scholarly journals Computational Flow Analysis on a Real Scale Run-of-River Archimedes Screw Turbine with a High Incline Angle

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3307
Author(s):  
Dylan Sheneth Edirisinghe ◽  
Ho-Seong Yang ◽  
Min-Sung Kim ◽  
Byung-Ha Kim ◽  
Sudath Prasanna Gunawardane ◽  
...  
Keyword(s):  
Inclination Angle ◽  
River Flow ◽  
Experimental Testing ◽  
Fluid Dynamic ◽  
New Technology ◽  
Flow Analysis ◽  
Maximum Efficiency ◽  
Incline Angle ◽  
Real Scale ◽  
Run Of River

The Archimedes screw turbine (AST) is the most sustainable mini-hydropower extraction method that offers number of economic, social, and environmental advantages. Nowadays, many researchers are interested in AST development as it is considered a new technology. Currently, a lot of researchers are conducting experimental testing of the screws, comparing their reliability with computational fluid dynamic (CFD) analyses. Almost all of them are lab-scale testing models that claiming an average 80% efficiency for low pitch angles. In the case of a real site with a small inclination angle, the length of the screw is large enough to cause severe problems, specially related to bending of the screw. Therefore, this research was conducted to analyze the CFD flow field in a real site-scale AST with the maximum possible inclination of 45 degrees. In addition, the design was done without the upper and lower reservoir as it was conceived as a run-of-river flow system. The simulated real scale AST result showed a maximum efficiency of around 82% for a 5.2 m hydraulic head and 0.232 m3/s discharge. Many researchers claim above 80% efficiency for low inclination angle ASTs with reservoirs. This CFD study indicates that even higher inclination angle ASTs can achieve 80% efficiency in run-of-river; real-scale applications.

scholarly journals The Design and Implementation of Fan Chips as Cooling for Milling Process on Aluminum Alloy 5086 to Increase Tool Life

2021 ◽  
Vol 2 (1) ◽  
pp. 29-42
Author(s):  
Agus Sifa ◽  
Dedi Suwandi ◽  
Tito Endramawan ◽  
Alam Aulia Rachman
Keyword(s):  
Aluminum Alloy ◽  
Tool Life ◽  
Experimental Testing ◽  
Fluid Dynamic ◽  
Milling Process ◽  
Machining Process ◽  
Central Character ◽  
Spindle Rotation ◽  
Cfd Method ◽  
Increase Tool Life

In the metal machining process, especially in the milling process, the parameters that affect the quality milling process results are cooling media because it affects the tool life used. This paper aims to determine the performance of using fan chips as the coolant in the dry milling process area. The method used is the computational fluid dynamic (CFD) method and the experimental milling process on a workpiece made from aluminum alloy 5086. In experimental testing using a variation of the milling machine spindle rotation. The simulation test results on the fluid flow character on fan chips with a protector producing a central character with a small area. In contrast, fan chips without a protector make a central character with a broader area. The wind speed data in simulation testing and experimental testing produced the same trend graph. The results of the performance of fan chips after experimented with variations in spindle rotation, cooling process on area occurs when the motor spindle rotates above 1120 Rpm on the fan chips with a protector, and the engine spindle rotates above 770 Rpm on the fan chips without a protector. The effect of fan chips on tool life affects increasing tool life by 8 minutes on installing fan chips with a protector and increasing tool life by 12 minutes on installing fan chips without a protector.

scholarly journals Intake Flow Analysis of a Pulsed Detonation Engine

2016 ◽  
Vol 139 (4) ◽  
Author(s):  
Joshua A. Strafaccia ◽  
Semih M. Ölçmen ◽  
John L. Hoke ◽  
Daniel E. Paxson
Keyword(s):  
Fluid Dynamic ◽  
Flow Analysis ◽  
Engine Performance ◽  
Fuel Injector ◽  
Pulse Detonation ◽  
Pulsed Detonation Engine ◽  
Pulsed Detonation ◽  
Fill Fraction ◽  
Detonation Engine ◽  
Intake Flow

Unsteady flow within the intake system of a hydrogen–air pulse detonation engine (PDE) has been analyzed using a quasi-one-dimensional (Q1D) computational fluid dynamic (CFD) code. The analysis provides insight into the unsteady nature of localized equivalence ratios and their effects on PDE performance. For this purpose, a code originally configured to model the PDE tube proper was modified to include a 6.1 m long intake with a single fuel injector located approximately 3.05 m upstream of the primary intake valve. The results show that constant fuel mass flow rate injection from the injector creates large local variations in equivalence ratio throughout the PDE within a cycle. The effect of fill fraction on the engine performance is better described with the presence of the inlet model. However, the effect of ignition delay is shown to be better predicted with a model without the inlet.

scholarly journals Studi Fluiditas dan Karakteristik Aliran pada Pengecoran Al-Si Alloy Menggunakan Simulasi Numerik

2018 ◽  
Vol 1 (1) ◽  
pp. 007-012
Author(s):  
Andri Willy Adianta ◽  
Suprianto Suprianto ◽  
Arnius Daely ◽  
Mikael F. Bangun
Keyword(s):  
Aluminum Alloy ◽  
Flow Velocity ◽  
Computational Fluid Dynamic ◽  
Surface Defects ◽  
Fluid Dynamic ◽  
Liquid Aluminum ◽  
Flow Analysis ◽  
Pouring Temperature ◽  
Gravity Casting ◽  
Aluminum Castings

Aluminium silikon alloy merupakan paduan aluminium yang banyak digunakan dalam bidang teknik. Paduan ini memiliki kekuatan yang baik dan banyak diproduksi menjadi suatu komponen melalui proses pengecoran. Kandungan silikon dapat mengakibatkan penurunan fluiditas coran alumunium yang pada akhirnya akan menurunkan kualitas coran, fluiditas ini juga dipengaruhi temperatur pada saat penuangan alumunium cair. Penelitian ini bertujuan untuk mengetahui efek temperatur penuangan terhadap fluiditas, karakteristik aliran dan cacat coran pada pengecoran aluminium silikon alloy menggunakan cetakan pasir. Pengecoran dilakukan dengan gravity casting, analisa aliran simulasi meliputi distribusi kecepatan aliran, temperatur, tekanan, cacat permukaan dan fluiditas yang terjadi pada saat proses pengisian rongga cetak serta perbandingan fluiditas coran dan cacat permukaan pada eksperimental. Temperatur penuangan 685, 710, 735, 760 dan 785°C dengan ketebalan cetakan pola 1, 3, 5, 7, 9, dan 12 mm. Proses simulasi menggunakan software berbasis computational fluid dynamic. Hasil penelitian diperoleh temperatur tuang 785oC memiliki kecepatan aliran tertinggi yaitu sebesar ±0.145 m/s pada rongga 12 mm dan distribusi temperatur yang tinggi yaitu sebesar ±759 oC pada rongga 3 mm, sedangkan temperatur tuang 685oC memiliki distribusi tekanan yang tinggi yaitu sebesar ±107287 Pa pada rongga 6 mm. Cacat permukaan terbanyak pada temperatur tuang 785oC dan temperatur tuang 685oC paling sedikit. Fluiditas coran terbaik pada temperatur 785oC dimana rongga 12, 9, 7, 5 dan 3 mm terisi penuh dan 1 mm mencapai 181.4 mm.   Aluminum silicon alloy is an aluminum alloy that is widely used in engineering. This alloy has good strength and plenty of it are produced into a component through the casting process. Silicon content could result in a decrease in fluidity of aluminum castings which in turn would reduce the quality of casting. This fluidity is also influenced by temperature at the time of pouring liquid aluminum. This study aims to determine the effect of pouring temperature on fluidity, flow characteristics and casting defects on aluminum alloy silicon casting by using sand mold. Casting was conducted by gravity casting, simulation flow analysis including flow velocity distribution, temperature, pressure, surface and fluidity defects that occured during the process of filling the mold cavity as well as the comparison of the fluidity of castings and surface defects in the experiment. Casting temperatures was 685, 710, 735, 760 and 785°C with a mold thickness of patterns 1, 3, 5, 7, 9 and 12 mm. The simulation process used software based on computational fluid dynamic. The result showed pouring temperature of 785oC had the highest flow velocity of ± 0.145 m/s in 12 mm cavity and a high temperature distribution of ± 759oC in cavity of 3 mm, while the pouring temperature of 685oC had a high pressure distribution of ± 107287 Pa in 6 mm cavity. Most surface defects occurred at pour temperature of 785oC and the least at pour temperature of 685oC. The best castings liquidity occurred at temperature of 785oC where the cavity of 12, 9, 7, 5 and 3 mm was fully filled and 1 mm reached 181.4 mm.

Implications of Phase Change on the Aerodynamics of Centrifugal Compressors for Supercritical Carbon Dioxide Applications

2020 ◽  
Author(s):  
Giacomo Persico ◽  
Lorenzo Toni ◽  
Paolo Gaetani ◽  
Ernani Fulvio Bellobuono ◽  
Alessandro Romei ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Power Systems ◽  
Phase Change ◽  
Critical Point ◽  
Fluid Dynamic ◽  
Flow Analysis ◽  
Design Strategy ◽  
Ideal Gas ◽  
New Challenges ◽  
Line Design

Abstract Closed Joule-Bryton cycles operating with carbon dioxide in supercritical conditions (sCO2) are nowadays collecting a significant scientific interest, due to their high potential efficiency, the compactness of their components, and the flexibility that makes them suitable to exploit diverse energy sources. However, the technical implementation of sCO2 power systems introduces new challenges related to the design and operation of the components. The compressor, in particular, operates in a thermodynamic condition close to the critical point, whereby the fluid exhibits significant non-ideal gas effects and is prone to phase change in the intake region of the machine. These new challenges require novel design concepts and strategies, as well as proper tools to achieve reliable predictions. In the present study, we consider an exemplary sCO2 power cycle with main compressor operating in proximity to the critical point, with an intake entropy level of the fluid lower than the critical value. In this condition, the phase change occurs as evaporation/flashing, thus resembling cavitation phenomena observed in liquid pumps, even though with specific issues associated to compressibility effects occurring in both the phases. The flow configuration is therefore highly nonconventional and demands the development of proper tools for fluid and flow modeling, which are instrumental for the compressor design. The paper discusses the modeling issues from the thermodynamic perspective and then highlighting the implications on the compressor aerodynamics. We propose tailored models to account for the effect of the phase change in 0D mean-line design tools as well as in fully 3D computational fluid-dynamic (CFD) simulations. In this way, a design strategy is build-up as a combination of mean-line tools, industrial design experience, and CFD for detailed flow analysis. The application of the design strategy reveals that the potential onset of the phase change might alter significantly the performance and operation of the compressor, both in design and in off-design conditions.

Cloud Computing for Secure Services in E-Government Architecture

2016 ◽  
pp. 1727-1746
Author(s):  
Sajjad Hashemi ◽  
Khalil Monfaredi ◽  
Seyyed Yasser Hashemi
Keyword(s):  
Cloud Computing ◽  
Query Processing ◽  
Data Security ◽  
New Technology ◽  
High Volume ◽  
Maximum Efficiency ◽  
Government Services ◽  
Security Service ◽  
Data Center Management ◽  
The Face

E-government tries to take advantage of new technology to provide better service to citizens. Some of the main challenges in the face of E-government are query processing high volume applications, data center management, data security and E-government services. Cloud computing can be a good option for responding to these issues and fixing them, and guarantee the realization of E-government, with maximum efficiency and maximum safety. In this paper, the authors propose a novel architecture for E-government by using Cloud computing architecture which can largely increase the integrity and security service in E-government, and also increase users' confidence in the system and may lead to increased participation.

scholarly journals Influence of Variable Viscosity on Peristaltic Motion of a Viscoelastic Fluid in a Tapered Microfluidic Vessel

2018 ◽  
Vol 7 (4.10) ◽  
pp. 49 ◽  
Author(s):  
J. Prakash ◽  
E. P.Siva ◽  
A. Govindarajan ◽  
M. Vidhya
Keyword(s):  
Viscoelastic Fluid ◽  
Axial Velocity ◽  
Variable Viscosity ◽  
Fluid Dynamic ◽  
Wave Train ◽  
Flow Analysis ◽  
Pressure Rise ◽  
Average Pressure ◽  
Peristaltic Motion ◽  
Long Wavelength

The peristaltic flow of a viscoelastic fluid in the tapered microchannel with variable viscosity is investigated. This study is reinvigorated by discovering fluid dynamic in peristaltic motion as signified by biological flows, pharmacodynamics and gastro-intestinal motility enhancement. The microchannel non-uniform and asymmetry is developed by choosing a peristaltic wave train on the wall with different amplitudes and phases. The flow analysis has been arisen for low Reynolds number and long wavelength case. The solutions for stream function, axial velocity and pressure gradient are obtained. The effects of pertinent parameters on the average pressure rise per wavelength are investigated by means of numerical integration. The axial velocity and phenomena of trapping are further discussed.  

Aerodynamic effects of bio-inspired corrugated wings on gliding and hovering performances

2020 ◽  
pp. 095440622091799
Author(s):  
Haibin Xuan ◽  
Jun Hu ◽  
Yong Yu ◽  
Jiaolong Zhang
Keyword(s):  
Inclination Angle ◽  
Fluid Dynamic ◽  
Angle Of Attack ◽  
Aerodynamic Forces ◽  
Limited Effect ◽  
Gliding Flight ◽  
Significant Difference ◽  
Inclination Angles ◽  
Underlying Mechanisms ◽  
Lift And Drag

Recently, numerous studies have been conducted to clarify the effects of corrugation wing on aerodynamic performances. The effects of the corrugation patterns and inclination angles were investigated using computational fluid dynamic method in gliding and hovering flight at Reynolds numbers of order 104. The instantaneous aerodynamic forces and the vorticity field around the wing models were provided to research the underlying mechanisms of aerodynamic effects of corrugated wing models. The findings can be concluded as follows: (1) the corrugation patterns have different effects on aerodynamic performance. The effect of noncamber corrugated wing is to decrease the lift and increase drag compared with a flat-plate when the angle of attack is less than 25° during gliding flight. The corrugated wing with a camber (corrug-2) after the valleys enhances the aerodynamic forces when angle of attack is higher than 35°. The valley inclination angle has limited effect on aerodynamic forces in gliding flight. (2) The lift forces of different corrugation patterns show significantly asymmetric during the upstroke and downstroke. The main reason leads to this phenomenon is the case that two sides of the corrugated wings are not symmetric around the pitching axis. The corrugated wing with only two valleys (corrug-1) changes the lift and drag very slightly. Corrug-2 produces larger peak during downstroke and smaller peak during upstroke. The increase in the inclination angle has limited effect on the aerodynamic forces. The possible reason for these small aerodynamic effects might be that the corrugated wings are smoothed by small vortices trapped in valleys. The main reason for the significant difference between plate and corrug-2 is that the recirculating vortices trapped in the saddle and hump reduce the pressure above the wing surface.

Application of Genetic Algorithm to Prediction of Artery Geometry

2007 ◽  
Author(s):  
M. Himeno ◽  
S. Noda ◽  
R. Himeno ◽  
K. Fukasaku
Keyword(s):  
Fluid Dynamics ◽  
Genetic Algorithm ◽  
Fluid Dynamic ◽  
Flow Analysis ◽  
Two Dimensional ◽  
Multi Objective Optimization ◽  
Curved Artery ◽  
Two Factors ◽  
Blood Flow Analysis ◽  
Significant Factors

We used the genetic algorithm (GA) and two-dimensional blood flow analysis to examine the fluid dynamic and engineering factors in multi-objective optimization of blood tubes (vessels). We supposed two factors from fluid dynamics: the wall shear stress (WSS) and the pressure loss, and one materials saving factor: the artery length. As a result, we could get the optimum shapes for each factor. In the case of WSS and artery length, both smoothly curved artery shapes and shapes with bulges were obtained as lower WSS cases. The shapes with bulges were similar to those of aneurysms. In this case, it was found that the WSS increases after the bulge is removed. This means bulges in artery vessel areas with higher WSSs effectively reduce the WSS value. Only the case of WSS and artery length produced a shape like an aneurysm. These results indicate that WSS and artery length are significant factors in determining artery shape.

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