментальные данные, были установлены зависимости токсических показателей дизеля при его работе на этаноло-топливной эмульсии. Также были выявлены изменения токсичности и дымности отработавших газов при разных составах топлива. Приведены графики нагрузочной характеристики (экологические показатели) работы двигателя на базовом топливе и на этаноло-топливной эмульсии с содержанием 20 и 50 этанола в смеси.The purpose of probes - experimental definition of toxic indicators of diesel engine D-245.5S2 at its work on etanolo-fuel emulsion with limiting the ethanol maintenance in a mixture. Object of probe: experimental installation (engine D-245.5S2, electrobrake stand RAPIDO SAK N670 with balancer by pendular car). Diesel engine tests were spent according to GOST 18509-88. Probes were spent on diesel fuel and etanolo-fuel emulsion with the maintenance of ethanol of 20 and 50 to mixtures. During carrying out of probes the adjusting characteristic, for definition of an optimum angle of an injection advance (a corner 22 to the top dead point (TDP)) acted in film. Then loading characteristics acted in film at rotary speed of a bent shaft of 1800 mines-1 both 1400 mines-1 and the high-speed characteristic. At all experimentals fixing of effective and ecological indicators was made. Leaning against the received experimental data as a result of tests, dependences of toxic indicators of a diesel engine have been established at its work on etanolo-fuel emulsion. Also changes of toxicity and smoke, the fulfilled gases are revealed at different structures of fuel. Schedules of the loading characteristic (ecological indicators) engine works on base fuel and on etanolo-fuel emulsion with the maintenance of 20 and 50 of ethanol in a mixture are resulted.