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맥동 압력을 받는 가열관 내부에서의 열전달 특성에 관한 실험적 연구
이건태,강병하,이재헌,이춘식 대한기계학회 1992 대한기계학회논문집 Vol.16 No.9
본 연구에서는 원관의 외벽에 일정 열 유속이 가해지고 원관 입구에 주기적인 압력이 주어질때 축방향으로 유동 및 온도가 주기적으로 완전 발달된 영역에서, 맥동 진동수 및 시간 평균 유량의 변화에 따른 원관 벽면과 원관 내부 유체 온도의 시간적 변화를 측정 하고자 하였다. 아울러 맥동 유동에서의 열전달 특성을 비맥동 유동 에서의 결과와 비교 검토 하였다. An experimental study of thermal transport from a uniformly heated pipe to a pulsating flow has been carried out. Surface of the pipe is imposed with constant heat flux providing by electric heating band. This problem is of particular interest in the design of Stirling engine heat exchangers and in understanding the blood flow in the aorta. Temporal Variatiens of temperature and pressure inside the circular pipe are measured. The dependence of temperature distributions and heat transfer rate on the mean flow rate in the pipe and on the pulsating frequency is investigated in detail. The experimental results indicate that the measured temporal variations of temperature and pressure become nearly sinusoidal The amplitude of temperature variation near the pipe wall is much more substantial than that in core of the pipe. It is also found that the heat transfer rate is increased significantly as the frequency of the pulsating pressure is increased or the mean flow rate in a pipe is increased. The results obtained are also compared with those for non-pulsating flow circumstance.
윤승원(S. W. Youn) 한국정밀공학회 2004 한국정밀공학회 학술발표대회 논문집 Vol.2004 No.10월
A mechanical type pulsation dampener for the diaphragm metering pump has been developed. The pulsation pressure is an inevitable phenomenon for the positive displacement pump such as cam operated or solenoid operated metering pump. The pulsation pressure of the metering pump could be the noise source and would be harmful for the piping system which delivers hydraulic fluid. Developed pulsation dampener consists of three coil springs which have different spring constant and height each other. Depending on pressure magnitude of the piping system, total hydraulic pressure on damping diaphragm which compresses coil springs will be varied. Force equilibrium of the pulsation dampener will be set by manual by adjusting the compressed coil spring height. During the discharge stroke, pulsation dampener stores potential energy that is released as the pumping diaphragm back to an initial position during the suction stroke.
뇌압 펄스에 의한 션트밸브의 압력-유량제어 특성의 변화
홍이송,이종선,장종윤 대한의용생체공학회 2002 의공학회지 Vol.23 No.5
수두증 환자를 치료하기 위해 머리에 시술 되는 션트밸브가 받는 뇌압 펄스가 밸브의 유량조절 특성에 미치는 영향을 수치적으로 해석하였다. 션트밸브를 통한 유량을 계산하기 위하여 밸브 다이아프램이 형성하는 유량 오리피스를 모델링 하여 맥동압력과 변동하는 압력에 의한 다이아프램의 움직임을 고려하였다. 연구 결과, 압력 펄스와 이에 따른 다이아프램의 움직임에 의하여 유량이 40% 이상 증가함을 보였다. 이 결과는, 뇌실에 시술 되는 션트밸브의 압력-유량 조절특성이 제조 직후 맥동이 없는 유량을 공급하는 시린지 펌프를 사용하여 구한 실험 결과와 상당히 다르다는 사실을 보여주었다. Shunt valves used to treat patient with hydrocephalus were numerically simulated to investigate influence of pressure pulsation on their flow control characteristics. We modeled flow orifice through the shunt valve and imposed pulsating pressure and valve diaphragm movement to compute flow through the valve. The results of our study indicated that flow rates increased more than 40% by introducing pressure pulsation and diaphragm movement on the shunt valve. Our results demonstrate the pressure-flow control characteristics of shunt valves implanted above human brain may be quite different from those obtained by syringe pump test just after manufacture that induces uniform pressure.
엑시얼 피스톤 펌프의 압력/유량 맥동 시뮬레이션에 관한 기초적 연구
최세령(S. R. Choi),신상균(S. S. Shin),이일영(I. Y. Lee),장동혁(D. H. Jang),권정호(J. H. Kwon) 유공압건설기계학회 2010 유공압건설기계학회 학술대회논문집 Vol.2010 No.10
This study suggests the numerical model of an axial piston pump focusing on pressure and flow ripple analysis. using the numerical model, simulation programs for analysing pressure and flow ripple in the pump are shown. the effectiveness of the simulation programs are verified by comparative considerations of the simulation results and experimented results. Effects of several physical parameters on simulation accuracy are investigated.
자동차 오일용 가변형 베인 펌프의 성능 특성에 관한 해석적 연구
곽명석(Myoungseok Kwak),조홍현(Honghyun Cho),김진복(Jinbok Kim) 대한기계학회 2012 대한기계학회 춘추학술대회 Vol.2012 No.5-3
본 연구에서는 자동변속기용 가변형 베인 펌프의 성능특성을 연구하기 위하여 3D 해석프로그램을 이용하여 베인 펌프의 성능에 대하여 해석적 연구를 진행하였다. 이를 수행하기 위하여 회전수 변화에 따라 베인 펌프의 토출압력, 로터와 베인에서 동력 변화 및 펌프 내에서 캐비테이션 발생유무를 확인하였다. 해석결과, 회전수가 증가할수록 압력 맥동이 커졌으며 저속조건에서는 토출측에서 오일의 역류가 많아져 압력맥동의 진폭에 영향을 주는 것으로 나타났다. 또한 베인과 로터의 동력은 회전수가 증가함에 동시에 증가하는 것으로 나타났으며 이로 인해 고속 운전조건에서 캠링과 베인 날개 끝부분에 캐비테이션이 발생하여 베인과 로터의 동력이 급격하게 증가하는 것을 확인할 수 있었다. Theocratical study on the performance characteristics of the variable displacement vane pump by using the 3D interpretative program. The performance analysis was carried out with the rotation speed, and the total outlet pressure, rotor and vane power, cavitation was investigated. As a result, pressure ripples increased with a rise of rotation speed. At low rotation speed condition, the oil flowed backward from the discharge side, and it had an effect on the amplitude of the pressure ripples. Besides, the vane and rotor power increased as the rotor rotation speed rose. Moreover, in high speed conditions, some cavitation occurs at the end of vane wing and cam ring rapidly, resulting an increased power consumption.
최세령(S. R. Choi),이일영(I. Y. Lee) 유공압건설기계학회 2017 유공압건설기계학회 학술대회논문집 Vol.2017 No.11
In general, a axial piston pump consists of an odd number of pistons (7 or 9). It is known that the amplitude of the flow pulsation decreases when the number of pistons is an odd number. In this paper, flow pulsation characteristics are simulated by varying the number of pistons. From the simulation results, we design a new axial piston pump with an even number of pistons that does not require a check valve.
Fuel Rail의 설계 인자별 압력맥동 특성에 관한 연구
허형석(Hyungseok Heo),배석정(Sukjung Bae),이헌균(Heonkyun Lee),송경석(Kyungsuk Song),박시우(Seewoo Park),김보겸(Bokyoum Kim) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
In general, pulsation damper is installed in fuel rail for conventional MPI engine to decrease undesirable cabin noise. However, pulsation damper is so expensive that there are prevailing studies to reduce fuel pressure pulsations with integrated damping effect. This paper is one of basic studies for development of fuel rail to abate pulsations with self-damping effect. Primarily, the pressure pulsation characteristics was investigated with aspect ratio of cross section, wall thickness, and materials of fuel rail. A high aspect ratio or thin wall was found to absorb the pressure pulsations effectively. But volume effects on the fuel pressure pulsation reductions were not especially significant than cross section effects because volume increment rate is larger than pressure pulsation reduction rate. The fuel rail made of aluminum is effective for reduction of pressure pulsation than that of low-carbon steel. Pressure change period increases on the basis of same lengths of supply line and fuel rail as the volume is enlarged and/or the thickness of wall is thinned.
흡기관 분사 방식 연료 레일의 압력 맥동 저감을 위한 연료 레일 형상 최적화
이상철(Sangcheol Lee),정재엽(Jaeyoup Jung),김홍기(Honggi Kim) 한국자동차공학회 2014 한국자동차공학회 부문종합 학술대회 Vol.2014 No.5
Fuel Line Hammer is defined as the audible noise heard in the vehicle passenger compartment resulting from fuel pressure pulsations in the fuel subsystem. The pressure pulsations are a result of injector-firing events and fuel line dynamics. The pressure pulsations consist of a multiple frequencies. Low frequency pulsations are the result of injector firing. High frequency pulsations are a result of line dynamics. Line dynamics are impacted by line diameter, length and stiffness of the fuel system components. Since the fuel feed line diameter and length are typically set by vehicle architecture, the stiffness (or compliance) of the fuel subsystem components is one of the few fuel system design variables available for effecting the pressure pulsations. Some kind of designs for fuel rails have been developed and introduced to reduce fuel pulsation for MPI (intake manifold port injection) system such as fuel rails with external damper or internal damper or integrated damping effect (called as self-damped fuel rail) in accordance with engine room design and noise requirements. Fuel rails integrated with internal dampers are introduced to reduce fuel pulsation effectively now a days instead of self-damped fuel rails even though they lead cost increase significantly. However some papers have introduced that the fuel rails with integrated damping effect (self-damped fuel rail) can reduce fuel pulsation effectively. This study focused on finding key parameter on fuel rail design with integrated damping effect to reduce fuel pulsation experimentally. It was found that the shape and volume are key factor to reduce fuel pulsation and the shape of fuel rail is more effective than the volume of fuel rail. : Static response, minimum the best, was characterized as parameter design.