Switching Phenomenon of a Bathtub Vortex

1994 ◽  
Vol 61 (4) ◽  
pp. 850-854 ◽  
Author(s):  
M. Shiraishi ◽  
T. Sato
Keyword(s):  
Linear Relationship ◽  
Flow Rate ◽  
Oscillation Frequency ◽  
Design Parameters ◽  
Water Tank ◽  
Fluid Level ◽  
Rate Difference ◽  
Switching Phenomenon ◽  
Double Orifice ◽  
Bathtub Vortex

Switching phenomenon of the bathtub vortex in a double-orifice water tank is experimentally investigated. This alternation between “vortexflow” and “nonvortex flow” is caused by flow rate differences through the two orifices. The oscillation frequency is experimentally examined by changing the design parameters, such as the orifice size, the distance between two orifices, and the fluid level. A linear relationship is obtained between the frequency and the flow rate difference.

Multi-objective optimization of squirrel cage fan for range hood based on Kriging model

2021 ◽  
pp. 095440622199586
Author(s):  
Qianhao Xiao ◽  
Jun Wang ◽  
Boyan Jiang ◽  
Weigang Yang ◽  
Xiaopei Yang
Keyword(s):  
Flow Rate ◽  
Optimization Design ◽  
Volume Flow Rate ◽  
Kriging Model ◽  
Volume Flow ◽  
Design Parameters ◽  
Multi Objective Optimization ◽  
Nsga Ii ◽  
Multi Objective ◽  
Squirrel Cage

In view of the multi-objective optimization design of the squirrel cage fan for the range hood, a blade parameterization method based on the quadratic non-uniform B-spline (NUBS) determined by four control points was proposed to control the outlet angle, chord length and maximum camber of the blade. Morris-Mitchell criteria were used to obtain the optimal Latin hypercube sample based on the evolutionary operation, and different subsets of sample numbers were created to study the influence of sample numbers on the multi-objective optimization results. The Kriging model, which can accurately reflect the response relationship between design variables and optimization objectives, was established. The second-generation Non-dominated Sorting Genetic algorithm (NSGA-II) was used to optimize the volume flow rate at the best efficiency point (BEP) and the maximum volume flow rate point (MVP). The results show that the design parameters corresponding to the optimization results under different sample numbers are not the same, and the fluctuation range of the optimal design parameters is related to the influence of the design parameters on the optimization objectives. Compared with the prototype, the optimized impeller increases the radial velocity of the impeller outlet, reduces the flow loss in the volute, and increases the diffusion capacity, which improves the volume flow rate, and efficiency of the range hood system under multiple working conditions.

scholarly journals The Enhancement of Pre-Storage Filtration Efficiency for the Rainwater Harvesting System in Malaysia

2018 ◽  
Vol 152 ◽  
pp. 02015
Author(s):  
Yoong Sion Ong ◽  
Ken Sim Ong ◽  
Y.k. Tan ◽  
Azadeh Ghadimi
Keyword(s):  
Stainless Steel ◽  
Flow Rate ◽  
Rainwater Harvesting ◽  
Filtration Efficiency ◽  
High Flow ◽  
High Flow Rate ◽  
Water Tank ◽  
Filtration System ◽  
Filter Screen ◽  
Water Piping

A conventional design of rainwater harvesting system collects and directs the rainwater through water piping from roof of building to the water storage. The filtration system which locates before the water tank storage and first flush bypass system is the main focus of the research. A filtration system consists of a control volume of filter compartment, filter screen (stainless steel mesh) and water piping that direct the water flow. The filtration efficiency of an existing filter “3P Volume Filter VF1” by industrial company is enhanced. A full scale filter design prototype with filter screen of 1000 μm stainless steel metal mesh is tested to compare with the original filter system design. Three types of water inlet setups are tested. Among the proposed water inlet setups, the 90° inlet setup with extension provides the best filtration rate per unit time, following by the 45° inlet setup. The 45° and 90° inlet setup has similar filtration efficiency at low to medium flow rate while 45° inlet setup has better efficiency at high flow rate. The filtration efficiency with the 90° inlet setup with extension is observed to maintain at highest value at medium to high flow rate. The overall filtration performance achieved by the 90° inlet setup with extension at low to high flow rate is between 34.1 to 35.7%.

Evaluation of Design Characteristics for Animal Mortality Composting Systems

2021 ◽  
Vol 65 (1) ◽  
pp. 23-30
Author(s):  
Tiago Costa ◽  
Neslihan Akdeniz
Keyword(s):  
Moisture Content ◽  
Linear Relationship ◽  
Compressive Stress ◽  
Flow Rate ◽  
Volumetric Flow Rate ◽  
Airflow Rate ◽  
List Type ◽  
Design Characteristics ◽  
The Impact ◽  
Composting Systems

HighlightsDesign characteristics for animal mortality compost cover materials were tested.Compressive stress was applied to simulate the effects of the mortalities on cover materials.The highest permeability was measured for sawdust at 25% moisture content.A linear relationship was found between the volumetric flow rate and the power required to aerate the piles.Abstract. Composting is an aerobic process that relies on natural aeration to maintain proper oxygen levels. Air-filled porosity, mechanical strength, and permeability are among the essential parameters used to optimize the process. This study’s objective was to measure the physical parameters and airflow characteristics of three commonly used cover materials at four moisture levels, which could be used in designing actively aerated swine mortality composting systems. A laboratory-scale experiment was conducted to measure pressure drops across the cover materials as a function of the airflow rate and the material’s moisture content. Compressive stress was applied for 48 h to simulate the impact of swine mortalities on the cover materials. The power required to aerate each material was determined as a function of volumetric flow rate and moisture content. As expected, air-filled porosity and permeability decreased with increasing bulk density and moisture content. The highest average permeability values were measured at 25% moisture content and ranged from 66 × 10-4 to 70 × 10-4 mm2, from 161 × 10-4 to 209 × 10-4 mm2, and from 481 × 10-4 to 586 × 10-4 mm2 for woodchips, ground cornstalks, and sawdust, respectively. For the range of airflow rates tested in this study (0.0025 to 0.0050 m3 s-1 m-2), a linear relationship (R2 = 0.975) was found between the volumetric flow rate (m3 s-1) and the power required to aerate the compost pile (W per 100 kg of swine mortality). Keywords: Airflow, Darcy’s law, Livestock, Modeling, Permeability, Pressure drop.

The Optimum Groove Geometry for Spiral Groove Viscous Pumps

1990 ◽  
Vol 112 (2) ◽  
pp. 409-414 ◽  
Author(s):  
Yuichi Sato ◽  
Kyosuke Ono ◽  
Akihiko Iwama
Keyword(s):  
Differential Equation ◽  
Flow Rate ◽  
Groove Width ◽  
Design Parameters ◽  
Width Ratio ◽  
Maximum Pressure ◽  
Spiral Groove ◽  
Clearance Ratio ◽  
Viscous Pump ◽  
Outflow Rate

The optimum geometries of disk and cylindrical sprial groove viscous pumps to provide the maximum pressure or flow rate are investigated theoretically. The geometrical design parameters, such as the groove angle, groove to ridge clearance ratio, groove width ratio and ridge clearance ratio, are considered as functions of meridional coordinate. Results are obtained from the solution of a differential equation for the smoothed overall pressure distribution of a spiral groove viscous pump. It is found that outflow rate increases with the increase of groove to ridge clearance ratio λ, and that for each value of λ there exist “optimum” values of groove angle and groove width ratio, which give a maximum outflow rate. However, the increase of λ decreases the ridge clearance.

scholarly journals Experimental on the protective performance of column bridge pier anti-scouring device

2021 ◽  
Vol 248 ◽  
pp. 01015
Author(s):  
Zhejiang Chen ◽  
Liang Liu ◽  
Yonglin Hu ◽  
Nan Ye ◽  
Xiaoli Shen ◽  
...  
Keyword(s):  
Optimal Parameter ◽  
Reduction Rate ◽  
Local Scour ◽  
Bridge Pier ◽  
Design Parameters ◽  
Water Tank ◽  
Protective Device ◽  
Measuring Point ◽  
Test Range ◽  
The Impact

Because of the problem of local scour caused by the change of the flow structure caused by the water-resistance of the column bridge pier, the theoretical analysis, and indoor water tank test were used to study the effect of installing a new anti-scouring device in front of the bridge pier on the local scour reduction effect; the influence of the main design parameters such as the height of the protective device, the angle of the protective device and the distance from the protective device to the bridge pier on the local scour of the bridge pier was selected, and the optimal parameter design combination was selected. The test results show that: under the same water flow conditions, the maximum scour depth reduction rate of the measuring point under the protection of the protective device is 48.4% to 74.2% compared with the unprotected scour; the reduction rate of the bridge pier is relative to the relative height of the device and the device equivalent. The angle and the distance between the device and the bridge pier are related, and the shock reduction rate decreases with the increase of the flow intensity. In the test range, the ratio of the device height to the water depth is 2/3, the device angle is 60 °, and the distance from the bridge pier is 3. When the diameter of the pier is doubled, the effect of reducing the impact on the pier is the best.

Development of a Latching Valve for Micro-Chem-Lab™

1999 ◽  
Author(s):  
C. Channy Wong ◽  
Douglas R. Adkins ◽  
Ronald P. Manginell ◽  
Gregory C. Frye-Mason ◽  
Peter J. Hesketh ◽  
...  
Keyword(s):  
Power Consumption ◽  
Gas Phase ◽  
Flow Rate ◽  
Integrated System ◽  
Dead Volume ◽  
Design Parameters ◽  
Working Fluid ◽  
Driving Voltage ◽  
Magnetic Actuation ◽  
Phase Detection

Abstract An integrated microsystem to detect traces of chemical agents (μChemLab™) is being developed at Sandia for counter-terrorism and nonproliferation applications. This microsystem has two modes of operation: liquid and gas phase detection. For the gas phase detection, we are integrating these critical components: a preconcentrator for sample collection, a gas chromatographic (GC) separator, a chemically selective flexural plate wave (FPW) array mass detector, and a latching valve onto a single chip. By fabricating these components onto a single integrated system (μChemLab™ on a chip), the advantages of reduced dead volume, lower power consumption, and smaller physical size can be realized. In this paper, the development of a latching valve will be presented. The key design parameters for this latching valve are: a volumetric flow rate of 1 mL/min, a maximum hold-off pressure of 40 kPa (6 psi), a relatively low power, and a fast response time. These requirements have led to the design of a magnetically actuated latching relay diaphragm valve. Magnetic actuation is chosen because it can achieve sufficient force to effectively seal against back pressure and its power consumption is relatively low. The actuation time is rapid, and valve can latch in either an open or closed state. A corrugated parylene membrane is used to separate the working fluid from internal components of the valve. Corrugations in the parylene ensure that the diaphragm presents minimum resistance to the actuator for a relativley large deflection. Two different designs and their performance of the magnetic actuation have been evaluated. The first uses a linear magnetic drive mechanism, and the second uses a relay mechanism. Preliminary results of the valve performance indicates that the required driving voltage is about 10 volts, the measured flow rate is about 50 mL/min, and it can hold off pressure of about 5 psi (34 kPa). Latest modifications of the design show excellent performance improvements.

Dynamic Characteristics Analysis of NuScale in Frequency Domain

2021 ◽  
Author(s):  
Jingrui Yang ◽  
Qian Ma ◽  
Lingtong Han ◽  
Peiwei Sun
Keyword(s):  
Frequency Domain ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Dynamic Characteristics ◽  
Water Desalination ◽  
Design Parameters ◽  
Mechanism Analysis ◽  
Secondary Loop ◽  
Calculation Results

Abstract NuScale is a small nuclear reactor that relies on natural circulation. Its modular production and inherent safety can not only be used to generate electricity in some remote areas, but also provide energy for water desalination and regional heating. However, the dynamic characteristics of the NuScale are different from those of the traditional PWRs because of its passive characteristic. Therefore, it is necessary to study and analyze the system dynamic characteristics of NuScale. The NuScale PWR model is established based on MATLAB&Simulink. It includes point-reactor kinetics model with six groups delayed neutrons, coolant system and steam generator system. The model is established based on the conservation equations of mass, energy and momentum. And the correctness of the model is verified by the comparison between the steady-state calculation results and the design parameters. Transient calculation results are verified by mechanism analysis. To evaluate the dynamic characteristics of NuScale, the sine function changes with different frequencies in reactor reactivity and feedwater mass flow rate are introduced. The amplitude and phase responses of reactor power, secondary loop steam pressure, secondary loop mass flow rate, secondary loop steam temperature, and coolant average temperature are recorded. Then the Bode plot can be drawn with amplitude and phase responses in different frequencies. To evaluate the NuScale dynamic characteristics, frequency domain analysis is performed.

The Theory and the Practical Validation of the Fluid Level Position in the Annulus During Lost Circulation

2021 ◽  
Author(s):  
Alexey Ruzhnikov ◽  
Edgar Echevarria
Keyword(s):  
Flow Rate ◽  
Drilling Fluid ◽  
Time Interval ◽  
Fluid Level ◽  
Drilling Tool ◽  
Lost Circulation ◽  
Hole Pressure ◽  
Bottom Hole Pressure ◽  
Bottom Hole ◽  
Carbonate Formations

Abstract Carbonate formations around the world and specifically in a Middle East are prone to have total losses while drilling. And the nature of the losses often related to the highly fractured formations of the pay zone. When such fracture(s) is crossed by the wellbore the lost circulation initiated and led to a drilling without a return to a surface. To avoid undesired well control event or wellbore instability and to maintain the constant bottom hole pressure the mud cap drilling strategy often used as a preventative measure. The mud cap can be either the continuous or based on some volume or time interval, depends on the local practices or the policy of an operator. The mud cap flow rate as well as mud cap mud weight are often based on the best practices, not supported by an engineering study. To understand the behavior of the drilling fluid level in the annulus while drilling with total losses the drilling bottom hole assembly equipped with annular pressure while drilling tool was used. As the drilling required to use the continuous mud cap, then the specific guideline was developed on measurement of the bottom hole pressure and further conversion of it to the fluid level. The study was performed across pay zone with one or several loss circulation zones identified. As the result it was confirmed that the used mud cap flow rate had minor to none effect on the fluid level position in the annulus and that the bottom hole pressure remained the same. It showed as well that different loss zones are behaving in a different way, what can be considered as a factor affecting their ability to be sealed. The obtained knowledge and the information should help to understand better the loss circulation behavior as well be an important step toward development of the product which may cure the losses in high fractured carbonate formations. The results of the study can be implemented in any other project or a field.

scholarly journals Application of the Robust Fixed Point Iteration Method in Control of the Level of Twin Tanks Liquid

Computation ◽  
2020 ◽  
Vol 8 (4) ◽  
pp. 96
Author(s):  
Hamza Khan ◽  
Hazem Issa ◽  
József K. Tar
Keyword(s):  
Numerical Simulation ◽  
Fixed Point ◽  
Nonlinear Systems ◽  
Flow Rate ◽  
Fluid Level ◽  
Process Industries ◽  
Fixed Point Iteration ◽  
Precise Control ◽  
Strongly Nonlinear ◽  
Simulation Results

Precise control of the flow rate of fluids stored in multiple tank systems is an important task in process industries. On this reason coupled tanks are considered popular paradigms in studies because they form strongly nonlinear systems that challenges the controller designers to develop various approaches. In this paper the application of a novel, Fixed Point Iteration (FPI)-based technique is reported to control the fluid level in a “lower tank” that is fed by the egress of an “upper” one. The control signal is the ingress rate at the upper tank. Numerical simulation results obtained by the use of simple sequential Julia code with Euler integration are presented to illustrate the efficiency of this approach.

Numerical Simulation and Experimental Study on Tar Decomposition of Low-Pressure Ejection Type Burner

2015 ◽  
Vol 1092-1093 ◽  
pp. 200-206
Author(s):  
De Fan Qing ◽  
Mao Kui Zhu ◽  
Yang Cheng Luo ◽  
Ya Long Zhang ◽  
Ai Rui Chen ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Flow Rate ◽  
Gas Flow ◽  
Low Pressure ◽  
Orthogonal Test ◽  
Nozzle Diameter ◽  
Design Parameters ◽  
Minor Effect ◽  
Gas Flow Rate ◽  
Tar Cracking

The tar decomposition of low-pressure ejection type burner was researched. The burner used software to simulate and analyse impact of the nozzle diameter d, the gas flow rate V and the distance of the nozzle to the wall L on tar cracking. The orthogonal test were used for design parameters d, V and L, the optimization values of these three parameters were carried out, and experimental method was used for test the numerical simulation results. Numerical simulation and experimental results showed that the greatest impact on tar cracking is the nozzle diameter d, the minor effect is the distance of the nozzle to the wall L and the weakest effect is the gas flow rate V, and when the nozzle diameter d=4 mm, the distance L=18 mm and the gas flow rate V=0.10 m3/h, the tar cracking is the most efficiency.

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