scholarly journals Head Loss Reduction in Surcharged Four-Way Junction Manholes

Water ◽  
2018 ◽  
Vol 10 (12) ◽  
pp. 1741 ◽  
Author(s):  
Jung Kim ◽  
Jun Jo ◽  
Sei Yoon
Keyword(s):  
Numerical Simulations ◽  
Physical Model ◽  
Flow Rate ◽  
Flow Characteristics ◽  
Head Loss ◽  
Loss Reduction ◽  
Effluent Flow Rate ◽  
Loss Coefficients ◽  
Drainage Capacity ◽  
Influent Flow

Head loss in surcharged four-way junction manholes is a factor that increases damage due to urban inundation; thus, the flow characteristics of such manholes must be analyzed to reduce the head loss. In this study, a physical model was constructed; this model included a manhole and a connection pipe, fabricated on a 1/5 scale by applying sewer facility standards to perform a physical model investigation. Numerical simulations were performed using the Fluent model to derive efficient benching designs that can reduce head loss. Physical model investigations were performed by varying the ratio of the lateral influent flow rate to the effluent flow rate as well as by varying the effluent flow rate and benching designs. The result of physical model investigations showed that the installation of half rectangular benching reduced the head loss coefficients by 7% and 10% on average compared with square and circular manholes, respectively. The installation of full rectangular benching reduced the head loss coefficients by 28% and 17% on average compared with square and circular manholes, respectively. Thus, the benching proposed herein can be installed and used to improve the drainage capacity of urban stormwater conduit facilities.

Performance Evaluation of the Flow in Micro Junctions: Head Change Versus Head Loss Coefficients

2013 ◽  
Author(s):  
Bastian Schmandt ◽  
Heinz Herwig
Keyword(s):  
Energy Transfer ◽  
Mass Flow Rate ◽  
Entropy Generation ◽  
Mass Flow ◽  
Flow Rate ◽  
Head Loss ◽  
Total Head ◽  
Single Mass ◽  
Flow Through ◽  
Loss Coefficients

Losses due to the flow through conduit components in a pipe system can be characterised by head loss coefficients. They basically account for the dissipation in the flow field or, in a more general sense, for the entropy generation due to the conduit component under consideration. When only one single mass flow rate is involved, an entropy based approach is straight forward and ṁ can be used as a general reference quantity. If, however, the mass flow rate is split or united like in junctions, some new aspects appear. In our study the general approach for these kind of conduit components is discussed. Like for single mass flow rates losses are accounted for by determining the entropy generation rates. New aspects for the branched flows are an additional parameter, the splitting ratio, and the fact that there is an energy transfer between the single branches that has to be accounted for appropriately. It turns out that this energy transfer changes the total head in each flow brach in addition to a sole loss of total head. Therefore, the coefficients should be named head change coefficients when this effect occurs. As an example the flow through a T-shaped junction is considered, for which head loss coefficients are determined for both branches and discussed with respect to their physical meaning.

scholarly journals Analisa Kerugian Head Akibat Perluasan Dan Penyempitan Penampang Pada Sambungan 90o

2021 ◽  
Vol 1 (1) ◽  
pp. 46-55
Author(s):  
Ahmad Yani ◽  
Ratnawati ◽  
Ardyanto Darmanto
Keyword(s):  
Stainless Steel ◽  
Cross Section ◽  
Flow Rate ◽  
Pipe Flow ◽  
Head Loss ◽  
Stainless Steel Pipe ◽  
Loss Coefficients ◽  
Pvc Pipe ◽  
The Cross ◽  
Loss Effect

PVC pipe (polyvinyl chloride), galvanized, and stainless steel are types of pipes that are widely used, especially for delivering clean water to people's homes or in the industrialized world. This research was conducted by collecting data such as: flow rate (Q), pressure height (h), pipe flow velocity (v), time (s), and head loss (H), data were collected and calculated to determine pressure loss, effect variations in discharge changes and loss coefficients. From the experimental results, it was found that for the narrowing of the cross section at a discharge of 25 liters / second the value of the head loss was greater, which was located in the galvanic pipe, namely 0.09568, then followed by a discharge of 20 liters / second the value was 0.06454 and a discharge of 15 ltr / second the value was 0 , 03723. While the smallest value in panampang narrowing lies in PVC pipe, at a discharge of 25 ltr / second the value is 0.05957, at a discharge of 20 ltr / second the value is 0.03989 and at a discharge of 15 ltr / second the value is 0.02303. Likewise in the expansion of the cross-section, the greatest value lies in the galvanized pipe. For a debit of 25 ltr / second the value obtained is 0.03526, a debit of 20 ltr / second the value is 0.02355, a debit of 15 ltr / second the value is 0.01352. While the smallest value is located on the stainless steel pipe, the value is 0.02688 for the flow rate of 25 liters / second, the value for 20 liters / second is 0.01811, the value for 15 liters / second is 0.01044.

scholarly journals In vitro testing of explanted shunt valves in hydrocephalic patients with suspected valve malfunction

2021 ◽  
Author(s):  
Christoph Bettag ◽  
Christian von der Brelie ◽  
Florian Baptist Freimann ◽  
Ulrich-Wilhelm Thomale ◽  
Veit Rohde ◽  
...  
Keyword(s):  
Flow Rate ◽  
Clinical Symptoms ◽  
Obstructive Hydrocephalus ◽  
Flow Characteristics ◽  
Normal Pressure ◽  
Diagnostic Tools ◽  
Programmable Valve ◽  
Significant Difference ◽  
Valve Malfunction

AbstractDiagnosis of symptomatic valve malfunction in hydrocephalic patients treated with VP-Shunt (VPS) might be difficult. Clinical symptoms such as headache or nausea are nonspecific, hence cerebrospinal fluid (CSF) over- or underdrainage can only be suspected but not proven. Knowledge concerning valve malfunction is still limited. We aim to provide data on the flow characteristics of explanted shunt valves in patients with suspected valve malfunction. An in vitro shunt laboratory setup was used to analyze the explanted valves under conditions similar to those in an implanted VPS. The differential pressure (DP) of the valve was adjusted stepwise to 20, 10, 6, and 4 cmH2O. The flow rate of the explanted and the regular flow rate of an identical reference valve were evaluated at the respective DPs. Twelve valves of different types (Codman CertasPlus valve n = 3, Miethke Shuntassistant valve n = 4, Codman Hakim programmable valve n = 3, DP component of Miethke proGAV 2.0 valve n = 2) from eight hydrocephalic patients (four male), in whom valve malfunction was assumed between 2016 and 2017, were replaced with a new valve. Four patients suffered from idiopathic normal pressure (iNPH), three patients from malresorptive and one patient from obstructive hydrocephalus. Post-hoc analysis revealed a significant difference (p < 0.001) of the flow rate between each explanted valve and their corresponding reference valve, at each DP. In all patients, significant alterations of flow rates were demonstrated, verifying a valve malfunction, which could not be objectified by the diagnostic tools used in the clinical routine. In cases with obscure clinical VPS insufficiency, valve deficiency should be considered.

Investigation of suction flow characteristic in the inertance hydraulic converters for efficiency improvement

2021 ◽  
pp. 095965182110248
Author(s):  
Xiaoming Chen ◽  
Yuchuan Zhu ◽  
Travis Wiens ◽  
Doug Bitner ◽  
Minghao Tai ◽  
...  
Keyword(s):  
Flow Rate ◽  
Flow Characteristic ◽  
Performance Indicator ◽  
Flow Characteristics ◽  
Check Valve ◽  
Analytical Models ◽  
Switching Frequency ◽  
Experimental Measurements ◽  
Efficiency Improvement ◽  
Suction Flow

The inertance hydraulic converter relies on fluid inertance to modulate flow or pressure and is considered to be a competitive alternative to the conventional proportional hydraulic system due to its potential advantage in efficiency. As the quantification of fluid inertance, the suction flow characteristic is the crucial performance indicator for efficiency improvement. To explore the discrepancy between the passive inertance hydraulic converter featured by the check valve and the active inertance hydraulic converter driven by an equivalent 2/3 way fast switching valve in regard to suction flow characteristics, analytical models of the inertance hydraulic converters were established in MATLAB/Simulink. The validated models of the respective suction components were incorporated in the overall analytical models and their suction flow characteristics were theoretically and experimentally discussed. The analytical predictions and experimental measurements for the current configurations indicated that the active inertance hydraulic converter yields a larger transient suction flow rate than that of the passive inertance hydraulic converter due to the difference of the respective suction components. The suction flow characteristic can be modulated using the supply pressure and duty cycle, which was confirmed by experimental measurements. In addition, the suction flow characteristics are heavily affected by the resistance of the suction flow passage and switching frequency. There is a compromise between the resistance and switching frequency for inertance hydraulic converters to achieve large suction flow rate.

scholarly journals Effect of Air Injection on the Internal Flow Characteristics in the Draft Tube of a Francis Turbine Model

Processes ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 1182
Author(s):  
Seung-Jun Kim ◽  
Yong Cho ◽  
Jin-Hyuk Kim
Keyword(s):  
Flow Rate ◽  
Draft Tube ◽  
Pressure Fluctuations ◽  
Flow Characteristics ◽  
Internal Flow ◽  
Air Injection ◽  
Low Flow ◽  
Francis Turbine ◽  
Navier Stokes ◽  
Vortex Rope

Under low flow-rate conditions, a Francis turbine exhibits precession of a vortex rope with pressure fluctuations in the draft tube. These undesirable flow phenomena can lead to deterioration of the turbine performance as manifested by torque and power output fluctuations. In order to suppress the rope with precession and a swirl component in the tube, the use of anti-swirl fins was investigated in a previous study. However, vortex rope generation still occurred near the cone of the tube. In this study, unsteady-state Reynolds-averaged Navier–Stokes analyses were conducted with a scale-adaptive simulation shear stress transport turbulence model. This model was used to observe the effects of the injection in the draft tube on the unsteady internal flow and pressure phenomena considering both active and passive suppression methods. The air injection affected the generation and suppression of the vortex rope and swirl component depending on the flow rate of the air. In addition, an injection level of 0.5%Q led to a reduction in the maximum unsteady pressure characteristics.

Pressure-Flow Characteristics During Peristaltic Transport of Non-Newtonian Fluid in Distensible Tube With Different Wave Forms

2003 ◽  
Author(s):  
Prasanna Hariharan ◽  
Rupak K. Banerjee
Keyword(s):  
Newtonian Fluid ◽  
Flow Rate ◽  
Flow Characteristics ◽  
Pressure Flow ◽  
Square Wave ◽  
Wall Movement ◽  
Power Law Fluids ◽  
Significant Difference ◽  
Wave Forms ◽  
Distensible Tube

This study analyzes the pressure-flow characteristics during the peristaltic pumping of power law fluids in an axi-symmetric non-uniform distensible tube. The analyzed geometry is of a diverging shape that is common in several biological flow conduits, especially in mammals. Using the Fourier series, the dimensionless wall coordinates for sinusoidal, triangular, trapezoidal, and square wave forms are obtained to simulate wall movement. Equations expressing the pressure-flow rate relationship for different wall shapes are developed from the wave equation. Pressure-flow and velocity plots are obtained by solving the equations numerically. The results indicate that there is significant difference in pressure-flow relationship between Newtonian and non-Newtonian fluid. Also, the maximum flow rate can be achieved when the wall movement follows a square wave form.

Experimental Investigation of Effect of Tip Coolant Ejection on Internal Flow Characteristics Within a Realistic Blade Coolant Channel

2013 ◽  
Author(s):  
Jian Pu ◽  
Zhaoqing Ke ◽  
Jianhua Wang ◽  
Lei Wang ◽  
Hongde You
Keyword(s):  
Experimental Investigation ◽  
Reynolds Number ◽  
Pressure Drop ◽  
Turbine Blade ◽  
Flow Rate ◽  
Flow Characteristics ◽  
Reynolds Numbers ◽  
Flow Ratio ◽  
Lp Turbine ◽  
Mass Flow Ratio

This paper presents an experimental investigation on the characteristics of the fluid flow within an entire coolant channel of a low pressure (LP) turbine blade. The serpentine channel, which keeps realistic blade geometry, consists of three passes connected by a 180° sharp bend and a semi-round bend, 2 tip exits and 25 trailing edge exits. The mean velocity fields within several typical cross sections were captured using a particle image velocimetry (PIV) system. Pressure and flow rate at each exit were determined through the measurements of local static pressure and volume flow rate. To optimize the design of LP turbine blade coolant channels, the effect of tip ejection ratio (ER) from 180° sharp bend on the flow characteristics in the coolant channel were experimentally investigated at a series of inlet Reynolds numbers from 25,000 to 50,000. A complex flow pattern, which is different from the previous investigations conducted by a simplified square or rectangular two-pass U-channel, is exhibited from the PIV results. This experimental investigation indicated that: a) in the main flow direction, the regions of separation bubble and flow impingement increase in size with a decrease of the ER; b) the shape, intensity and position of the secondary vortices are changed by the ER; c) the mass flow ratio of each exit to inlet is not sensitive to the inlet Reynolds number; d) the increase of the ER reduces the mass flow ratio through each trailing edge exit to the extent of about 23–28% of the ER = 0 reference under the condition that the tip exit located at 180° bend is full open; e) the pressure drop through the entire coolant channel decreases with an increase in the ER and inlet Reynolds number, and a reduction about 35–40% of the non-dimensional pressure drop is observed at different inlet Reynolds numbers, under the condition that the tip exit located at 180° bend is full open.

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