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This work presents a comparative study of design and development, in addition, of analyses of variable span morphing of the tapered wing (VSMTW) for the unmanned aerial vehicle (UAV). The proposed concept consists in the sliding of the inner section into the fixed part along the wing with varying the angle of the inner section inside the fixed part (parallel with the leading edge and the moving-wing axis is coincident to the fixed-wing axis) within two configurations. The wing design is based on a NACA 4412 aerofoil with the root chord of 0.675m and the tip chord of 0.367m for the fixed segment and 0.320m for the moving segment. Morphing wing analysis occurs at three selected locations that have been specified for extending and modifying span length by (25%, 50%, and 75%) of its original length to fulfill various flight mission requirements. The main objective of this paper is to compare the aerodynamic characteristics for several span lengths and sweep angles and to find their most efficient combinations. The wing is optimised for different velocities during all phases of flight (min speed, loiter, cruise, and max speed) which are 17, 34, 51, and 68m/s, respectively. The analyses are performed by computing forces (drag and lift) and moments at various altitudes, such as at the sea level, at 5,000 and 10,000ft. Two-dimensional aerodynamic analyses are carried out using XFLR5 code, and the ANSYS Fluent solver is used for investigating the flow field on the three-dimensional wing structure. It has been observed that a variable span morphing of tapered wing technology with a variable sweep angle can deliver up to 32.93% improved aerodynamic efficiency. This concept design can also be used for the aircraft roll motion technique instead of conventional control devices. Furthermore, the range flight mission increases up to 46.89% when the wing is placed at its full length compared to an original position. Finally, it has been concluded from this study that the wing design is more sensitive to the changing angle of the inner section and more efficient in terms of aerodynamic characteristics. [ABSTRACT FROM AUTHOR]

A fluidic oscillator with a bent outlet nozzle was investigated to find the effects of the bending angle on the characteristics of the oscillator with and without external flow. Unsteady aerodynamic analyses were performed on the internal flow of the oscillator with two feedback channels and the interaction between oscillator jets and external flow on a NACA0015 airfoil. The analyses were performed using three-dimensional unsteady Reynolds-averaged Navier-Stokes equations with a shear stress transport turbulence model. The bending angle was tested in a range of 0–40°. The results suggest that the jet frequency increases with the bending angle for high mass flow rates, but at a bending angle of 40°, the oscillation of the jet disappears. The pressure drop through the oscillator increases with the bending angle for positive bending angles. The external flow generally suppresses the jet oscillation, and the effect of external flow on the frequency increases as the bending angle increases. The effect of external flow on the peak velocity ratio at the exit is dominant in the cases where the jet oscillation disappears.

A fluidic oscillator with a bent outlet nozzle was investigated to find the effects of the bending angle on the characteristics of the oscillator with and without external flow. Unsteady aerodynamic analyses were performed on the internal flow of the oscillator with two feedback channels and the interaction between oscillator jets and external flow on a NACA0015 airfoil. The analyses were performed using three-dimensional unsteady Reynolds-averaged Navier-Stokes equations with a shear stress transport turbulence model. The bending angle was tested in a range of 0–40°. The results suggest that the jet frequency increases with the bending angle for high mass flow rates, but at a bending angle of 40°, the oscillation of the jet disappears. The pressure drop through the oscillator increases with the bending angle for positive bending angles. The external flow generally suppresses the jet oscillation, and the effect of external flow on the frequency increases as the bending angle increases. The effect of external flow on the peak velocity ratio at the exit is dominant in the cases where the jet oscillation disappears. [ABSTRACT FROM AUTHOR]

This study reports on experiments designed to examine the effects of a variably occluded face mask (VOFM) on (a) estimated subglottal pressure (P sub) in normophonic participants and (b) aerodynamic and acoustic characteristics of voice in dysphonic participants. A prospective design was used for experiment 1, and a prospective, randomized cohort design was used for experiment 2. The outlet ports of disposable anesthesia face masks were fitted with plastic caps with variable diameter drilled openings (9.6, 6.4, 3.2, and 1.6 mm) to create a series of mask openings. In experiment 1, P sub was measured in normophonic participants using the face mask during syllable repetitions in unoccluded and variable diameter opening conditions. In experiment 2, aerodynamic and acoustic measures were obtained in a group of dysphonic speakers before and after syllable and speech repetition tasks using the VOFM. In experiment 1, mean P Sub was observed to decrease while using the VOFM in all occlusion conditions versus nonocclusion, with a significant reduction in P sub observed between the baseline and the 6.4 mm condition. In experiment 2, standardized mean differences showed that many dysphonic participants produced reduced P sub , increased airflow, and improved acoustic measures after the use of the VOFM in at least one occlusion condition. Beneficial changes in both aerodynamic and acoustic characteristics of voice may be obtained in dysphonic speakers using a VOFM. By moving the place of occlusion outside of the oral cavity, therapeutic stimuli options may be extended beyond vowel and humming elicitations to syllable and speech contexts and assist with generalization of voice therapy targets to conversational speech. [ABSTRACT FROM AUTHOR]