Impacts of some parameters affecting the hydraulic performance of U-shaped side spillways

2006 ◽  
Vol 33 (5) ◽  
pp. 552-560
Author(s):  
A Montazar ◽  
S A. Salehi Neyshabori
Keyword(s):  
Pressure Fluctuations ◽  
Considerable Effect ◽  
Hydraulic Performance ◽  
Side Channel ◽  
Performance Pressure ◽  
Flow Turbulence ◽  
Sill Height ◽  
Bed Slope ◽  
Qualitative Index ◽  
Side Weirs

Side channel spillways are one type of outlet works at dams with wide applications in irrigation and drainage systems and in water and wastewater facilities. When the flow enters the side channel through the end and two side weirs of the spillway, it is called a three-sided spillway. Based on the results of laboratory experiments, the present study investigates the impacts of variation in end-sill elevation and location and the bed slope of the side channel for different inflow rates into a spillway. In these evaluations, variation in flow regime is taken as a qualitative index and the flow turbulence index is taken as a quantitative index. The values for the latter index were calculated from readings of momentary pressures using a datalogger system. The results showed that the sill elevation had the greatest effect on pressure fluctuations and on the hydraulic performance of the side channel in these spillways. Increasing the sill height decreased the quantitative value of the water turbulence index in the side channel. According to the findings of the present study, the location of the sill in relation to the side channel does not have a considerable effect on pressure fluctuations. It was also found that increasing the channel bed slope reduces pressure fluctuations by about 3%. Greater increases in the bed slope cause increased flow turbulence. Increasing the channel bed slope in the reverse (negative) direction had considerable effects on reducing the channel flow turbulence.Key words: hydraulic performance, pressure fluctuations, spatially varied flow, three-sided channel spillway, U-shaped spillway.

Hydraulic Performance of Asymmetric Labyrinth Side Weirs Located on a Straight Channel

2012 ◽  
Vol 138 (8) ◽  
pp. 766-772 ◽  
Author(s):  
A. Parvaneh ◽  
S. M. Borghei ◽  
M. R. Jalili Ghazizadeh
Keyword(s):  
Hydraulic Performance ◽  
Straight Channel ◽  
Side Weirs

Contribution of Acoustic and Structural Sources to the Tonal Sound Radiation of Side Channel Blowers

2014 ◽  
Author(s):  
Sven Münsterjohann ◽  
Stefan Becker ◽  
Thomas Grohmann ◽  
Rudi Dittmar
Keyword(s):  
Pressure Fluctuations ◽  
Second Step ◽  
Side Channel ◽  
Acoustic Excitation ◽  
Far Field ◽  
Sound Emission ◽  
Direct Production ◽  
Flow Phenomena ◽  
Acoustic Sources ◽  
Structural Excitation

Structural excitation and direct production of acoustic sources in the flow lead to the sound emission of side channel blowers. Pressure fluctuations in the region of the interrupter excite the structure and result in a tonal sound emission at the blade passing frequency (BPF). Furthermore the flow phenomena produce acoustic sources that are radiated in the far field. These different mechanisms of the structural and acoustic excitation are calculated in a simplified way. In a second step each source is separately coupled into the side channel blower. The structural excitation is realized with a shaker. The acoustic sources are generated with a horn driver (speaker) and are induced into the system through the outlet of the blower. Using this setup, the contribution of each source to the tonal sound in the far field can be estimated and compared to the total measured sound pressure level (SPL) at the corresponding frequency.

scholarly journals Total pressure fluctuations and two-phase flow turbulence in self-aerated stepped chute flows

2016 ◽  
Vol 51 ◽  
pp. 8-20 ◽  
Author(s):  
Gangfu Zhang ◽  
Hubert Chanson ◽  
Hang Wang
Keyword(s):  
Total Pressure ◽  
Two Phase Flow ◽  
Pressure Fluctuations ◽  
Phase Flow ◽  
Two Phase ◽  
Flow Turbulence ◽  
Stepped Chute

Dynamic pressure analysis as a tool for determination of sharkskin instability by extrusion of molten polymers

2012 ◽  
Vol 32 (6-7) ◽  
pp. 335-341 ◽  
Author(s):  
Mateusz Barczewski ◽  
Roman Barczewski ◽  
Tomasz Sterzynski
Keyword(s):  
Autocorrelation Function ◽  
Dynamic Pressure ◽  
Pressure Fluctuations ◽  
Extrusion Process ◽  
Processing Technique ◽  
Considerable Effect ◽  
Visual Observation ◽  
Fast Fourier Transformation ◽  
Signal Acquisition ◽  
Signal Processing Technique

Abstract Increasing requirements which extruded polymeric products should accomplish are imposed to quantitatively characterize the factors which have a considerable effect on extrusion stability. Investigation has been realized by means of a rheological measurement device including a single screw extruder, as well as a rheological die, signal acquisition and analysis system. Due to a specially designed measurement track and modern signal processing technique, the separation of cyclic instabilities from received signals (representing the course of melt pressure) and the definition of the influence on the extrusion process were feasible. This paper demonstrates an example of the application of two new methods which facilitate the detection of sharkskin instability, irrespective of visual observation of the extrudate. Autocorrelation function and frequency analysis based on a fast Fourier transformation (FFT) were used as numeric tools applied to register and control the extrusion process. The flow of molten polymer was studied under various processing conditions, giving an opportunity to split high frequency pressure fluctuations by means of the autocorrelation function and fast Fourier transform, and to create, in the future, a catalogue of data which can be used to define particular distortions in technological investigations.

scholarly journals Effects of Biochar Addition on Rill Flow Resistance

Water ◽  
2021 ◽  
Vol 13 (21) ◽  
pp. 3036
Author(s):  
Alessio Nicosia ◽  
Vincenzo Pampalone ◽  
Vito Ferro
Keyword(s):  
Reynolds Number ◽  
Friction Factor ◽  
Flow Resistance ◽  
Accurate Estimate ◽  
Power Equation ◽  
Flow Turbulence ◽  
Bed Slope ◽  
The Relationship ◽  
Resistance Equation ◽  
Rill Flow

The development of rills on a hillslope whose soil is amended by biochar remains a topic to be developed. A theoretical rill flow resistance equation, obtained by the integration of a power velocity distribution, was assessed using available measurements at plot scale with a biochar added soil. The biochar was incorporated and mixed with the arable soil using a biochar content BC of 6 and 12 kg m−2. The developed analysis demonstrated that an accurate estimate of the velocity profile parameter Гv can be obtained by the proposed power equation using an exponent e of the Reynolds number which decreases for increasing BC values. This result pointed out that the increase of biochar content dumps flow turbulence. The agreement between the measured friction factor values and those calculated by the proposed flow resistance equation, with Гv values estimated by the power equation calibrated on the available measurements, is characterized by errors which are always less than or equal to ±10% and less than or equal to ±3% for 75.0% of cases. In conclusion, the available measurements and the developed analysis allowed for (i) the calibration of the relationship between Гv, the bed slope, the flow Froude number, and the Reynolds number, (ii) the assessment of the influence of biochar content on flow resistance and, (iii) stating that the theoretical flow resistance equation gives an accurate estimate of the Darcy–Weisbach friction factor for rill flows on biochar added soils.

scholarly journals Flow Bifurcation at a Longitudinal Training Dam: Effects on Local Morphology

2018 ◽  
Vol 40 ◽  
pp. 05020 ◽  
Author(s):  
Timo de Ruijsscher ◽  
Suleyman Naqshband ◽  
Ton Hoitink
Keyword(s):  
Three Dimensional ◽  
Laser Scanner ◽  
Flow Characteristics ◽  
Side Channel ◽  
Physical Mechanisms ◽  
Mobile Bed ◽  
First Results ◽  
Acoustic Doppler Velocimetry ◽  
Sill Height ◽  
Set Up

Longitudinal training dams (LTDs) have been built over a length of 10 km in the Dutch River Waal as an alternative to groyne fields, splitting the river in a fairway and a bank-connected side channel in the inner bend. Here, we study the physical mechanisms governing the three-dimensional flow and its effect on local morphology at the flow divide using a mobile bed physical model of an LTD, centred around a side channel intake. In line with previous experiments, polystyrene granules are used as a lightweight sediment that allows to achieve dynamic similarity between the model and the prototype. An Acoustic Doppler Velocimetry (ADV) profiler is used to monitor the flow characteristics, whereas a line laser scanner set-up is used to measure the morphological imprint of the flow near the bifurcation point. To study the dependence of the results on the sill height at the side channel intake, different forms and heights of the sill are used. First results show striking similarities with measurements from the field pilot in the Waal River, as well as larger sedimentation in the side channel for a uniform low sill compared to a downstream increasing sill height.

Noise Controlling Using Porous Stabilizers in a Cross-Flow Fan

2012 ◽  
Author(s):  
Huanxin Lai ◽  
Hongbo Zhang ◽  
Jin Yao ◽  
Gailan Xing
Keyword(s):  
Pressure Fluctuations ◽  
Cross Flow ◽  
Internal Flow ◽  
Considerable Effect ◽  
Performance Curve ◽  
Fan Noise ◽  
Radiated Noise ◽  
Instantaneous Pressure ◽  
The Cross ◽  
Cross Flow Fan

Experimental measurements and simulations are carried out to study the performances and the unsteady internal flow fields of a cross-flow fan (CFF), which uses a kind of porous stabilizers proposed by the authors in an attempt to control the noise. The performance curve and sound radiation of the fan as well as instantaneous pressure fluctuations in the flowfield are measured and analysed. Transient calculations of the flowfield are carried out to study the vortical flows inside the fan as well as in the porpous stabilizers. The results show that the porous stabilizers have not produced considerable effect on the cross-flow fan’s performance curve, but the amplitude of the pressure fluctuation and the level of radiated noise are affected. This qualitative study indicates the cross-flow fan noise may be controlled by using the porous stabilizers if the porosity is properly selected.

Hydraulic performance of labyrinth side weirs using vanes or piles

2011 ◽  
Vol 164 (5) ◽  
pp. 229-241 ◽  
Author(s):  
Abdorreza Kabiri-Samani ◽  
Seyed Mahmood Borghei ◽  
Hojat Esmaili
Keyword(s):  
Hydraulic Performance ◽  
Side Weirs

scholarly journals Numerical Delineation of 3D Unsteady Flow Fields in Side Channel Pumps for Engineering Processes

Energies ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1287 ◽  
Author(s):  
Fan Zhang ◽  
Ke Chen ◽  
Desmond Appiah ◽  
Bo Hu ◽  
Shouqi Yuan ◽  
...  
Keyword(s):  
Channel Flow ◽  
Pressure Fluctuation ◽  
Pressure Fluctuations ◽  
Flow Fields ◽  
Operational Reliability ◽  
Side Channel ◽  
Velocity Fluctuations ◽  
Flow Passage ◽  
Flow Fluctuations ◽  
Noise Vibration

Side channel pumps are important machines for handling toxic, explosive or other dangerous liquids in various engineering processes. However, the operational reliability of these pumps is directly affected by the intensity of the pressure and velocity fluctuations, thus the flow fluctuations existing within the pump cannot be neglected because of their direct influence on the noise, vibration and harshness performance. Therefore, describing precisely the zones of highly unsteady and turbulent flow fields is a key research topic. Moreover, the size of the wrapping angle strongly affects the levels of pressure and velocity fluctuations, thus numerical calculations of the pressure and velocity fluctuation intensities in side channel pump models with different wrapping angles were conducted in this work. The results indicated that the pressure fluctuation coefficient increased gradually from the inflow to the outflow. At the interrupter, the flow experienced the most irregular flow patterns in the pump. The flow at the inflow region in both the impeller and side channel passage rendered weak pressure fluctuation intensities. All three pump cases operated with 24 blades but after one complete circulatory cycle, cases 1, 2 and 3 revealed 21, 20 and 19 regular pressure fluctuations respectively in the impeller flow passage. On the other hand, the side channel flow passage rather produced 24 regular pressure fluctuations. Furthermore, the main frequency harmonic excitations for all studied monitoring points in the impeller and side channel flow passages of the three pump cases occurred at 600 Hz (24 × fn), 1200 Hz (48 × fn), and 1800 Hz (72 × fn). For this reason, exchanged flow times between the impeller and side channel is mainly responsible for the pressure fluctuation which subsequently affects the noise and vibration generation in the side channel pump. Hence, the results could be used as a reference for Noise-Vibration-Harshness (NVH) study in turbomachinery especially modifying the side channel pump in order to improve the operational reliabilities for many engineering processes.

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