• Title/Summary/Keyword: shroud system

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A study on the Vibration Damping of a gun barrel using Dynamically Tuned Shroud (차열관을 이용한 포신의 진동 감쇠에 대한 연구)

  • Koh, Jae-Min;Kim, Kyeon-Sik;Kim, Jin-Woo;Jung, Hyun-Woo;Hwang, Jai-Hyuk;Bae, Jai-Sung
    • Journal of Aerospace System Engineering
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    • v.4 no.4
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    • pp.28-36
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    • 2010
  • Current tanks have been developed to increase mobility and firepower, and its maximum range and destructive power are improved. This great change causes remained vibration of a gun barrel after firing. For this reason, people are trying to control vibration of gun barrel effectively. This thesis presents a modeling method and analysis results for gun barrel by using a thermal shroud as an absorber mass. DTS(Dynamically Tuned Shroud) is a vibration damping system using a thermal shroud as an added mass for decreasing remained vibration. The model has an advantage that the gun barrel's vibration can be decreased by dissipating a kinetic energy of thermal shroud without install an additional dynamic absorber to tip of the gun barrel. For analyzing the damping performance of the DTS, We derived an equation of motion of the barrel after setting a mathematical modeling, and found out the frequency analysis and tendency according to stiffness ratio between barrel and shroud.

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A Study on the Shroud, according to Change of Mourning & Funeral Custom (상장례문화의 변화에 따른 수의연구)

  • 이민주
    • The Research Journal of the Costume Culture
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    • v.8 no.6
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    • pp.887-898
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    • 2000
  • Mourning & funeral ritual means a various kinds of ritual procedures which begins at the time of death, buried and created a graveyard, a manner of wearing funeral garment being mourning the death, finally go back to everyday life. Our mourning & funeral custom was burial at first time. After going through the era of the Three kingdoms, The unified Shilla and Korea dynasty, cremation method has been prevailed. However, based on Chu-tzu celebration in Chosun dynasty, the burial custom has been widely spread again. Nowadays, due to effective land utilization issue, excessive cost for burial and the change of thinking for cremation, the cremation is recognized as remedy of righteous funeral system. At this point, a shroud following existing burial custom burdens considerably for quality, price, size and design of it. Accordingly, it needs anew style of shroud corresponding to cremation system. As an alternative, the shroud is required simplification and standardization ; Firstly, in size, a shroud should be larger than plain clothes and differentiated in small, medium and large. Secondly, the material of a shroud would be white cotton, which can keep from pollution during burning time. Thirdly, it unifies the item. In case of man, 바지(把特, those are trousers), 저고리(赤古里, Korean-style jacket) and Durumagi(周衣, Korean topcoat). In case of woman, 치마(赤 , those are skirt), 저고리(赤古里, Koran-style jacket) and Durumagi(周衣, Korean topcoat).

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Hydrodynamic forces of impeller shroud and wear-ring seal on centrifugal pump (고성능 원심펌프에서 임펠러 시라우드 및 마모 시일의 유체가진력 해석)

  • Ha, Tae-Woong
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.22 no.1
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    • pp.102-110
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    • 1998
  • The analysis of lateral hydrodynamic forces in the leakage path between a shrouded pump impeller through wear-ring seal and its housing is presented. Governing equations are derived based on Bulk-flow and Hirs' turbulent lubrication model. By using a perturbation analysis and a numerical integration method, governing equations are solved to yield leakage and rotordynamic coefficients of force developed by the impeller shroud and wear-ring seal. The variation of rotordynamic coefficients of pump impeller shroud and wear-ring seal is analyzed as parameters of rotor speed, pressure difference, shroud clearance, wear-ring seal clearance, and circumferential velocity at the entrance of impeller shroud for a typical multi-stage centrifugal pump.

Analysis of Flow Velocity Change in Blade Installed Shroud System for Tidal Current Generation (블레이드가 설치된 조류발전용 쉬라우드 시스템 내 유속 변화 분석)

  • Lee, Uk Jae;Han, Seok Jong;Jeong, Shin Taek;Lee, Sang Ho
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.31 no.1
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    • pp.9-16
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    • 2019
  • Flow velocity changes in the shroud system for tidal current power generation due to experimental flow velocities and blade geometry changes were analyzed by hydraulic experiment and numerical simulation. Through the hydraulic experiment, flow velocities at inlet of shroud system and RPM according to blade geometry were measured, and numerical simulation was used to analyze flow velocity changes in shroud. When the experimental flow velocity was increased by about 28% and the shape of the airfoil was applied, the measured flow velocity at the shroud inlet tended to increase by up to about 56%. On the other hand, when airfoil-shaped blades were installed, the flow velocity at the inlet tended to increase by up to 14% compared to conventional blades, and RPM was also the highest at the same conditions. The hydraulic experiment and numerical simulation results showed an error of about 13%, and the trends of the flow velocity changes in each result are similar. Numerical simulation of the flow velocity changes in the shroud showed that the flow velocity tended to increase 1.7 times at the front of the blade compared to the inlet. The results of the flow velocity change analysis in the shroud system obtained from this study will provide the basic data necessary for the development of efficient shroud system for tidal current power generation.

Root Cause Analysis on the Steam Turbine Blade Damage of the Combined Cycle Power Plant (복합화력발전소 증기터빈 동익 손상 원인분석)

  • Kang, M.S.;Kim, K.Y.;Yun, W.N.;Lee, W.K.
    • Journal of Power System Engineering
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    • v.12 no.4
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    • pp.57-63
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    • 2008
  • The last stage blade of the low pressure steam turbine remarkably affects turbine plant performance and availability Turbine manufacturers are continuously developing the low pressure last stage blades using the latest technology in order to achieve higher reliability and improved efficiency. They tend to lengthen the last stage blade and apply shrouds at the blades to enhance turbine efficiency. The long blades increase the blade tip circumferential speed and water droplet erosion at shroud is anticipated. Parts of integral shrouds of the last stage 40 inch blades were cracked and liberated recently in a combined cycle power plant. In order to analyze the root cause of the last stage blades shroud cracks, we investigated operational history, heat balance diagram, damaged blades shape, fractured surface of damaged blades, microstructure examination and design data, etc. Root causes were analyzed as the improper material and design of the blade. Notches induced by erosion and blade shroud were failed eventually by high cycle fatigue. This paper describes the root cause analysis and countermeasures for the steam turbine last stage blade shroud cracks of the combined cycle power plant.

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A Study on the Vibration Damping of a Barrel Using Vibration Absorber (동흡진기를 이용한 포신의 진동감쇠에 대한 연구)

  • Kwag, Dong-Gi;Bae, Jae-Sung;Hwang, Jai-Hyuk;Kim, Hun-Soo
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.21 no.5
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    • pp.408-415
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    • 2011
  • Advanced tanks in the future combat system are expected to have the trends of large caliber, high explosive shell and light weight for destructive power and improvement in mobility. Their guns are required to have longer barrels to meet increased muzzle exit velocities. However, as the length of the barrel is extended, the vibrations induced by the breech forces in fire and the terrain lead to increased muzzle pointing errors. Therefore, the fire-induced and terrain-induced vibrations must be attenuated. A method to reduce these vibrations without the significant increase of the gun mass is to use the forward thermal shroud as part of a tuned mass damper. In this study, the dynamically-tuned-shroud using this shroud and leaf springs is introduced and its effectiveness on the vibration attenuations of the barrel are verified. The parametric studies on the stiffness of these leaf springs are performed and the analytical results are verified using the experimental model of the dynamically-tuned-shroud.

A Study on the Scavenging Efficiency Evaluation for the RSSV Configuration of 2-Stroke Engine with Popet Valve Type Using Single-Cycle Method (Single-Cycle 기법을 이용한 포핏밸브형 2-행정기관의 RSSV 형상에 따른 소기효율 측정에 관한 연구)

  • 이진욱;강건용;정용일;이주헌;박정규
    • Transactions of the Korean Society of Automotive Engineers
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    • v.5 no.2
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    • pp.69-79
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    • 1997
  • This paper deals with the measurement and analysis on the scavenging performance of the oppet-valve type two-stroke engine with different shroud system. The scavenging flow characteristics is investigated by flow visualization under steady condition, in which a dye is introduced into single-cycle method using the difference of specific gravity between two working fluids is used to evaluate the scavenging efficiency and the trapping efficiency. The 90° shroud system was found to be the highest efficiency system through both flow visualization and single-cycle test, as well as the shroud system to generally be efficient for reducing a short-circuiting flow during scavenging process in a two-stoke engine.

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Optimization of Shroud Shape and Fan Location for Increasing Exhaust Flow Rate of Air Conditioner Outdoor Unit (실외기 토출 유량 증대를 위한 Shroud 형상 및 휀 위치 최적 설계)

  • Ryu, Ki-Jung;Kim, Yoo-Yil;Lee, Kwan-Soo;Cha, Woo-Ho
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.21 no.11
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    • pp.599-605
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    • 2009
  • This paper presents a numerical evaluation of the flow rate of air conditioner outdoor unit by investigating the effects of fan location and shroud shape. To determine optimal design parameters, we investigated the exhaust flow rate by changing shroud height, fan height, fan guide height, and fan width. The 3rd order central composite design was performed to select three most important parameters affecting the exhaust flow rate. According to the result of response surface method, the exhaust flow rate of the optimum model increased by 6.25% compared to that of the base model.

Numerical Analysis for the Optimum Design of Shroud Tidal Stream Generation System (쉬라우드 조류 발전 시스템 상부 두께 변화에 따른 유속 변화에 관한 연구)

  • Lee, Uk Jae;Lee, Sang Ho;Han, Seok Jong;Jeong, Shin Taek;Choi, Hyuk Jin;Ko, Dong Hui
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.30 no.3
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    • pp.134-141
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    • 2018
  • Numerical simulations were carried out to investigate the flow velocity changes in the flow field due to the variation in the thickness of the upper part of the shroud tidal power generation system. In this study, it was performed under constant flow velocity condition. In addition, performance analysis of shroud was performed under the same conditions. As the height of the upper part increases, the flow velocity rate gradually increases, and it tends to decrease at a certain height. As a result of analyzing the shape of the blade and the shape of the blade combined with the shroud, the torque of the blade increased due to the increase of the flow rate by the shroud system. It is expected that the shape of the structure obtained by this study and the analysis of the flow velocity distribution in the flow field can provide the data necessary for the development of an efficient shroud tidal power generation system.

A study on aerodynamic characteristics of jet-vane thrust vector control system enclosed by a shroud (Shroud를 포함한 제트베인의 공기역학적 특성 연구)

  • Park, Soon-Jong;Kim, Kyoung-Rean;Park, Jong-Ho
    • Proceedings of the KSME Conference
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    • 2007.05b
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    • pp.3203-3208
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    • 2007
  • The performance study shows the result using two different methods which are used to control missile or aircraft. One is the Thrust Vector Control(TVC) method for the aviation of next generation and the other is the present effective Shroud Jet-vane System(SJVS) method for the satellite effector development. The research was done through the performance estimation using the numerical simulation analysis, the modelling, the performance measuring using the model, the investigation of the flow visualization and aerodynamic performance with the enforced power to the vane and the result comparison.

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