Analysis of the Maximum Pressure Difference of PSI(pound per square inch) depending on the Size of the Y-shape Connecting Tube of the Automatic Contrast Medium Injector

At present, cost reduction and environmental protection are the mainstream of blast furnace (BF) development and the high lump ore ratio is an effective means. Therefore, it is significant to explore the relationship and mechanism of burden soft-melt dropping and its primary-slag formation behaviors under increasing lump ore ratio. In this paper, the melt–drop test is carried out on the single ore and mixed burden, and obtained primary-slag properties are subjected to analysis. The experimental results show that the primary-slag of lump ore contains a large amount of FeO and SiO2, so it simply produces many low melting point compounds, which cause terrible soft-melt dropping properties and primary-slag formation behaviors. Notably, mixing with sinter and pellet can effectively improve both the properties. With the increase in lump ore ratio, the CaO in the primary-slag decreases, FeO and SiO2 increase, resulting in the melting temperature of the primary-slag sequentially decreasing and the cohesive zone moves to the low temperature zone. In addition, the maximum pressure difference increases, and the gas permeability deteriorates. Increasing the sinter ratio can overcome the defect of high lump ore ratio that can effectively improve the poor softening performance, melting performance and the position and thickness of the cohesive zone. However, because of the pulverization performance, the maximum pressure difference and gas permeability of the burden become worse.

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Theoretical Investigation of Gas Filling and Leaking in Inertial Confinement Fusion Hohlraum

Sustainability ◽

10.3390/su10103763 ◽

2018 ◽

Vol 10 (10) ◽

pp. 3763 ◽

Cited By ~ 1

Author(s):

Cheng Yu ◽

Suchen Wu ◽

Weibo Yang

Keyword(s):

Pressure Difference ◽

Inertial Confinement Fusion ◽

Polymeric Films ◽

Lower Probability ◽

Maximum Pressure ◽

Inertial Confinement ◽

Cross Sectional ◽

Confinement Fusion ◽

Variation Rate ◽

Sectional Shape

The gas filling and retention of inertial confinement fusion (ICF) hohlraum is an important issue in ICF studies. In this study, a theoretical model of gas filling and leaking processes for ICF hohlraum is developed based on the unified flow theory. The effects of the fill tube size and the filling pressure on the gas filling and leaking performance are investigated. The results indicate that an increase in the variation rate of the filling/leaking pressure leads to a larger maximum pressure difference between the inside and outside of the ICF hohlraum during the filling/leaking process. The critical pressure difference of the filling process is nearly equal to that of the leaking process. Increase in fill tube diameter and decrease in its length both lead to a lower probability of the rupture of polymeric films at two ends of the hohlraum, and thus increases the security of the hohlraum. In addition, a departure in cross sectional shape of fill tube from circle to rectangle triggers an increase in pressure difference between the inside and outside of the ICF hohlraum, which raises the risk of polymeric films rupture and decreases the security of the hohlraum structure.

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Detection of Cavitation in a Venturi Injector With a Combined Method of Strain Gauges and Numerical Simulation

Journal of Fluids Engineering ◽

10.1115/1.4026879 ◽

2014 ◽

Vol 136 (8) ◽

Cited By ~ 3

Author(s):

Yuncheng Xu ◽

Yan Chen ◽

Jianqiang He ◽

Haijun Yan

Keyword(s):

Flow Rate ◽

Pressure Difference ◽

Volume Fraction ◽

Operating Conditions ◽

Strain Gauges ◽

Maximum Pressure ◽

Operating Pressure ◽

Average Growth ◽

Rate Of Increase ◽

Suction Flow

The fertilizer suction capability of a Venturi injector is dependent on the vacuum pressure in the throat portion. As the vacuum level drops below the saturation vapor pressure, the pressure decreases to a particular value corresponding to the maximum pressure difference (Δpmax) between inlet and outlet pressures, and critical cavitation is likely to occur, leading to an unstable suction flow rate and low fertilization uniformity. A new method of using strain gauges to detect cavitation in Venturi injectors was explored experimentally and verified numerically under various operating conditions. The standard deviation (SD) of the measured strain values and the simulated values of the vapor-phase volume fraction (Vf) were used to evaluate the influence of cavitation. The results showed that both the rate of increase (ηm) of the average SD and the average growth rate (AGR) of the simulated cavitation length reach relatively large values at the maximum pressure difference (Δpmax), where the measured suction flow rate simultaneously reaches a maximum. In addition, SD and Vf shared similar variation trends at pressure differences larger than the corresponding Δpmax under various conditions. This new cavitation detection method has been proved to be feasible and reliable. It helps to determine accurately the value of Δpmax at different inlet pressures and to ensure that the Venturi injector runs in a safe operating-pressure range.

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Hydraulic Transients in the Long Diversion-Type Hydropower Station with a Complex Differential Surge Tank

The Scientific World JOURNAL ◽

10.1155/2014/241868 ◽

2014 ◽

Vol 2014 ◽

pp. 1-11 ◽

Cited By ~ 10

Author(s):

Xiaodong Yu ◽

Jian Zhang ◽

Ling Zhou

Keyword(s):

Pressure Difference ◽

Mathematic Model ◽

Hydropower Station ◽

Maximum Pressure ◽

Surge Tank ◽

Hydraulic Transients ◽

Rotating Speed ◽

Spiral Case ◽

Two Sides ◽

Breast Wall

Based on the theory of hydraulic transients and the method of characteristics (MOC), a mathematic model of the differential surge tank with pressure-reduction orifices (PROs) and overflow weirs for transient calculation is proposed. The numerical model of hydraulic transients is established using the data of a practical hydropower station; and the probable transients are simulated. The results show that successive load rejection is critical for calculating the maximum pressure in spiral case and the maximum rotating speed of runner when the bifurcated pipe is converging under the surge tank in a diversion-type hydropower station; the pressure difference between two sides of breast wall is large during transient conditions, and it would be more serious when simultaneous load rejections happen after load acceptance; the reasonable arrangement of PROs on breast wall can effectively decrease the pressure difference.

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A single cell model for pretreatment of wood by microwave explosion

Holzforschung ◽

10.1515/hf.2010.095 ◽

2010 ◽

Vol 64 (5) ◽

Cited By ~ 7

Author(s):

Xianjun Li ◽

Yongdong Zhou ◽

Yonglin Yan ◽

Zhiyong Cai ◽

Fu Feng

Keyword(s):

Pressure Difference ◽

Critical Pressure ◽

Cell Model ◽

Circumferential Stress ◽

Longitudinal Direction ◽

Critical Conditions ◽

Maximum Pressure ◽

Parenchyma Cells ◽

Ray Parenchyma ◽

Ray Parenchyma Cells

Abstract A theoretical model was developed to better understand the process of microwave explosion treatment of wood cells. The cell expansion and critical conditions concerning pressure and temperature of ray parenchyma cells in Eucalyptus urophylla were simulated during microwave pretreatment. The results indicate that longitudinal and circumferential stresses were generated in the cell walls owing to the internal steam pressure during extensive microwave treatment. The circumferential stress is twice as high as the longitudinal stress. The pressure difference reaches its maximum value of 0.84 MPa when the extension ratio is 1.20 for the longitudinal direction and 1.62 for the circumferential direction. The maximum pressure difference at the theoretical yielding point is the critical pressure difference that can eventually rupture the ray cell. The critical pressure difference decreases with increasing cell radius and decreasing shear modulus in the cell wall. This simulated result provides useful information to modify wood at the level of ray parenchyma cells.

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Linking Large-scale Circulation Descriptors to Precipitation Variability in the Northern French Alps

10.5194/ems2021-224 ◽

2021 ◽

Author(s):

Antoine Blanc ◽

Juliette Blanchet ◽

Jean-Dominique Creutin

Keyword(s):

Pressure Difference ◽

Large Scale ◽

Western Europe ◽

Precipitation Variability ◽

Medium Size ◽

Maximum Pressure ◽

Large Scale Circulation ◽

French Alps ◽

Mountainous Catchment ◽

The North

<p>This work analyses the link between Western Europe large-scale circulation and precipitation variability in the Northern French Alps from 1950 to 2017. We consider simple descriptors characterizing the daily 500hPa geopotential height fields. They are the Maximum Pressure Difference - representing the range of geopotential heights over Western Europe -, and the singularity - representing the mean distance between a geopotential shape and its closest analogs, i.e. the way this geopotential shape is reproduced in the climatology. These descriptors are compared to the occurrence of different atmospheric influences - Atlantic, Mediterranean, Northeast, Anticyclonic - and to the leading mode of large-scale circulation variability over Europe - the North Atlantic Oscillation (NAO) - for explaining precipitation variability in the Is&#232;re River catchment from one day to 10 years. We show that the Maximum Pressure Difference and the singularity of geopotential shapes explain a significant part of precipitation variability in the Northern French Alps from 10 days to 10 years, especially in winter (correlation values of 0.7). These descriptors provide much better performance than NAO and the same performance as the occurrence of the Atlantic influence, which is the best performing atmospheric influence. This means that simple characteristics of large-scale circulation - that are easy to implement - provide as much information as weather pattern classification to explain precipitation variability over a medium size mountainous catchment. Furthermore, we show that NAO does not drive the pressure gradient in a domain spreading from the Iberic Peninsula to Southern Great Britain and weakly explains precipitation variability in the Northern French Alps.</p>

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Experimental and numerical study on the thrust of a water-retaining curtain

Journal of Hydroinformatics ◽

10.2166/hydro.2017.095 ◽

2017 ◽

Vol 20 (2) ◽

pp. 316-331 ◽

Cited By ~ 2

Author(s):

Wei He ◽

Jijian Lian ◽

Fang Liu ◽

Chao Ma ◽

Shunqi Pan

Keyword(s):

Pressure Difference ◽

Numerical Study ◽

Experimental Tests ◽

Maximum Pressure ◽

Arc Length ◽

Practical Application ◽

Force Analysis ◽

Height Ratio ◽

Maximum Value ◽

Inflow Condition

Abstract A water-retaining curtain (WRC) has become a useful facility in selective withdrawal and sedimentation control, but the force analysis of a curved curtain is still lacking. Based on flume experimental tests and numerical simulations, this paper analyzes the variation laws of pressure difference and thrust of WRC. The results show that under the uniform inflow condition, the distribution of pressure difference on the WRC is relatively even, and the maximum value is located at the upper part of the curtain. When arc length–height ratio increases, the location of maximum pressure difference gets lower. In addition, the variation law of thrust of WRC conforms to the classical resistance equation. The drag coefficient is found to fit a power function of the water-retaining ratio, a second-degree polynomial function of arc length–height ratio, and linear function of inclination ratio. The results also yield a simplified forecasting formula of thrust of WRC which is proposed and verified using flume simulations and a real reservoir model test. The newly developed formula systematically considers the water-retaining height, arc length and inclination degree, providing a rapid and accurate algorithm to predict the thrust, and lays a theoretical foundation for practical application.

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Can pulsatile CSF flow across the cerebral aqueduct cause ventriculomegaly? A prospective study of patients with communicating hydrocephalus

Fluids and Barriers of the CNS ◽

10.1186/s12987-019-0159-0 ◽

2019 ◽

Vol 16 (1) ◽

Cited By ~ 1

Author(s):

P. Holmlund ◽

S. Qvarlander ◽

J. Malm ◽

A. Eklund

Keyword(s):

Pressure Difference ◽

Cardiac Cycle ◽

Third Ventricle ◽

Pressure Effects ◽

Maximum Pressure ◽

Cerebral Aqueduct ◽

Communicating Hydrocephalus ◽

Cross Sectional ◽

Net Pressure ◽

A Prospective Study

Abstract Background Communicating hydrocephalus is a disease where the cerebral ventricles are enlarged. It is characterized by the absence of detectable cerebrospinal fluid (CSF) outflow obstructions and often with increased CSF pulsatility measured in the cerebral aqueduct (CA). We hypothesize that the cardiac-related pulsatile flow over the CA, with fast systolic outflow and slow diastolic inflow, can generate net pressure effects that could source the ventriculomegaly in these patients. This would require a non-zero cardiac cycle averaged net pressure difference (ΔPnet) over the CA, with higher average pressure in the lateral and third ventricles. Methods We tested the hypothesis by calculating ΔPnet across the CA using computational fluid dynamics based on prospectively collected high-resolution structural (FIESTA-C, resolution 0.39 × 0.39 × 0.3 mm3) and velocimetric (2D-PCMRI, in-plane resolution 0.35 × 0.35 mm2) MRI-data from 30 patients investigated for communicating hydrocephalus. Results The ΔPnet due to CSF pulsations was non-zero for the study group (p = 0.03) with a magnitude of 0.2 ± 0.4 Pa (0.001 ± 0.003 mmHg), with higher pressure in the third ventricle. The maximum pressure difference over the cardiac cycle ΔPmax was 20.3 ± 11.8 Pa and occurred during systole. A generalized linear model verified an association between ΔPnet and CA cross-sectional area (p = 0.01) and flow asymmetry, described by the ratio of maximum inflow/outflow (p = 0.04), but not for aqueductal stroke volume (p = 0.35). Conclusions The results supported the hypothesis with respect to the direction of ΔPnet, although the magnitude was low. Thus, although the pulsations may generate a pressure difference across the CA it is likely too small to explain the ventriculomegaly in communicating hydrocephalus.

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A multiunit model of solute and water removal by inner medullary vasa recta

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1998.274.4.h1202 ◽

1998 ◽

Vol 274 (4) ◽

pp. H1202-H1210 ◽

Cited By ~ 22

Author(s):

Aurélie Edwards ◽

Thomas L. Pallone

Keyword(s):

Pressure Difference ◽

Renal Medulla ◽

Blood Flow Rate ◽

Maximum Pressure ◽

Hydraulic Pressure ◽

Pressure Gradients ◽

Vasa Recta ◽

Rate Ratios ◽

Limiting Case ◽

Small Solute

A recent model of volume and solute microcirculatory exchange in the renal medulla based on a single descending vasa rectum (DVR) was extended to account for the varying number of vessels along the corticomedullary axis. The assumption that concentration polarization at the walls of ascending vasa recta (AVR) during volume uptake eliminates transmural oncotic pressure gradients was examined. In this limiting case, small hydrostatic pressure gradients can drive AVR volume uptake if the pressure in the interstitium exceeds that in the AVR lumen. The calculated hydraulic pressure difference across AVR yielding agreement between predicted and measured values of AVR-to-DVR blood flow rate ratios was found to be smaller than the reported maximum pressure difference AVR can sustain. Simulations also confirmed previous conclusions suggesting that the presence of urea transporters in DVR counterbalances that of water channels that would otherwise decrease the efficiency of small solute trapping in the renal medulla.

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Through-Building Ducts for Mounting Wind Turbines: A Numerical Study

10.1115/power2021-64181 ◽

2021 ◽

Author(s):

Hadi Mirian ◽

Morteza Anbarsooz ◽

Abbas Hoshyar ◽

Alireza ArabGolarcheh

Keyword(s):

Wind Turbine ◽

Wind Power ◽

Wind Turbines ◽

Pressure Difference ◽

Urban Areas ◽

High Speed ◽

Numerical Study ◽

Pressure Coefficient ◽

Maximum Velocity ◽

Maximum Pressure

Abstract Yet, several locations for mounting the wind turbines in urban areas have been proposed, which can be categorized into four main groups; (a) on the rooftops, (b) between the buildings, (c) integrated into the buildings’ skin and (d) inside a though-building hole. Through-building holes take advantage of the pressure difference between the windward and leeward facades of the building to generate a high-speed velocity zone for mounting the wind turbine. In the current study, three-dimensional numerical simulations of atmospheric turbulent boundary layer flow around high-rise buildings are carried out to determine the optimum location and size of the duct. For this purpose, square cross-section buildings (20 × 20 m) with heights of H0 = 60, 120 and 180 m are considered. Numerical results showed that the difference of the pressure coefficient on the windward and leeward facades of the building without the hole can predict the best location for mounting the wind turbine with acceptable accuracy. Then, circular holes with various diameters of D = 2.5, 5.0, 7.5, 10 and 12.5m are created at z/H0 = 0.8, where the maximum pressure difference is close to the maximum. It is found that the maximum velocity increment occurs for D = 10 m and it is 31% greater than the U10 velocity of the incident wind profile. This means that the available wind power inside the duct is 2.25 times greater than the incident wind power.

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