b number of arc segments within curve CF thrust coefficient CF;w weighted thrust coefficient Cx nozzle length-weight coefficient E numerical error k turbulent kinetic energy, m s−2 L total contour axial length, m Ma Mach number P static pressure, Pa r radius, m TW thrust-to-weight ratio x horizontal distance, m y vertical distance, m ε turbulent dissipation rate, m s−3 θ angle, deg ω specific d...

Compressible gas flow inside a convergent-divergent nozzle and its exhaust plume atdifferent nozzle pressure ratios (NPR) have been numerically studied with severalturbulence models. The numerical results reveal that, the SST k–ω model give the bestresults compared with other models in time and accuracy. The effect of changes in value ofdivergence half-angle (ε ) on the nozzle performance, thru...

This paper presents frictional characteristics of thrust bearing in scroll compressor. The coefficient of friction in thrust bearing was measured by both elemental friction test and loss classification based on the performance test of actual scroll compressor, and investigated frictional characteristics focusing on the behavior of sliding portion which affects the generation of oil film by expe...

compressible gas flow inside a convergent-divergent nozzle and its exhaust plume atdifferent nozzle pressure ratios (npr) have been numerically studied with severalturbulence models. the numerical results reveal that, the sst k–ω model give the bestresults compared with other models in time and accuracy. the effect of changes in value ofdivergence half-angle (ε ) on the nozzle performance, thru...

The current work presents the numerical prediction method to determine small-scale propeller performance. The study is implemented using the commercially available computational fluid dynamics (CFD) solver, FLUENT. Numerical results are compared with the available experimental data for an advanced precision composites (APC) Slow Flyer propeller blade to determine the discrepancy of the thrust c...

Unmanned aerial vehicles are being utilized by numerous groups around the world for various missions. Most of the smaller vehicles that have been developed use commercially-offthe-shelf parts, and little information about the performance characteristics of the propulsion systems is available in the archival literature. In light of this, the aim of the present research was to determine the perfo...

Today’s unmanned aerial vehicles are being utilized by numerous groups around the world for various missions. Most of the smaller vehicles that have been developed use commercially-off-the-shelf parts, and little information about the performance characteristics of the propulsion systems is available in the archival literature. In light of this, the aim of the present research was to determine ...

This experiment was conducted in attempt of improving hydrodynamic efficiency of the propulsion mechanism by installing a spring to the wing so that the opening angle of the wing in one stroke can be changed automatically, compared to the existing method of fixed maximum opening angle in Weis-Fogh type ship propulsion mechanism. Average thrust coefficient was almost fixed with all velocity rati...

A practical flapping wing micro air vehicle should have ability to withstand stochastic deviations of flight velocities. To design a flapping airfoil with this ability, it is necessary to evaluate the impacts of velocity deviations on the flapping performances numerically or analytically. In this paper, the responses of the time-averaged thrust coefficient and the propulsive efficiency with res...

This paper presents the friction and anti-wear characteristics of nano-oil with a mixture of refrigerant oil and carbon nano-particles in the thrust slide-bearing of scroll compressors. Frictional loss in the thrust slide-bearing occupies a large part of total mechanical loss in scroll compressors. The characteristics of friction and anti-wear using nano-oil is evaluated using a thrust bearing ...