The Design of Curved Endwall with Leading-edge Deformation
Issue:
Volume 9, Issue 1, January 2020
Pages:
1-10
Received:
22 December 2019
Accepted:
30 December 2019
Published:
27 January 2020
Abstract: The inlet boundary layer separates in front of the leading edge of the blade on the endwall and forms the pressure side leg of horseshoe vortex and the suction side one. The pressure side leg of the horseshoe vortex immediately moves toward to the suction side and form a stronger vortex, ”passage vortex”, in the cascade. These vortices mentioned above are called secondary flows which will result in an increase of secondary flow losses and a reduction of stage efficiency. In this paper, the flow characteristics are analyzed in the leading edge region and inside the cascade based on the numerical simulation results of the Langston cascade. A new type endwall design method, curved endwall structure combined with the deformation in the leading edge region, is established and optimized. It can be observed that the new structure can efficiently reduce the strength of the horseshoe vortex and suppress the generation of the leading edge separation line and saddle point. The uses of the new structure also decrease the pressure gradient between the pressure side and the suction side in the streamline direction, which suppresses the deviation of the pressure side horseshoe vortex from the pressure side of the endwall to the suction side and delays the formation position of the passage vortex. The rate of increase in the total pressure loss coefficient along the mainstream direction also decreases 25.34% in the exit of the cascade.
Abstract: The inlet boundary layer separates in front of the leading edge of the blade on the endwall and forms the pressure side leg of horseshoe vortex and the suction side one. The pressure side leg of the horseshoe vortex immediately moves toward to the suction side and form a stronger vortex, ”passage vortex”, in the cascade. These vortices mentioned ab...
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Low Carbon Transition of Residential Electricity Consumption in Nigeria: A System Dynamics Modeling Approach
Babajide Epe Shari,
Yacouba Moumouni,
Abiodun Suleiman Momodu
Issue:
Volume 9, Issue 1, January 2020
Pages:
11-21
Received:
10 January 2020
Accepted:
31 January 2020
Published:
10 March 2020
Abstract: It is imperative that Nigeria reduces wastage in residential electricity consumption and motivate energy saving behaviors through energy efficiency measures. These strategies aim to minimize frequent power sheds, which in turn increase reliability, thus benefiting the environment and electricity consumers. This article examines the effects of such innovative approaches to electricity savings in Nigeria through: 1) prepaid electricity metering systems and 2) fast replacements of inefficient and aging appliances. Relationships between residential electricity consumption, energy efficiency, and carbon footprint were also assessed vis-à-vis the replacement of old energy appliances and analogue electricity billing systems with more efficient devices and through prepaid metering systems, respectively. These techniques intend to promote energy saving behaviors. A System Dynamics model built on Stella platform, is used to analyze the implication of energy efficiency policy implementation on residential electricity consumption based on a simulation period of 41 years (2010 - 2050). Secondary data were sourced from the Bureau of Statistics, published articles, Nigerian power sector, World Bank, and primary data using cross sectional surveys of residential electricity consumers. Results, not only revealed that availability and utilization of prepaid electric meters and efficient appliances would motivate electricity saving behaviors, but also showed that efficient technologies could be the main drivers to future energy savings. Results also showed that carbon emissions were cut down by 45% in 2050. In addition, changes in electricity tariffs did not have any consequential effect on electricity consumption, but would rather influence electricity demand. Also, large number of occupant per house might have a negative impact on the Nigerian economic growth. Finally, results suggest that subsidies should be used on new household appliances as an effective energy policy measures. The developed model can be replicated in similar sectors in other emerging economies.
Abstract: It is imperative that Nigeria reduces wastage in residential electricity consumption and motivate energy saving behaviors through energy efficiency measures. These strategies aim to minimize frequent power sheds, which in turn increase reliability, thus benefiting the environment and electricity consumers. This article examines the effects of such ...
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