Mihai Schiaua - Academia.edu (original) (raw)
Papers by Mihai Schiaua
Journal of Engineering Studies and Research, Mar 13, 2017
2017 International Conference on ENERGY and ENVIRONMENT (CIEM), 2017
This paper proposes a procedure for developing reservoir elevation-area-storage capacity curves a... more This paper proposes a procedure for developing reservoir elevation-area-storage capacity curves and bathymetric charts of a reservoir from depth sounding surveys. The Morii Reservoir, located in Bucharest (Romania), on Dambovita River, was chosen as case study. A single beam bathymeter with GPS was used in 2016 to survey the reservoir's bed. The acquired bathymetric data were denoised with a custom-made program written in Python, that uses the Butterworth filter and a zero-phase noise cancellation function. The decontaminated data were subsequently interpolated in ArcGIS to produce a gridded DEM of the reservoir bed surface and a bathymetric chart with contour lines. The area-capacity-elevation curves were obtained by calculating the 2D area and volume between horizontal planes and the interpolated bed surface. Comparisons with bathymetric survey from 2010 show differences of less than 14% in terms of storage capacity and 8% of the area of the reservoir during these 6 years.
Known as Benard-von Karman vortex street, the formation of alternate vortices in a wake past a no... more Known as Benard-von Karman vortex street, the formation of alternate vortices in a wake past a nonstreamlined object (named bluff body) is a classical fluid mechanics problem studied theoretically and experimentally for more than decades. This paper is an experimental approach of a viscous fluid which is flowing around a simple flat plate configuration. The behavior of the flow field around a bluff body, (“T” profile), is investigated by a classical technique of visualization using the Photo Tracer Method. Also, the fluid interaction on the “T” structure plates is monitoring by using three accelerometers mounted directly on the three directions of the “T” profile. The experiments are made for Reynolds numbers between 1·104 and 3.5 . 104. Interesting findings have resulted with applicability to vortex meters.
The aim of the present paper is to investigate the vibrations that occur during the operation of ... more The aim of the present paper is to investigate the vibrations that occur during the operation of a low power Banki turbine. The turbine was tested at different operating regimes in a laboratory installation, where it can operate with or without a variable load provided by a hydrodynamic brake coupled to the turbine shaft. Vibrations were measured on the turbine casing, on one of the turbine bearings, and on the brake. Dominant frequencies pertaining to each subassembly were identified. Measurements were also carried out with an added mass that simulates a piece of debris stuck inside the runner, causing an unbalance. The results obtained suggest that the bearings are a source of high frequency vibrations while relatively low frequency vibrations are caused by the turbine load. Very low frequency vibrations were also identified, which might be transmitted from the installation through the upstream pipe. The results underline the importance of vibration diagnostics to identify possibl...
Journal of Engineering Studies and Research, 2017
The purpose of the paper is to visualise the vortex shedding process behind a bluff body. It was ... more The purpose of the paper is to visualise the vortex shedding process behind a bluff body. It was considered a plane flow of a viscous fluid (water) around a ²T² profile having the geometric sizes modified. It was measured the fluid flow speed in the section of the measurements and the frequency of the vortex detachment from the profile. The vortex development phenomenon depends by the profile’s geometry and the Reynolds number of the flow. The relation between Reynolds number and Strouhal number was obtained for different sizes ²T² profiles. The experimental study is necessary to improve the vortex flowmeter performances.
Applied Mechanics and Materials, 2013
This paper investigates both experimentally and numerically the flow of a viscous fluid around T-... more This paper investigates both experimentally and numerically the flow of a viscous fluid around T-profiles, i.e. T-shaped bodies, having different geometries. Of main interest it was the vortex shedding behind the T-profiles with an eye towards its application to flow measurement in open channels. Another purpose of the study was to assess to what extent different numerical models can be used to accurately predict the flow in the vortex street behind T-profiles.
Journal of Engineering Studies and Research, Mar 13, 2017
2017 International Conference on ENERGY and ENVIRONMENT (CIEM), 2017
This paper proposes a procedure for developing reservoir elevation-area-storage capacity curves a... more This paper proposes a procedure for developing reservoir elevation-area-storage capacity curves and bathymetric charts of a reservoir from depth sounding surveys. The Morii Reservoir, located in Bucharest (Romania), on Dambovita River, was chosen as case study. A single beam bathymeter with GPS was used in 2016 to survey the reservoir's bed. The acquired bathymetric data were denoised with a custom-made program written in Python, that uses the Butterworth filter and a zero-phase noise cancellation function. The decontaminated data were subsequently interpolated in ArcGIS to produce a gridded DEM of the reservoir bed surface and a bathymetric chart with contour lines. The area-capacity-elevation curves were obtained by calculating the 2D area and volume between horizontal planes and the interpolated bed surface. Comparisons with bathymetric survey from 2010 show differences of less than 14% in terms of storage capacity and 8% of the area of the reservoir during these 6 years.
Known as Benard-von Karman vortex street, the formation of alternate vortices in a wake past a no... more Known as Benard-von Karman vortex street, the formation of alternate vortices in a wake past a nonstreamlined object (named bluff body) is a classical fluid mechanics problem studied theoretically and experimentally for more than decades. This paper is an experimental approach of a viscous fluid which is flowing around a simple flat plate configuration. The behavior of the flow field around a bluff body, (“T” profile), is investigated by a classical technique of visualization using the Photo Tracer Method. Also, the fluid interaction on the “T” structure plates is monitoring by using three accelerometers mounted directly on the three directions of the “T” profile. The experiments are made for Reynolds numbers between 1·104 and 3.5 . 104. Interesting findings have resulted with applicability to vortex meters.
The aim of the present paper is to investigate the vibrations that occur during the operation of ... more The aim of the present paper is to investigate the vibrations that occur during the operation of a low power Banki turbine. The turbine was tested at different operating regimes in a laboratory installation, where it can operate with or without a variable load provided by a hydrodynamic brake coupled to the turbine shaft. Vibrations were measured on the turbine casing, on one of the turbine bearings, and on the brake. Dominant frequencies pertaining to each subassembly were identified. Measurements were also carried out with an added mass that simulates a piece of debris stuck inside the runner, causing an unbalance. The results obtained suggest that the bearings are a source of high frequency vibrations while relatively low frequency vibrations are caused by the turbine load. Very low frequency vibrations were also identified, which might be transmitted from the installation through the upstream pipe. The results underline the importance of vibration diagnostics to identify possibl...
Journal of Engineering Studies and Research, 2017
The purpose of the paper is to visualise the vortex shedding process behind a bluff body. It was ... more The purpose of the paper is to visualise the vortex shedding process behind a bluff body. It was considered a plane flow of a viscous fluid (water) around a ²T² profile having the geometric sizes modified. It was measured the fluid flow speed in the section of the measurements and the frequency of the vortex detachment from the profile. The vortex development phenomenon depends by the profile’s geometry and the Reynolds number of the flow. The relation between Reynolds number and Strouhal number was obtained for different sizes ²T² profiles. The experimental study is necessary to improve the vortex flowmeter performances.
Applied Mechanics and Materials, 2013
This paper investigates both experimentally and numerically the flow of a viscous fluid around T-... more This paper investigates both experimentally and numerically the flow of a viscous fluid around T-profiles, i.e. T-shaped bodies, having different geometries. Of main interest it was the vortex shedding behind the T-profiles with an eye towards its application to flow measurement in open channels. Another purpose of the study was to assess to what extent different numerical models can be used to accurately predict the flow in the vortex street behind T-profiles.