PurposeThis paper aims to focus on the effect of the operating condition such as the impeller speed on the centrifugal fan performance and flow characteristics. The ability to predict the behavior of the airflow motion in a centrifugal blower is essential for obtaining the topology optimization design.Design/methodology/approachA physical model of the air blower consisting of these main parts in a blower system: collector, impeller, outlet flange and volute casing, and the appropriate boundary conditions are set up by ANSYS software. Computation fluid dynamics are performed for the numerical analysis. The calculation of blower performance parameters such as total pressure, efficiency and flow rate is based on the Reynolds averaged Navier–Stokes equations and k-εturbulence flow model.FindingsThe numerical results show that the change in operating conditions has a significant effect on the blower performance, and the pressure maintained inside the blower is higher for a larger impeller rotational speed.Originality/valueThis work is original and has not yet been submitted to elsewhere or published previously.
In this study, numerical computation is used to investigate the hydrodynamic characteristics of a torpedo-shaped underwater glider. The physical model of a torpedo-shaped underwater glider is developed by Myring profile equations and analyzed by the computational fluid dynamics approach. The Navier–Stokes equations and the energy equation coupled with the appropriate boundary conditions are solved numerically by using Comsol Multiphysics software. The numerical results contribute to the major part of reducing the effects of fluid flow on the glider’s profile and make the underwater glider more hydrodynamically efficient. The drag and lift forces acting on the underwater glider are enhanced by a higher velocity and a larger angle of attack of the underwater glider. Since the obtained results show a good observation with the experimental works, the need and the practicality of using CFD in the glider design process are proven.
Performances, emissions from the gas turbine engine,
and soot formations
in diffusion flames of kerosene (Jet A1) and its mixture with 5% by
volume bioparaffins (known as BK-5) are reported in the present study.
A Rover 1S/60 gas turbine engine was used for recording performance
parameters and emissions. Soot characteristics were investigated in
smoke-free coannular wick-fed diffusion flames. This study is the
next step that must be performed in the certification process of a
new aviation biofuel before it is tested in the aircraft. The results
show that BK-5 produced a similar performance against Jet A1. Throughout
the whole power range under investigation, BK-5 emitted 3.4% NOx higher
than Jet A1, while Jet A1 released CO and HC at the rates that are,
respectively, 1.8 and 4.5% greater than its counterpart. The soot
emissions from the BK-5 and Jet A1 were comparable across the measured
flame height range. The results encouraged future studies to carry
out the modern engine and flight tests. The production process for
bioparaffins employed in this work has been demonstrated to be viable
and appropriate for tropical developing nations. The current process
should also continue to be improved by eliminating high-distillation
temperature components in bioparaffins.
PurposeThe purpose of this paper is to investigate the effect of different guide fins structures (i.e. single-layer and double-layer guide fins) on the exhaust flow and thermal uniformity of the motorcycle exhaust thermoelectric generator.Design/methodology/approachOne single-layer guide fins structure and three double-layer guide fins structures are numerically investigated in terms of exhaust flow uniformity with different exhaust properties. Then, the double-layer guide fins structure achieving the highest flow uniformity is fabricated and experimentally investigated on a motorcycle at different engine speeds together with the single-layer guide fins structure to evaluate the thermal uniformity.FindingsThe double-layer guide fins structure obtains a better flow uniformity and thermal uniformity compared to the single-layer structure. Among surveyed structures, the double-layer structure with three closed V-shape guide fins achieves the highest flow uniformity. This structure also improves the thermal uniformity from 3.0 to 90.1% in comparison with the single-layer structure in experiments.Originality/valueIn this paper, the double-layer guide fins structures are derived from the improvement of the single-layer guide fins structure. The fluid flow uniformity index is applied as a measure for assessing the exhaust flow uniformity. The enhancement of thermal uniformity of the double-layer guide fins structure is expected to increase the longevity and performance of the motorcycle exhaust thermoelectric generator.
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