Initiation of Waterhammer in Horizontal and Nearly Horizontal Pipes Containing Steam and Subcooled Water

1984 ◽  
Vol 106 (4) ◽  
pp. 835-840 ◽  
Author(s):  
R. W. Bjorge ◽  
P. Griffith
Keyword(s):  
Analytical Model ◽  
Stratified Flow ◽  
Experimental Results ◽  
Critical Conditions ◽  
Piping System ◽  
Flow Conditions ◽  
Horizontal Pipes ◽  
Subcooled Water ◽  
Low Pressures ◽  
Steam Bubble

Localized slug formation from a stratified flow of steam and subcooled water in a pipe traps a steam bubble, which collapses rapidly and causes a waterhammer. This phenomenon was studied experimentally at low pressures. Several tests, including measurement of the critical conditions for waterhammer initiation, were performed. An analytical model was developed that can predict whether waterhammer initiation will occur for given flow conditions. Predictions of this model agree well with experimental results. The use of the model in evaluating the susceptibility of a piping system to condensation waterhammer is described.

Avoiding Steam Bubble Collapse-Induced Water Hammer in the Auxiliary Piping of Steam Power Plants

1994 ◽  
Vol 116 (1) ◽  
pp. 49-56
Author(s):  
C. A. O. C. Lobo ◽  
P. Griffith
Keyword(s):  
Power Plants ◽  
Water Hammer ◽  
Design Guidelines ◽  
Bubble Collapse ◽  
Piping System ◽  
Steam Power ◽  
Horizontal Pipes ◽  
Steam Power Plants ◽  
Inclined Pipes ◽  
Steam Bubble

The mechanisms of steam bubble collapse-induced water hammer are identified for nominally horizontal or inclined pipes. On the basis of these observations, two methods of preventing steam bubble collapse-induced water hammer in nominally horizontal pipes are proposed. They are inclining them and injecting the water at a controlled rate at either the lowest point or injecting the water at several locations. The success of these methods is demonstrated for horizontal pipes and for pipes of other orientations. These ways of preventing steam bubble collapse-induced water hammer are then used to test filling strategies for “L”-shaped pipes oriented in practically every way. Both methods are found to work though the application of multiple injection ports and has complications when applied to a complex piping system. The use of the recommended design guidelines for avoiding steam bubble collapse-induced water hammer is demonstrated in an example problem.

scholarly journals Saturated-Subcooled Stratified Flow in Horizontal Pipes

2010 ◽  
Author(s):  
Richard R. Schultz ◽  
Hiral J. Kadakia ◽  
Jim C. P. Liou ◽  
Brian G. Williams
Keyword(s):  
Free Surface ◽  
Liquid Layer ◽  
Stratified Flow ◽  
Reactor Vessel ◽  
Saturated Steam ◽  
Saturated Liquid ◽  
Horizontal Pipes ◽  
Subcooled Water ◽  
Saturated Water ◽  
Accident Conditions

Advanced light water reactor systems are designed to use passive emergency core cooling systems with horizontal pipes that provide highly subcooled water from water storage tanks or passive heat exchangers to the reactor vessel core under accident conditions. Because passive systems are driven by density gradients, the horizontal pipes often do not flow full and thus have a free surface that is exposed to saturated steam and stratified flow is present. The subcooled water flows into the reactor vessel via the downcomer—which is an annular region separated from the core by a cylindrical, steel, inner liner. Under accident conditions, where the horizontal pipes are only partially full, both saturated water and saturated steam from the downcomer are likely to be present in the pipe. The saturated water is quasi-static and the fraction of the free surface that is saturated water is dictated by the physics of the flow. The saturated steam is usually flowing in the countercurrent direction to the subcooled water. Consequently the flow may be a three-layered system with saturated steam over a static saturated liquid layer over a flowing subcooled layer. The conditions leading to a saturated liquid layer that separates the saturated steam from flowing subcooled water are explored. The variables that influence the formation of the saturated liquid layer and enable the saturated layer to be maintained for a spectrum of conditions, including steam flow in the countercurrent direction to the subcooled water, are derived, and compared to experimental data. Conclusions regarding this type of flow are given. Finally, typical steam flow velocities that may induce wave-bridging, leading to condensation-induced-water hammer, are identified.

scholarly journals Generalized analytical model based on harmonic coupling for hybrid plasmonic modes: comparison with numerical and experimental results

2015 ◽  
Vol 23 (21) ◽  
pp. 27376 ◽  
Author(s):  
Mitradeep Sarkar ◽  
Jean-François Bryche ◽  
Julien Moreau ◽  
Mondher Besbes ◽  
Grégory Barbillon ◽  
...  
Keyword(s):  
Analytical Model ◽  
Experimental Results ◽  
Model Based

scholarly journals Research on the Dynamic Responses of Simply Supported Horizontal Pipes Conveying Gas-Liquid Two-Phase Slug Flow

Processes ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 83
Author(s):  
Gang Liu ◽  
Zongrui Hao ◽  
Yueshe Wang ◽  
Wanlong Ren
Keyword(s):  
Slug Flow ◽  
Peak Frequency ◽  
Dynamic Responses ◽  
Piping System ◽  
Transverse Displacement ◽  
Vibration Acceleration ◽  
Two Phase ◽  
Horizontal Pipes ◽  
Simply Supported ◽  
Superficial Gas Velocity

The dynamic responses of simply supported horizontal pipes conveying gas-liquid two-phase slug flow are explored. The intermittent characteristics of slug flow parameters are mainly considered to analyze the dynamic model of the piping system. The results show that the variations of the midpoint transverse displacement could vary from periodic-like motion to a kind of motion whose amplitude increases as time goes on if increasing the superficial gas velocity. Meanwhile, the dynamic responses have certain relations with the vibration acceleration. By analyzing the parameters in the power spectrum densities of vibration acceleration such as the number of predominant frequencies and the amplitude of each peak frequency, the dynamic behaviors of the piping system like periodicity could be calculated expediently.

Convective Losses From Cavity Solar Receivers—Comparisons Between Analytical Predictions and Experimental Results

1983 ◽  
Vol 105 (1) ◽  
pp. 29-33 ◽  
Author(s):  
A. M. Clausing
Keyword(s):  
Experimental Data ◽  
Experimental Evidence ◽  
Analytical Model ◽  
Excellent Agreement ◽  
Experimental Results ◽  
Simple Analytical Model ◽  
Refined Model ◽  
Wall Area

Cavity solar receivers are generally believed to have higher thermal efficiencies than external receivers due to reduced losses. A simple analytical model was presented by the author which indicated that the ability to heat the air inside the cavity often controls the convective loss from cavity receivers. Thus, if the receiver contains a large amount of inactive hot wall area, it can experience a large convective loss. Excellent experimental data from a variety of cavity configurations and orientations have recently become available. These data provided a means of testing and refining the analytical model. In this manuscript, a brief description of the refined model is presented. Emphasis is placed on using available experimental evidence to substantiate the hypothesized mechanisms and assumptions. Detailed comparisons are given between analytical predictions and experimental results. Excellent agreement is obtained, and the important mechanisms are more clearly delineated.

scholarly journals Adaptive Broadcasting Mechanism for Bandwidth Allocation in Mobile Services

2014 ◽  
Vol 2014 ◽  
pp. 1-14
Author(s):  
Gwo-Jiun Horng ◽  
Chi-Hsuan Wang ◽  
Chih-Lun Chou
Keyword(s):  
Analytical Model ◽  
Bandwidth Allocation ◽  
Data Dissemination ◽  
Data Access ◽  
Experimental Results ◽  
Bandwidth Utilization ◽  
Access Latency ◽  
The Mean ◽  
Access Efficiency ◽  
Broadcast Program

This paper proposes a tree-based adaptive broadcasting (TAB) algorithm for data dissemination to improve data access efficiency. The proposed TAB algorithm first constructs a broadcast tree to determine the broadcast frequency of each data and splits the broadcast tree into some broadcast wood to generate the broadcast program. In addition, this paper develops an analytical model to derive the mean access latency of the generated broadcast program. In light of the derived results, both the index channel’s bandwidth and the data channel’s bandwidth can be optimally allocated to maximize bandwidth utilization. This paper presents experiments to help evaluate the effectiveness of the proposed strategy. From the experimental results, it can be seen that the proposed mechanism is feasible in practice.

Laminar Swirling Pipe Flow

1954 ◽  
Vol 21 (1) ◽  
pp. 1-7
Author(s):  
L. Talbot
Keyword(s):  
Swirling Flow ◽  
Nonlinear Effects ◽  
Critical Conditions ◽  
Flow Conditions ◽  
Rotationally Symmetric ◽  
Rate Of Decay ◽  
Linearized Theory ◽  
The Stability ◽  
Experimental Values ◽  
Rates Of Decay

Abstract The problem of the decay of a rotationally symmetric steady swirl superimposed on Poiseuille flow in a round pipe was investigated theoretically and experimentally. The object was to determine the degree to which the rate of decay of the swirl as predicted by a linearized theory agreed with measured rates of decay at flow conditions near the critical conditions for swirl instability. The solution to the linearized equation of motion for the swirl was obtained. Swirling flow was produced experimentally by rotating a section of the test pipe. Swirl velocities were determined from motion-picture studies of colored oil droplets introduced in the flow. The stability of the swirl was investigated through visualization of a dye filament, and a critical curve for swirl instability was determined experimentally relating the angular velocity of the rotating section to the Reynolds number. The theoretical and experimental values for the decay parameter were found to agree closely, even at conditions of flow near the critical conditions for instability. It was concluded that in the problem under consideration the nonlinear effects are not appreciable for stable decay of the swirl.

An Analytical Model for the Effective Dielectric Constant of a 0-3-0 Composite

2010 ◽  
Author(s):  
K. A. Cook-Chennault ◽  
S. Banerjee
Keyword(s):  
Dielectric Constant ◽  
Aspect Ratio ◽  
Analytical Model ◽  
Experimental Results ◽  
Effective Dielectric Constant ◽  
The Third ◽  
Third Phase ◽  
Three Phase ◽  
Phase 0 ◽  
Experimental Values

An analytical expression for prediction of the effective dielectric constant of a three phase 0-3-0 ferroelectric composite is presented. The analytical results are verified with the experimental results from Nan et al [1]. We extend the analytical model, so that the influence of the shape of the third phase inclusion, on the effective dielectric constant of the composite, can be investigated. The results indicate that the dielectric constant increases ∼7 times, when the aspect ratio of the conductive inclusion is increased from 1 (sphere) to 10 (spheroid). The analytical predictions compare favorably with the experimental values.

scholarly journals Surge Limit Prediction for Automotive Air-Charged Systems

2019 ◽  
Vol 4 (4) ◽  
pp. 34
Author(s):  
Johannes Bühler ◽  
Sebastian Leichtfuß ◽  
Heinz-Peter Schiffer ◽  
Thomas Lischer ◽  
Simon Raabe
Keyword(s):  
Development Process ◽  
Experimental Testing ◽  
Piping System ◽  
Economic Perspective ◽  
Flow Conditions ◽  
Strong Variation ◽  
Piston Engine ◽  
Hot Gas ◽  
Compressor Surge ◽  
Compressor Aerodynamics

Compressor surge has been investigated and predicted since the early days of turbomachinery research. Experimental testing of turbomachinery applications is still needed to determine whether stable compressor operation is possible in the expected application regime. Measuring compressor maps and operating ranges on hot gas test stands is common. The test benches are designed and optimized to ensure ideal inflow and outflow conditions as well as low measurement uncertainty. Compressor maps are used to match turbocharger and application. However, a shift in surge limit, caused by the piping system or application, can only be adequately addressed with full engine tests. Ideal measurements use the corresponding piston engine in the charged-air system. This can only take place in the development process, when surge detection is unfavorable from an economic perspective. The surge model for turbochargers presented here is an extension of the Greitzer’s surge model, which considers the effect of inlet throttling. Application components, such as air filters, pipe elbows and flow straighteners, reduce pressure in front of the compressor and flow conditions might differ from those in laboratory testing. Experimental results gathered from the hot gas test stand at TU Darmstadt indicate strong variation in surge limit, influenced by inlet throttling. An extension to the surge model is developed to explain the observed phenomena. The model was validated using extensive experimental variations and matches the experienced surge limit shift. Additional measurements with a piston engine downstream of the turbocharger demonstrated the validity of the surge model. The results also show that surge is a system-dependent phenomenon, influenced by compressor aerodynamics and boundary conditions.

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