oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Search Results: 1 - 10 of 10 matches for " Throttling "
All listed articles are free for downloading (OA Articles)
Page 1 /10
Display every page Item
Hydraulic Domestic Heating by Throttling  [PDF]
Mohammad A. K. Alia, Tariq Younes, Hussein Sarhan
Engineering (ENG) , 2010, DOI: 10.4236/eng.2010.26060
Abstract: In this work an experimental investigation was carried out in order to explore the possibility of realizing a domestic heating system by throttling hydraulic oil. Considering the continuous increasing price of diesel oil, this work gains unique importance. Generating heat directly by throttling is realized using a simple environment friendly system which does not require oil transportation and storage, and eliminates the need for chimneys and annual preventive maintenance, as it is the case with heating by utilizing oil burners, which is prevailing in Jordan. Experimental results show that it is possible to raise the room temperature up to 70?C during 15 minutes which is not a limit value. Experimental results show that temperature rate could be increased by selecting the appropriate pump power and by connecting a number of throttles in parallel.
The Corpse Is a Silent Witness Who Never Lies—A Case Report  [PDF]
Vijay Pal, Pawan Mittal, Jitender K. Jakhar, Yogesh Kumar Vashist, A. D. Aggarwal, Bhavesh Bohra
Forensic Medicine and Anatomy Research (FMAR) , 2014, DOI: 10.4236/fmar.2014.23008
Abstract: There are two very common sayings about corpse (dead body). The first common saying is that “the corpse is a silent witness who never lies” and the other common saying is that “the dead body is extremely eloquent and honestly informative, if one exercises patience in listening to it.” Both these sayings were proved in one of our cases. In the present case, decomposed body of an unidentified female individual aged about 25 - 26 years was recovered from the bank of western Yamuna canal in Haryana. The police made the efforts for establishing the identity of the deceased but could not succeed. The body was forwarded to the district hospital for autopsy along with the inquest report. However, the body being in advanced stage of decomposition so it was referred from the district hospital to the department of Forensic Medicine, PGIMS, Rohtak (Haryana) for the examination and the expert opinion regarding the cause of death. The findings observed on examination of the body helped to deduce the cause, time and manner of death whereas certain important objective features of identification were also observed and ultimately proper identity of the deceased could be established beyond the reasonable doubt by DNA profile of the samples preserved at autopsy. The autopsy findings, DNA profile and the results of examination of other materials (exhibits) taken from the body not only revealed the truth from the silent witness—the corpse, but also provided objective and scientific evidence to establish the corpus delicti in this case.
Performance of Closed Type Impeller Designed for Easy Manufacturability
Mária arnogurská, Peter Ga parovi
Acta Mechanica Slovaca , 2010, DOI: 10.2478/v10147-011-0003-2
Abstract: The impeller of the semi-open type from a refrigerator unit is redesigned to improve efficiency and to reduce the pressure pulsations of the front case. Therefore, the closedtype impeller with outer shroud is chosen. Dimensions are scaled according to Cordier diagram with rotational speed preserved. The resulting geometry is constrained by requirement of easy manufacturability by injection moulding process. These constrains don't permit to improve efficiency by redesigning impeller.
A New Strategy to Achieve Radical Combustion Through Exhaust Port Throttling for Two Stroke Engine
Saqaff Ahmed Alkaff, Mohamed A. Khan
International Journal of Engineering , 2010,
Abstract: Radical combustion is a critical condition behind control. In two stroke engine, acondition of radical combustion could be achieved through control of the trappedexhaust gases at a certain condition, might include, the engine load, speed,concentration of the unburned hydrocarbons, their temperature and otheroperational parameters.An earlier work was conducted towards the achievement of the radicalcombustion. The mechanism was made to throttle the opening of the exhaustport at a range of 1% to 8 % [1]. However, several difficulties were faced, mainlywith the control mechanism of throttling. In addition there is a complexity inidentifying the critical conditions at which the radical combustion could beachieved.In this paper, a new strategy was used to control the exhaust port throttling in away to manage the amount of exhaust gases trapped and avoiding thedrawbacks of the throttling mechanism in the earlier work. Three trial plateswere used, one-sixth closed, one-third closed and half closed to throttle theexhaust gases leaving the combustion chamber.Results reveal the possibility of achieving radical combustion, when using theone-sixth closed plate under relatively higher load. Therefore, partial trapping ofthe exhaust gases should be carried, through the restriction of the opening of theexhaust port not to exceed 15% of the port exit area. However, it is moreinteresting, that throttling of the exhaust gases of the two stroke engine haveclear influence on the quality and stability of the combustion and hence its directeffect on the fuel consumption and the rate of pollutants expelled to theenvironment.
流量连续可调火箭发动机极度富燃燃烧特性
成鹏, 李清廉, 张新桥, 康忠涛,
CHENG Peng
, LI Qinglian, ZHANG Xinqiao, KANG Zhongtao

- , 2016, DOI: 10.11887/j.cn.201602003
Abstract: 以气氧/煤油作为推进剂对火箭发动机进行流量连续调节试验,研究火箭发动机连续变工况过程中的燃烧特性。火箭发动机通过可调气蚀文氏管连续调节煤油流量。试验在富燃工况(混合比0.405~0.690)下成功点火,并实现了混合比、燃气总流量连续调节。试验发现流量连续调节过程中,当混合比小于0.535时,燃烧室压力随煤油流量减小而增大;当混合比大于0.535时,燃烧室压力随煤油流量减小而减小。同时,特征速度和燃烧效率随混合比增大而增大,并且混合比小于0.535时特征速度、燃烧效率增大的速率大于混合比大于0.535时的速率。研究表明推进剂流量与燃烧效率同时影响燃烧室压力。当混合比小于0.535时,燃烧效率的影响占优;混合比大于0.535时,推进剂流量影响占优。
To study the combustion characteristics of a rocket engine under continuous throttling, a continuous throttling experiment was conducted by using GOX(gaseous oxygen)/kerosene as propellants. Mass flow rate of kerosene was continuously throttled by a throttleable cavitation Venturi nozzle. Successful ignition under fuel rich condition (mixture ratio ranged from 0.405 to 0.690) and the continuous throttling of mixture ratio and combustion gas flow rate were achieved. Results show that chamber pressure increases with the decrease of kerosene flow when the mixture ratio is less than 0.535 but decreases when the mixture ratio is greater than 0.535. Meanwhile, characteristic velocity and combustion efficiency increase with the increasing mixture ratio, but the increasing ratio is bigger when the mixture ratio is less than 0.535 than that when the mixture ratio is greater than 0.535. The results indicate that the mass flow rate of propellants and combustion efficiency simultaneously affect the chamber pressure. Combustion efficiency dominates the chamber pressure when the mixture ratio is less than 0.535 while mass flow rate of propellants dominates when the mixture ratio is greater than 0.535.
线性可调音速喷嘴工作特性仿真
成鹏, 李清廉, 张新桥, 康忠涛, 陈慧源
CHENG Peng
, LI Qinglian, ZHANG Xinqiao, KANG Zhongtao, CHEN Huiyuan

- , 2015, DOI: 10.11887/j.cn.201506011
Abstract: 为了满足组合发动机模态转换的要求,连续稳定调节推进剂流量十分关键。为此,针对气体推进剂,在常规音速喷嘴的基础上设计了一种可调音速喷嘴。通过塞锥改变音速喷嘴的节流面积,进而实现流量的连续调节。采用两次包络线方法设计塞锥型面,使得可调音速喷嘴具有线性的流量特性。采用计算流体动力学数值仿真研究可调音速喷嘴的工作特性。仿真结果表明反压小于临界反压时,可调音速喷嘴流量不受反压影响。可调音速喷嘴保持临界状态的临界反压比随流量的减小呈增大的趋势。线性可调音速喷嘴的流量与塞锥位置有较好的线性关系,其流量系数高且几乎不受塞锥位置的影响。
The mode transition of combined-cycle engine makes it necessary to throttle the mass flow rate of propellants continuously and stably. Aiming at gaseous propellant, a throttleable sonic nozzle was designed on the basis of normal sonic nozzle. The throttleable sonic nozzle achieves continuous throttling through a plug moving along axis. By adopting the twice-envelope method, the contour of the plug was designed to satisfy the linear characteristic of mass flow rate. Performances of the throttleable sonic nozzle were investigated through the numerical simulation of computational fluid dynamics. It is found that the mass flow rate is independent under the back pressure when the back pressure is lower than the critical back pressure and the critical back pressure ratio increases as mass flow rate decreases. The linear relationship between mass flow rate of linear throttleable sonic nozzle and location of plug was verified and results show that the discharge coefficient is high and hardly be affected by the location of plug.
限流细长孔板阻力特性实验研究与关联式评价
Experimental Investigation on Resistance Characteristics of Thin and Long Throttling Orifices and Evaluation of the Resistance Correlations

胡娟娟,李会雄,盛天佑,倪士尧,王耀东,谢恩飞
- , 2018, DOI: 10.7652/xjtuxb201807013
Abstract: 为研究限流细长孔板阻力随孔板几何尺寸的变化规律,在高温高压条件下,以去离子水为工质,对其进行了实验研究。结果表明,质量流量一定时,孔板直径是影响阻力的决定性因素,其次是孔板长度,而与孔板相连的管道直径对阻力基本无影响。以实验数据为基础,对现有孔板阻力计算关联式进行了整理、评价,结果表明现有关联式对本文细长孔板阻力的预测精度不高,适用范围普遍较窄,且部分关联式并未考虑孔板长度对阻力的影响。基于本文实验数据,通过拟合建立了细长孔板阻力的新计算关联式,包括了孔板长度、孔板直径及雷诺数对细长孔板阻力的影响。新建立的阻力关联式具有较高的预测精度,对于长径比为5~70、入口雷诺数为1.5×105~3.0×106的限流细长孔板的阻力特性,预测精度为±15%。本研究为限流细长孔板的设计与应用提供了可靠依据。
To study the resistance characteristics of thin and long throttling orifices with change of geometric size, experimental research was carried out with deionized water under high temperature and high pressure conditions. Experimental results showed that the diameter of orifice is the decisive factor influencing resistance, and the length of orifice has a small influence on resistance; the diameter of the pipe has little influence on the resistance when the mass flow is constant. On the basis of the experimental data, evaluations of the existing orifice resistance calculation correlations were conducted. It is found that the existing correlations with narrow application ranges are not precise, and some correlations do not take the influence of orifice length on its resistance into account. Considering the influences of orifice length, orifice diameter and Reynolds number on the orifice resistance, a new correlation with higher prediction accuracy is presented. This new correlation can be used to accurately predict the resistance characteristics of the orifices with the length??to??diameter ratios between 5 and 70 and the Reynolds number between 1.5×105 and 3.0×106, providing a reliable basis for the design and application of thin and long throttling orifices
多路阀阀芯节流槽拓扑结构组合的神经网络模型
A Neural Network Model for Spool Throttling Groove Topology Combination of Multi??Way Valves

姜涛,黄伟,王安麟
- , 2016, DOI: 10.7652/xjtuxb201606006
Abstract: 针对多路阀设计中阀芯节流槽结构的拓扑形态表达和其流固耦合响应的大组合、大自由度解析问题,提出多路阀阀芯节流槽拓扑结构组合的神经网络模型。在利用多路阀动态特性台架实验验证其三维流体解析结果的基础上,将节流槽拓扑结构分类为由半圆槽、U型槽、圆孔等结构的参数化组合构成,通过正交实验法得到各参数组合条件下的多路阀三维流体解析响应,作为反向传播神经网络的训练样本,实现其节流槽拓扑结构组合的神经网络表达;采用进化神经网络优化训练过程的初始权重和阈值,优化后的神经网络能够对非训练样本集合的多路阀三维流体解析响应实现准确预测。研究结果表明,此模型为阀芯节流槽结构设计中拓扑形态表达提供了一种新的思路,对多路阀数字化设计具有实际意义。
A neural network model for the spool throttling groove topology combination of multi??way valves is proposed to deal with the problem that there exist various combinations of topological form expression of throttling groove structure on spool and huge degrees of freedom of analysis of fluid??structure coupling response in the design of multi??way valves. The throttling groove topological structures are classified into semicircle groove, U??shaped groove, round hole groove and so on, and form different parameterized combinations of these structures based on validation of analytical results in using the multi??way valve dynamic characteristic test. The orthogonal experiment method is used to obtain three??dimensional fluid analytical responses of the multi??way valve for each parameter combination, then these responses are used as training samples of a back propagation neural network to achieve the neural network expression of the throttling groove topology combination. The initial weights and threshold of training process are optimized by an evolutionary neural network to improve prediction accuracy of the model, so that accurate predictions for non??training samples are achieved. The results show that the proposed model provides a new idea for topological form expression in the design of spool throttling groove structures, and has practical significance for digital design of multi??way valves
Research on Computer Virus Spread and Control Strategy in Complex Networks
复杂网络上计算机病毒传播和控制策略研究

ZHU Gang,ZHANG Ning,MA Liang,
朱刚
,张宁,马良

计算机应用研究 , 2006,
Abstract: Computer virus and worms spread in networks that lie on the structure of networks. The structure of networks affects the speeds and scales of computer infection. This paper gives a research on computer virus spread and control strategy in different networks based on character of network spread of realistic world.
多路换向阀换向耦合阀口节流结构拓扑设计
Topology Design Method for Coupling Valve Throttle Structure of Multi??Way Directional Valves

姜涛,黄伟,王安麟
- , 2016, DOI: 10.7652/xjtuxb201608005
Abstract: 为解决多路换向阀换向过渡过程中分流特性所带来的阀口间节流结构耦合作用问题,提出多路换向阀换向耦合阀口节流结构拓扑设计方法。将耦合阀口节流槽结构分类为由U型槽、半圆槽、圆孔槽等结构组成的参数化组合构成,构建出多路换向阀工作口流量与其阀口节流槽结构变量间的函数模型;在验证多路换向阀三维流体解析与其动态特性台架实验结果的基础上,以设定的多路换向阀换向过渡过程工作口流量变化为评价目标,采用粒子群算法求解阀口节流槽结构拓扑设计问题,实现了耦合阀口节流结构响应与换向过渡过程节流特性的较好吻合。研究结果表明,该方法对满足多路换向阀换向过渡特性要求的耦合阀口节流结构拓扑设计具有实际意义。
A topology design method for coupling valve ports throttling structure of multi??way directional valves is proposed to solve the coupling problem between the valve ports caused by flow distribution characteristic in the process of reversing transition. The throttling structures of coupling valve ports are classified into semicircle groove, U??shaped groove, round hole groove and so on, and formed by different parameterized combinations of these structures. A model to describe the function between work flow of multi??way directional valve and variables of its coupling valve ports throttling groove structure is constructed. The work flow in the process of reversing transition of multiple directional control valve is set as an evaluation target based on the validation of three??dimensional fluid dynamic analysis of multi??way directional valve and its dynamic characteristics results of test bench. Then a particle swarm algorithm is used to solve the topology design problem of valve ports throttling groove structure, so that a good agreement between the response of coupling valve throttling structure and the throttling characteristic in the process of reversing transition is realized. The results show that the method has a reference value of engineering for the topology design of coupling valve ports throttling structure in meeting the requirements of reversing transition characteristics of multi??way directional valves
Page 1 /10
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.