scholarly journals Performance Evaluation of Different Combined Drainage Forms on Flooding and Waterlogging Removal

Water ◽  
2021 ◽  
Vol 13 (21) ◽  
pp. 2968
Author(s):  
Xiaolei Ren ◽  
Shaoli Wang ◽  
Peiling Yang ◽  
Yuan Tao ◽  
Haorui Chen
Keyword(s):  
Flow Rate ◽  
Southern China ◽  
Subsurface Drainage ◽  
Flow Rates ◽  
Removal Time ◽  
Change Characteristics ◽  
Tank Experiment ◽  
Two Factors ◽  
Research Findings ◽  
Good Agreement

Farmland in southern China is prone to flooding and waterlogging alternation after short-term heavy rainfall. Single drainage form cannot meet the requirements of the farmland flooding and waterlogging removal. Drainage measures and layout forms should be explored to alleviate flooding and waterlogging threat and improve crop yield. So, based on an indoor sand tank experiment, this paper presents a combined drainage form: conventional subsurface drainage as an auxiliary drainage measure and is alternatively combined with open ditch (OD), filter drainage (FD), conventional (CD) and improved subsurface drainage (ID), respectively, under equal and unequal drain depth. The performance of different combined drainage forms and the effect of auxiliary drainage measures are discussed for stable ponding and receding water. During the experiment, two factors—drainage measure and drain depth—are considered. The results indicate that compared with the conventional subsurface drainage alone, the flow rates of the open-ditch, thin-improved, and thick-improved subsurface drainage combined with conventional subsurface drainage can be increased by 22.4–32.3%, 10.6–16.2%, and 29.8–32%, respectively, under equal drain depth in stable ponding water. Among the four combined drainage forms, the flow rate of shallow–deep combination is 8.1–17.1% higher than that of the shallow–shallow combination. Compared with a single drainage form, the flow rates of the combined drainage have the same change characteristics over time. Additionally, the use of auxiliary, conventional, subsurface drainage can improve the flooding and waterlogging removal efficiency in farmland. For the combined drainage forms, the contribution degree of the open-ditch and thin-improved subsurface drainage is 51.3–56.7%, while the thick-improved subsurface drainage is approximately 61.0%, under equal drain depth conditions in the flooding removal process. Moreover, open-ditch and thick-improved subsurface drainage combined with conventional subsurface drainage have significant advantages in flooding and waterlogging removal, which were 11.5–38.1% and 37.1–48.6% faster than conventional subsurface drainage in flooding removal time, 14.3–157.1% and 14.3–44.4% faster than conventional subsurface drainage in the waterlogging removal time. The synergistic application of shallow–deep and medium–medium combinations can be carried out by exploiting the advantages of each drainage measure. The experimental flow rate observation is in good agreement with the theoretically calculated value, with a relative error of less than 5%. These research findings could provide technical support for the increased application of combined drainage forms in areas prone to flooding and waterlogging.

Prediction of Ingestion Through Turbine Rim Seals—Part II: Externally Induced and Combined Ingress

2010 ◽  
Vol 133 (3) ◽  
Author(s):  
J. Michael Owen
Keyword(s):  
Experimental Data ◽  
Flow Rate ◽  
Gas Turbines ◽  
Swirling Flows ◽  
Published Data ◽  
Flow Rates ◽  
Hot Gas ◽  
Predicted Values ◽  
Good Agreement

Ingress of hot gas through the rim seals of gas turbines can be modeled theoretically using the so-called orifice equations. In Part I of this two-part paper, the orifice equations were derived for compressible and incompressible swirling flows, and the incompressible equations were solved for axisymmetric rotationally induced (RI) ingress. In Part II, the incompressible equations are solved for nonaxisymmetric externally induced (EI) ingress and for combined EI and RI ingress. The solutions show how the nondimensional ingress and egress flow rates vary with Θ0, the ratio of the flow rate of sealing air to the flow rate necessary to prevent ingress. For EI ingress, a “saw-tooth model” is used for the circumferential variation of pressure in the external annulus, and it is shown that ε, the sealing effectiveness, depends principally on Θ0; the theoretical variation of ε with Θ0 is similar to that found in Part I for RI ingress. For combined ingress, the solution of the orifice equations shows the transition from RI to EI ingress as the amplitude of the circumferential variation of pressure increases. The predicted values of ε for EI ingress are in good agreement with the available experimental data, but there are insufficient published data to validate the theory for combined ingress.

Prediction of Ingestion Through Turbine Rim Seals—Part 2: Externally-Induced and Combined Ingress

2009 ◽  
Author(s):  
J. Michael Owen
Keyword(s):  
Experimental Data ◽  
Flow Rate ◽  
Gas Turbines ◽  
Swirling Flow ◽  
Published Data ◽  
Flow Rates ◽  
Hot Gas ◽  
Predicted Values ◽  
Good Agreement

Ingress of hot gas through the rim seals of gas turbines can be modelled theoretically using the so-called orifice equations. In Part 1 (ASME GT 2009-59121) of this two-part paper, the orifice equations were derived for compressible and incompressible swirling flow, and the incompressible equations were solved for axisymmetric rotationally-induced (RI) ingress. In Part 2, the incompressible equations are solved for non-axisymmetric externally-induced (EI) ingress and for combined EI and RI ingress. The solutions show how the nondimensional ingress and egress flow rates vary with Θ0, the ratio of the flow rate of sealing air to the flow rate necessary to prevent ingress. For EI ingress, a ‘saw-tooth model’ is used for the circumferential variation of pressure in the external annulus, and it is shown that ε, the sealing effectiveness, depends principally on Θ0; the theoretical variation of ε with Θ0 is similar to that found in Part 1 for RI ingress. For combined ingress, the solution of the orifice equations shows the transition from RI to EI ingress as the amplitude of the circumferential variation of pressure increases. The predicted values of ε for EI ingress are in good agreement with available experimental data, but there are insufficient published data to validate the theory for combined ingress.

Liquid Transport Properties in Sub-Micron Channel Flows

2001 ◽  
Author(s):  
K. Johan A. Westin ◽  
Kenneth S. Breuer ◽  
Chang-Hwan Choi ◽  
Peter Huang ◽  
Zhiqiang Cao ◽  
...  
Keyword(s):  
Flow Rate ◽  
Low Flow ◽  
Slip Boundary Conditions ◽  
Liquid Transport ◽  
Flow Rates ◽  
Slip Boundary ◽  
Laminar Channel Flow ◽  
Flow Through ◽  
Set Up ◽  
Good Agreement

Abstract An experimental set-up for pressure driven liquid flow through microchannels have been designed and tested. The flow rate is determined by tracking the free liquid surface in a precision bore hole using a laser distance meter. Measurements of the flow rate through silicon microchannels with a height of less than 0.9 μm show good results for Newtonian fluids (silicon oil, ethanol) at flow rates as low as 0.2 nl/s. The experimental results are also in very good agreement with predictions based on laminar channel flow using no-slip boundary conditions, indicating that standard macroscopic assumptions are still valid for these fluids under these conditions. However, experiments with aqueous solutions show anomalies in the form of unexpectedly low flow rates and time dependent variations. Possible explanations to these observations are discussed.

Low-power micro-fabricated liquid flow-rate sensor

2015 ◽  
Vol 7 (9) ◽  
pp. 3981-3987 ◽  
Author(s):  
Wen-Chi Lin ◽  
Mark A. Burns
Keyword(s):  
Low Power ◽  
Water Flow ◽  
Flow Rate ◽  
Liquid Flow ◽  
Liquid Flow Rate ◽  
Experimental Results ◽  
Flow Sensors ◽  
Flow Rates ◽  
Rate Sensor ◽  
Good Agreement

We have constructed micro-fabricated flow sensors that can measure water flow rates of 0.1 to 2.0 gallons per minute (GPM), and the experimental results we obtained are in good agreement with those from COMSOL simulations.

scholarly journals Predicting Hourly Traflc Noise from Traflc Flow Rate Model: Underlying Concepts for the DYNAMAP Project

Noise Mapping ◽  
2016 ◽  
Vol 3 (1) ◽  
Author(s):  
M. Smiraglia ◽  
R. Benocci ◽  
G. Zambon ◽  
H.E. Roman
Keyword(s):  
Traffic Flow ◽  
Flow Rate ◽  
Traffic Noise ◽  
Simple Analytical Model ◽  
Rate Model ◽  
Flow Rates ◽  
Dynamic Noise ◽  
The City ◽  
Noise Map ◽  
Good Agreement

AbstractThe DYNAMAP project aims at obtaining a dynamic noise map of a large residential area such as the City of Milan (Italy), by recording traffic noise from a limited number of noise sensors. To this end,we perform a statistical analysis of road stretches and group them into different clusters showing a similar measured hourly traffic noise behavior. In the sameway,we group simulated hourly traffic flow rates and compare their compositions with those of the traffic noise groups. The best agreement with the traffic noise was found by using the so-called normal traffic flow rate, yielding overlaps between 68 and 97%. Finally, we derive a simple analytical model to predict the hourly traffic noise from the simulated normal traffic flow, in very good agreement with the measured values.

scholarly journals Visualisation of flow pattern and measurement of liquid distribution in a random packed column using electrical resistance tomography (ERT)

2021 ◽  
Author(s):  
Nazar Aoda
Keyword(s):  
Flow Pattern ◽  
Flow Rate ◽  
Electrical Resistance ◽  
Packed Column ◽  
Operating Conditions ◽  
Flow Mode ◽  
Electrical Resistance Tomography ◽  
Liquid Distribution ◽  
Flow Rates ◽  
Good Agreement

The aim of this research is to use Electrical Resistance Tomography technique (ERT) to measure factors that affect local mass transfer at various axial locations in a random packed column with diameter 0.3m and bed height 150cm filled with 2 cm plastic spheres. These factors are: liquid maldistribution, velocity profiles, and flow pattern. The system was designed to run in a trickling down-flow mode and a full liquid up-flow mode. Experiments were performed at flow rates of 3, 6, and 9 gpm (or 0.27 x 10⁻², 0.54 x 10⁻² and 0.8 x 10⁻² m³/m² s) and under normal operating conditions of 25C° and atmospheric pressure. The liquid maldistribution factors were measured via ERT technique and the conventional liquid collection method. Both measurements were conducted at various fluid flow rates at different bed heights. The results of ERT were in very good agreement with the conventional method. The standard deviation values were 17% and 21% at flow rates 3 and 6 gpm respectively. The numerical values of velocity for full liquid up flow at 3 gpm were 0.83cm/s, 1.2cm/s, 1.2 cm/s and 1.11 cm/s for different heights of 30, 60 and 90 cm respectively and the numerical values of velocity for trickle down flow at 3 gpm were 16.5 cm/s, 22.5 cm/s and 24 cm/ for different heights of 30, 60 and 90 cm respectively. The values of the liquid maldistribution factor for flow rate 3 gpm were 0.43 (30cm), 0.33(60cm) and 0.30 (90cm) and for flow rate 6 gpm were 0.33(30cm), 0.27(60cm) and 0.22 (90cm). By comparison with findings of many studies conducted on liquid distribution in packed bed column, a good agreement was observed on the relation of Mf and flow rates and bed heights.

Experimental Measurements of Ingestion Through Turbine Rim Seals: Part 5 — Fluid Dynamics of Wheel-Space

2013 ◽  
Author(s):  
Carl M. Sangan ◽  
Yogesh Lalwani ◽  
J. Michael Owen ◽  
Gary D. Lock
Keyword(s):  
Flow Rate ◽  
Static Pressure ◽  
Outer Region ◽  
Turbine Stage ◽  
Rotating Disc ◽  
Flow Rates ◽  
Hot Gas ◽  
Fluid Core ◽  
Swirl Velocity ◽  
Good Agreement

This paper discusses the flow structure in typical rotor-stator systems with ingress and egress. Measurements of concentration, velocity and pressure were made using a rotating-disc rig which experimentally simulated hot gas ingestion into the wheel-space of an axial turbine stage. Externally-induced ingress through rim seals was generated from the non-axisymmetric pressures produced by the flow over the vanes and blades in the external annulus. Measurements were conducted using several single- and double-seal geometries and for a range of sealing flow rates and rotational speeds. The concentration measurements showed that the amount of ingress, which increased with decreasing sealing flow rate, depended on the seal geometry. The swirl velocity in the fluid core increased with decreasing sealing-flow rate but, outside the outer region in the wheel-space, it was largely unaffected by the seal geometry or by the amount of ingress. The radial distribution of static pressure, calculated from the measured swirl velocity in the core, was in good agreement with the pressures measured on the stator. The data for the double seals demonstrated that the ingested gas was predominately confined to the region between the seals near the periphery of the wheel-space; in the inner wheel-space, the effectiveness is shown to be significantly higher.

scholarly journals Visualisation of flow pattern and measurement of liquid distribution in a random packed column using electrical resistance tomography (ERT)

2021 ◽  
Author(s):  
Nazar Aoda
Keyword(s):  
Flow Pattern ◽  
Flow Rate ◽  
Electrical Resistance ◽  
Packed Column ◽  
Operating Conditions ◽  
Flow Mode ◽  
Electrical Resistance Tomography ◽  
Liquid Distribution ◽  
Flow Rates ◽  
Good Agreement

The aim of this research is to use Electrical Resistance Tomography technique (ERT) to measure factors that affect local mass transfer at various axial locations in a random packed column with diameter 0.3m and bed height 150cm filled with 2 cm plastic spheres. These factors are: liquid maldistribution, velocity profiles, and flow pattern. The system was designed to run in a trickling down-flow mode and a full liquid up-flow mode. Experiments were performed at flow rates of 3, 6, and 9 gpm (or 0.27 x 10⁻², 0.54 x 10⁻² and 0.8 x 10⁻² m³/m² s) and under normal operating conditions of 25C° and atmospheric pressure. The liquid maldistribution factors were measured via ERT technique and the conventional liquid collection method. Both measurements were conducted at various fluid flow rates at different bed heights. The results of ERT were in very good agreement with the conventional method. The standard deviation values were 17% and 21% at flow rates 3 and 6 gpm respectively. The numerical values of velocity for full liquid up flow at 3 gpm were 0.83cm/s, 1.2cm/s, 1.2 cm/s and 1.11 cm/s for different heights of 30, 60 and 90 cm respectively and the numerical values of velocity for trickle down flow at 3 gpm were 16.5 cm/s, 22.5 cm/s and 24 cm/ for different heights of 30, 60 and 90 cm respectively. The values of the liquid maldistribution factor for flow rate 3 gpm were 0.43 (30cm), 0.33(60cm) and 0.30 (90cm) and for flow rate 6 gpm were 0.33(30cm), 0.27(60cm) and 0.22 (90cm). By comparison with findings of many studies conducted on liquid distribution in packed bed column, a good agreement was observed on the relation of Mf and flow rates and bed heights.

The effect of two-phase flow regime on hydrodynamics and mass transfer in a horizontal-tube gas-liquid reactor

1985 ◽  
Vol 50 (3) ◽  
pp. 745-757 ◽  
Author(s):  
Andreas Zahn ◽  
Lothar Ebner ◽  
Kurt Winkler ◽  
Jan Kratochvíl ◽  
Jindřich Zahradník
Keyword(s):  
Mass Transfer ◽  
Pressure Drop ◽  
Flow Regime ◽  
Liquid Flow ◽  
Horizontal Tube ◽  
Liquid Holdup ◽  
Two Phase ◽  
Flow Rates ◽  
Type Relation ◽  
Good Agreement

The effect of two-phase flow regime on decisive hydrodynamic and mass transfer characteristics of horizontal-tube gas-liquid reactors (pressure drop, liquid holdup, kLaL) was determined in a cocurrent-flow experimental unit of the length 4.15 m and diameter 0.05 m with air-water system. An adjustable-height weir was installed in the separation chamber at the reactor outlet to simulate the effect of internal baffles on reactor hydrodynamics. Flow regime maps were developed in the whole range of experimental gas and liquid flow rates both for the weirless arrangement and for the weir height 0.05 m, the former being in good agreement with flow-pattern boundaries presented by Mandhane. In the whole range of experi-mental conditions pressure drop data could be well correlated as a function of gas and liquid flow rates by an empirical exponential-type relation with specific sets of coefficients obtained for individual flow regimes from experimental data. Good agreement was observed between values of pressure drop obtained for weirless arrangement and data calculated from the Lockhart-Martinelli correlation while the contribution of weir to the overall pressure drop was well described by a relation proposed for the pressure loss in closed-end tubes. In the region of negligible weir influence values of liquid holdup were again succesfully correlated by the Lockhart-Martinelli relation while the dependence of liquid holdup data on gas and liquid flow rates obtained under conditions of significant weir effect (i.e. at low flow rates of both phases) could be well described by an empirical exponential-type relation. Results of preliminary kLaL measurements confirmed the decisive effect of the rate of energy dissipation on the intensity of interfacial mass transfer in gas-liquid dispersions.

Hydraulic model of a water cooling system in a chemical plant

1988 ◽  
Vol 53 (4) ◽  
pp. 788-806
Author(s):  
Miloslav Hošťálek ◽  
Jiří Výborný ◽  
František Madron
Keyword(s):  
Flow Rate ◽  
Cooling System ◽  
Cooling Water ◽  
Graph Algorithm ◽  
Automatic Generation ◽  
Hydraulic Calculation ◽  
Return Flow ◽  
Flow Rates ◽  
Pressure Losses ◽  
Controlled Flow

Steady state hydraulic calculation has been described of an extensive pipeline network based on a new graph algorithm for setting up and decomposition of balance equations of the model. The parameters of the model are characteristics of individual sections of the network (pumps, pipes, and heat exchangers with armatures). In case of sections with controlled flow rate (variable characteristic), or sections with measured flow rate, the flow rates are direct inputs. The interactions of the network with the surroundings are accounted for by appropriate sources and sinks of individual nodes. The result of the calculation is the knowledge of all flow rates and pressure losses in the network. Automatic generation of the model equations utilizes an efficient (vector) fixing of the network topology and predominantly logical, not numerical operations based on the graph theory. The calculation proper utilizes a modification of the model by the method of linearization of characteristics, while the properties of the modified set of equations permit further decrease of the requirements on the computer. The described approach is suitable for the solution of practical problems even on lower category personal computers. The calculations are illustrated on an example of a simple network with uncontrolled and controlled flow rates of cooling water while one of the sections of the network is also a gravitational return flow of the cooling water.

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