cross section change
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Author(s):  
Agnieszka Malesinska ◽  
Michal Kubrak ◽  
Mariusz Rogulski ◽  
Pierfabrizio Puntorieri ◽  
Vincenzo Fiamma ◽  
...  

Abstract Contractions and expansions are common features in various types of pipeline systems. The purpose of this study is to investigate the influence of a sudden cross-section change on transient pressure waves. The paper presents laboratory data and numerical calculations of pressure oscillations during the valve-induced water hammer in serially connected steel pipes. Five different variants of experiments were conducted which included recording pressure changes at the downstream end of the pipeline system. The more sections with different diameters there are connected in series, the more complex the transient wave recorded is. Laboratory data indicate a significant influence of individual pipeline sections on the final course of pressure oscillations. Transient equations were solved using the explicit MacCormack scheme. In order to numerically simulate water hammer in pipe series, the improved junction boundary condition was established. It involves assigning two sets of values, which describe flow parameters, to the connection node thus causing it to act as two separate nodes. The numerical model was calibrated with the unsteady friction factor. The derivation of equations that take into account a sudden change in diameter in the connected pipes allowed the reproduction of the wave nature of the water hammer phenomenon, results were satisfactory as compared to experimental data. Numerical model correctly reproduced pressure wave interactions and pressure amplitudes.


2016 ◽  
Vol 449 ◽  
pp. 134-147 ◽  
Author(s):  
M. Ghods ◽  
L. Johnson ◽  
M. Lauer ◽  
R.N. Grugel ◽  
S.N. Tewari ◽  
...  

2016 ◽  
Vol 693 ◽  
pp. 504-510
Author(s):  
Xiao Juan Jiao ◽  
Jian Min Ma

s The longitudinal impact between rigid body and variable cross-section elastic rod with fixed boundary condition was studied, the velocity and stress distribution law during 1st impact wave period was derived for the variable cross-section rod, the influence of cross-section change rate on rod response was discussed. Some examples calculations were carried on, It is shown that the cross-section change rate is a significant influencing factor for the velocity and stress distribution in the rod during impact.


2013 ◽  
Vol 747-748 ◽  
pp. 535-539 ◽  
Author(s):  
Wei Dong Xuan ◽  
Zhong Ming Ren ◽  
Huan Liu ◽  
Ting Sheng Tu

The formation mechanism of stray grains in cross-section change region of casting clusters for single crystal superalloy DD483 were investigated experimentally during the conventional directional solidification. The results showed that the stray grains formation was different on the two sides of the platform. Indeed, stray grains formation in the region of the cross-section change on the shadow side showed a high probability, while the heater side, no stray grains appeared. Additionally, the cooling curves at the cross-section change region also showed that the distribution of temperature was different on the two side of the platform. The formation of stray grain can be attributed to the local undercooling at the cross-section change region is exceed the critical undercooling for nucleation, led to the heterogeneous nucleation, while the asymmetric temperature distribution should be responsible for asymmetrical formation of stray grains on the two sides of the platform.


2004 ◽  
Vol 2004.53 (0) ◽  
pp. 385-386
Author(s):  
Hideyuki SUZUKI ◽  
Yoshihisa UCHIDA ◽  
Niichi HAYASHI

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