Study on Flow Characteristics inside a Spillway Tunnel of Hydropower Station

2014 ◽  
Vol 716-717 ◽  
pp. 219-222
Author(s):  
Hong Qing Zhang ◽  
Bing Cao ◽  
Yi Long Lou ◽  
Wei Kai Tan
Keyword(s):  
Flow Velocity ◽  
High Speed ◽  
Flow Characteristic ◽  
Flow Characteristics ◽  
Hydropower Station ◽  
Turbulent Model ◽  
Cross Sectional ◽  
Vof Model ◽  
Spillway Tunnel ◽  
The Right

VOF model and turbulent model were used in this paper to study on flow characteristic inside a certain spillway tunnel of hydropower station, which includes cross sectional distributions of flow velocity in pressure section and non-pressure section. The results show that flow velocity distribution in the pressure section of the spillway tunnel is basically symmetrical. After turning, flow velocity is well-distributed and move ahead; flow velocity in the right side of non-pressure section in the spillway tunnel is 1m/s faster than that in the left side. When two high-speed water flow come together after passing through the central division pier, flow velocity distributions in the both sides of the spillway tunnel are all uniform. The conclusions obtained can improve the design of the spillway tunnel.

Numerical Simulation of Ventilation Characteristics in a Hydropower Station Spillway Tunnel with High Head and Large Discharge

2014 ◽  
Vol 926-930 ◽  
pp. 3527-3530
Author(s):  
Hong Qing Zhang ◽  
Yi Long Lou ◽  
Wei Ping Xing ◽  
Jun Jun Tan
Keyword(s):  
Wind Speed ◽  
Hydropower Station ◽  
Aerated Flow ◽  
Speed Distribution ◽  
Vof Model ◽  
High Head ◽  
Spillway Tunnel ◽  
The Right ◽  
Ventilation Hole ◽  
Large Discharge

High wind speedandloudnoise usually occur in the hydropower station spillway tunnel, which will impact the producing environment of operators. In this paper, turbulent model and VOF modelwere combinedto simulate wind speed and the volume of ventilated airin ventilation holeandthreeaeratorsin the spillway tunnel on the right bank of a hydropower station in China. The results show thatVOF modelcan well simulate ventilated air induced by water drag, andthe volume of ventilated air in ventilation hole is the largest.Wind speed distribution on the longitudinal sectionof the inlet of ventilation hole is non-uniform,and loud noisewill occurthere. Wind speed on the left side of three aerators is higher than that on the right side. The results of the volume of ventilated airin threeaerators simulated by VOF modelare credible, but we should improve the VOF model to more accurately simulate aerated flow.

Study of Flow Characteristics of Oil and Water in the Process of Stirring

2013 ◽  
Vol 353-356 ◽  
pp. 3190-3193
Author(s):  
Zong Rui Hao ◽  
Juan Xu ◽  
Hai Yan Bie ◽  
Zhong Hai Zhou
Keyword(s):  
Flow Field ◽  
Flow Pattern ◽  
Cross Section ◽  
Radial Flow ◽  
Flow Characteristics ◽  
Stirred Tank ◽  
Turbulent Model ◽  
Vof Model ◽  
Circular Flows ◽  
Oil Water

To study the flow pattern in the process of oil-water stirring in three paddle stirring tank, RNG k-ε turbulent model and VOF model are adopted to simulate the flow field at different time in the stirred tank with the baffle. The results showed that, in the stirring process, inverted cone manifold was formed in the center of the stirring shaft. The stratified area was formed in the baffle and gradually transported to the bottom of the tank. The two circular flows were formed among three groups of blades. And the axially acting of the fluid was strong, which made homogeneous stirring in the stirred tank. At the same time the radial flow of the cross-section inside the tank increased because of the baffle.

scholarly journals Measurement of Circumferential Liquid Film Based on LIF and Virtual Stereo Vision Sensor

2016 ◽  
Vol 2016 ◽  
pp. 1-5 ◽  
Author(s):  
Ting Xue ◽  
Xiaokang Lin ◽  
Liuxiangzi Yang
Keyword(s):  
Liquid Film ◽  
Stereo Vision ◽  
High Speed ◽  
Annular Flow ◽  
Flow Characteristic ◽  
Thickness Distribution ◽  
Flow Characteristics ◽  
Industrial Applications ◽  
Vision Sensor ◽  
Feature Parameters

Gas-liquid annular flow is widely used in many industrial applications such as petroleum, chemical, and nuclear engineering. The feature parameters of liquid film in the annular flow are of great significance to understand the flow characteristics and measure the flow precisely. For the annular flow, the circumferential features of liquid film are more important than the axial features to acquire abundant flow structures and reveal the flow mechanism. In the paper, a measurement platform based on the laser-induced fluorescence (LIF) and virtual stereo vision sensor is presented. The virtual stereo vision sensor comprises a high-speed camera and two optical reflection sets, which can acquire the liquid film from two views simultaneously and reconstruct the features of liquid film. Image processing techniques are proceeded with to extract the feature parameters of liquid film; then the circumferential flow characteristic can be reconstructed by views transformation and fusion. The flow characteristic based on the thickness distribution is analysed. The experimental results show that the method is valid and effective, which can give a more detailed and accurate description for the liquid film in annular flows.

Pressure Distribution of Pressure and Non-Pressure Sections of a Hydropower Station Spillway Tunnel

2014 ◽  
Vol 716-717 ◽  
pp. 244-247
Author(s):  
Hong Qing Zhang ◽  
Wei Kai Tan ◽  
Yi Long Lou ◽  
Qian Zhao
Keyword(s):  
Pressure Distribution ◽  
Model Experiment ◽  
Hydropower Station ◽  
Maximum Pressure ◽  
Turbulent Model ◽  
Sudden Drop ◽  
Sudden Enlargement ◽  
High Head ◽  
Spillway Tunnel ◽  
Large Discharge

In this paper, we used VOF combining turbulent model to simulate pressure distribution of pressure section and non-pressure section in a hydropower station spillway tunnel with high head and large discharge in China. The results show that in the pressure section of the spillway tunnel, the values of pressure of emergency gate slot, working gate and the pressing slope, getting from physical model experiment and numerical simulation, are all positive. While in the non-pressure section, the No.1、2、3 aerators of the sudden enlargement and sudden drop occur the maximum pressure. And at the back of the No.1、2、3 aerators, where the values of pressure are negative, forms cavity. The conclusions obtained can improve the design of spillway tunnel.

The 3D Numerical Simulation of Flow Field on Y-Shape Flaring Gate Piers Combined with Stepped Spillway

2013 ◽  
Vol 864-867 ◽  
pp. 2200-2206
Author(s):  
Ju Rui Yang ◽  
Xiao Xia Hou ◽  
Qiu Yue Zhang
Keyword(s):  
Water Vapor ◽  
Flow Velocity ◽  
Three Dimensional ◽  
Iterative Solution ◽  
Average Error ◽  
Stepped Spillway ◽  
Two Phase ◽  
Vof Model ◽  
The Right ◽  
Volume Method

The energy dissipater of stepped spillway combined with flaring gate pier is widely used in china's hydraulic engineering. The finite volume method is applied to discrete analysis, with the RNG turbulence model and VOF model of water vapor two-phase, iterative solution of geometry reconstruction format unsteady flow to generate free surface. Adopting structured grid for geometric shape, numerically simulated the water vapor two-phase flow from the reservoir to stilling basin. The parabolic water-vapor interface , overall flow pattern, water wings, section depth and other hydraulic characteristics was produced by simulating the three-dimensional flow field.Compared the simulated results of water depth, flow velocity in stilling pool, the board pressure with experiment data, the average error is: the left side depth of 3 # table hole of 7.1%, and the right of 7.4%; the underside flow velocity of 3 # table hole of 5%;1 # table hole stilling pool board pressure of 7.6%,3 # table hole stilling pool board pressure of 6.6%.

scholarly journals Fluid Flow Characteristics of a Co-Flow Fluidic Slot Jet Thrust Augmentation Propulsion System

2020 ◽  
Author(s):  
Brian Garrett ◽  
Kareem Ahmed
Keyword(s):  
Fluid Flow ◽  
Turbulent Mixing ◽  
High Speed ◽  
High Performance ◽  
Flow Characteristics ◽  
Propulsion System ◽  
Secondary Flows ◽  
High Momentum ◽  
Cross Sectional ◽  
Bulk Fluid

Abstract The UAV industry is booming with investments in research and development on improving UAV systems. Current UAV machines are developed according to the quadcopter design which consists of a rotary propulsion system providing lift needed for flight. This design has some flaws; namely safety concerns and noise/vibration production both of which come stem from the rotary propulsion system. As such, a novel propulsion system using slip stream air passed through high performance slot jets is proposed and an analysis of the fluid characteristics is presented in this report. The test section for the experiment is developed using 3D printed ABS plastic airfoils modified with internal cavities where pressurized air is introduced and then expelled through slot jets on the pressure side of the airfoils. Entrainment processes develop in the system through high momentum fluid introduction into a sedentary secondary fluid. Entrainment is governed by pressure gradients and turbulent mixing and so turbulent quantities that measure these processes are extracted and analyzed according to the independent variable’s effects on these quantities. Pitot probe testing extracted one dimensional fluid information and PIV analysis is used to characterize the two-dimensional flow aspects. High slot jet velocities are seen to develop flows dominated by convection pushing momentum mixing downstream reducing the mixing in the system while low slot jet speeds exhibit higher mass fluxes and thrust development. Confinement spacing is seen to cause a decrease in flow velocity and thrust as the spacing is decreased for high speed runs. The most constricted cross sectional runs showed high momentum mixing and developed combined self-similar flow through higher boundary layer interactions and pressures, but this also hurts thrust development by minimizing secondary flows. The Angle of Attack of the assembly proved to be the most important variable. Outward angling showed the influence of coanda effects but also demonstrated the highest bulk fluid flow with turbulence driven momentum mixing. Inward angling created combined fluid flow downstream with high momentum mixing upstream driven by pressure. Minimal mixing is seen when the airfoils are not angled, and high recirculation zones occur along the boundaries. The optimal setup is seen when the airfoils are angled outwards where the highest thrust and bulk fluid movement is developed driven by the turbulent mixing induced by the increasing cross sectional area of the system.

Capillary Driven Fluid Flow in Medical Devices

2008 ◽  
Author(s):  
Fiachra A. O’Leary ◽  
Philip C. Griffin
Keyword(s):  
Contact Angle ◽  
High Speed ◽  
Computational Models ◽  
Fluid Velocity ◽  
Initial Pressure ◽  
Cardiac Risk ◽  
Cross Sectional ◽  
Aspect Ratios ◽  
Vof Model ◽  
Epoxy Material

Microscale fluid dynamics has played a significant role in the development of many applications in the medical diagnostic sector and in recent years many devices have implemented advances in this field. Capillary driven assays are commonly used in diagnostic areas, such as, cardiac risk, fertility, drug abuse and infectious diseases1. Typically a platform is used where bodily fluids or samples are taken, filtered and by means of small microchannels, transported and mixed with a variety of antibodies2. In order to perform correctly, these antibodies need to bind to the proteins in the fluid. It is therefore essential that the exposure of the proteins to the antibodies is maximized. To achieve this, capillary dimensions can be altered to obtain the required flow rates and exposure times3. This paper focuses on controlling these parameters. In this paper, a study was conducted in which the flows in four straight rectangular microchannels of varying cross sectional areas were assessed. The four microchannels were fabricated from an epoxy material. The microchannel widths varied from 100μm to 1000μm with each channel having a dept of 200μm. The four microchannels had aspect ratios of 0.5, 1, 2 and 10. The microchannels were sealed using a heat sealing hydrophilic tape. Fluid velocity rates were measured experimentally using an X-Stream XS-4 high speed camera at 500 frames per second. Preliminary contact angle results between water and the epoxy material gave a contact angle of 81.5 degrees +/− 6 degrees. Computational models of the four microchannels were performed using a Volume Of Fluid (VOF) model in Fluent 6.2.16, a commercially available CFD code. The computational models had four boundary types: pressure inlet, pressure outlet, epoxy wall and hydrophilic tape wall. The inlet boundary has an initial pressure applied to it, capillary pressure between the water and air interface in the microchannel. It was found that as the dimensions of the microchannels increased, the governing equations were less accurate in predicting the experimental fluid velocity in the microchannels.

scholarly journals Studi Epidemiologi Kejadian Kecelakaan Lalu Lintas Di Kota Pontianak

2018 ◽  
Vol 4 (2) ◽  
pp. 90
Author(s):  
Iskandar Arfan ◽  
Wulandari Wulandari
Keyword(s):  
Traffic Accident ◽  
High Speed ◽  
Traffic Accidents ◽  
Design Research ◽  
Public Awareness ◽  
Sampling Technique ◽  
Cross Sectional ◽  
Purposive Sampling ◽  
Cross Sectional Design ◽  
The Right

Abstract: Epidemiological Study Events Of Traffic Accidents In Pontianak City. The number of traffic accidents in Pontianak City in 2014 is 477 cases, 2015 by 454 cases, in 2016 as many as 542 cases. Important research is done to know the main cause faktors of the accident so that policy makers can pursue the right and maximum intervention. The purpose of this research is to know the epidemiology of traffic accident incident on the motorcycle and cars in Pontianak City. The research used descriptive cross sectional design. Research sample 94 people who have experienced Traffic Accident the last 3 months recorded in data Polresta Pontianak with sampling technique using purposive sampling. The results showed that most of the frequency distribution of epidemiological variables in traffic accidents were as follows: age 26-45 years (45.7%), male gender (70.2%), no driver license (82%). Drivers are driven by high-speed driving habits (67%), vehicle drivers are not routinely caring for vehicles (44.7%), environmental faktors are mostly drivers in dark road conditions (17%). It is expected to raise public awareness about safety driving measures and increase the strength of traffic police and volunteers at crowded traffic points to control traffic especially over the weekend as well as strict regulation of drivers’ faktors, especially the ownership of driving licenses, vehicle maintenance, and improvement of road environmental facilitiesAbstrak: Studi Epidemiologi Kejadian Kecelakaan Lalu Lintas Di Kota Pontianak.  Angka kecelakaan lalu lintas di Kota pontianak terus menerus terjadi peningkatan setiap tahun. tahun 2014 sebanyak 477 kasus, tahun 2015 sebanyak 454 kasus dan tahun 2016 sebanyak 542 kasus, penelitian penting dilakukan untuk mengetahui faktor penyebab utama kecelakaan sehingga pengambil kebijakan dapat mengupayakan intervensi yang tepat dan maksimal. Tujuan penelitian  untuk mengetahui epidemiologi kejadian kecelakaan lalu lintas pada pengendara motor dan mobil di Kota Pontianak. Penelitian menggunakan desain cross sectional deskriptif. Sampel penelitian 94 orang yang pernah mengalami kecelakaan lalu lintas 3 bulan terakhir yang tercatat di data Polresta Kota Pontianak dengan teknik pengambilan sampel menggunakan purposive sampling. Hasil penelitian menunjukan sebagian besar distribusi frekuensi variabel epidemiologi pada kasus kecelakaan lalu lintas adalah sebagai berikut: usia 26-45 tahun (45.7%), jenis kelamin laki-laki (70.2%), tidak memiliki SIM (82%). Berdasarkan faktor pengemudi sebagian besar memiliki kebiasaan berkendara dengan kecepatan tinggi (67%), faktor kendaraan sebagian besar pengemudi tidak rutin merawat kendaraan (44.7%), faktor lingkungan sebagian besar pengemudi dalam kondisi jalan gelap (17%). Diharapkan meningkatkan kesadaran masyarakat tentang langkah-langkah keselamatan berkendara dan meningkatkan kekuatan polisi lalu lintas dan sukarelawan di titik-titik lalu lintas yang padat untuk mengontrol lalu lintas terutama selama akhir pekan serta pengaturan ketat dari faktor pengemudi khususnya kepemilikan surat ijin mengemudi, perawatan kendaraan, dan perbaikan fasilitas lingkungan jalan. 

Experimental Study on Dam-Break Hydrodynamic Characteristics Under Different Conditions

2017 ◽  
Vol 12 (1) ◽  
pp. 198-207 ◽  
Author(s):  
Hui Liu ◽  
◽  
Haijiang Liu ◽  
Keyword(s):  
Flow Velocity ◽  
Water Level ◽  
High Speed ◽  
Flow Characteristics ◽  
Dam Break ◽  
Hydrodynamic Characteristics ◽  
High Temporal Resolution ◽  
Initial Water ◽  
Water Head ◽  
Reservoir Length

In this study, a series of dam-break experiments was carried out to investigate the influence of the initial downstream water depth, water head settings, and upstream reservoir length on the dam-break wave movement. The instantaneous water level and flow velocity were measured at two specified downstream locations. Considering the requirements for precise data measurement with high temporal resolution, the synchronization of different instruments was realized based on high-speed camera recording. Even with the same initial water head setting, the water level and flow velocity variations of the dam-break wave propagating downstream on the wet bed show noteworthy differences in flow characteristics compared to the initial dry bed, caused by the interactions between the upstream and downstream water. Hydrodynamic formulae proposed by Lauber and Hager (1998) [1] are not applicable for the wet-bed condition, although their solution of wave profiles for the initial dry-bed condition performs well at the location farther from the gate. The non-dimensional average front velocity of the wet-bed condition, which mainly depends on the initial water head setting, is smaller than that of the dry-bed case. In addition, the maximum water level and flow velocity at the downstream location are mainly controlled by the initial water head setting, while the duration of the large values is influenced by the reservoir length.

scholarly journals Analysis of the possibility of using high-speed pneumatic directional valves to regulate the flow of compressed air

2019 ◽  
Vol 213 ◽  
pp. 02084
Author(s):  
Jakub Takosoglu
Keyword(s):  
Flow Rate ◽  
High Speed ◽  
Flow Characteristic ◽  
Position Control ◽  
Experimental Studies ◽  
Flow Characteristics ◽  
Control Signal ◽  
Compressed Air ◽  
Flow Parameters ◽  
Proportional Flow

Most often, proportional flow valves or flow servovalves are used for position control of pneumatic drives. In case of this type of valves, flow characteristic of the valve represents a dependence of flow rate upon analogue control signal (voltage or current). The paper presents experimental studies of two high-speed pneumatic 3/2 directional valves (3-way 2-position) in order to determine the flow characteristics and flow parameters. One has analysed the option to use the directional valves to control the flow rate of compressed air using frequency-based signals.

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