Vo Duy Tan

Minhyeong Ahn (안민형)

Gi-Deuk Park (박기득)

Seung Gi Kim (김승기)

Hyeon Kyun Lee (이현균)

Van Thanh Ho

Dam Mai Thanh

Woo Jin Sung (성우진)

Byung Wook Kim (김병욱)

Hyun Woo Jung (정현우)

Kyeong Sik Jang (장경식)

Taehak Kang

Jae Sung Oh (오재성)

Myung Gon Choi (최명곤)

Seung II Baek (백승일)

Sang Jun Lee (이상준)

We investigate flow and thermal characteristics of complex scientific and engineering problems using theoretical and computational methods (CFD), aiming to provide innovative solutions.
세상을 잇는 흐름, 미래를 여는 유체
Flows Connecting the World, Fluids Unlocking the Future

세상을 잇는 흐름, 미래를 여는 유체
Flows Connecting the World, Fluids Unlocking the Future

수소 재순환 시스템을 위한 동축 바이패스 이젝터의 개발(Design Process of Coaxial-Bypass Ejector for Hydrogen Recirculation System)

Wake Turbulence Characteristics Downstream of a High-Pressure Vane in a Hydrogen Gas Turbine

Key Technologies and Recent Research Trends for Flexible Operation of Francis Turbines

Numerical analysis of boundary-layer thickness effects on shock wave/turbulent boundary layer interactions

Prediction of Drag Reduction Effects on Underwater Vehicles Using Slip-Length-Based Superhydrophobic Surface Modeling

Aerodynamic loss characteristics of a hydrogen-blended gas turbine vane

Performance Enhancement of a Refrigeration Centrifugal Compressor Using Multi-Objective Optimization

Neck 4D Flow MRI as boundary condition for cerebral hemodynamic simulation

Numerical Simulation and Optimization of SiC Deposition in a CVD Process for Semiconductor Applications

Theoretical Prediction of Shock Wave Attenuation in a Pipe

Numerical Study of Oblique Shock Wave and Thickened Boundary Layer Interactions

Numerical Investigation on Multi-objective Optimization for a Centrifugal Compressor

Numerical Analysis on Effect of Economizer Gas Injection in Two-stage Centrifugal Compressor

Effects of Hydrogen Blending on Gas Turbine Aerodynamics and Heat Transfer Characteristics under Operational Constraints

Numerical Analysis of Tip Leakage Thermal-Fluid Characteristics in Hydrogen Gas Turbines

Effect of Hydrogen Combustion on Film Cooling Characteristics in Gas Turbines

Predicting Aneurysm Initiation and Rupture Using Pre-Aneurysmal Modeling: A Simulation-Based Study

Hemodynamic changes in patient with fetal-type posterior cerebral artery: the impact of posterior communicating artery occlusion

A Study on the Design Improvement of Bypass Ejector for Enhanced Performance of Hydrogen Recirculation Systems

Numerical Simulation of Silicon Carbide Deposition in a Methyltrichlorosilane-H2 CVD Process

Influence of A1 Hypoplasia or Aplasia on Morphological Characteristics and Recurrence Risk of Anterior Communicating Artery Aneurysms: A Radiomics-Based Study

Hemodynamic Analysis of the Carotid Web as a Potential Cause of Stoke

Risk factors that affects paraclinoid aneurysm rupture and growth

Increased Rupture Risk in PComA Aneurysms Associated with Fetal-Type Posterior Cerebral Artery: A Morphological Study

Numerical Analysis and Optimization Study of Centrifugal Compressor Using R1234ze(E) Refrigerant

Conjugate Heat Transfer Analysis of a Gas Turbine Blade with Full-Cooling Structure under Rotational Effect

Numerical Investigation on the Aerodynamic Characteristics of a Centrifugal Compressor Using Alternative Refrigerants

Numerical Investigation on Film Cooling Performance of Hydrogen Gas Turbine

Hemodynamic Simulation for Safe Surgical Clipping of Intracranial Aneurysms: Temporary Strangulation of the Common Carotid Artery

Investigation of high-speed flow past a sphere in open and confined spaces

Investigation on the Aerodynamic Characteristics of a Centrifugal Compressor Using R-1234ze(E) Refrigerant

Numerical Analysis and Kriging-Based Optimization of Centrifugal Compressors for Refrigeration Systems

Analysis of the Effects of Shear Stress and Heat Transfer on Shock Wave Attenuation in a Pipe

Investigation of aerodynamic characteristics of high-speed object in open and confined spaces

Hemodynamic Simulation after Temporary Strangulation of the Common Carotid Artery during Surgical Clipping of Middle Cerebral Bifurcation Aneurysms

Quasi-1D Analytical And Numerical Study on Compressible Flow Phenomena of an Object in a Straight Pipe

Numerical Investigation of Heat Transfer Characteristics in Rotating Cooling Gas Turbine Blade

Hemodynamic Effects of Fetal-Type Posterior Cerebral Artery on Cerebral Blood Flow and Wall Shear Stress: A Patient-Specific CFD Study

FSI Simulation of intracranial aneurysms and effect of wall thickness and domain size to hemodynamic indexes

Effect of hydrogen combustion on flim cooling on the first-stage rotor vane

Numerical Analysis on the Effects of Environmentally Friendly Refrigerant on Aerodynamic Characteristics of Centrifugal Compressor

Aerodynamic and Heat Transfer Characteristics of Hydrogen Gas Turbine 1 st Stage Vane

MCA 동맥류 해석 범위 최적화 및 출구 경계조건 안정성 조사

Computational Assessment of the Relationship Between Intracranial Aneurysm and Ipsilateral Common Carotid Artery Stenosis

Conjugate Heat Transfer Simulation of High-Pressure Cooling Blade Under Rotational Conditions in a Gas Turbine

SLIP LENGTH를 활용한 난류 채널 유동에서 초발수표면의 저항저감 효과에 대한 수치 해석적 연구

전산 해석을 통한 유선 방향 미세 구조 적용 SUBOFF 모델에 나타나는 항력 효과 관찰

Quasi-one-dimensional analysis and its verification of compressible flow phenomena and aerodynamics in Hyperloop system

Numerical analysis of the aerothermal characteristics on the Hyperloop pod

A Numerical Study of Streamwise Microstructure Effects on Hydrodynamic Drag applied to SUBOFF Model

Hemodynamic Simulation of Aneurysms and Major Arteries after Temporary Strangulation of the Common Carotid Artery during Surgical Clipping of Middle Cerebral Bifurcation Aneurysms

A Multi-Physics Dataset and Benchmarks for Machine Learning

Investigation of Compressible Flow and Wave Phenomena in Hyperloop System

Investigating the Impact of Nose Shapes and Tail Shapes/Lengths on Aerodynamic Forces and Pressure Waves in Hyperloop System

Numerical investigation on combustion characteristics and emissions of Hydrogen/methane blends in Flamesheet combustor

Uncertainty Quantification for the Drag Reduction of Microbubble-laden Fluid Flow in a Horizontal Channel

Effect of Mainstream Turbulence Intensity on the Particles of Mist-Assisted Film Cooling on a Flat Plate

Numerical Investigation of mist/air cooling in a two-pass ribbed channel at high-rotational speed conditions

A Numerical Study of Drag Reduction by Streamwise Riblet Structures on SUBOFF Bare Hull Model

3D Hemodynamic Simulation in Middle Cerebral Artery Bifurcation Aneurysm acrroding to Common Carotid Artery Stenosis

Numerical analysis of thermal/flow characteristics and fatigue life of F class gas turbine blade

Turbulence effect of mist particles on flat plate film cooling

Numerical investigation of crack formation in HP gas turbine blade subject to low cycle fatigue

Numerical analysis on the influence of new parameters on leakage in straight-through labyrinth seal

Dispersion analysis of respiratory events in transfer vehicles

A parametric study of projectile launched by compressed air-cannon

Analysis of newly designed silencer to reduce exhaust noise in pneumatic artificial muscles

Investigation of compressible flow phenomena and aerodynamic characteristics in Hyperloop system under cracked-tube

Numerical and theoretical analysis of aerodynamic characteristics of Hyperloop system with compressor

A Numerical Study of Noise Propagation From Surface-Treated Submarine Using Acoustic Analogy (전산 소음 해석 기법을 이용한 잠수함 표면 처리에 따른 소음 효과 관찰)

Numerical Simulation of Hemodynamic Nature in Carotid Endarterectomy Patients: Comparison of Primary Closure and Patch Angioplasty

Hemodynamic simulation of aortic-cerebral vasculature under progression of carotid stenosis focusing on the changes in blood flow

Flow-induced noise analysis on surface-treated submarine using FW-H method

A Study on Aerodynamic Drag and Pressure Waves in Hyperloop System

전기방사를 이용한 PVDF-TrFE 소재의 압전 센서 제조 방법 및 장치

착탈식 가변 용량 세탁조 및 이를 포함하는 와류식 세탁기

좌심방이 폐색술에 대한 시뮬레이션 방법 및 장치

동축 바이패스 이젝터

래버린스실 누설유량 저감 장치

적외선 영역대 펄스 CO2 레이저를 이용한 고품질 질화갈륨 박막 제조 방법 및 장치

가스 터빈용 로터 및 가스 터빈용 로터의 표면 가공위치 선정 방법

청진기 음파 분석을 통한 혈관 협착 평가 방법

전 방향 바람에서 에너지를 생성하는 스택형 디스크 모양 마찰대전 발전기 및 그 작동방법

공압 시스템 소음 저감 장치

공압 액츄에이터 구동을 위한 가스 공급시스템 및 그 작동방법

웨어러블 마우스

웨어러블 공압 근육 소음 저감 장치

요로 조영술 영상 데이터에 기반한 방광 내압 진단 방법

유체의 확산 성능을 향상시키는 반도체 공정용 다공판 방법

압축기체를 이용한 측면비행이 가능한 무인비행체 및 그 작동방법

머신러닝을 활용한 경동맥 협착증 진단 방법

건물 외부의 무선중계기를 이용한 고층빌딩 화재 구난시스템 및 구난방법

반도체 공정용 유체 확산 성능 향상을 위한 베인 어셈블리

바람의 집중 또는 확산의 제어가 가능한 에어 서큘레이터 디자인

결로, 결빙 방지용 열교환기를 갖는 공기흡입형 화재감지시스템

하부 개폐형 음식물 쓰레기통

스크류드라이버

드론을 이용한 화재 진압 모듈 및 이를 포함하는 화재 진압 장치

Turbulence structure behind the shock in canonical shock–vortical turbulence interaction

Numerical analysis of aerodynamic characteristics of hyperloop system

Vorticity dynamics after the shock–turbulence interaction

Enhanced performance of microfluidic soft pressure sensors with embedded solid microspheres

Effects of compressible flow phenomena on aerodynamic characteristics in Hyperloop system

A coupled lumped-parameter and distributed network model for cerebral pulse-wave hemodynamics

Numerical investigation of aerodynamic drag and pressure waves in hyperloop systems

Numerical study on the influence of coolant temperature, pressure, and thermal barrier coating thickness on heat transfer in high-pressure blades

Numerical investigation of crack initiation in high-pressure gas turbine blade subjected to thermal-fluid-mechanical low-cycle fatigue

Influence of perforated fin on flow characteristics and thermal performance in spiral finned-tube heat exchanger

Experimental study on the fire-spreading characteristics and heat release rates of burning vehicles using a large-scale calorimeter

Study of supersonic wave components in high-speed turbulent jets using an LES database

Bubbleml: A multiphase multiphysics dataset and benchmarks for machine learning

Experimental analysis of aerodynamic characteristics in the Hyperloop system

Investigating broadband shock-associated noise of axisymmetric jets using large-eddy simulation

Numerical study on the influence of the nose and tail shape on the aerodynamic characteristics of a Hyperloop pod

Numerical study of the axial gap and hot streak effects on thermal and flow characteristics in two-stage high pressure gas turbine

Numerical study of unsteady compressible flow induced by multiple pods operating in the Hyperloop system

Effects of progressive carotid stenosis on cerebral haemodynamics: Aortic-cerebral 3D patient-specific simulation

Effects of tail shapes/lengths of Hyperloop pod on aerodynamic characteristics and wave phenomenon

Thanh Dam Mai

Daniel Livescu

Duy-Tan Vo

Kyoungsik Chang

Sanjiva Lele

Debanjan Mukherjee

Xiao Hu

Shawn C. Shadden

Hyung Ju Lee

Seong Hyuk Lee

Yong-Lae Park

Daniel Bodony

Jaiyoung RYU

The interaction between vortical isotropic turbulence (IT) and a normal shock wave is studied using direct numerical simulation (DNS) and linear interaction analysis (LIA). In previous studies, agreement between the simulation results and the LIA predictions has been limited and, thus, the significance of LIA has been underestimated. In this paper, we present high-resolution simulations which accurately solve all flow scales (including the shock-wave structure) and extensively cover the parameter space (the shock Mach number, -dependent increase in the correlation between strain and rotation.

The Hyperloop system is a new concept that allows a train to travel through a near-vacuum tunnel at transonic speeds. Aerodynamic drag is one of the most important factors in analyzing such systems. The blockage ratio (BR), pod speed/length, tube pressure, and temperature affect the aerodynamic drag, but the specific relationships between the drag and these parameters have not yet been comprehensively examined. In this study, we investigated the flow phenomena of a Hyperloop system, focusing on the effects of changes in the above parameters. Two-dimensional axisymmetric simulations were performed in a large parameter space covering various BR values (0.25, 0.36), pod lengths (10.75–86 m), pod speeds (50–350 m/s), tube pressures (~100–1000 Pa), and tube temperatures (275–325 K). As BR increased, the pressure drag was significantly affected. This is because of the smaller critical Mach number for a larger BR. As the pod length increased, the total drag and pressure drag did not change significantly, but there was a considerable influence on the friction drag. As the pod speed increased, strong shock waves occurred near the end of the pod. At this point, the flows around the pod were severely choked at both BR values, and the ratio of the pressure drag to the total drag converged to its saturation level. At tube pressures above 500 Pa, the friction drag increased significantly under the rapidly increased turbulence intensity near the pod surface. High tube temperatures increase the speed of sound, and this reduces the Mach number for the same pod speed, consequently delaying the onset of choking and reducing the …

The interaction of a shock wave with quasi-vortical isotropic turbulence (IT) represents a basic problem for studying some of the phenomena associated with high speed flows, such as hypersonic flight, supersonic combustion and Inertial Confinement Fusion (ICF). In general, in practical applications, the shock width is much smaller than the turbulence scales and the upstream turbulent Mach number is modest. In this case, recent high resolution shock-resolved Direct Numerical Simulations (DNS) (Ryu and Livescu, J Fluid Mech 756:R1, ) show that the interaction can be described by the Linear Interaction Approximation (LIA). Using LIA to alleviate the need to resolve the shock, DNS post-shock data can be generated at much higher Reynolds numbers than previously possible. Here, such results with Taylor Reynolds number approximately 180 are used to investigate the changes in the vortical structure as a function of the …

The cross-sectional geometry of an embedded microchannel influences the electromechanical response of a soft microfluidic sensor to applied surface pressure. When a pressure is exerted on the surface of the sensor deforming the soft structure, the cross-sectional area of the embedded channel filled with a conductive fluid decreases, increasing the channel’s electrical resistance. This electromechanical coupling can be tuned by adding solid microspheres into the channel. In order to determine the influence of microspheres, we use both analytic and computational methods to predict the pressure responses of soft microfluidic sensors with two different channel cross-sections: a square and an equilateral triangular. The analytical models were derived from contact mechanics in which microspheres were regarded as spherical indenters, and finite element analysis (FEA) was used for simulation. For experimental …

In this study, numerical simulations were conducted at various pod speeds (v p o d= 100–350 m/s) using an unsteady, compressible solver with the Reynolds-averaged Navier–Stokes model to analyze the aerodynamic characteristics and pressure wave behavior in the Hyperloop system. Furthermore, the aerodynamic drag and pressure wave behavior were theoretically predicted based on quasi-one-dimensional assumptions. The flow around the pod is classified into three regimes according to the pod speed based on the compressible flow phenomena. In regime 1 (v p o d= 100–170 m/s), the compression waves develop into normal shock waves even without the occurrence of choking at the throat. In regime 2 (v p o d= 180–230 m/s), choking occurs at the throat and an oblique shock wave appears within the pod tail section. In regime 3 (v p o d= 240–350 m/s), a trailing shock wave propagates at the end of the …

The cerebral circulation is unique in its ability to maintain blood flow to the brain under widely varying physiologic conditions. Incorporating this autoregulatory response is necessary for cerebral blood flow (CBF) modeling, as well as investigations into pathological conditions. We discuss a one-dimensional (1D) nonlinear model of blood flow in the cerebral arteries coupled to autoregulatory lumped-parameter (LP) networks. The LP networks incorporate intracranial pressure (ICP), cerebrospinal fluid (CSF), and cortical collateral blood flow models. The overall model is used to evaluate changes in CBF due to occlusions in the middle cerebral artery (MCA) and common carotid artery (CCA). Velocity waveforms at the CCA and internal carotid artery (ICA) were examined prior and post MCA occlusion. Evident waveform changes due to the occlusion were observed, providing insight into cerebral vasospasm monitoring …

Hyperloop is a new, alternative, very high-speed mode of transport wherein Hyperloop pods (or capsules) transport cargo and passengers at very high speeds in a near-vacuum tube. Such high-speed operations, however, cause a large aerodynamic drag. This study investigates the effects of pod speed, blockage ratio (BR), tube pressure, and pod length on the drag and drag coefficient of a Hyperloop. To study the compressibility of air when the pod is operating in a tube, the effect of pressure waves in terms of propagation speed and magnitude are investigated based on normal shockwave theories. To represent the pod motion and propagation of pressure waves, unsteady simulation using the moving-mesh method was applied under the sheer stress transport k–ω turbulence model. Numerical simulations were performed for different pod speeds from 100 to 350 m/s. The results indicate that the drag coefficient increases with increase in BR, pod speed, and pod length. In the Hyperloop system, the compression wave propagation speed is much higher than the speed of sound and the expansion wave propagation speed that experiences values around the speed of sound.

Several studies have focused on investigating the heat transfer in blades; however, these studies have primarily adopted numerical approaches, and the heat transfer in an actual turbine blade remains unclear thus far, owing to the complex topology of the blade. To address this gap in literature, this study investigates the influences of the thermal barrier coating (TBC) thickness and coolant on the mainstream hot gas pressure ratio ( p c /p t ) and temperature ratio ( T c /T g ) in blade film cooling, respectively, by simulating the conjugate heat transfer (CHT) in the first-stage cooling blade of an W501F engine. A complete blade design is used to obtain a realistic heat transfer profile. The results demonstrate equivalent high-thermal-stress regions between the simulation and industrial patterns. The leading tip (LT), trailing tip (TT), platform, and leading edge (LE) regions have higher thermal stresses than the other regions …

A thermo-fluid-structural analysis procedure was proposed in this study to investigate the lifespan of a realistic cooling gas turbine blade. The temperature and pressure data extracted from computational fluid dynamics simulations were applied as the loading force to calculate the strain and stress using the finite element (FE) method. Subsequently, a fatigue analysis was conducted to estimate the blade life and predict the position of cracks. Here, the fatigue model used to calculate the blade life and damage was based on the strain-life model. The results showed that although the cooling film covered the entire blade surface, inefficient cooling was still observed in some regions, such as the tip and platform, which lead to blade overheating. A high pressure distribution of approximately 1.374 MPa was formed primarily on the leading tip (LT) of the pressure side (PS) blade; this pressure decreased toward the suction …

The present study conducts the numerical investigation of flow characteristics and thermal performance of spiral finned-tube heat exchangers. The effects of location of perforations (90°, 120°, and 150°) on heat transfer and pressure drop are analyzed for the air-side. The commercial computational fluid dynamics code ANSYS Fluent (V.17.0) is used for simulations with the RNG k - ε model based on the Reynolds-averaged Navier–Stokes equations. The velocity field, Colburn j -factor, and friction factor are analyzed to evaluate the heat transfer and pressure drop characteristics. Because of the flow through the perforations, the boundary layers on the fin surfaces are interrupted. This results in increased flow disturbances close to the fin, and the heat transfer performance increases compared to the reference case. The pressure drop, which is one of the disadvantages of spiral finned tubes comparing to plate or circular fins, decreases with perforations on the fin. Overall, the cases with perforated fin exhibit greater performance of area goodness factor considering the relationship between the heat transfer and the pressure drop.

In this article, large-scale experimental studies were conducted to figure out the fire characteristics, such as fire-spreading, toxic gases, and heat release rates, using large-scale calorimeter for one- and two-vehicle fires. The initial ignition position was the passenger seat, and thermocouples were attached to each compartment in the vehicles to determine the temperature distribution as a function of time. For the analysis, the time was divided into sections for the various fire-spreading periods and major changes, e.g., the fire spreading from the first vehicle to the second vehicle. The maximum temperature of 1400 °C occurred in the seats because they contained combustible materials. The maximum heat release rates were 3.5 MW and 6 MW for one and two vehicles, respectively. Since the time to reach 1 MW was about 240 s (4 min) before and after, the beginning of the car fire appears to be a medium-fast growth type. It shows the effect on the human body depending on the concentration of toxic substances such as carbon monoxide or carbon dioxide.

Near-field characteristics of supersonic wave components in turbulent jets are investigated using the well-validated large eddy simulation (LES) database by Bodony and Lele (2005)[1]. Three unheated (constant stagnation temperature) jets with a jet Mach number ranging from 0.51 to 1.95, and one heated (T j/T∞= 2.3) transonic jet are considered. The Reynolds number based on the exit diameter ranges from 79,000 to 336,000. The supersonic wave components of the flow variables are decomposed from the full flow-field using wavenumber–frequency domain filtering. The spatial structure of the fluctuating pressure field is obtained by the proper orthogonal decomposition (POD) of the full and filtered data. POD modes of unheated subsonic jets reveal large scale-disparity between the full and supersonic components. For the supersonic jet at M j= 1.95, the energetic structures of the pressure field also contribute …

In the field of phase change phenomena, the lack of accessible and diverse datasets suitable for machine learning (ML) training poses a significant challenge. Existing experimental datasets are often restricted, with limited availability and sparse ground truth, impeding our understanding of this complex multiphysics phenomena. To bridge this gap, we present the BubbleML dataset which leverages physics-driven simulations to provide accurate ground truth information for various boiling scenarios, encompassing nucleate pool boiling, flow boiling, and sub-cooled boiling. This extensive dataset covers a wide range of parameters, including varying gravity conditions, flow rates, sub-cooling levels, and wall superheat, comprising 79 simulations. BubbleML is validated against experimental observations and trends, establishing it as an invaluable resource for ML research. Furthermore, we showcase its potential to facilitate the exploration of diverse downstream tasks by introducing two benchmarks:(a) optical flow analysis to capture bubble dynamics, and (b) neural PDE solvers for learning temperature and flow dynamics. The BubbleML dataset and its benchmarks aim to catalyze progress in ML-driven research on multiphysics phase change phenomena, providing robust baselines for the development and comparison of state-of-the-art techniques and models.

Hyperloop aerodynamic characteristics (eg, the pressure wave in front of the pod) are analyzed experimentally and theoretically in this study. A scaled Hyperloop aerodynamic experimental equipment that has a scale of d pod= 8.75 cm, BR= 0.34 and l t= 16 m is developed; it can be used to run experiments in the range from 160–320 m/s of v pod at approximately 1/1,000 atm (p ref= 150 Pa). Further, this experiment has an observed v a, which is not revealed in the analysis of the ideal case. The v a is generated during the pod acceleration process and has a significant effect on v LSW. Three pressure waves (LSW 1, FEW, and LSW 2) are measured in front of the pod. v LSW 1, v FEW, and v LSW 2 are similar at v pod< 250 m/s, and LSW 1, FEW, and LSW 2 are located in this order. However, at v pod> 250 m/s, the positions of LSW 1, FEW, and LSW 2 become increasingly close, and LSW 2 eventually catches up to …

When a nozzle is designed to produce a supersonic jet a set of target conditions are given. If the nozzle is operated at conditions other than those for which it was designed a standing wave will develop within the jet stream due to the pressure mismatch at the nozzle exit. Characteristics of the standing waves, also called shock-cells, depend on the extent of the pressure difference and whether the nozzle exit pressure is below the back pressure (an overexpanded jet) or above the back pressure (an underexpanded jet). As most jets are turbulent the interaction of the turbulence with the standing wave pattern leads to an additional source of noise termed ‘shock-associated noise.’The additional noise can occur in commercial aircraft in the climb-cruise maneuver when the fan stream becomes supersonic, subsequently annoying passengers sitting in the forward sections. In the case of military aircraft operating at high …

The Hyperloop has been proposed as a high-speed vactrain system for freight and passenger transport. Given that the Hyperloop aims to operate at subsonic to supersonic speeds, the aerodynamic environment within the tube needs to be carefully considered. The shape of a pod is also very important with regard to reduction of aerodynamic drag and lift. Therefore, this study investigates the influence of the nose and tail shape of a Hyperloop pod on its aerodynamic drag, lift, and pitching moment by comparing five pod shapes: symmetrical, downward nose–upward tail (N d T u ), upward nose–upward tail (N u T u ), downward nose–downward tail (N d T d ), and upward nose–downward tail (N u T d ). Six pod speeds from 100 to 350 m/s at 50-m/s intervals are simulated under steady-state conditions and the shear-stress transport k- ω model. The shape of the nose and tail has only a slight effect on aerodynamic drag, with …

Combined cycle power plants (CCPPs) are becoming more important as the global demand for electrical power increases. The power and efficiency of CCPPs are directly affected by the performance and thermal efficiency of the gas turbines. This study is the first unsteady numerical study that comprehensively considers axial gap (AG) in the first-stage stator and first-stage rotor (R1) and hot streaks in the combustor outlet throughout an entire two-stage turbine, as these factors affect the aerodynamic performance of the turbine. To resolve the three-dimensional unsteady-state compressible flow, an unsteady Reynolds-averaged Navier–Stokes (RANS) equation was used to calculate a k−ω SST γ turbulence model. The AG distance d was set as 80% (case 1) and 120% (case 3) for the design value case 2 (13 mm or d/Cs 1 = 0.307) in a GE-E 3 gas turbine model. Changes in the AG affect the overall flow field characteristics and efficiency. If AG decreases, the time-averaged maximum temperature and pressure of R1 exhibit differences of approximately 3 K and 400 Pa, respectively. In addition, the low-temperature zone around the hub and tip regions of R1 and second-stage rotor (R2) on the suction side becomes smaller owing to a secondary flow and the area-averaged surface temperature increases. The area-averaged heat flux of the blade surface increases by a maximum of 10.6% at the second-stage stator and 2.8% at R2 as the AG decreases. The total-to-total efficiencies of the overall turbine increase by 0.306% and 0.295% when the AG decreases.

This study investigated the variations in aerodynamic drag and the pressure wave effects caused by more than two pods operating in a Hyperloop tube. Three speeds, i.e., 100, 200, and 300 m/s, and two distances between two separate pods, i.e., 43 and 86 m, were simulated using SST k-ω turbulence model. The results indicate that drag of single- and multi-pod systems have similar tendencies that increase with increasing pod speed. For pod speed exceeding the critical Mach number, irrespective of the connectedness or separation of the pods, the last pod always experiences the highest drag. Otherwise, at lower speeds, the differences between the drag acting on each of the pods is negligible. The distance between two pods has a minor influence of less than 4% on the drag. The effects of two different pod shapes, i.e. rectangular and semicircular, on the drag of three connected pods are also small. The …

We investigated the effects of atherosclerosis in the carotid region on cerebral haemodynamics. A total of 15 stenosis cases following NASCET criteria were modelled using patient-specific medical image data and an open-source package, SimVascular. The formulation adopted the stabilised Petrov–Galerkin scheme with Newtonian and incompressible assumptions. The boundary conditions employed pulsatile inflow and three-element lumped Windkessel outlet conditions with a rigid wall assumption. We present transitions in the represented CoW during stenosis progression using three-dimensional aortic-cerebral vasculature for the first time. This was driven by the conserved total cerebral blood flow to 50% carotid stenosis (CS) ( P -value, P > 0.05), which deteriorated during subsequent stages of CS ( P < 0.01), and the effective collateral capability of the communicating arteries (CoAs) activated from a degree of …

This study provides a view of the primary aerodynamic design of Hyperloop pod considering the influence of tail shape and length on aerodynamic forces (drag and lift) and flow behaviors (pressure, Mach number, and temperature). Numerical simulations are performed considering two tail shapes (i.e., upward and downward tails) and five lengths of the downward tail (i.e., 1.725, 3.45, 6.9, 13.35, and 13.8 m). The dynamic overset mesh method utilizing polyhedral meshes is applied to simulate the movement of the pod. A simplified three-dimensional model is simulated using the unsteady Reynolds-averaged Navier–Stokes shear stress transport k– ω turbulence model, compressible ideal gas, and a pod speed of 300 m/s. The results indicate that the two tail shapes only have a minor effect on aerodynamic drag (i.e., the difference between the upward and downward tails is only 0.75%), generating two tendencies of …

Computational Fluid Dynamics Lab

교수님 소개

유재영

연구실 소개

연구실 키워드

알럼나이가 간 회사

연구실 지원 방법

대우 조건

연도별 논문 인용수

저널 & 학회 논문 출판 수

연구실 논문 목록

수소 재순환 시스템을 위한 동축 바이패스 이젝터의 개발(Design Process of Coaxial-Bypass Ejector for Hydrogen Recirculation System)

Wake Turbulence Characteristics Downstream of a High-Pressure Vane in a Hydrogen Gas Turbine

Key Technologies and Recent Research Trends for Flexible Operation of Francis Turbines

연구실 보유 특허

대학별 입시끈

우리 연구실 모집

교수님 소개

유재영

연구실 키워드

알럼나이가 간 회사

연구실 지원 방법

대우 조건

연도별 논문 인용수

저널 & 학회 논문 출판 수

연구실 논문 목록

수소 재순환 시스템을 위한 동축 바이패스 이젝터의 개발(Design Process of Coaxial-Bypass Ejector for Hydrogen Recirculation System)

Wake Turbulence Characteristics Downstream of a High-Pressure Vane in a Hydrogen Gas Turbine

Key Technologies and Recent Research Trends for Flexible Operation of Francis Turbines

연구실 보유 특허

최근 3년간 연구실적 높은 연구실

대학별 입시끈

우리 연구실 모집