Steam Flow in Nozzle and the Nozzle Calculation

2013 ◽  
Vol 433-435 ◽  
pp. 1975-1978
Author(s):  
Ya Rong Wang ◽  
Pei Rong Wang
Keyword(s):  
Flow Velocity ◽  
Air Conditioning ◽  
Steam Flow ◽  
Power Equipment ◽  
Steam Turbines ◽  
Flow Process ◽  
Flow Area ◽  
Adiabatic Flow ◽  
Impeller Type ◽  
The Relationship

The adiabatic flow process of gas or steam in a nozzle is not only widely used in steam turbines or other power equipment, but also applied to ejectors, impeller-type compressors, burners and other thermal devices in air conditioning, ventilation and gas engineering. In this paper we will describe steam flow in nozzle and the nozzle calculation, especially the relationship between the flow velocity and the flow area. We will describe the calculation on the velocity through a nozzle and the calculation on the area of the nozzle by an example.

The Effect of Irreversibility on the Capacity of a Turbine Blade Row

1981 ◽  
Vol 195 (1) ◽  
pp. 127-137 ◽  
Author(s):  
L Fielding
Keyword(s):  
Thermodynamic Analysis ◽  
Mass Flow ◽  
Maximum Flow ◽  
Sonic Velocity ◽  
Maximum Mass ◽  
Flow Area ◽  
Adiabatic Flow ◽  
Blade Row ◽  
Inlet Conditions ◽  
The Relationship

If the assumption is made that the process followed by the expansion of a gas in a converging blade row is isentropic, thermodynamic analysis leads to the result that the attainment of maximum mass flow, for a given flow area and predetermined inlet pressure and temperature, occurs when sonic velocity is reached at the throat. If, however, as in practice, the expansion proceeds with internal frictional losses, and if certain common assumptions are made regarding these losses, then, assuming adiabatic flow, thermodynamic analysis shows that the maximum flow will occur at a Mach number less than unity. If this paradox is not noticed, it may lead to an appreciable underestimate of the mass flow passed by a blade row for a given set of inlet conditions. This paper examines the relationship between blade row losses and boundary layer characteristics in an attempt to rationalize the calculation of the capacity of a turbine as modified by irreversibility.

The relationship between an aortic isthmus blood flow velocity index and the postnatal neurodevelopmental status of fetuses with placental circulatory insufficiency

2005 ◽  
Vol 192 (2) ◽  
pp. 497-503 ◽  
Author(s):  
Jean-Claude Fouron ◽  
Julie Gosselin ◽  
Marie-Josée Raboisson ◽  
Julie Lamoureux ◽  
Claudine-Amiel Tison ◽  
...  
Keyword(s):  
Blood Flow ◽  
Flow Velocity ◽  
Blood Flow Velocity ◽  
Aortic Isthmus ◽  
Circulatory Insufficiency ◽  
The Relationship

scholarly journals The Interiority of Proximity Between Nature and Architecture in Contemporary and Tropically Context with Cases Studies

2019 ◽  
Vol 3 (2) ◽  
pp. 129-144
Author(s):  
Budi Pradono
Keyword(s):  
Information Technology ◽  
Case Studies ◽  
Temperature Difference ◽  
Air Conditioning ◽  
The Other ◽  
Asian Countries ◽  
Tropical Countries ◽  
Large Cities ◽  
Tropical Climates ◽  
The Relationship

The interiority of buildings in tropical countries requires specific characteristics unlike those in countries with four distinct seasons. Buildings in non-tropical climates must protect their inhabitants from extreme weather, meaning that the architecture’s connection with nature is necessarily limited by a boundary which can withstand extreme climatic differences. In tropical countries, on the other hand, the temperature does not fluctuate much throughout the year, so the temperature difference between seasons is not extreme. This characteristic is reflected in traditional Nusantara architecture, which incorporates a breathable wall so that free winds come in, reducing heat. The roof is tilted or saddled-shaped to keep rain water away from the building. The architecture uses organic materials and includes terraces for dialogue with nature. Modern Indonesian architecture, however, particularly in large cities, is mostly closed off, severely limiting the interaction with nature. Since the advent of air conditioning (AC) technology during the 1980’s, architecture has changed to seal the boundaries of the building. Advances in information technology such as Internet and smartphones have made for further changes to architecture in the area; some functional spaces are being discarded, while others are expanded. The relationship between architecture and nature is now constrained by impenetrable materials such as brick, concrete and glass, as opposed to the more traditional, permeable boundary. In contrast to this trend, modern Indonesian society is tempted to form a closer relationship with nature. This paper examines how a relationship between nature and the interior of buildings may be accommodated again, presenting some existing projects by several architects from Europe and Asian countries—including the authors’ own work—as case studies.

scholarly journals Left atrial appendage orifice area and morphology is closely associated with flow velocity in patients with nonvalvular atrial fibrillation

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Lei Chen ◽  
Changjiang Xu ◽  
Wensu Chen ◽  
Chaoqun Zhang
Keyword(s):  
Atrial Fibrillation ◽  
Flow Velocity ◽  
Left Atrial ◽  
Left Atrial Appendage ◽  
Linear Regression Analysis ◽  
Left Ventricular ◽  
Atrial Appendage ◽  
Mechanical Function ◽  
Orifice Area ◽  
The Relationship

Abstract Background Thromboembolic events are the most serious complication of atrial fibrillation (AF), and the left atrial appendage (LAA) is the most important site of thrombosis in patients with AF. During the period of COVID-19, a non-invasive left atrial appendage detection method is particularly important in order to reduce the exposure of the virus. This study used CT three-dimensional reconstruction methods to explore the relationship between LAA morphology, LAA orifice area and its mechanical function in patients with non-valvular atrial fibrillation (NVAF). Methods A total of 81 consecutive patients with NVAF (36 cases of paroxysmal atrial fibrillation and 45 cases of persistent atrial fibrillation) who were planned to undergo catheter radiofrequency ablation were enrolled. All patients were examined by transthoracic echocardiography (TTE), TEE, and computed tomography angiography (CTA) before surgery. The LAA orifice area was obtained according to the images of CTA. According to the left atrial appendage morphology, it was divided into chicken wing type and non-chicken wing type. At the same time, TEE was performed to determine left atrial appendage flow velocity (LAAFV), and the relationship between the left atrial appendage orifice area and LAAFV was analyzed. Results The LAAFV in Non-chicken wing group was lower than that in Chicken wing group (36.2 ± 15.0 cm/s vs. 49.1 ± 22.0 cm/s, p-value < 0.05). In the subgroup analysis, the LAAFV in Non-chicken wing group was lower than that in Chicken wing group in the paroxysmal AF (44.0 ± 14.3 cm/s vs. 60.2 ± 22.8 cm/s, p-value < 0.05). In the persistent AF, similar results were observed (29.7 ± 12.4 cm/s vs. 40.8 ± 17.7 cm/s, p-value < 0.05). The LAAFV in persistent AF group was lower than that in paroxysmal AF group (34.6 ± 15.8 cm/s vs. 49.9 ± 20.0 cm/s, p-value < 0.001). The LAAFV was negatively correlated with left atrial dimension (R = − 0.451, p-value < 0.001), LAA orifice area (R= − 0.438, p-value < 0.001) and left ventricular mass index (LVMI) (R= − 0.624, p-value < 0.001), while it was positively correlated with LVEF (R = 0.271, p-value = 0.014). Multiple linear regression analysis showed that LAA morphology (β = − 0.335, p-value < 0.001), LAA orifice area (β = −  0.185, p-value = 0.033), AF type (β = − 0.167, p-value = 0.043) and LVMI (β = − 0.465, p-value < 0.001) were independent factors of LAAFV. Conclusions The LAA orifice area is closely related to the mechanical function of the LAA in patients with NVAF. The larger LAA orifice area and LVMI, Non-chicken wing LAA and persistent AF are independent predictors of decreased mechanical function of LAA, and these parameters might be helpful for better management of LA thrombosis.

A novel method for measuring the coarse water droplets in wet steam flow in steam turbines

2001 ◽  
Vol 10 (2) ◽  
pp. 123-126 ◽  
Author(s):  
Xiaoshu Cai ◽  
Lili Wang ◽  
Yongzhi Pan ◽  
Xin Ouyan ◽  
Jianqi Shen
Keyword(s):  
Steam Flow ◽  
Steam Turbines ◽  
Wet Steam ◽  
Water Droplets ◽  
Novel Method ◽  
Wet Steam Flow

scholarly journals Discharge Estimation Using Tsallis and Shannon Entropy Theory in Natural Channels

Water ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1786
Author(s):  
Jitendra Kumar Vyas ◽  
Muthiah Perumal ◽  
Tommaso Moramarco
Keyword(s):  
Flow Velocity ◽  
Surface Flow ◽  
Tsallis Entropy ◽  
Accurate Estimation ◽  
Mean Flow ◽  
Flow Area ◽  
Cross Sectional ◽  
The Cross ◽  
Discharge Estimation ◽  
Mean Flow Velocity

Streamflow measurements during high floods is a challenge for which the World Meteorological Organization fosters the development of innovative technologies for achieving an accurate estimation of the discharge. The use of non-contact sensors for monitoring surface flow velocities is of interest to turn these observed values into a cross-sectional mean flow velocity, and subsequently, into discharge if bathymetry is given. In this context, several techniques are available for the estimation of mean flow velocity, starting from observed surface velocities. Among them, the entropy-based methodology for river discharge assessment is often applied by leveraging the theoretical entropic principles of Shannon and Tsallis, both of which link the maximum flow velocity measured at a vertical of the flow area, named the y-axis, and the cross-sectional mean flow velocity at a river site. This study investigates the performance of the two different entropic approaches in estimating the mean flow velocity, starting from the maximum surface flow velocity sampled at the y-axis. A velocity dataset consisting of 70 events of measurements collected at two gauged stations with different geometric and hydraulic characteristics on the Po and Tiber Rivers in Italy was used for the analysis. The comparative evaluation of the velocity distribution observed at the y-axis of all 70 events of measurement was closely reproduced using both the Shannon and Tsallis entropy approaches. Accurate values in terms of the cross-sectional mean flow velocity and discharge were obtained with average errors not exceeding 10%, demonstrating that the Shannon and Tsallis entropy concepts were equally efficient for discharge estimation in any flow conditions.

Effect of Blockage Size on Pipe Vibration

2012 ◽  
Vol 626 ◽  
pp. 993-996
Author(s):  
N. Liyana Tajul Lile ◽  
M.J. Hasnul ◽  
R.A. Siregar ◽  
J.C. Leong
Keyword(s):  
Flow Velocity ◽  
Turbulence Intensity ◽  
Vibration Analysis ◽  
Vibration Response ◽  
Circular Pipe ◽  
Flow Area ◽  
Circular Pipes ◽  
External Objects ◽  
Vibration Parameters ◽  
Pipe Vibration

Circular pipes are widely used to convey goods to a desired location. Flow inside a pipe needs to be smoothed and unobstructed to ensure an optimize flow of particle. However, pipes are prone to clogging or blocking due to deposition of unwanted impurities and external objects. Built up inside a circular pipe will affect the flow velocity and pressure within the pipe. This paper presents a method of assessing blockage inside a pipe by using vibration analysis. The effect of blockage was observed through changes in pipe vibration response and also turbulence intensity. The changes in vibration parameters were identified together with the reduction of flow area due to increasing blockage size.

Representing Polydispersed Droplet Behavior in Nucleating Steam Flow

2007 ◽  
Vol 129 (11) ◽  
pp. 1404-1414 ◽  
Author(s):  
A. G. Gerber ◽  
A. Mousavi
Keyword(s):  
Method Of Moments ◽  
Current Practice ◽  
Complex Geometry ◽  
Steam Flow ◽  
Steam Turbines ◽  
Two Phase ◽  
Cfd Models ◽  
Pressure Steam ◽  
Droplet Behavior ◽  
Computational Fluid Dynamics Cfd

The quadrature method of moments (QMOM) is applied to the particle size distribution (PSD) present in nucleating steam flow, with a particular emphasis on conditions relevant to low-pressure steam turbines. These machines exhibit heterogeneous and homogeneous phase transition in the presence of strong flow discontinuities due to shocks and complex geometry. They offer a particularly difficult two-phase modeling situation. The present work shows that QMOM is a robust and efficient method and, in comparison to current practice of using a monodispersed PSD in computational fluid dynamics (CFD) models, offers promise for dealing with the complex two-phase conditions present in real machines.

Research on Traffic Flow Velocity Characteristic at Temporary Reversible Lane

2014 ◽  
Vol 505-506 ◽  
pp. 1189-1193
Author(s):  
Yi Cao ◽  
Zhong Yi Zuo ◽  
Hui Zhi Xu
Keyword(s):  
Flow Velocity ◽  
Traffic Flow ◽  
Existing Problems ◽  
Before And After ◽  
Relationship Model ◽  
Velocity Characteristic ◽  
Utilization Ratio ◽  
The Individual ◽  
Lane Utilization ◽  
The Relationship

In order to analyze the existing problems of temporary reversible lane, traffic flow velocity characteristic at the period of direction changing was analyzed. Taking Huangpu road as the investigation object, the traffic flow velocity parameters before and after direction changing were investigated respectively. By the method of mathematical statistics, the individual vehicles velocities and the traffic flow velocity before and after direction changing were compared and analyzed. Using the method of regression analysis, the relationship model between velocity and density of reversible lane was constructed. This paper also discussed the problems of this kind of lane. The research showed that, in terms of traffic flow operation velocity of temporary reversible lane, there is obvious and regular difference between before and after direction changing. There is a certain relationship between the velocity and density. The problem of lower lane utilization ratio of temporary reversible lane usually exists.

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