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Numerical Investigation of Short Blades Effect on the Performance of a Centrifugal Pump
Sami Abdelfatah Abd Elkgany El-Shaikh,
Mohamed Attia Abdellatif,
Abdullah Hussein Ibrahim Aboelnil
Issue:
Volume 5, Issue 4, August 2017
Pages:
186-193
Received:
7 May 2017
Accepted:
15 May 2017
Published:
5 July 2017
Abstract: Improvement performance of centrifugal pumps is critical to reduce the consumption of electrical energy. One to improve the performance is to break down the circulation near the impeller exit. This can be achieved through the use of shorted blades. Effect of different sizes of shorted blade on pump performance is studied theoretically in this research which, test rig for testing centrifugal pump with standard impeller is constructed. Three impeller configurations with different size shorted blade are installed. The head, flow rate and shaft power are measured at 1500 rotational speed for the standard pump only. Also computational model using “Fluent” under ANSYS is constructed to predict the performance parameters of centrifugal pumps and to analyze the flow field in the impellers’ passages. Standard impeller (A) and three impellers configuration with different shorted blade length of 0.25 (configuration B), 0.2 (configuration C), and 0.15 (configuration D) of the full blade length are analyzed. Computational results show a reduction in flow circulation for all shorted blades impeller comparing to standard impeller. Also static pressure distributions at impeller exit become more uniform for impeller with 0.25, 0.2, and 0.15 shorted blades. The present work proves that the length of short blades have different effects for all pump cases. The best performance in this study occurred when shorted blades have length 25% from the original blade length. So when the effect of shorted blades is needed to study, each case of centrifugal pump should be investigated separately.
Abstract: Improvement performance of centrifugal pumps is critical to reduce the consumption of electrical energy. One to improve the performance is to break down the circulation near the impeller exit. This can be achieved through the use of shorted blades. Effect of different sizes of shorted blade on pump performance is studied theoretically in this resea...
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Leakage-Resilient Certificateless Short Signature Scheme
Issue:
Volume 5, Issue 4, August 2017
Pages:
194-202
Received:
22 March 2017
Accepted:
10 May 2017
Published:
6 July 2017
Abstract: For a certificateless short signature scheme to be applied in practical applications, it should without various leakage attacks. In this paper, we present a new leakage-resilient certificateless short signature scheme whose security is based on the classical decisional Diffie-Hellman (DDH) assumption. Our scheme is leakage-resilient signature scheme, and leaked information is a maximum value (upper bound). What is more, our scheme also enjoys a higher relative leaked information rate and still semantically secure against adaptive chosen message attack. Besides these good performance features, we have formally proved the security of our scheme in the random oracle model under the hardness of the DDH problem. With these import features, our proposal may have some significant value in the practical applications. Compared to existing schemes, our new scheme has two advantages: (1) Our scheme is leakage-resilient certificateless short signature scheme; (2) Our Scheme is leakage-resilient signature scheme, and leaked information is a maximum value (upper bound).
Abstract: For a certificateless short signature scheme to be applied in practical applications, it should without various leakage attacks. In this paper, we present a new leakage-resilient certificateless short signature scheme whose security is based on the classical decisional Diffie-Hellman (DDH) assumption. Our scheme is leakage-resilient signature schem...
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Researches on Stress Concentration and Fatigue Damage for Ferromagnetic Specimen by Permeability Testing Technology
Ren Shangkun,
Ren Xianzhi,
Yang Meifang
Issue:
Volume 5, Issue 4, August 2017
Pages:
203-207
Received:
7 May 2017
Accepted:
22 May 2017
Published:
10 July 2017
Abstract: The permeability testing technology are new testing and evaluating method, which based on the electromagnetic induction principle, can realize the test and evaluate high sensitively of stress concentration and fatigue damage for ferromagnetic specimen. Taking Q235 and 45 steel for examples, the relationships of the detection signal and the tensile stress, residual stress, fatigue damage are studied from experiments. The results indicate that permeability testing technology can be used effectively to measure the stress state of specimen and the maximum stress suffered before. According to the residual stress signal after suffer tensile, the maximum stress to be suffered before can be determined with high sensitively. It shows that detection sensitivity of the fatigue damage is less than that of stress concentration. The detection sensitivity of fatigue damage for Q235 steel is greater than that of steel 45 steel. The results indicate that the permeability testing technology has a broad application prospect.
Abstract: The permeability testing technology are new testing and evaluating method, which based on the electromagnetic induction principle, can realize the test and evaluate high sensitively of stress concentration and fatigue damage for ferromagnetic specimen. Taking Q235 and 45 steel for examples, the relationships of the detection signal and the tensile ...
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Finite Element Analysis of EA 113 Gasoline Engine Connecting Rod
Jing Zhang,
Zhiyuan Qiu,
Yan Zhang
Issue:
Volume 5, Issue 4, August 2017
Pages:
208-213
Received:
19 July 2017
Published:
19 July 2017
Abstract: For the Santana EA 113 gasoline engine connecting rod, the motion law of connecting rod and stresses in movement were analyzed using the theory knowledge of kinematics and dynamics. Based on the finite element method, the three-dimensional model of four-cylinder four-stroke gasoline engine connecting rod was established and then the stiffness and stress distribution and strain condition of connecting rod under different working conditions were analyzed. In modal analysis and transient dynamic analysis, the frequencies of rod in resonance and the stress, displacement and velocity of connecting rod at each moment were obtained, which provide the basis for the optimal design of connecting rod.
Abstract: For the Santana EA 113 gasoline engine connecting rod, the motion law of connecting rod and stresses in movement were analyzed using the theory knowledge of kinematics and dynamics. Based on the finite element method, the three-dimensional model of four-cylinder four-stroke gasoline engine connecting rod was established and then the stiffness and s...
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A New Approach of Gas Turbine Component Matching for Electrical Power Generation
Munzer S. Y. Ebaid,
Qusai Z. Al-Hamdan
Issue:
Volume 5, Issue 4, August 2017
Pages:
214-222
Received:
27 February 2017
Accepted:
7 March 2017
Published:
4 August 2017
Abstract: Gas turbines are often required to operate at different power levels and under varying environmental conditions. But by the nature of the thermodynamic processes in the engine, it is not possible to obtain the same level of efficiency within the entire range of operation. Therefore, depending on the particular application, for example for power generation, the rotational speed would be constant and dictated by the electrical generating machine. Gas turbine engine consists of various components which are linked together in such a way that there exists a mechanical and thermodynamic interdependence among some components. This means that some operational compatibility (matching) between components will be required for a steady state or equilibrium operation. The steady state of gas turbine engine for power generation can be achieved by the matching of its compressor and turbine. The usual approach of matching the compressor and the turbine is usually based on using an iterative procedure to determine the turbine operating points which are then plotted on the compressor characteristics. The draw back of this process is being laborious and time consuming. The new approach developed overcomes this by superimposing the turbine performance characteristics on the compressor performance characteristics while meeting the components matching conditions. This can be done by introducing a new mass flow dimensionless parameter. Superimposing the turbine map on the compressor map cannot be totally accepted until both maps axes (the abscissa and the ordinate) are identical. This paper explains the new approach adopted to a single shaft gas turbine engine. Theoretically, the developed techniques can be applied to other gas turbine engines.
Abstract: Gas turbines are often required to operate at different power levels and under varying environmental conditions. But by the nature of the thermodynamic processes in the engine, it is not possible to obtain the same level of efficiency within the entire range of operation. Therefore, depending on the particular application, for example for power gen...
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A Model for Design Optimization of Electrochemical Mechanical Polishing Polish Pad
Bian Yanfei,
Wang Zhenxuan,
Cai Meng,
Wang Ruofu,
Tian Jingqun
Issue:
Volume 5, Issue 4, August 2017
Pages:
223-227
Received:
11 July 2017
Accepted:
19 July 2017
Published:
11 August 2017
Abstract: The polishing pad plays a vital role in achieving the desired removal rate and level of surface planarity during the electrochemical mechanical planarization (ECMP) process. Material removal rate (MRR) and within wafer non-uniformity (WIWNU) are two important factors in determining the polishing performance. In this work, a theoretical model for predicting the radial distribution of tribasic ammonium citrate (TAC) concentration on the wafer is proposed. The experimentally measured MRR was found as a function of the TAC concentration in the slurry. Hence, the model could not only predict the removal rate at a given point on the wafer surface, but also reflect the WIWNU. Model predictions are in good agreement with the experimental data. The proposed model are used to perform an analysis of the effect of pad designs on the MRR and WIWNU of the wafer.
Abstract: The polishing pad plays a vital role in achieving the desired removal rate and level of surface planarity during the electrochemical mechanical planarization (ECMP) process. Material removal rate (MRR) and within wafer non-uniformity (WIWNU) are two important factors in determining the polishing performance. In this work, a theoretical model for pr...
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Economic Viability of Compressor Washing Methods for Maximum Power Output
Enyia James Diwaa,
Archibong Eso Archibongb,
Dodeye Ina Igbongc,
Ukpabio E. Eyod
Issue:
Volume 5, Issue 4, August 2017
Pages:
228-238
Received:
22 September 2016
Accepted:
21 January 2017
Published:
21 August 2017
Abstract: It is no longer news that gas turbines deteriorates after some period in operation, and if the deterioration effect is not taken into consideration, the gas turbine operator or owner will run into huge economic loss. Availability and reliability have been very important tools to every gas turbine owner, and there are various methods by which these engines have been investigated to prolong its life span, as such, it has become imperative to use different methods such as online and offline washing so as to advise the engine operator on which of the methods that will be more beneficial economically. The engine is kept clean the often it is been washed and thus produces more power, but how economically viable will it be washing the engine for this much times in a year has been the crux, considering the cost of wash fluids, equipment cost, labour cost, and so on. Hence this research technical paper. In this technical paper, it has been investigated that though keeping power high is very important but does not necessarily means saving cost. An online compressor washing was investigated and it was a 30% power recovery on each time online compressor water wash was administered, and the washing took place ones in every 7days, which gives a total of 54 washes per annum. The offline wash took place ones in every 3 months, making a total of 4 washes per annum with 85% power recovery after each offline compressor water wash, and the maximum limit of engine deterioration never exceed 10% of the original power at each given point. The engine modelled for this study was similar to that of GE LM2500+. The performance simulation was carried out via TURBOMATCH/PYTHIA which is Cranfield University software for gas turbine performance simulation. The output result was fed into a techno-economic model where the total financial involvement was computed for both the online and the offline compressor water wash. The cost implications have shown that though more power could be saved when the engine is washed regularly, but not necessarily economically viable as any engine owner or operator would have wanted. It has been shown in financial terms that fouling actually has significant effect on gas turbine performance, and the more economically viable compressor water wash method has been investigated via the economic model.
Abstract: It is no longer news that gas turbines deteriorates after some period in operation, and if the deterioration effect is not taken into consideration, the gas turbine operator or owner will run into huge economic loss. Availability and reliability have been very important tools to every gas turbine owner, and there are various methods by which these ...
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