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저속 풍동시험 시 NASA Common Research Model의 Belly Sting 모형 지지부에 의한 간섭효과에 관한 연구
차경환(Kyunghwan Cha),김남균(Namgyun Kim),고성호(Sungho Ko) 한국항공우주학회 2021 韓國航空宇宙學會誌 Vol.49 No.3
NASA Common Research Model의 29.7% 축소 모형에 대하여 저속 풍동시험 조건으로 수치해석을 수행하였다. 낮은 레이놀즈수 영역인 0.3×10<SUP>6</SUP>에서 Belly sting 모형 지지부를 장착한 CRM의 공력계수를 측정하는 시험이 수행되었으며, 수치해석 결과와 비교하였다. 해석의 타당성을 검증하기 위해 선행연구 조건으로 전산해석을 수행하여 비교하였다. Belly sting 모형 지지부 유무에 대한 해석 결과 지지부에 의한 간섭 효과로 동체뿐만 아니라 주날개, 꼬리날개까지 공력에 영향이 있음을 확인하였다. Computational Fluid Dynamics (CFD) was performed under low-speed wind tunnel test conditions using a 29.7% scale model of the NASA common research model. A wind tunnel test was conducted to measure the aerodynamic coefficient of the CRM with Belly sting model support configuration at a low Reynolds number of 0.3×10<SUP>6</SUP> and it was compared with the aerodynamic coefficient of CFD analysis. In order to verify the validation of the analysis, a computational analysis under the conditions of the advance research was performed and compared. The interference effect of the Belly sting model support affected not only the fuselage but also the main and tail wings.
다중이용건물의 실내 공조 실시간 예측을 위한 축소차수모델
차경환(Kyunghwan Cha),강경혁(Gyeonghyeok Kang),이명성(Myungsung Lee),김주한(Joo-Han Kim) 대한기계학회 2023 대한기계학회 춘추학술대회 Vol.2023 No.11
To build a simulation-based digital twin, rapid result prediction through simulation technology is essential. Reduced-order models are being increasingly used for a wide range of predictions, offering high-fidelity results quickly once sufficient data is available. To apply a reduced order model for predicting indoor HVAC in multi-use buildings, validation of simulation methods in necessary. For simulation validation, we divided the testbed area based on sensor measurement data, calculating HVAC loads for each zone, which were then incorporated into the simulations. By applying measurement data as input conditions for the simulations, we conducted simulations for ten cases and performed temperature comparisons. The results of comparing the simulations with measurement data confirmed that highly accurate predictions with an error rate within 7% are achievable. Furthermore, we defined parameter ranges based on equipment capacity calculations and seasonal operational data, conducting analyses for a total of 260 cases to create a reduced order model.
디지털트윈 기반 건물의 에너지 관리 최적화를 위한 간이장치를 통한 축소차수모델 검증
강경혁(Gyeonghyeok Kang),차경환(Kyunghwan Cha),이명성(Myungsung Lee),김주한(Joo-Han Kim) 대한기계학회 2022 대한기계학회 춘추학술대회 Vol.2022 No.11
Recently power consumption in data centers is increasing due to the introduction of high-performance IT (Information Technology) equipment. Cooling energy consumption of data centers is 40% of the total, which is a large proportion, and it is necessary to develop a management system to reduce it. A digital twin is a virtual representation that embodies the real space in the digital space. Through a real-time management system applying digital twin, it is possible to predict the change in previously and also optimized air conditioning control is possible. In the present study, a simplified device was built to verify the reduced-order model in previous, to study on optimizing energy management of buildings based on digital twins. The simplified device consists of a single channel containing a fan, sensors and heating elements. The sensors is measuring the actual temperature data at the inlet and outlet of simple device. The measured inlet temperature data is applied to the digital twin system model by Ansys Twin Builder, a commercial software, and the reduced-order model can predict the outlet temperature in real time through the accumulated data. The accuracy of the digital twin system was verified with a one-dimensional model through Modelica. As a result of applying the reduced-order model to the verified digital twin system, an error occurred of 0.9% based on the maximum wind speed of 2.5 m/s, and the trend of the overall predicted value according to the wind speed was similar to the actual measured value.
디지털트윈 기반 건물의 에너지 관리 최적화를 위한 간이장치를 통한 축소차수모델 검증
강경혁(Gyeonghyeok Kang),차경환(Kyunghwan Cha),이명성(Myungsung Lee),김주한(Joo-Han Kim) 대한기계학회 2022 대한기계학회 춘추학술대회 Vol.2022 No.11
Recently power consumption in data centers is increasing due to the introduction of high-performance IT (Information Technology) equipment. Cooling energy consumption of data centers is 40% of the total, which is a large proportion, and it is necessary to develop a management system to reduce it. A digital twin is a virtual representation that embodies the real space in the digital space. Through a real-time management system applying digital twin, it is possible to predict the change in previously and also optimized air conditioning control is possible. In the present study, a simplified device was built to verify the reduced-order model in previous, to study on optimizing energy management of buildings based on digital twins. The simplified device consists of a single channel containing a fan, sensors and heating elements. The sensors is measuring the actual temperature data at the inlet and outlet of simple device. The measured inlet temperature data is applied to the digital twin system model by Ansys Twin Builder, a commercial software, and the reduced-order model can predict the outlet temperature in real time through the accumulated data. The accuracy of the digital twin system was verified with a one-dimensional model through Modelica. As a result of applying the reduced-order model to the verified digital twin system, an error occurred of 0.9% based on the maximum wind speed of 2.5 m/s, and the trend of the overall predicted value according to the wind speed was similar to the actual measured value.
페어링을 이용한 벨리 스팅 모형지지부의 직접 간섭효과 감소방안 연구
김남균(Namgyun Kim),이재호(Jaeho Lee),차경환(Kyunghwan Cha),고성호(Sungho Ko) 한국항공우주학회 2020 韓國航空宇宙學會誌 Vol.48 No.10
A wind tunnel test of 29.7% scaled model of NASA Common Research Model with belly model support was performed in small low speed wind tunnel. The static aerodynamic forces and moments of CRM were measured with belly sting support configuration. Pitching moments of belly sting with various fairings were compared and small interference fairing shape was found. The belly sting model support interference and reducing effect of fairing shapes with CFD analysis. 29.7% 축소 NASA Common Research Model을 벨리 스팅 모형지지부에 장착하여 저속에서 풍동시험을 수행하였다. 다양한 형상의 페어링을 장착한 벨리 스팅 모형지지부에 대하여 공력계수를 측정하는 시험을 수행하였으며 그 결과를 고찰하였다. 벨리 스팅 모형지지부에 장착된 CRM 형상을 이용하여 힘과 모멘트를 측정하였다. 벨리 스팅 페어링 형상 변화에 따른 피칭모멘트로부터 벨리 스팅 간섭 효과를 감소시키는 형상을 찾았다. 전산해석을 통해 벨리 스팅 모형지지부의 간섭과 시험부 페어링의 간섭 감소효과를 확인하였다.
수직 원심 펌프 시스템의 실시간 성능 예측을 위한 축소차수모델 기반 디지털트윈 구축
강경혁(Gyeonghyeok Kang),김수현(Soohyun Kim),차경환(Kyunghwan Cha),이명성(Myungsung Lee),김주한(Joo-Han Kim) 대한기계학회 2023 대한기계학회 춘추학술대회 Vol.2023 No.11
A vertical centrifugal pump is widely used in building water supply and HVAC systems, and improving energy efficiency is a key issue. However, in real-world buildings, energy demands occur irregularly over time due to various environmental conditions. To ensure the efficient operation of the pump system, it is essential to accurately match the energy demand required at the time. In this study, a reduced-order model based digital twin was developed to predict real-time performance of a vertical centrifugal pump system. A digital twin accurately reflects the real-world environment in a digital space, allowing for simulation and optimization, and is a core tool for monitoring and interpreting the pump system in real time. To build the digital twin system, the commercial program ANSYS Twin Builder was used. The virtual pump system was modeled similarly to the real pump system utilizing a reduced-order model and Modelica. Virtual sensor data for head, flow rate, shaft power and efficiency were calculated according to real-time operating conditions. To verify the accuracy of the digital twin, we compared measured data and virtual sensor data, and they are in good agreement.