scholarly journals Experimental Analysis and CFD Modeling for Conventional Basin-Type Solar Still

Energies ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 5734
Author(s):  
Mahmoud S. El-Sebaey ◽  
Asko Ellman ◽  
Ahmed Hegazy ◽  
Tarek Ghonim
Keyword(s):  
Fresh Water ◽  
Water Depth ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Cfd Modeling ◽  
Solar Still ◽  
Cfd Model ◽  
Climate Conditions ◽  
Experimental Values ◽  
Multi Phase

With the rising population, environmental pollution, and social development, potable water is reducing and being contaminated day by day continually. Thus, several researchers have focused their studies on seas and oceans in order to get potable fresh water by desalination of their saltwater. Solar still of basin type is one of the available technologies to purify water because of free solar energy. The computational fluid dynamic CFD model of the solar still can significantly improve means for optimization of the solar still structure because it reduces the need for conducting large amount of experiments. Therefore, the main purpose of this study is presenting a multi-phase, three-dimensional CFD model, which predicts the performance of the solar still without using any experimental measurements, depending on the CFD solar radiation model. Simulated results are compared with experimental values of water and glass cover temperatures and yield of fresh water in climate conditions of Sheben El-Kom, Egypt (latitude 30.5° N and longitude 31.01° E). The simulation results were found to be in acceptable agreement with the experimental measured data. The results indicated that the daily simulated and experimental accumulated productivities of the single-slope solar still were found to be 1.982 and 1.785 L/m2 at a water depth of 2 cm. In addition, the simulated and experimental daily efficiency were around 16.79% and 15.5%, respectively, for the tested water depth.

scholarly journals CFD Investigation of Vehicle’s Ventilation Systems and Analysis of ACH in Typical Airplanes, Cars, and Buses

2021 ◽  
Vol 13 (12) ◽  
pp. 6799
Author(s):  
Behrouz Pirouz ◽  
Domenico Mazzeo ◽  
Stefania Anna Palermo ◽  
Seyed Navid Naghib ◽  
Michele Turco ◽  
...  
Keyword(s):  
Energy Demand ◽  
Infection Prevention ◽  
Fluid Dynamic ◽  
Demand Management ◽  
Three Dimensional ◽  
Hvac Systems ◽  
Cfd Modeling ◽  
Cfd Model ◽  
Cabin Environment

The simulation of the ventilation and the heating, ventilation, and air conditioning (HVAC) systems of vehicles could be used in the energy demand management of vehicles besides improving the air quality inside their cabins. Moreover, traveling by public transport during a pandemic is a concerning factor, and analysis of the vehicle’s cabin environments could demonstrate how to decrease the risk and create a safer journey for passengers. Therefore, this article presents airflow analysis, air changes per hour (ACH), and respiration aerosols’ trajectory inside three vehicles, including a typical car, bus, and airplane. In this regard, three vehicles’ cabin environment boundary conditions and the HVAC systems of the selected vehicles were determined, and three-dimensional numerical simulations were performed using computational fluid dynamic (CFD) modeling. The analysis of the airflow patterns and aerosol trajectories in the selected vehicles demonstrate the critical impact of inflow, outflow, and passenger’s locations in the cabins. The CFD model results exhibited that the lowest risk could be in the airplane and the highest in the bus because of the location of airflows and outflows. The discrete CFD model analysis determined the ACH for a typical car of about 4.3, a typical bus of about 7.5, and in a typical airplane of about 8.5, which were all less than the standard protocol of infection prevention, 12 ACH. According to the results, opening windows in the cars could decrease the aerosol loads and improve the low ACH by the HVAC systems. However, for the buses, a new design for the outflow location or an increase in the number of outflows appeared necessary. In the case of airplanes, the airflow paths were suitable, and by increasing the airflow speed, the required ACH might be achieved. Finally, in the closed (recirculating) systems, the role of filters in decreasing the risk appeared critical.

Numerical Designed Experiment to Optimize a Ported Shroud to Extend the Operability Margin of a Centrifugal Compressor

2005 ◽  
Author(s):  
J. Slovisky ◽  
M. L. Mansour ◽  
M. T. Barton ◽  
D. L. Palmer
Keyword(s):  
Centrifugal Compressor ◽  
High Speed ◽  
Numerical Technique ◽  
Fluid Dynamic ◽  
Constant Width ◽  
Three Dimensional ◽  
Cfd Modeling ◽  
Stall Margin ◽  
Designed Experiment ◽  
Ported Shroud

This paper describes the Computational Fluid Dynamic (CFD) numerical optimization of a modern centrifugal compressor impeller with a ported shroud for increased surge margin. The vent configuration selected was a full circumference, constant-width slot. A multiblock, steady flow three dimensional (3D) viscous RANS model (ADPAC) is used with parallel processing capability to increase computational speed. Grid generation is performed in an automated fashion to enable the timely optimization of the ported shroud configuration. A designed experiment (DoE) approach is used to minimize the number of vent configurations to be modeled, to ensure that factor interaction effects are captured, and to facilitate the definition of an optimum vent configuration. The DoE is a 2 factor, 2 level full factorial experiment with a center point included to detect possible curvature in the solution surface. The factors optimized are slot width and the flow-wise location of the slot. The numerical technique verifies the ability of the ported shroud to extend compressor stall margin at the part-speed operating condition, while maintaining acceptable high speed performance, in good agreement with test data for a similar impeller with a ported shroud. The use of a DoE method coupled with CFD modeling identified an optimized vent configuration with a minimum of time and effort. The CFD results also provide enhanced understanding of the device physics.

scholarly journals NUMERICAL INVESTIGATION OF THE EFFECTS OF GEOMETRICAL PARAMETERS ON THE VORTEX SEPARATION PHENOMENON INSIDE A RANQUE-HILSCH VORTEX TUBE USED AS AN AIR SEPARATOR IN A HELICOPTER’S ENGINE

Aviation ◽  
2018 ◽  
Vol 22 (1) ◽  
pp. 13-23 ◽  
Author(s):  
Adib Bazgir ◽  
Nader Nabhani
Keyword(s):  
Vortex Tube ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Temperature Fields ◽  
Geometrical Parameters ◽  
Cfd Model ◽  
Steady State Condition ◽  
Axial Angle ◽  
Temperature Reduction ◽  
Vortex Separation

Air separators are fitted to helicopter engine intakes to remove potentially harmful dust from the influent air. Their use is necessary in desert environments to eliminate the risk of rapid engine wear and subsequent power deterioration. However, their employment is concomitant with an inherent loss in inlet pressure and, in some cases, auxiliary power. There are three main technologies: vortex tubes, barrier filters, and integrated inlet particle separators. In this work, a vortex tube is investigated numerically. The study was conducted on the number and axial angle of inlet nozzles. Two and three-dimensional models are investigated at a steady state condition then the standard k-ε turbulence model is utilised for determining the flow and temperature fields. The finite volume method base on a Computational Fluid Dynamic (CFD) model is verified through the comparison with experimental data and numerical results of a vortex tube, reported in literature sources. Increasing the number of inlet nozzles, increases the sensitivity of the temperature reduction and the highest possible temperature reduction can be obtained. A vortex tube with an axial angle inlet nozzle of yields better performance. The numerical simulation results indicated that the CFD model is capable of predicting the vortex separation phenomenon inside a Ranque-Hilsch vortex tube with different geometrical parameters.

scholarly journals Experimental Investigation and CFD Modeling of Slush Cryogen Flow Measurement Using Circular Shape Capacitors

Sensors ◽  
2020 ◽  
Vol 20 (7) ◽  
pp. 2117 ◽  
Author(s):  
Bogdan Florian Monea ◽  
Eusebiu Ilarian Ionete ◽  
Stefan Ionut Spiridon
Keyword(s):  
Flow Measurement ◽  
High Performance ◽  
Solid Phase ◽  
Experimental Testing ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Cfd Modeling ◽  
Two Phase ◽  
Circular Shape ◽  
Experimental Stand

The measurement of two-phase cryogenic fluid mixtures flow, also known as slush cryogen flow, with its most attractive form (liquid and solid) is of great interest for various applications, due to its thermodynamic advantages. This paper presents a newly developed device, under the form of a circular capacitor prototype, together with an experimental stand for slush formation. Slush nitrogen was used as testing fluid during the experimental work. Then, the experimental data for slush cryogen flow measurement using the proposed circular shape capacitor were compared with theoretical results obtained by simulation. A three-dimensional flow field model was built and solved for the innovative design slush flowmeter using a computational fluid dynamic (CFD) model. Nitrogen slush density of 874 kg/m3, representing approximately 30% solid fraction, was reported for both the modeling and experimental testing, although the numerical investigation is not limited to these values. By comparing experimental vs. simulation results, a deeper view on the designed configuration can be achieved, thus improving the progress in producing high-performance next generation devices for two-phase flow measurement in terms of physical dimensions, length and space between armatures. Even so, the mathematical model has limitations when mixtures with higher percentages of solid phase and particle sizes are encountered.

Research on Windage Power Loss of Spur Gear Base on CFD

2012 ◽  
Vol 184-185 ◽  
pp. 450-455 ◽  
Author(s):  
Ning Zhao ◽  
Qing Jian Jia
Keyword(s):  
Computational Fluid Dynamic ◽  
Power Loss ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Spur Gear ◽  
Cfd Model ◽  
Major Parameter ◽  
Proportional Relationship ◽  
Tooth Flank ◽  
Icem Cfd

The paper established three-dimensional Computational fluid dynamic (CFD) model of the oil-air mixture in the gearbox after meshing by ICEM CFD simulated the turbulence model by the CFD. The method of calculate the windage power loss (WPL) of the spur gear were put forward. In order to reduced the WPL, compared the results between the CFD model with different modulus、clearance of the shroud and radius of the modification of gear top. The modulus is major parameter to WPL; the gear with shroud have lower WPL , WPL of the tooth flank and clearance of the tooth flank shroud do not show the proportional relationship, the gear with smallest clearance of gear side have lowest WPL，the modification of gear top can reduce the eddy scale which can reduce the WPL.

The three-dimensional hydrodynamics of tadpole locomotion.

1997 ◽  
Vol 200 (22) ◽  
pp. 2807-2819 ◽  
Author(s):  
H Liu ◽  
R Wassersug ◽  
K Kawachi
Keyword(s):  
Unsteady Flow ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Small Region ◽  
High Amplitude ◽  
Three Dimensions ◽  
Cfd Model ◽  
Hind Limbs ◽  
Lower Amplitude ◽  
Low Efficiency

Tadpoles are unusual among vertebrates in having a globose body with a laterally compressed tail abruptly appended to it. Compared with most teleost fishes, tadpoles swim awkwardly, with waves of relatively high amplitude at both the snout and tail tip. In the present study, we analyze tadpole propulsion using a three-dimensional (3D) computational fluid dynamic (CFD) model of undulatory locomotion that simulates viscous and unsteady flow around an oscillating body of arbitrary 3D geometry. We first confirm results from a previous two-dimensional (2D) study, which suggested that the characteristic shape of tadpoles was closely matched to their unusual kinematics. Specifically, our 3D results reveal that the shape and kinematics of tadpoles collectively produce a small 'dead water' zone between the head-body and tail during swimming precisely where tadpoles can and do grow hind limbs--without those limbs obstructing flow. We next use our CFD model to show that 3D hydrodynamic effects (cross flows) are largely constrained to a small region along the edge of the tail fin. Although this 3D study confirms most of the results of the 2D study, it shows that propulsive (Froude) efficiency for tadpoles is overall lower than predicted from a 2D analysis. This low efficiency is not, however, a result of the high-amplitude undulations of the tadpole. This was demonstrated by forcing our 'virtual' tadpole to swim with fish-like kinematics, i.e. with lower-amplitude propulsive waves. That particular simulation yielded a much lower Froude efficiency, confirming that the large-amplitude lateral oscillations of the tadpole do, indeed, provide positive thrust. This, we believe, is the first time that the unsteady flow generated by an undulating vertebrate has been realistically modelled in three dimensions. Our study demonstrates the feasibility of using 3D CFD methods to model the locomotion of other undulatory organisms.

A Modeling Approach to Study the Fluid-Dynamic Forces Acting on the Spool of a Flow Control Valve

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Emma Frosina ◽  
Adolfo Senatore ◽  
Dario Buono ◽  
Kim A. Stelson
Keyword(s):  
Flow Control ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Control Valve ◽  
Maximum Error ◽  
Cfd Modeling ◽  
Flow Control Valve ◽  
Pressure Force ◽  
Modeling Approach ◽  
Balance Of Forces

This paper introduces an approach to study a valve's internal fluid dynamics. During operation, the flow causes forces on the spool. These forces must be correctly balanced. Since these forces cannot be measured, a three-dimensional (3D) computational fluid dynamic (CFD) modeling approach is needed. A case study has been undertaken to verify the approach on a two-way pressure compensated flow control valve. Since forces vary during operation, the analysis must be transient. From the initial zero spool position, the flow goes through the valve causing a spool shift inside the valve's housing until the spool stops at its final position. Forces depend on the spring reaction, the inlet pressure force, the pressure force of the fluid inside the spool, and the spring holder volumes, and the balance of forces influences the outlet flow rate at the final spool position. First, the initial case geometry was modeled, prototyped, and tested, and this geometry was studied to verify the model accuracy compared to experimental data. The comparison shows good agreement with a maximum error of 3%. With the same approach, several other geometries were designed, but only the best geometry was prototyped and tested. The model was adopted to make several analyses of velocity contouring, streamlines trends, and pressure distribution in the fluid volume. The modeled and tested results achieved the expected performance confirming the effectiveness of the methodology.

scholarly journals Clap-and-fling mechanism in a hovering insect-like two-winged flapping-wing micro air vehicle

2016 ◽  
Vol 3 (12) ◽  
pp. 160746 ◽  
Author(s):  
Hoang Vu Phan ◽  
Thi Kim Loan Au ◽  
Hoon Cheol Park
Keyword(s):  
Drag Force ◽  
Cfd Simulation ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Flapping Wing ◽  
Micro Air Vehicle ◽  
Force Generation ◽  
Vertical Force ◽  
Cfd Model ◽  
Air Vehicle

This study used numerical and experimental approaches to investigate the role played by the clap-and-fling mechanism in enhancing force generation in hovering insect-like two-winged flapping-wing micro air vehicle (FW-MAV). The flapping mechanism was designed to symmetrically flap wings at a high flapping amplitude of approximately 192°. The clap-and-fling mechanisms were thereby implemented at both dorsal and ventral stroke reversals. A computational fluid dynamic (CFD) model was constructed based on three-dimensional wing kinematics to estimate the force generation, which was validated by the measured forces using a 6-axis load cell. The computed forces proved that the CFD model provided reasonable estimation with differences less than 8%, when compared with the measured forces. The measurement indicated that the clap and flings at both the stroke reversals augmented the average vertical force by 16.2% when compared with the force without the clap-and-fling effect. In the CFD simulation, the clap and flings enhanced the vertical force by 11.5% and horizontal drag force by 18.4%. The observations indicated that both the fling and the clap contributed to the augmented vertical force by 62.6% and 37.4%, respectively, and to the augmented horizontal drag force by 71.7% and 28.3%, respectively. The flow structures suggested that a strong downwash was expelled from the opening gap between the trailing edges during the fling as well as the clap at each stroke reversal. In addition to the fling phases, the influx of air into the low-pressure region between the wings from the leading edges also significantly contributed to augmentation of the vertical force. The study conducted for high Reynolds numbers also confirmed that the effect of the clap and fling was insignificant when the minimum distance between the two wings exceeded 1.2c (c = wing chord). Thus, the clap and flings were successfully implemented in the FW-MAV, and there was a significant improvement in the vertical force.

A Comparative Study of a Morphing Wing

2017 ◽  
Author(s):  
Eun Jung Chae ◽  
Amin Moosavian ◽  
Alexander M. Pankonien ◽  
Daniel J. Inman
Keyword(s):  
Fluid Dynamic ◽  
Three Dimensional ◽  
Aerodynamic Performance ◽  
Operating Conditions ◽  
Superior Performance ◽  
Cfd Modeling ◽  
Navier Stokes ◽  
Morphing Wing ◽  
Trailing Edge ◽  
Analytical Approaches

Along with recent advancements in novel materials and manufacturing processes, the interest in morphing wings has increased in order to further improve the aerodynamic performance of flying bodies. The morphing wing can be tailored to deliver superior performance, compared to its non-morphing counterparts, for multiple operating conditions and in varying flows. In particular, the morphing wing is implemented for drag reduction and lift enhancement, and hence, the maneuverability, adaptability, and capability of the morphing wing can encompass an even wider spectrum by changing the wing shape. In this research, an existing morphing UAV wing design, Spanwise Morphing Trailing Edge (SMTE), actuated by bending Macro Fiber Composites (MFCs), is considered to generate the spanwise sinusoidal variations on the trailing edge of the morphing wing. A comparative aerodynamic study of the morphing wing by varying the spatial frequency (i.e., number of waves along the span) and the phase shift (i.e., wave shape along the span) at different angles of attack is conducted through analytical approaches and numerical Computational Fluid Dynamic (CFD) simulations, which are validated with previous experimental measurements. The analytical approach uses the three-dimensional (3D) Prandtl lifting line theory, and the CFD modeling in turbulence flow solves the 3D Reynolds-Averaged Navier-Stokes (RANS) equations with the k-ω Shear Stress Transport (SST) turbulence model. Note that the numerical simulations of a morphing wing focus on the pre-stall condition to estimate the aerodynamic performance. This work extends a prior study about a nominal flight condition testing a morphing wing at multiple flight conditions to evaluate multi-point 1 performance. The results show that there are governing aerodynamic efficiency zones of the lift-to-drag ratio, endurance, and aircraft range within a zone of angles of attack. Therefore, the morphing wing is shown to have a good aerodynamic performance as compared to the non-morphing wing.

A Review on Different Design Modifications Employed in Inclined Solar Still for Enhancing the Productivity

2018 ◽  
Vol 141 (3) ◽  
Author(s):  
A. E. Kabeel ◽  
A. Muthu Manokar ◽  
Ravishankar Sathyamurthy ◽  
D. Prince Winston ◽  
S. A. El-Agouz ◽  
...  
Keyword(s):  
Surface Area ◽  
Fresh Water ◽  
Water Depth ◽  
Human Population ◽  
Human Society ◽  
The Sun ◽  
Rapid Rise ◽  
Solar Still ◽  
Major Constraint ◽  
Distillate Yield

The current challenge of human society is to meet the large demand of freshwater, which is depleting at a faster rate due to a rapid rise in human population and fast urbanization. Solar still is the economical way to obtain fresh water since it solely requires the energy from the sun alone for its operation, which is abundantly and freely available in nature. The major constraint in conventional solar still (CSS) is to maintain a large surface area of water with a minimum water depth. The best solution for the above constraint is to prefer inclined solar still (ISS) in which the surface area of water is large with a minimum water depth. In order to improvise the performance and efficiency of ISS, numerous works have been incorporated by increasing the free surface area of water. The distillate yield collected from the passive ISS was found as 1000–8100 mL/m2 whereas active ISS produced the distillate yield of 1045–9000 mL/day. In this review, an attempt is made to analyze the present status of different designs in ISS to motivate further research in ISS technology for meeting the demand of fresh water.

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