The development of microchannels with open flow for use in irrigation and rainy areas is challenged by electricity generation via hydrokinetic devices in shallow and low velocity flows.Conventional hydrokinetic turbin...The development of microchannels with open flow for use in irrigation and rainy areas is challenged by electricity generation via hydrokinetic devices in shallow and low velocity flows.Conventional hydrokinetic turbines are known to be highly dependent on current speed and water depth.Another drawback of conventional turbines is their low efficiency.These shortcomings lead to the need to accelerate the flow in the channel system to enhance the extracted power.The method of deploying a novel turbine configuration in irrigation channels can help overcome the low performance of conventional hydrokinetic turbines.Therefore,this study experimentally presents a bidirectional diffuser-augmented channel that includes dual cross flow/Banki turbines.Results show that the maximum efficiency of the overall system with two turbines is nearly 55.7%.The efficiency is low relative to that of hydraulic turbines.Nevertheless,the result can be considered satisfactory given the low head of the present system.The use of this system will contribute to a highly efficient utilization of flows in rivers and channels for electrical energy generation in rural areas.展开更多
Wind-lens turbines(WLTs)exhibit the prospect of a higher output power and more suitability for urban areas in comparison to bare wind turbines.The wind-lens typically comprises a diffuser shroud coupled with a flange ...Wind-lens turbines(WLTs)exhibit the prospect of a higher output power and more suitability for urban areas in comparison to bare wind turbines.The wind-lens typically comprises a diffuser shroud coupled with a flange appended to the exit periphery of the shroud.Wind-lenses can boost the velocity of the incoming wind through the turbine rotor owing to the creation of a lowpressure zone downstream the flanged diffuser.In this paper,the aerodynamic performance of the wind-lens is computationally assessed using high-fidelity transient CFD simulations for shrouds with different profiles,aiming to assess the effect of change of some design parameters such as length,area ratio and flange height of the diffuser shroud on the power augmentation.The power coefficient(Cp)is calculated by solving the URANS equations with the aid of the SST k–ωmodel.Furthermore,comparisons with experimental data for validation are accomplished to prove that the proposed methodology could be able to precisely predict the aerodynamic behavior of the windlens turbine.The results affirm that wind-lens with cycloidal profile yield an augmentation of about 58%increase in power coefficient compared to bare wind turbine of the same rotor swept-area.It is also emphasized that diffusers(cycloid type)of small length could achieve a twice increase in power coefficient while maintaining large flange heights.展开更多
基金This project is sponsored by the Ministry of Education Malaysia under ERGS Fund No.4 L.125.
文摘The development of microchannels with open flow for use in irrigation and rainy areas is challenged by electricity generation via hydrokinetic devices in shallow and low velocity flows.Conventional hydrokinetic turbines are known to be highly dependent on current speed and water depth.Another drawback of conventional turbines is their low efficiency.These shortcomings lead to the need to accelerate the flow in the channel system to enhance the extracted power.The method of deploying a novel turbine configuration in irrigation channels can help overcome the low performance of conventional hydrokinetic turbines.Therefore,this study experimentally presents a bidirectional diffuser-augmented channel that includes dual cross flow/Banki turbines.Results show that the maximum efficiency of the overall system with two turbines is nearly 55.7%.The efficiency is low relative to that of hydraulic turbines.Nevertheless,the result can be considered satisfactory given the low head of the present system.The use of this system will contribute to a highly efficient utilization of flows in rivers and channels for electrical energy generation in rural areas.
文摘Wind-lens turbines(WLTs)exhibit the prospect of a higher output power and more suitability for urban areas in comparison to bare wind turbines.The wind-lens typically comprises a diffuser shroud coupled with a flange appended to the exit periphery of the shroud.Wind-lenses can boost the velocity of the incoming wind through the turbine rotor owing to the creation of a lowpressure zone downstream the flanged diffuser.In this paper,the aerodynamic performance of the wind-lens is computationally assessed using high-fidelity transient CFD simulations for shrouds with different profiles,aiming to assess the effect of change of some design parameters such as length,area ratio and flange height of the diffuser shroud on the power augmentation.The power coefficient(Cp)is calculated by solving the URANS equations with the aid of the SST k–ωmodel.Furthermore,comparisons with experimental data for validation are accomplished to prove that the proposed methodology could be able to precisely predict the aerodynamic behavior of the windlens turbine.The results affirm that wind-lens with cycloidal profile yield an augmentation of about 58%increase in power coefficient compared to bare wind turbine of the same rotor swept-area.It is also emphasized that diffusers(cycloid type)of small length could achieve a twice increase in power coefficient while maintaining large flange heights.
