• 한국압력기기공학회 논문집
• /
• 제13권1호
• /
• pp.54-60
• /
• 2017

When a sudden rupture occurs in high energy lines, ejection of inner fluid with high temperature and pressure causes blast wave as well as thrust forces on the ruptured pipe itself. The present study is to examine pipe whip behaviors and blast wave phenomena under postulated pipe break conditions. In this context, typical numerical models were generated by taking a MSL (Main Steam Line) piping, a steam generator and containment building. Subsequently, numerical analyses were carried out by changing break locations; one is pipe whip analyses to assess displacements and stresses of the broken pipe due to the thrust force. The other is blast wave analyses to evaluate the broken pipe due to the blast wave by considering the pipe whip. As a result, the stress value of the steam generator increased by about 7~21% and von Mises stress of steam generator outlet nozzle exceeded the yield strength of the material. In the displacement results, rapid movement of pipe occurred at 0.1 sec due to the blast wave, and the maximum displacement increased by about 2~9%.

• 대한기계학회논문집
• /
• 제16권11호
• /
• pp.2169-2180
• /
• 1992

본 연구에서는 비정상적인 효과가 매우 클 경우에 추진제가 고체-용융층-기체 의 상변화를 거쳐 변환된 기체가 화학반응을 할 때, Vieille의 관계식이 얼마나 수정 되어야 하는가를 검토한다. 그러나, 연소실내의 파의 전파까지 고려하면 문제가 너 무 커지므로, 시간의 함수로 주어진 압력에 대하여 기체의 생성등이 어떻게 응답하는 가 만이 연구되었다.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2005년도 창립60주년 기념 추계 학술대회
• /
• pp.82.1-82.1
• /
• 2005

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 1998년도 제10회 학술강연회논문집
• /
• pp.19-19
• /
• 1998

최근 화학, 연소, 동력, 제철 등의 각종 플랜트에서 조업압력이 고압화되어 가고 있으며, 이에 수반하여 배관계를 통하는 고압가스 유동에 관한 연구가 활발하게 진행되고 있다. 배관계를 통하는 고압가스의 유동에 있어서 유량의 적절한 제어, 유동에 의하여 야기되는 배관계의 소음·진동, 그리고 배기가스의 적절한 처리법 등은 공학적으로 매우 중요한 문제로 알려져 왔다. 일반적으로 정상운전을 하는 플랜트에서 고압 배기가스의 문제는 배기가스 Expander에 의하여 에너지를 회수하는 방법이 생각될 수 있으나, 실제 공업현장에서는 배기가스를 안전하고, 또 소음·진동을 발생시키지 않도록 적절하게 처리하는 것이 매우 중요한 기술적 과제로 남아 있다. 일반적으로 배기가스의 압력이 임계압력(critical pressure) 이상으로 되는 경우(실제 대부분의 플랜트에서 배기가스의 압력은 임계압력보다 매우 높다), 배관계 내부에서 충격파(shock-wave)가 발생하여 난류와동 혹은 난류경계층과 간섭하게 됨으로써 강력한 공기역학적 소음이나 진동을 발생시키게 된다. 이와 같은 소음·진동에 대한 대책으로는 현재 가스배출부에 감압밸브를 직렬로 설치하거나, 유로에 다공판(porous plates)들을 삽입하여 감압과정을 공간적으로 분산시킴으로써, 충격파가 발생하지 않도록 하는 방법을 주로 채택하고 있다. 그러나 이러한 방법을 적용하는 경우 배기가스 유동에 대한 유량의 제어기능이 저하되는 문제가 발생한다.

• 한국자동차공학회논문집
• /
• 제3권5호
• /
• pp.47-55
• /
• 1995

Cylindrical chokes are used widely as components of hydraulic equipments. The dynamic charac teristics between flowrate and pressure drop through the cylindrical chokes were discussed by the frequency characteristics of the chokes. It was assumed no pressure recovery occured at the downstream neighborhood of the choke. The pulsating jetflow from outlet of cylindrical chokes shows very complex behaviours which are quite different from the steady jetflow but it is not clarified quantitatively. In order to utilize the chokes as a flowmeter, it is indispensable to discuss the estimation of the dynamics of pressure drop in the downstream jetflow region of cylindrical chokes. In this experimental study, the dynamic behaviours of the jetflow in the downstream region of cylindrical chokes are investigated precisely by using flow visualization. In the results of experimental sutdy, it is clarified that the retachment length depended on pressure wave is compared with it depended on velocity wave.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2000년도 춘계학술대회논문집B
• /
• pp.835-840
• /
• 2000

The objective of the present study is to investigate the characteristics of pressure wave propagation of viscous fluid flow in a circular pipe line. The goal of this study is to select the best frequency of each control factor of a circular pipe. We intend to approach a formalized mathematical model by a very exact and reasonable polynomial for fluid transmission lines. and we computed this mathematical model by computer. The results show that the oil viscosity decreased as the length of the circular pipe increases. and The energy of pressure wave propagation decreased as the pipe diameter decreases. The factor is that density of oil was changed resonant frequency. It has been found the viscosity characteristics is changed largely by length of hydraulic pipe and volume of cavity tank.

• 에너지공학
• /
• 제12권1호
• /
• pp.29-34
• /
• 2003

압력파의 일종인 열음향파는 압축성유체를 급속히 가열 또는 냉각하는 경계면 근처에서 유체가 순간적으로 압축 및 팽창하는 경우에 발생하는 현상으로 자연대류가 일어나지 않는 우주공간에서는 매우 중요한 열전달 메커니즘이다. 본 연구에서는 공기로 채워진 공간에서 급속한 가열에 의하여 발생한 열음향파의 전달특성을 수치적인 방법에 의하여 평가하고자 유한체적법을 기반으로 비정상 지배방정식을 이산화하였으며, PISO알고리즘과 2계 상향기법을 적용하여 해석을 수행하였다. 안정적인 수치해는 50 $\times$ 800 개의 셀과 1 $\times$ $10^{-9}$ 시간간격을 적용하여 얻을 수 있었으며, 생성된 열음향파는 유체 속을 통과하면서 점성과 열소산에 의하여 점점 감쇠하여 가는 경향을 보였다. 생성된 압력파는 날카로운 전단과 점점 감소하여 길게 늘어지는 후단부를 갖는 형상을 보였다.

• 설비공학논문집
• /
• 제12권7호
• /
• pp.697-702
• /
• 2000

This study is to investigate the pressure wave characteristics and the maximum pressure rise generated by instantaneous valve closure at the end of the straightening copper piping system. Experiments were conducted under the following conditions : initial pressure 1~5 bar, flow velocity 0.6~3.0 m/s and water temperature $20^{\circ}C$ . Results indicated that the peak pressure generated by quick valve closure reached Joukowsky's value. And we also found that the maximum pressure rise and the pressure history were depended on not only closing time but also flow velocity.

• 한국유체기계학회 논문집
• /
• 제17권5호
• /
• pp.54-59
• /
• 2014

The new high speed combi train prototype project was developed which named HSB. It runs over the speed of 330km/h. As the speed of the train exceeds over 300km/h, due to pressure change in tunnel, aerodynamic problems such as sudden drag increase, severe acoustic noise, passenger discomfort and tunnel pressure sonic boom were occurred. This aerodynamic characteristics in tunnel should be reviewed in early design state to enhance the performance and driving quality of new high speed train. In this paper, the aerodynamic characteristics in tunnel for HSB such as pressure waves in tunnel, a rate of pressure change in cabin and micro pressure wave that cause sonic boom outside tunnel are analyzed by 2D axisymmetric CFD simulations. The results are also compared with the value for ordinary high speed train like the KTX-Sancheon. It is helpful how to design the configuration of HSB train. Finally it shows that the HSB train was well designed in tunnel condition because all values fulfill the criterions on UIC code and Korean national regulations.

• 한국철도학회논문집
• /
• 제5권4호
• /
• pp.260-266
• /
• 2002

A numerical simulation has been performed to estimate the transient pressure variation in the tunnel when G7 test train passes through the test tunnel in the Kyoeng-Bu high-speed railway. A modified patched grid scheme is developed to handle the relative motion between a train and a tunnel. Also, a hybrid dimensional approach is proposed to calculate the train-tunnel interaction problem efficiently. An axi-symmetric unsteady Euler solve using the Roe's FDS is used for analyzing a complicated pressure field in tunnel during the test train is passing through the tunnel. Usually, this complex phenomenon depends ell the train speed, train length, tunnel length, blockage ratio between train and tunnel cross-sectional area, relative position between train and tunnel, etc. Therefore, numerical simulation should be done carefully in consideration of these factors. Numerical results in this study would be good guidance to make test plans, test equipments selection and to decide their measuring locations. They will also supply important information to the pressurization equipment for high-speed train.