suction performance
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2022 ◽  
Vol 10 (1) ◽  
pp. 70
Author(s):  
Yibing Zhao ◽  
Canjun Yang ◽  
Yanhu Chen ◽  
Jia Li ◽  
Siyue Liu ◽  
...  

In order to adhere to the wall stably in an underwater environment, a vortex suction cup that injects high-pressure water inside via two axisymmetrically side-distributed inlets to create a negative pressure area in the center is the necessary component for the underwater climbing robot (UCR). However, the suction force of this vortex suction cup is reduced and periodically unstable due to unstable cavitation. The aim of this paper is to propose a cavitation reduction optimization method for vortex suction cups and to verify the effectiveness of the optimization. Analyses of this vortex flow, including streamlines, pressure, and cavitation number fluctuations, were carried out by the introduced computational fluid dynamics (CFD) simulating methods based on the multiphase RNG k−ε model to study the periodic fluctuations of the suction force of the original suction cup and the optimized ones. Force measurement and vortex observation experiments were conducted to compare the suction force of the original vortex suction cup and the optimized suction cup, as well as the cavitation and pressure fluctuation phenomenon. Results of simulation and experiments prove the existence of the effect of vortex cavitation on the suction performance and verify the rationality of optimization as well.


2021 ◽  
Vol 6 (1) ◽  
pp. 112-120
Author(s):  
Magdy Mohamed Abou Rayan ◽  
N. Gadelhak
Keyword(s):  

Author(s):  
Changhyun Kim ◽  
Chang-Ho Choi ◽  
Semi Kim ◽  
Jehyun Baek

In a projectile, a turbopump is widely used to pressurize oxidizer and fuel to gain high thrust instead of using high pressure tank which has a disadvantage in total weight. Pumps in a turbopump employ an inducer upstream to prevent performance degradation by increasing pressure at the impeller inlet. However, cavitation and related instabilities take place frequently, so numerous analysis have been conducted for turbopumps. In this study, the pumps with and without an inducer were numerically studied using ANSYS CFX 13.0 to analyze the effects of installing an inducer, which was rarely treated before. By comparing these two pumps, the merits and demerits of installing an inducer can be analyzed in the aspects of hydraulic/suction performances and internal flow characteristics. Also, the role of an inducer can be understood in both of non-cavitating and cavitating conditions. As a result, head rise and efficiency of the pump were degraded by installing an inducer in non-cavitating conditions. The inducer could not play a role at high flow rate, and efficiency of the inducer was steeply declined in the off-design conditions. However, suction performance of the pump was greatly improved by adopting the inducer. Head of the pump with an inducer abruptly decreased at the low cavitation numbers, while head of the pump without an inducer started to decline gradually at the high cavitation numbers. In spite of high cavitation number, severe cavitation appeared in the case without an inducer, so it can be said that installing an inducer can prevent performance deterioration from the cavitation and satisfies stable operation which is more important for pumps rather than obtaining high hydraulic performance.


Buildings ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 225
Author(s):  
Rizuwana Parween ◽  
Mohan Rajesh Elara ◽  
Zaki Saptari Saldi ◽  
Thomas Ng ◽  
Madan Mohan Rayaguru

For glass façade cleaning, we developed a reconfigurable robot, Mantis-mini, with a dry cleaning mechanism and linear actuator based transitioning mechanism. It consists of three suction modules, connected by a support structure and each suction module has individual differential drive wheels with independent steering capability. This paper focuses on the detailed design of the platform, static structural analysis for and kinematic formulation. The adhesion performance of the suction module is evaluated using experiments, Computational Fluid Dynamics (CFD) simulations, and analytically formulated estimation. The suction pressure magnitude predicted from the simulations increases with suction impeller speed and agrees well with measurements and analytical calculation in terms of order of magnitude and qualitative trend. An adaptive proportional-integral (PI) controller is designed and implemented for regulating suction pressure and motion controller of the platform. The suction performance of the platform is validated through real-time experiments of the platform on the glass surface.


2021 ◽  
Vol 14 (1) ◽  
pp. 13-24
Author(s):  
Yohei Tanaka ◽  
Takahiro Kitabata ◽  
Satoshi Watanabe ◽  
Satoru Ohashi ◽  
Akira Sakata ◽  
...  
Keyword(s):  

2020 ◽  
Vol 13 (4) ◽  
pp. 750-758
Author(s):  
Yohei Tanaka ◽  
Satoshi Watanabe ◽  
Satoru Ohashi ◽  
Yasushi Matsunaga

2020 ◽  
Author(s):  
Katherine A Corn ◽  
Christopher M Martinez ◽  
Edward D Burress ◽  
Peter C Wainwright

Abstract Trade-offs caused by the use of an anatomical apparatus for more than one function are thought to be an important constraint on evolution. However, whether multifunctionality suppresses diversification of biomechanical systems is challenged by recent literature showing that traits more closely tied to trade-offs evolve more rapidly. We contrast the evolutionary dynamics of feeding mechanics and morphology between fishes that exclusively capture prey with suction and multifunctional species that augment this mechanism with biting behaviors to remove attached benthic prey. Diversification of feeding kinematic traits was, on average, over 13.5 times faster in suction feeders, consistent with constraint on biters due to mechanical trade-offs between biting and suction performance. Surprisingly, we found that the evolution of morphology contrasts directly with these differences in kinematic evolution, with significantly faster rates of evolution of head shape in biters. This system provides clear support for an often postulated, but rarely confirmed prediction that multifunctionality stifles functional diversification, while also illustrating the sometimes weak relationship between form and function.


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