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Influence of impeller blade rounding and surface roughness on the internal hydraulics and performance of pump as turbine

Rahul Gaji Ashish Doshi Mukund Bade Punit Singh

Archive of Mechanical Engineering | 2023 | vol. 70 | No 2 | 219-245 | DOI: 10.24425/ame.2023.145581

Keywords pump as turbine impeller blade rounding CFD analysis of PAT simple modifications in PAT hydraulic analysis

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Abstract

The Pump As Turbine (PAT) is an important technology for low-cost micro-hydropower and energy recovery, and hence the internal hydraulics of PAT needs to be clearly understood. Additionally, during its operation, the sediments in the water increase the roughness of the internal surfaces and may alter the internal hydraulics and PAT performance similar to a centrifugal pump or Francis turbine. The researchers tried hard to perform simple modifications such as impeller blade rounding to increase the efficiency of PAT. In this paper, the developed test rig is used to analyze the performance of the impeller blade rounding and is validated with a numerical model. This numerical model is further used to study the influence of impeller blade rounding and surface roughness on internal hydraulics and PAT performance. The impeller blade rounding at the most increased the PAT efficiency by 1-1.5 % at the Best efficiency point (Q=16.8 lps), mainly due to the wake reduction on the suction side and increased flow area. With increasing the surface roughness from 0-70 μm, the PAT efficiency is decreased maximum by 4 %. The efficiency was mainly reduced due to increased hydraulic losses at flow zone and disk friction losses at the non-flow zone.

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Bibliography

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Authors and Affiliations

Rahul Gaji

1 2

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ORCID:

Ashish Doshi

e-mail:

ORCID:

Mukund Bade

e-mail:

ORCID:

Punit Singh

Annasaheb Dange College of Engineering and Technology, Ashta, India
Sardar Vallabhbhai National Institute of Technology, Surat, India
Centre for Sustainable Technologies, Indian Institute of Science, Bangalore, India

Terahertz dielectric characterisation of fibres in a time-domain spectrometer

Adam Pacewicz Paweł Kopyt Jerzy Cuper Mateusz Krysicki Bartłomiej Salski

Opto-Electronics Review | 2023 | 31 | 2 | e144596 | DOI: 10.24425/opelre.2023.144596

Keywords terahertz spectroscopy fibre characterisation dielectric materials

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Abstract

An innovative measurement setup for the dielectric characterisation of fibres in a terahertz time-domain spectrometer using an HDPE elliptical lens for coupling into the fibres has been built and validated by measurements of several different types of samples. The setup is based on a commercial all fibre-coupled terahertz time-domain spectrometer. Measurements of the effective refractive index have been conducted on polypropylene-based three-dimensional printing filaments, silica glass rods, and a polytetrafluoroethylene cord of lowered density, covering the frequency range of approximately 100 GHz to 1 THz. The theoretical part of the work includes numerical calculations performed via the finite difference eigenmode method and the characteristic equations of a uniform circular dielectric waveguide for a few guided modes, from which it is clear that primarily the fundamental mode propagates along the fibre. Details on model-based phase corrections, crucial to the accurate determination of the effective refractive index of dispersive fibres, have been presented as well.

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Authors and Affiliations

Adam Pacewicz

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Paweł Kopyt

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ORCID:

Jerzy Cuper

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ORCID:

Mateusz Krysicki

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Bartłomiej Salski

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Institute of Radioelectronics and Multimedia Technology, Warsaw University of Technology, Nowowiejska 15/19, 00-665 Warsaw, Poland

Design and performance evaluation of vehicular visible light communication system under different weather conditions and system parameters

Eslam S. El-Mokadem Nagwan I. Tawfik Moustafa H. Aly Walid S. El-Deeb

Opto-Electronics Review | 2023 | 31 | 2 | e145580 | DOI: 10.24425/opelre.2023.145580

Keywords visible light communication beam divergence bit error rate vehicular communication laser diode

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Abstract

Vehicular visible light communication is an emerging technology that allows wireless communication between vehicles or between vehicles and infrastructure. In this paper, a vehicular visible light communication system is designed using a non-return to zero on-off keying modulation scheme under the effect of different weather conditions such as clear, haze, and fog. The first model is a light emitting diode-based system and the second is a laser diode-based system. For both models, the influence of system parameters such as beam divergence, transceiver aperture diameters, and receiver responsivity is studied. The impact of the use of the trans-impedance amplifier is also investigated for both models. It was concluded that in the presence of the amplifier, output power of the light emitting diode and laser diode model are increased by 98.46 µW and 0.4719 W, respectively. The performance of the two proposed models is evaluated through bit error rate, quality factor, eye diagram, and output power to have some insightful results about the quality of service for the two proposed models. Under a specific weather condition, the performance of the system would be critical and other techniques should be applied. The maximum achievable link distance for the laser-based and light-emitting diode-based systems is 190 m at a data rate of 25 Gbps and 80 m at a data rate of 60 kbps, respectively, under the same system parameters and weather conditions. The obtained results provide a full idea about the availability of constructing our proposed model in a practical environment, showing a higher performance of the laser diode-based model than that of the light emitting diode-based model.

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Authors and Affiliations

Eslam S. El-Mokadem

Nagwan I. Tawfik

Moustafa H. Aly

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Walid S. El-Deeb

Department of Electronics and Communications Engineering, Higher Technological Institute, 10th of Ramadan City, Egypt
Arab Academy for Science, Technology and Maritime Transport, 1029 Alexandria, Egypt
Department of Electronics and Communications Engineering, Zagazig University, 44519 Zagazig, Egypt

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Influence of impeller blade rounding and surface roughness on the internal hydraulics and performance of pump as turbine

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Authors and Affiliations

Terahertz dielectric characterisation of fibres in a time-domain spectrometer

Abstract

Authors and Affiliations

Design and performance evaluation of vehicular visible light communication system under different weather conditions and system parameters

Abstract

Authors and Affiliations