Delta Wing-Fuselage Interactions - Experimental Study

2011 ◽  
Vol 274 ◽  
pp. 43-52
Author(s):  
I. Boumrar ◽  
A. Ouibrahim
Keyword(s):  
Experimental Study ◽  
Subsonic Flow ◽  
Delta Wing ◽  
Aerodynamic Characteristics ◽  
Apex Angle ◽  
Delta Wings ◽  
Mean Velocity ◽  
Cylindrical Form ◽  
The Mean ◽  
The Impact

Experiments were conducted on thin delta wings to investigate, for subsonic flow, the effect of both privileged apex angle values and the wing-fuselage interactions on the aerodynamic characteristics, i.e. the distribution of the defect pressure on the extrados, the drag and the lift coefficients. For this purpose, several delta wing models of various apex angle (β = 75, 80 and 85°) were realized and tested without and with fuselages of cylindrical form, with diameters of 20 and 30 mm, downstream the apex and appropriately disposed on the extrados. The impact of the apex angle as well as the interaction on the defect pressure were specially considered along the apex vortices where the pressure defect is usually maximum. The above mentioned effects were investigated via the variations of the mean velocity in the wind tunnel and the incidence (attack) angle.

scholarly journals Endoscopic vein harvesting Impact of learning curve on results and rehabilitation

2005 ◽  
Vol 64 (2) ◽  
Author(s):  
Alessandro Piccardo ◽  
Luigi Martinelli ◽  
Giancarlo Passerone
Keyword(s):  
Learning Curve ◽  
Left Internal Mammary Artery ◽  
Consecutive Series ◽  
Short Term ◽  
Mean Velocity ◽  
Reliable Technique ◽  
Endoscopic Vein Harvesting ◽  
The Mean ◽  
The Impact ◽  
Vein Harvesting

Background: The tendency of modern surgery is towards the reduction of invasiveness. The aim of this study is to evaluate the impact of the learning curve, the reliability, the short term results and the advantages in terms of rapid rehabilitation of endoscopic vein harvesting (EVH) in a consecutive series of 20 patients operated on of aorto-coronary bypass surgery. Methods: Between February and June 2005, 20 patients between 61 e 82 years of age underwent EVH with the use of Vasoview® 5 (Guidant Corporation, Indianapolis, USA). To evaluate the impact of learning curve on the total operative time, patients were divided in 4 chronologically consecutive groups (G1, G2, G3, G4). Intraoperative characteristics and short term results were evaluated. Results: The mean velocity and the mean time of harvesting in G4 were 0,68 cm/min and 45 min. respectively, similar to the time required for a scheletonized left internal mammary artery harvesting. In the first 5 patients 2 conversions were required, one of them related to the EVH technique. No bleeding, functional impairment or infective complications are reported. Active mobilization was possible in every case in the first post-operative day. Conclusions: EVH is a reliable technique and the learning curve can be limited to the first 5 cases. The foreseeble reduction of infectious complications, the absence of pain and the immediate mobilization of the leg allow a rapid and effective rehabilitation.

scholarly journals Balance Tests in Pre-Adolescent Children: Retest Reliability, Construct Validity, and Relative Ability

2020 ◽  
Vol 17 (15) ◽  
pp. 5474
Author(s):  
Vedrana Sember ◽  
Janja Grošelj ◽  
Maja Pajek
Keyword(s):  
Construct Validity ◽  
Mean Amplitude ◽  
Body Sway ◽  
Mean Velocity ◽  
Eyes Closed ◽  
Relative Ability ◽  
Balance Tests ◽  
Balance Ability ◽  
The Mean ◽  
The Impact

Balance is an essential prerequisite for the normal physical development of a child. It consists of the ability to maintain the body’s centre of mass over its base of support, which is enabled by automatic postural adjustments, and maintain posture and stability in various conditions and activities. The present study aimed to determine the measurement characteristics (reliability and concurrent validity) and the relative ability of balance tests and different motor tests in healthy 11-year-olds. We also evaluated the impact of vision on balance ability. Our results showed high interrater reliability (from 0.810 to 0.910) and confirmed the construct validity of the included balance tests. Girls performed significantly better than boys in laboratory tandem stance in following balance components: total sway path with eyes open (BSEO) (t = 2.68, p = 0.01, effect size (ES) = 0.81), total body sway with eyes closed of centre of pressure (CoP) displacement in the a-p direction (BSEC) (t = 1.86, p = 0.07, ES = 0.57), mean velocity of CoP displacements (VEO) (t = 2.67, p = 0.01, ES = 0.83), mean amplitude of CoP displacements in the a-p direction (AapEO) (t = 3.38. p = 0.00, ES = 1.01) and in mean amplitude of CoP displacements in the m-l direction (AmlEO) (t = 3.68, p = 0.00, ES = 1.19). With eyes closed, girls performed significantly better (t = 2.28, p = 0.03, ES = 0.70) than boys did in the mean amplitude of COP displacements in the a-p direction (AapEO) and significantly better (t = 2.37, p = 0.03, ES = 0.71) in the mean amplitude of COP displacements in the m-l direction (AmlEC). Insignificant correlations between different balance tests, except for a correlation between the flamingo test and one-leg stance on a low beam (r = 0.558, p < 0.01), show that each test assesses different aspects of balance ability; therefore, balance cannot be assessed with a single test.

Aerodynamic characteristics of delta wing–body combinations at high angles of attack

1994 ◽  
Vol 98 (975) ◽  
pp. 159-170 ◽  
Author(s):  
P. R. Viswanath ◽  
S. R. Patil
Keyword(s):  
Vortex Breakdown ◽  
Delta Wing ◽  
Aerodynamic Characteristics ◽  
Surface Flow ◽  
Flow Visualisation ◽  
Symmetric Flow ◽  
Gradual Process ◽  
Wing Sweep ◽  
The Mean ◽  
High Angles Of Attack

AbstractAn experimental study investigating the aerodynamic characteristics of generic delta wing-body combinations up to high angles of attack was carried out at a subsonic Mach number. Three delta wings having sharp leading edges and sweep angles of 50°, 60° and 70° were tested with two forebody configurations providing a variation of the nose fineness ratio. Measurements made included six-component forces and moments, limited static pressures on the wing lee-side and surface flow visualisation studies. The results showed symmetric flow features up to an incidence of about 25°, beyond which significant asymmetry was evident due to wing vortex breakdown, forebody vortex asymmetry or both. At higher incidence, varying degrees of forebody-wing vortex interaction effects were seen in the mean loads, which depended on the wing sweep and the nose fineness ratio. The vortex breakdown on these wings was found to be a gradual process, as implied by the wing pressures and the mean aerodynamic loads. Effects of forebody vortex asymmetry on the wing-body aerodynamics have also been assessed. Comparison of Datcom estimates with experimental data of longitudinal aerodynamic characteristics on all three wing-body combinations indicated good agreement in the symmetric flow regime.

scholarly journals The Impact of Teaching Oriental Music using Blended Learning Approach: An Experimental Study

2019 ◽  
Vol 16 (Number 1) ◽  
pp. 81-103
Author(s):  
Chamila Nishanthi Edward ◽  
David Asirvatham ◽  
Gapar Johar
Keyword(s):  
Experimental Study ◽  
Sri Lanka ◽  
Learning Environment ◽  
Blended Learning ◽  
Secondary Level ◽  
Control Group ◽  
Control Groups ◽  
The Mean ◽  
The Impact ◽  
Experimental Group

Purpose - The purpose of this experimental study is to investigate the impact of teaching Oriental Music using Blended Learning (BL) approach for the students of senior secondary level in Sri Lanka specifically focusing on their achievement on required competencies of Oriental Music at Ordinary Level. The study analyzes the academic performance of students with detailed comparison of BL environment and traditional learning environment. Authors propose the application of BL approach to teach Oriental Music and study its impact on improvement of students’ competency. The study conducted with the application of a mixed instructional design model of objectivist and constructivist approaches for the design of the blended learning course in a student centred learning environment. Methodology - The study was directed by using true experimental study design with pretest and posttest control groups. BL was applied to the experimental group and the traditional instruction method was applied to control group. 9 schools from Colombo district were randomly selected for the experimental and control groups covering all the three existing school types of Sri Lanka. The study group consisted of 360 students of Grade 10 and Grade 11 who has been studying Oriental Music as a subject for General Certificate of Education Ordinary Level. To analyze the data Descriptive statistics, Paired samples t test, Independent samples t test were utilized. Findings - The findings of the experiment indicated that students who has studied Oriental Music under BL strategy showed a significant improvement in their music academic performances after the intervention. The mean post-test of the experimental group was 71.75 which is significantly higher than the mean control group which was 52.07. The mean difference was 19.68 1.91. Hence, there is a statistically significant increase in the performance of students who studied Oriental Music under blended learning. Thus, it is clearly evident that the blended instruction was effective. Significance - This study indicated a positive platform to mould and cater the entire teaching learning process by introducing BL strategy to Sri Lankan secondary education system and fulfilled an existing research gap by utilizing BL to teach highly traditional abstract art. Results of the study contributes to the curriculum designing field with novel ideas to adapt blended instructions to teach secondary level students effectively.

Impact of Gurney Flaplike Strips on the Aerodynamic and Vortex Flow Characteristic of a Reverse Delta Wing

2016 ◽  
Vol 138 (6) ◽  
Author(s):  
T. Lee
Keyword(s):  
Vortex Flow ◽  
Delta Wing ◽  
Lift Coefficient ◽  
Leading Edge ◽  
Aerodynamic Characteristics ◽  
Force Balance ◽  
Vortex Control ◽  
Lift Curve ◽  
Lift And Drag ◽  
The Impact

The impact of Gurney flaplike strips, of different geometric configurations and heights, on the aerodynamic characteristics and the tip vortices generated by a reverse delta wing (RDW) was investigated via force-balance measurement and particle image velocimetry (PIV). The addition of side-edge strips (SESs) caused a leftward shift of the lift curve, resembling a conventional trailing-edge flap. The large lift increment overwhelmed the corresponding drag increase, thereby leading to an improved lift-to-drag ratio compared to the baseline wing. The lift and drag coefficients were also found to increase with the strip height. The SES-equipped wing also produced a strengthened vortex compared to its baseline wing counterpart. The leading-edge strips (LESs) were, however, found to persistently produce a greatly diffused vortex flow as well as a small-than-baseline-wing lift in the prestall α regime. The downward LES delivered a delayed stall and an increased maximum lift coefficient compared to the baseline wing. The LESs provide a potential wingtip vortex control alternative, while the SESs can enhance the aerodynamic performance of the RDW.

scholarly journals Experimental study on the mean velocity profile in the high Reynolds number turbulent pipe flow

2015 ◽  
Vol 81 (826) ◽  
pp. 15-00091-15-00091 ◽  
Author(s):  
Yuki WADA ◽  
Noriyuki FURUICHII ◽  
Yoshiya TERAO ◽  
Yoshiyuki TSUJI
Keyword(s):  
Experimental Study ◽  
Reynolds Number ◽  
Velocity Profile ◽  
Pipe Flow ◽  
High Reynolds Number ◽  
Turbulent Pipe Flow ◽  
Mean Velocity ◽  
The Mean ◽  
High Reynolds

Investigation on lift characteristics of a double-delta wing pitching in various reduced frequencies

2021 ◽  
pp. 095441002199220
Author(s):  
Tianxiang Hu ◽  
Yue Zhao ◽  
Peiqing Liu ◽  
Qiulin Qu ◽  
Hao Guo ◽  
...  
Keyword(s):  
Delta Wing ◽  
Lower Surface ◽  
Sweep Angle ◽  
Delta Wings ◽  
Surface Pressure Distribution ◽  
Reduced Frequency ◽  
Wing Sweep ◽  
The Difference ◽  
The Impact ◽  
Double Delta Wing

The unsteady lift characteristics of a double-delta wing were studied using both experimental and numerical approaches, which were also compared with a single-delta wing with the same main wing sweep angle. It was found that by increasing the reduced frequency of pitching, the hysteresis effect of lift was magnified. Moreover, in the high reduced frequency case k = 0.48, the difference between the lift coefficients of single- and double-delta wings became rather subtle. The wing surface pressure distribution results indicated the flow phenomenon of dramatic lift losses was due to the effect of lower surface suction during the wing being pitched downstroke. It was observed that, as the reduced frequency became sufficiently high, the virtual camber effect induced by pitching could dominate the flow field, which would mitigate the impact of wing geometry on the lift characteristics.

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