scholarly journals Discharge Flow Rate for the Initiation of Jet Flow in Sky-Jump Spillways

Water ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1814
Author(s):  
Raffaella Pellegrino ◽  
Miguel Ángel Toledo ◽  
Víctor Aragoncillo
Keyword(s):  
Flow Rate ◽  
Direct Determination ◽  
Jet Flow ◽  
Effective Solution ◽  
Discharge Flow Rate ◽  
Impact Area ◽  
Experimental Laboratory ◽  
New Formula ◽  
The Impact

The sky-jump spillway is an economical and effective solution to return water to a river, eventually complemented by a pre-excavated basin. However, an inappropriate design could endanger spillways and even the dam itself. For the design of a sky-jump it is necessary to evaluate the position and dimensions of the potential pre-excavated basin based on the characteristics of the water flow to be evacuated and the geometric configuration of the sky-jump. The jump of the water jet occurs when a certain flow rate is reached. This flow rate for the initiation of the jet flow determines the position of the impact area closest to the spillway. We propose a new formula for the determination of the flow rate for the initiation of the jet flow, which incorporates as a novelty the influence of the curvature of the flip bucket. A methodology for the direct determination of the flow rate for the initiation of the jet flow is also presented. The new formula and methodology, based on experimental laboratory work and numerical modeling, will support the designer to choose the energy dissipation way, in the riverbed or inside the flip bucket, for low and frequent discharge flows.

Optimizing and Predicting CHF in Spray Cooling of a Square Surface

1996 ◽  
Vol 118 (3) ◽  
pp. 672-679 ◽  
Author(s):  
I. Mudawar ◽  
K. A. Estes
Keyword(s):  
Flow Rate ◽  
Flux Distribution ◽  
Spray Cooling ◽  
Liquid Volume ◽  
Optimum Configuration ◽  
New Correlation ◽  
Impact Area ◽  
Hot Surface ◽  
The Impact ◽  
Volumetric Flux

Spray cooling of a hot surface was investigated to ascertain the effect of nozzle-to-surface distance on critical heat flux (CHF). Full cone sprays of Fluorinert FC-72 and FC-87 were used to cool a 12.7 × 12.7 mm2 surface. A theoretical model was constructed that accurately predicts the spray’s volumetric flux (liquid volume per unit area per unit time) distribution across the heater surface. Several experimental spray sampling techniques were devised to validate this model. The impact of volumetric flux distribution on CHF was investigated experimentally. By measuring CHF for the same nozzle flow rate at different nozzle-to-surface distances, it was determined CHF can be maximized when the spray is configured such that the spray impact area just inscribes the square surface of the heater. Using this optimum configuration, CHF data were measured over broad ranges of flow rate and subcooling, resulting in a new correlation for spray cooling of small surfaces.

Detection of L-Tert-Leucine in the Enzyme-Catalyzed Reaction System

2013 ◽  
Vol 641-642 ◽  
pp. 717-720
Author(s):  
Sheng Deng ◽  
Li Cui ◽  
Li Min Ma
Keyword(s):  
Quality Control ◽  
Correlation Coefficient ◽  
Flow Rate ◽  
Catalytic Reaction ◽  
Reaction System ◽  
Direct Determination ◽  
Average Recovery ◽  
Enzyme Catalytic Reaction

Direct Determination of L-Ter-Leucine in Enzyme Catalytic Reaction System by HPLC Was Studied. the Detection Were Performed on a Kromasil 700-5C18 Column Using a Eluant Containing 0.25% (NH4)H2PO4 and 100% Methanol (V((NH4)H2PO4):V(methanol)=100:5) with the Flow Rate of 0.8 Ml/min at,detection Wavelength of 205nm. there Was a Good Line Correlation between Peak Area and Contents in the Rang of 0.2-10 Mg/ml, the Correlation Coefficient Was 0.9986, the Average Recovery Was 98.88% with a Relative Stand Deviation of 0.78% (n=5). this Method Is Simple, Stable, Accurate and Reliable for the Quality Control of L–ter-Leucine.

scholarly journals Nonperturbative Uncertainties on the Transverse Momentum Distribution of Electroweak Bosons and on the Determination of the W Boson Mass at the LHC

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Giuseppe Bozzi ◽  
Andrea Signori
Keyword(s):  
Transverse Momentum ◽  
W Boson ◽  
Direct Determination ◽  
Boson Mass ◽  
Proton Proton ◽  
Theoretical Predictions ◽  
Quark Transverse Momentum ◽  
The Impact ◽  
Proton Proton Collisions

In this contribution we present an overview of recent results concerning the impact of a possible flavour dependence of the intrinsic quark transverse momentum on electroweak observables. In particular, we focus on the qT spectrum of electroweak gauge bosons produced in proton-proton collisions at the LHC and on the direct determination of the W boson mass. We show that these effects are comparable in size to other nonperturbative effects commonly included in phenomenological analyses and should thus be included in precise theoretical predictions for present and future hadron colliders.

scholarly journals Cavitation in swirling flows of hydraulic spillways

2019 ◽  
Vol 91 ◽  
pp. 07022
Author(s):  
Genrikh Orekhov
Keyword(s):  
Flow Rate ◽  
Vortex Flow ◽  
Structural Elements ◽  
Flow Energy ◽  
Operating Modes ◽  
Swirl Angle ◽  
Energy Dissipators ◽  
High Head ◽  
The Impact

During operation of high-head hydraulic spillway systems, cavitation phenomena often occur, leading to destruction of structural elements of their flow conductor portions. The article is devoted to the study of erosion due to cavitation in the circulation flows of eddy hydraulic spillways, including those equipped with counter-vortex flow energy dissipators. Cavitation destructive effects depend on many factors: intensity consisting in the rate of decrease in the volume or mass of a cavitating body per unit of time, the stage of cavitation, geometric configuration of the streamlined body, the content of air in water, the flow rate, the type of material. The objective of the study consisted in determination of cavitation impacts in circulating (swirling) water flows. The studies were conducted by a method of physical modeling using high-head research installations. Distribution of amplitudes of pulses of shock cavitation impact is obtained according to the frequency of their occurrence depending on the flow velocity, the swirl angle, the height of the cavitating drop wall and the stage of cavitation. The impact energy depending on the stage of cavitation and the flow rate is given for different operating modes of the counter-vortex flow energy dissipators of a hydraulic spillway. In the conclusions, it is noted that cavitation impacts in the circulation flows occur mainly inside the flow, which is a fundamental difference from similar processes in axial flows.

FLOW MODIFICATION INDUCED BY QUINCKE ROTATION IN A CAPILLARY

2002 ◽  
Vol 16 (17n18) ◽  
pp. 2603-2609 ◽  
Author(s):  
A. CEBERS ◽  
E. LEMAIRE ◽  
L. LOBRY
Keyword(s):  
Cross Section ◽  
Flow Rate ◽  
Effective Viscosity ◽  
Rectangular Cross Section ◽  
Colloidal Suspension ◽  
Direct Determination ◽  
Flow Modification ◽  
Insulating Liquid ◽  
Quincke Rotation

When particles immersed in a semi-insulating liquid are submitted to a sufficiently high DC field, they can rotate spontaneously around any axis perpendicular to the field (Quincke rotation). Recently we have shown that due to Quincke effect the effective viscosity of a colloidal suspension could be reduced. When the suspension is submitted to a shear, the particles rotation is amplified by the electric torque and drives the suspending liquid. For a flow in a capillary, this effect manifests itself by an increase of the flow rate. We present the results of our experiments carried out with a rectangular cross section capillary. These results are compared with the direct determination of the apparent viscosity in a Couette flow rheometer.

scholarly journals X. A method of measuring the pressure produced in the detonation of high, explosives or by the impact of bullets

1914 ◽  
Vol 213 (497-508) ◽  
pp. 437-456 ◽  
Keyword(s):  
Practical Interest ◽  
Direct Determination ◽  
High Explosives ◽  
Time Curve ◽  
Considerable Difficulty ◽  
Cylindrical Steel ◽  
Set Up ◽  
The Right ◽  
The Impact

The determination of the actual pressures produced by a blow such as that of a rifle bullet or by the detonation of high explosives is a problem of much scientific and practical interest but of considerable difficulty. It is easy to measure the transfer of momentum associated with the blow, which is equal to the average pressure developed, multiplied by the time during which it acts, but the separation of these two factors has not hitherto been effected. The direct determination of a force acting for a few hundred-thousandths of a second presents difficulties which may perhaps be called insuperable, but the measurement of the other factor, the duration of the blow, is more feasible. In the case of impacts such as those of spheres or rods moving at moderate velocities the time of contact can be determined electrically with considerable accuracy.* The present paper contains an account of a method of analysing experimentally more violent blows and of measuring their duration and the pressures developed. If a rifle bullet be fired against the end of a cylindrical steel rod there is a definite pressure applied on the end of the rod at each instant of time during the period of impact and the pressure can be plotted as a function of the time. The pressure-time curve is a perfectly definite thing, though the ordinates are expressed in tons and the abscissae in millionths of a second; the pressure starts when the nose of the bullet first strikes the end of the rod and it continues until the bullet has been completely set up or stopped by the impact. Subject to qualifications, which will be considered later, the result of applying this varying pressure to the end is to send along the rod a wave of pressure which, so long as the elasticity is perfect, travels without change of type. If the pressure in different sections of the rod be plotted at any instant (fig. l) then at a later time the same curve shifted to the right by a distance proportional to the time will represent the then distribution of pressure. The velocity with which the wave travels in steel is approximately 17,000 feet per second. As the wave travels over any section of the rod, that section successively experiences pressures represented by the successive ordinates of the curve as they pass over it. Thus the curve also represents the relation between the pressure at any point of the rod and the time, the scale being such that one inch represents the time taken by the wave to travel that distance which is very nearly 1/200,000 of a second. In particular the curve giving the distribution of pressure in the rod along its length is, assuming perfect elasticity, the same as the curve connecting the pressure applied at the end and the time, the scale of time being that just given.

scholarly journals Visibility study of Galileo satellites from a VLBI network

2021 ◽  
Author(s):  
Helene Wolf ◽  
Johannes Böhm ◽  
Matthias Schartner ◽  
Urs Hugentobler
Keyword(s):  
Reference Frames ◽  
Direct Determination ◽  
Satellite Constellation ◽  
Long Baseline ◽  
Space Geodetic Techniques ◽  
Satellite Scheduling ◽  
Observation Geometry ◽  
The Impact

<p>Over the last years, ideas have been proposed to install a Very Long Baseline Interferometry (VLBI) transmitter on one or more satellites of the Galileo constellation. Satellites transmitting signals that can be observed by VLBI telescopes provide the opportunity of extending the current VLBI research with observations to geodetic satellites. These observations offer a variety of new possibilities such as high precision tying of space geodetic techniques but also the direct determination of the absolute orientation of the satellite constellation with respect to the International Celestial Reference Frame (ICRF) and have implications on the determination of long-term reference frames. </p><p>This contribution provides a visibility study of the Galileo satellites from a VLBI network. The newly developed satellite scheduling module in VieSched++ is used to determine the time periods during which a satellite is observable from a VLBI network. The possible satellite observations are evaluated through the number of stations from which a satellite is observable. Moreover, the impact on determining the orientation of the satellite constellation, caused by the observation geometry, is investigated with using the UT1-UTC Dilution of Precision (UDOP) factor.</p>

Heat Transfer of Impinging Jet-Row Onto Trapezoidal Channel With Different Effusion and Discharge Conditions

2020 ◽  
Author(s):  
Shyy Woei Chang ◽  
Pei-An Chiang ◽  
Wei Ling Cai
Keyword(s):  
Heat Transfer ◽  
Flow Rate ◽  
Impinging Jet ◽  
Reynolds Numbers ◽  
Jet Flow ◽  
Airflow Rate ◽  
Discharge Condition ◽  
Axial Distribution ◽  
Trapezoidal Channel ◽  
The Impact

Abstract The heat transfer performances of the trapezoidal channel with the impinging row jets normal to the channel apex wall with no effusion and three effusion conditions from one, two and three rows of bleeding holes along the channel apex, or, and, channel sidewalls were studied. At each effusion condition, the airflow extraction from the channel tip were regulated as full open conditions, and 0% (full close), 5%, 10% of the total airflow rate fed into the trapezoidal channel via the impinging row jets. For each effusion and discharge condition, the full-field heat transfer data over the channel apex and sidewalls were measured at channel Reynolds numbers of 5000, 7500, 10000, 12500 and 15000 using the steady-state infrared thermography method. The corresponding axial distributions of the jet mass flow rate at each effusion and discharge condition were measured at all the Reynolds numbers tested. While the crossflow and channel flow confinement significantly affected the axial distribution of the jet flow rate for the channel without effusion, the impact of effusion and discharge conditions on the distribution of the airflow rate through the row jet was negligible for the effusion channels. Without effusion, the strong crossflow effects acted with the weakened jet momentums near the sealed channel hub to substantially reduce the regional heat transfer rates. With effusion, the flow confinement formulated by the cavity-like channel hub and the crossflow developed along the test channel were significantly suppressed, leading to the even distribution of jet flow and the recovered impinging-jet heat transfer properties over the channel hub region. The preferential heat transfer performances among the present test channels with and without effusion gave rise to the channel with three rows of effusion holes. Relative to the heat transfer impacts caused by varying the row number of the effusion holes, the impacts of tip extraction were less evident; but the overall heat transfer performance was improved by reducing tip discharge. With leading-edge cooling applications to a gas turbine blade, three sets of heat transfer correlations that evaluated the regionally averaged Nusselt numbers over the channel apex and side walls with and without effusions at various tip extractions were devised.

A Novel Ammonia Sensor Utilizing Cataluminescence on Nano-TiW3Cr2O14

2011 ◽  
Vol 694 ◽  
pp. 184-188 ◽  
Author(s):  
Kao Wen Zhou ◽  
Zi Qiao Zhang ◽  
Li Jing Xing ◽  
Xin Li ◽  
Chun Xue Fu
Keyword(s):  
Detection Limit ◽  
Flow Rate ◽  
Active Carbon ◽  
Room Temperature ◽  
High Selectivity ◽  
Direct Determination ◽  
Ammonia Sensor ◽  
On Line ◽  
Versus Concentration

A new sensor based on cataluminescence (CTL) produced on the surface of nanosized TiW3Cr2O14 was demonstrated for direct determination of ammonia in air. Trace ammonia was firstly absorbed on active carbon at room temperature to concentrate, then desorbed at 105°C to determine. The sensor showed high selectivity to ammonia at wavelength of 540 nm, satisfying activity at temperature of 275°C and good stability at air carrier flow rate of 115 ml/min. The linear range of CTL intensity versus concentration of ammonia was 1.0~50 mg/m3 (γ=0.9990), and the detection limit (3σ) was 0.5 mg/m3. The recovery of artificial sample was 97.45%—102.73% by this method. There was no response to benzene, SO2, CO and formaldehyde, and insignificant response to ethanol. This gas sensor allows on-line monitoring of ammonia in air.

A Rapid and Sensitive Ether Sensor Utilizing Thermal Desorption Coupled with Cataluminescence

2013 ◽  
Vol 641-642 ◽  
pp. 238-241 ◽  
Author(s):  
Zhi Gang Cui ◽  
Shao Tong Zhang ◽  
Jin Zhao ◽  
Kao Wen Zhou
Keyword(s):  
Detection Limit ◽  
Gas Sensor ◽  
Thermal Desorption ◽  
Flow Rate ◽  
Active Carbon ◽  
Room Temperature ◽  
High Selectivity ◽  
Direct Determination ◽  
Versus Concentration

A rapid and sensitive cataluminescence (CTL)-based gas sensor using nanosized Y2Zr1.5O6 as a probe was proposed for direct determination of ether in air. Trace ether was firstly absorbed on active carbon at room temperature to concentrate, then desorbed at 65°C to determine. The sensor showed high selectivity to ether at wavelength of 510nm, satisfying activity at temperature of 310°C and good stability at carrier flow rate of 110 ml/min. The linear range of CTL intensity versus concentration of ether was 2~100 mg/m3, and the detection limit (3σ) was 1.1 mg/m3. The recovery of artificial sample was 95.4%—106.7% by this method. The response to formaldehyde, benzene, NH3 and ethanol was insignificant, and there was no response to SO2, CO and acetone. The technique is a convenient and fast way of determining ether in air.

Sign in / Sign up

Export Citation Format

Share Document