다실린더기관 흡기관내의 압력변동과 체적효율에 관한 연구

서정일,조진호,김형섭,김병주 대한기계학회 1990 대한기계학회논문집 Vol.14 No.1

The characteristic of volumetric efficiency considering gas exchange process in a reciprocating engine is presented in this paper. The characteristic method is used for solving gas exchange problems of engine system in theoretical studies. The validity of the simulation is investigated by a comparison with the results obtained by the experiment which have been performed on the practical 4-cycle, 4-cylinder gasoline engine. The relationship between the volumetric efficiency and the intake pressure variation according to configuration of intake pipe, position of branch point, valve timing, compression ratio is clarified through simulation and experiment. The results predicted by the simulation are found to be in approximate agreement with those obtained by the experiment. 본 연구에서는 4사이클, 4실린더기관을 대상으로 하고 흡배기계의 유동특성에 관계되는 인자들을 고려하여 가스교환 과정 시뮬레이션과 실험을 수행하였다. 관내 의 유동현상의 해석에는 압력, 속도의 변화에 대하여 추종성이 좋은 특성곡선법을 이 용하였으며 실험에 있어서 흡기관내의 압력은 직접 제작한 데이터처리장치를, 실린더 내의 압력은 연소압력계측장치를 이용하여 측정하였다. 연구의 목적은 시뮬레이션에 의하여 흡기관내의 압력변동 및 체적효율을 계산한 결과와 실험결과를 비교검토함으로 서 특성곡선법에 의한 본 해석결과의 타당성과 실제기관에의 적용성을 확인하고 흡배 기계의 형상과 치수, 흡배기밸브의 개폐시기, 압축비 등과 체적효율 및 관내의 압력변 동과의 관계를 구명하여 흡기관의 동적효과를 이용할 수 있는 흡기계의 최적설계 및 개선을 위한 자료를 얻고자 한다.

흡기포트압력을 이용한 SI엔진의 체적효율 및 토크 성능 분석

이영주,홍성준 대한기계학회 1992 대한기계학회논문집 Vol.16 No.7

본 연구에서는 여러가지 흡기관 조건 및 밸브타이밍 변화에 대하여, 현재까지 연구에서 확인된 IVC에서 흡기포트압력 값의 체적효율에 대한 영향을 검토하고, 흡기 밸브가 열리는 동안 흡기 포트압력의 어느 부분 또는 지점이 엔진의 체적효율 변화를 설명해 줄 수가 있는지를 실험적으로 규명하고자 하였다.이 목적을 위해 각 흡입조 건에 대한 흡기포트압력 및 엔진 성능값을 측정.분석하여 서로의 연관성을 비교, 검토 하였다. The valve timing and intake system in SI engine is chosen in order to get the maximum performance at the target rpm. This is a compromise and the performance reduction is expected in a certain rpm range. Therefore, to accomplish the possible engine capacity all over the operation ranges, it is required to investigate the effects of intake system and valve timing on engines more thoroughly. In this paper, it was attempted to examine closely the combined effects on the torque and the volumetric efficiency due to the change of valve timing and intake system dimensions. For this, the inlet port pressure was chosen as a primary parameter to represent engine performance characteristics together with surge tank pressure and induction pressure as secondaries. The inlet port pressure was analyzed in connection with both the secondaries and the performance data. Especially the relation between the inlet port pressure and the torque and volumetric efficiency was investigated on the operating conditions. In this experiment, it was acquired that the performances at specific rpm range could be improved by the combinations of valve timing and intake system. Then it was verified that pressure at a intake system contained useful data for the engine performance. By the analysis of inlet port pressure with the others, it was obtained that the properties of the torque and the volumetric efficiency due to the change of valve timing and intake conditions were able to be defined by the average and the maximum inlet port pressures, the pressure near before the intake valve closing(IVC) point as well as the pressure at IVC point during the intake valve opening duration. These results could be applied to almost all over the experimental conditions.

4사이클 왕복동식 엔진에 있어서 흡배기 변동압 측정치를 이용한 흡기효율 최적화 컴퓨터 시뮬레이션

오세종,진영욱,정재화 대한기계학회 1989 대한기계학회논문집 Vol.13 No.3

본 논문에서는 흡배기 변동압을 실측하여 이것을 계산의 입력수치로 사용 하는 전산프로그램을 개발하여 간단하면서도 정확한 사이클 시뮬레이션이 가능하도록 하여 체적효율을 예측하였다. The improvement of volumetric efficiency of air charging into combustion chamber is a primary requirement to obtain better mean effective pressure of an engine. Since parameters such as the air resistances in intake and exhaust flow passages, valve lift and valve timing influence greatly to the volumetric efficiency, it is very convenient and time saving if we can optimize these parameters by computation before we enter into long time fact finding engine tests. In this study we have developed a semi-empirical engine simulation program for the determinations of intake and exhaust valve timings, valve lifts, intake and exhaust port diameters in order to obtain highest volumetric efficiency. In this computation it requires only the measured variational pressures in intake and exhaust port. Using these variational pressures as an input data for our simulation program, we can calculate volumetric efficiency more accurately and can save computing time drastically. To confirm the validity of our simulation program we have made engine operation test in parallel and taken the experimental data. Comparing the computation result with the experimental data obtained through real engine test it has shown only the difference of 3%.

사축식 피스톤 펌프의 성능 특성에 관한 연구

이태영,김수태 國立 昌原大學校 産業技術硏究所 1998 産技硏論文集 Vol.12 No.-

In this study, the performance characteristics of bent axial piston pump are studied. The experiments are carried out by measuring pressure, flow rate and torque with temperature of oil and rotational speed of pump. And the volumetric, mechanical and overall efficiency curves are obtained. The results of this study are summarized as follows. First, with an application of the new method which can confirm the gap condition between value plate and manifold that can affect a performance of pump, it is possible to find the relation between the gap condition and the pump performance. Second, by measuring discharge flow rate according to discharge pressures and rotational speeds, high performance characteristics on bent axial piston pump are obtained, the volumetric efficiency 97% and mechanical efficiency 88~91%. Third, with oil temprature 45℃, the good volumetric efficiency 96% is obtained. The last, it is confirmed that bent axial piston pump in this study has the good performance characteristics, and is suitable for hydraulic devices requiring high rotational speed and discharge pressure.

4기통 디젤기관의 체적효율 예측에 관한 수치해석 및 실험적 연구

이재순,윤건식,심현수,박상기 대한기계학회 1992 대한기계학회논문집 Vol.16 No.10

본 연구에서는 흡.배기관내에서의 상태변화를 계산하기 위하여 벽면과의 마찰 과 열전달, 단면적 및 엔트로피 변화를 고려하는 일반화된 특성곡선법을 채택하여 관 내 각 위치에서의 크랭크각에 따른 상태량의 변화를 계산하였으며, 실린더내의 연소과 정은 예혼합연소와 확산연소 각각을 나타내는 Wiebe의 연소함수를 조합한 Double Wie- be's Function을 이용하여 열발생률을 계산하였다. In this study, a computer program has been developed which predicts the variation of the volumetric efficiency with the change of design of the intake system effectively by the analysis of the flow in each part of a multi-cylinder compression ignition engine. For the calculation of the flow in the intake and exhaust systems, the method of characteristics has been used, and the double Wiebe's function has been adopted for the calculation of the heat release rate in the cylinders. The accuracy of presented method has been proved through the comparison between the simulation and experimental results over the various engine speeds and intake pipe lengths.

4기통 디젤기관의 체적효율 예측에 관한 수치해석 및 실험적 연구 : 맥동차수의 체적효율 예측 적용에 대하여

이재순 건국대학교 1992 學術誌 Vol.36 No.2

다기통 압축점화기관의 운전조건과 설계사양에 따른 기관의 상태 변화를 효과적으로 예측하는 전산프로그램을 작성하기 위하여, 실린더내 과정에 대하여는 실린더내 전 가스가 균일한 상태량을 가지며 연소에 따른 열발생은 Double Wiebe Function에 의하여 결정되는 것으로 간주하는 단일영역모델을 적용하고, 흡ㆍ배기관내에서의 가스 거동은 특성곡선법을 이용하여 기관 각 계통에서의 유동 현상을 해석하였다. 이 프로그램을 이용하여 여러 운전조건에서 시뮬레이션을 시행하고 이를 실험 결과와 비교, 검토하여 양자가 잘 일치하고 있음을 확인하였다. In this study, a computer program has been developed which predicts the variation of the volumetric efficiency with the chance of design of the intake system effectively by the analysis of the flow in each part of a multi-cylinder compression ignition engine. For the calculation of the flow in the intake and exhaust systems, the method of characteristics has been used, and the double Wiebe's function has been adopted for the calculation of the heat release rate in the cylinders. The accuracy of presented method has been proved through the comparison between the simulation and the experimental results over the various engine speeds and intake pipe lengths.

다채널 체적식 태양열 흡수기에서 열전달 수치해석

이현진(Hyun Jin Lee),김종규(Jong Kyu Kim),이상남(Sang Nam Lee),강용혁(Yong Heack Kang) 대한기계학회 2011 대한기계학회 춘추학술대회 Vol.2011 No.5

공기식 태양열 발전에 사용하는 다채널 체적식 흡수기에서 열전달 특성을 수치적으로 해석하였다 몬테카를로 광선추적법에 기반한 광학 모델링을 수행하여, 흡수 소재의 흡수율과 채널 크기에 따라 변하는 태양 열유속의 영향에 초점을 맞추었다. 균일 확산 광원 가정하에서 얻어진 태양 열유속을 포함한 일차원 전도, 대류, 복사 지배방정식을 풀어 채널 벽과 공기의 온도 분포를 얻었다. 반경 대비 큰 길이의 채널 형상으로 인해, 대부분의 태양 복사에너지는 15 ㎜ 이내의 매우 짧은 채널 깊이에서 흡수되었다. 효율 측면에서 흡수 소재의 흡수율의 영향은 미미하고, 작은 크기의 채널과 많은 질량 유량이 좋은 것으로 밝혀졌다. 본 연구에서 제시된 해석 방법과 결과는 흡수기의 성능 개선을 위한 소재의 물성 변경이나 형상 설계에 적용 가능하다. Heat transfer characteristics in the multi-channeled volumetric solar receiver that is an essential element in concentrating solar power technology were numerically analyzed. Special efforts for optical modeling with the Monte Carlo ray-tracing method were made in order to account for the effects of solar flux variations associated with material absorptivity and channel size. Solutions of 1D conduction, convection, and radiation governing equations including the solar fluxes calculated under the assumption of uniform and diffuse emission resulted in temperature distributions of channel wall and air. Most solar radiation energy is absorbed within very short channel lengths around 15 ㎜ because of large length-to-radius ratios. In terms of efficiency, the effect of material absorptivity is insignificant whereas small channel sizes or large mass flow rates are positive. Both the approach and the results presented are applicable to guiding material property modification or receiver design for performance enhancement.

원기둥 및 정다각기둥의 체적비에 따른 인공어초 후류역의 효율성 평가

정소미,나원배 해양환경안전학회 2020 해양환경안전학회 학술발표대회 논문집 Vol.2020 No.11

CFD 해석 기반 평판형 체적흡수식 태양열 집열기의 열 및 엑서지 효율분석

함정균(Jeonggyun Ham),김혜민(Hyemin Kim),조홍현(Honghyun Cho) 대한설비공학회 2022 대한설비공학회 학술발표대회논문집 Vol.2022 No.11

디젤기관의 흡기 맥동류가 체적효율에 미치는 영향

강희영(H. Y. Kang),고대권(D. K. Koh),안수길(S. K. Ahn) 한국동력기계공학회 2004 한국동력기계공학회 학술대회 논문집 Vol.- No.-

Empirical experiments have been undertaken to investigate the effects of Intake Pulsating Flow on volumetric efficiency in a diesel engine which significantly affects to intake manifold of induction system. It is well known facts that the intake and exhaust gas exchange processes close relate to a diesel engine performance. In this paper the effects of change in length of the pipes and engine speed on volumetric efficiency was examined and evaluated to obtain a preliminary data which have a analytical solution basis on a non-linear one-dimensional unsteady flow by the method of characteristics. It was found that volumetric efficiency was affected by intake pulsating flow with engine speed and the pipe length. The results obtained were considered by adopting a theory of wave action.