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Study on Equivalent Sloshing Mass Locations for Liquid-Filled Cylindrical Tanks

JOURNAL OF SPACECRAFT AND ROCKETS 2022年第2期59卷 691-696页

作者： Hu, Pengxiang Zhao, Zhihua Yang, Shutao Zeng, Yaoxiang Qi, Feng Beijing Inst Astronaut Syst Engn Dept Syst Design Beijing 100076 Peoples R China Tsinghua Univ Sch Aerosp Beijing 100084 Peoples R China

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Iron mesh-supported vertically aligned Co-Fe layered double oxide as a novel monolithic catalyst for catalytic oxidation of toluene

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CHEMICAL ENGINEERING JOURNAL 2020年 384卷

作者： Xue, Tianshan Li, Renna Gao, Yanshan Wang, Qiang Beijing Forestry Univ Coll Environm Sci & Engn 35 Qinghua East Rd Beijing 100083 Peoples R China

A novel monolithic catalyst composed of iron mesh-supported vertically aligned Co-Fe layered double oxide (CoFe-LDO/IM) was successfully developed for the first time. The catalytic activity, water resistance, thermal stability, and computational fluid dynamics (CFD) simulation of CoFe-LDO/IM were comparatively studied with those of a conventional CoFe-LDO/cordierite catalyst. The optimal catalyst 30-CoFe-LDO/IM showed a 26 degrees C lower T-90 than CoFe-LDO/cordierite, significantly enhanced water vapor resistance (toluene conversion was 84% vs. 75%, 73% vs. 56% and 61% vs. 45% under 3, 5, 10 vol% H2O at T-90), and better thermal resistance within 5 cycles. CFD simulation demonstrated that the iron mesh-based monolithic catalyst possesses better heat distribution, which can prevent the partial deactivation of the catalyst and benefit the catalytic activity. We are fully convinced that this work can help pave the way for the design of next-generation monolithic catalysts with high activity and resistance for VOC oxidation.

关键词： LDHs In situ growth Volatile organic compounds computational fluid dynamics simulation Water resistance Heat conductivity

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A tunable extruded 3D printing platform using thermo-sensitive pastes

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INTERNATIONAL JOURNAL OF PHARMACEUTICS 2020年 583卷 119360页

作者： Yang, Yan Wang, Xiaoyue Lin, Xiao Xie, Lingxiao Ivone, Ryan Shen, Jie Yang, Gensheng Zhejiang Univ Technol Coll Pharmaceut Sci Hangzhou Peoples R China Univ Rhode Isl Coll Pharm Dept Biomed & Pharmaceut Sci Kingston RI 02881 USA Univ Rhode Isl Coll Engn Dept Chem Engn Kingston RI 02881 USA

Extruded 3D printing is emerging as an attractive fabrication technology in the field of personalized oral medicines. The objective of this study was to develop a tunable extruded 3D printing platform based on thermo-sensitive gelatin pastes to meet the needs of achieving different drug release characteristics with flexible dosing and design. The printability and mechanisms of extrusion and deposition of the gelatin pastes were systematically studied. Ibuprofen and diclofenac sodium were used as model drugs for immediate- and sustained-release formulations, respectively. Following the optimization of formulation and process parameters, ibuprofen immediate-release formulations with different designs, and reservoir-type diclofenac sodium sustained-release formulations were printed. Target drug release patterns were successfully obtained for both model drugs. Rheological studies revealed that additives such as microcrystalline cellulose and hydroxypropyl methylcellulose can act as both thickeners and proppants of gelatin matrix. Furthermore, computational fluid dynamics simulation was used to visualize the printing process, and quantitatively analyze the influence of material viscosity, inlet velocity and nozzle diameter on the pressure and velocity of extrusion flow field. The present study demonstrated the great potential of extruded 3D printing technology using the thermo-sensitive gelatin paste platform for personalized oral medicines.

关键词： Extruded 3D printing Thermo-sensitive gelatin paste Immediate release matrix Sustained release matrix Rheological study computational fluid dynamics simulation

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computational Study of NASA's Quadrotor Urban Air Taxi Concept

Computational Study of NASA's Quadrotor Urban Air Taxi Conce...

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AIAA Science and Technology Forum and Exposition (AIAA SciTech)

作者： Diaz, Patricia Ventura Yoon, Seokkwan NASA Ames Res Ctr Sci & Technol Corp Moffett Field CA 94035 USA NASA Ames Res Ctr Adv Supercomp Div Moffett Field CA 94035 USA

ISBN: (数字)9781624105951

ISBN: (纸本)9781624105951

High-fidelity computational fluid dynamics simulations have been carried out in order to analyze NASA's quadrotor urban air taxi concept for urban air mobility, also know as on-demand mobility applications. High-order accurate schemes, dual-time stepping, and the delayed detached-eddy simulation model have been employed. The flow solver has been loosely coupled with a rotorcraft comprehensive analysis code. The vehicle simulated is a six-passenger quadrotor for air taxi operations. A study of power reduction as a function of the rear-rotor to front-rotors vertical separation has been performed, for a quad-rotor without the airframe, in cruise flight conditions. Then, the quadrotor without the airframe has been simulated in hover. The airloads and wake geometries are analyzed. To finish the study the complete quadrotor vehicle is presented. NASA's quadrotor air taxi concept is one of the many concepts being developed by NASA in support of aircraft development for vertical take-off and landing air taxi operations.

关键词： Quad Rotor computational fluid dynamics simulation Coaxial Rotor Landing Gear Urban Air Mobility Vertical Take off and Landing Freestream Velocity Reynolds Averaged Navier Stokes Vortex Wake Computer Aided Design

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computational fluid dynamics simulation of Pilot-Plant-Scale Two-Phase Separators

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CHEMICAL ENGINEERING & TECHNOLOGY 2011年第2期34卷 296-306页

作者： Laleh, Ali Pourahmadi Svrcek, William Y. Monnery, Wayne D. Univ Calgary Dept Chem & Petr Engn Calgary AB T2N 1N4 Canada Chem Pet Proc Tech Ltd Calgary AB Canada

Two computational fluid dynamics (CFD) modeling approaches, the discrete phase model (DPM) and the combination of volume of fluid (VOF) and DPM, are developed to simulate the phase separation phenomenon in four pilot-plant-scale separators. The incipient vapor phase velocity, at which liquid droplet carry-over occurs, and separation efficiency plots are used as criteria for evaluating the developed CFD models. The simulation results indicate that the VOF-DPM approach is a substantial modification to the DPM approach in terms of the predicted separation efficiency data and diagrams. CFD simulation profiles demonstrate that all the separators are essentially operating at a constant pressure. The CFD results also show that mist eliminators may operate more efficiently in horizontal separators than in vertical separators.

关键词： computational fluid dynamics simulation Multiphase flows Phase separation Two-phase separator

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Investigation of frequency and step responses of pressure sensors with semi-closed structures based on numerical simulations and experiments

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SENSORS AND ACTUATORS A-PHYSICAL 2021年 332卷

作者： Toriyama, Taiju Ono, Hana Takaoka, Naoto Ohkawa, Masashi Niigata Univ Grad Sch Sci & Technol Nishi Ku 8050 Ikarashi 2 No Cho Niigata 9502181 Japan Niigata Univ Fac Engn Nishi Ku 8050 Ikarashi 2 No Cho Niigata 9502181 Japan

We are developing a pressure sensor to detect very small pressure fluctuations produced during tsunami formation. For example, such a pressure fluctuation of +/- 50 Pa was actually observed in the 2011 Great East Japan Earthquake. The sensor has a semi-closed structure with a small hole which provides a unique high -pass filter function. Cutoff frequency of the high-pass characteristic is an important index to detect pressure fluctuations due to tsunami formation without interfering with normal atmospheric pressure change. Cutoff frequency can be evaluated from frequency response of the sensor. On the other hand, the step response of the sensor is also significant in providing a unique index, called the 'duration time of induced pressure difference,' which is defined as the time required for the pressure difference between the inside and outside of the semi-closed structure to disappear. If a connection between the cutoff frequency and the duration time can be established, the cutoff frequency could be estimated from the duration time obtained by a one-step simple measurement of the step response. In this study, this connection was considered based on the simulated results of frequency and step responses dependent on small-hole area, semi-closed-structure volume and pressure amplitude. Then, the connection was experimentally verified using a fabricated prototype of the semi-closed structure. (c) 2021 Elsevier B.V. All rights reserved.

关键词： Pressure sensor computational fluid dynamics simulation Frequency response Step response Tsunami

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computational and Experimental Investigation of Inclined Choked Injection of Gaseous Jet

Computational and Experimental Investigation of Inclined Cho...

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AIAA Science and Technology Forum and Exposition (AIAA SciTech)

作者： Srivastava, S. Sheridan, A. M. Henneke, M. Sallam, K. A. John Zink Hamworthy Combust Tulsa OK 74116 USA Oklahoma State Univ Tulsa OK 74106 USA

ISBN: (数字)9781624105951

ISBN: (纸本)9781624105951

The injection of choked gaseous jets into still air is investigated computationally and experimentally. The objective is to compare the performance of three turbulence models - Realizable k-epsilon, SST k-omega and Reynolds Stress Transport to resolve the effect of injection angle on the jet mixing with ambient air. The experimental methods consist of particle image velocimetry (PIV) using pulsed Nd:YAG lasers of a choked gas jet, seeded with aluminum oxide particles, injected into still air that has been seeded with water fog. The test conditions include injection angles of 0 degrees and 15 degrees. The results including jet velocities and the vorticity field are presented. The flow field is not symmetric along the injection axis due to the asymmetric triggering of expansion fans at the jet exit due to the inclined injection plane. Moreover, the numerical simulation reveals the complex interaction mechanism of the expansion fans and shockwaves within the injection port.

关键词： Adverse Pressure Gradient Turbulence Models Particle Image Velocimetry computational fluid dynamics simulation Kinetic Energy Shock Diamond Compressible Flow Prandtl Meyer Expansion Fan Chamber Pressure Nozzle Geometry

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Effect of Interface Thermal Resistance and Coatings on Hypersonic Heat Flux Reconstruction Schemes

Effect of Interface Thermal Resistance and Coatings on Hyper...

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AIAA Science and Technology Forum and Exposition (AIAA SciTech)

作者： Nguyen, N. Massa, L. Virginia Polytech Inst & State Univ Kevin T Crofton Dept Aerosp & Ocean Engn 460 Old Turner St Blacksburg VA 24061 USA

ISBN: (数字)9781624105951

ISBN: (纸本)9781624105951

The present study investigates the effects of material discontinuities and thermal resistances on the temperature reconstruction and heat flux evaluation from heat flux sensors in hypersonic wind tunnel tests. Thin coating layers and adhesive interfaces lead to a localized multidimensional temperature perturbation and a significant alteration of the near-surface thermal field. A numerical method is developed for the real-time evaluation of the heat flux. The main idea is to approximate the heat conduction Green's function given the distributed temperature data. The proposed approach is efficient and robust. Efficient because the Green's function must be evaluated once for a given geometry, and robust because it allows one to reconstruct the heat flux as the optimal time-space distribution in a chosen basis, which minimizes the deviation from the set of temperature measurements. Evaluating the Green's function for three-dimensional irregular problems with material discontinuities is generally difficult. A new method is developed where the Green's function is evaluated independently for the regular partitions of the domain (subdomains) and appropriate connection conditions are derived to determine the full "system" Green's function. This paper describes the verification, validation and application of the approach to the heat flux reconstruction for a non-axisymmetric flat-faced article with coating and potting interfaces. The article was tested at Mach-6 in the Virginia Tech Hypersonic wind tunnel using four temperature sensors arranged in a cross pattern on the flat face. Good agreement was obtained between steady CFD predictions and the heat flux deduced from the experiments using the new data analysis method.

关键词： Thermal Diffusivity Heat Flux Distribution Green's Function Hypersonic Wind Tunnels Heat Flux Sensor Temperature Sensors Data Analysis Thermal Conductivity computational fluid dynamics simulation Hypersonic Flows

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High-Fidelity Numerical Analysis of Arc-Jet Aerothermal Environments

High-Fidelity Numerical Analysis of Arc-Jet Aerothermal Envi...

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AIAA Science and Technology Forum and Exposition (AIAA SciTech)

作者： Diaz, Patricia Ventura Parente, Almudena Meurisse, Jeremie B. E. Yoon, Seokkwan Mansourz, Nagi N. NASA Ames Res Ctr Moffett Field CA 94035 USA Sci & Technol Corp Hampton VA 23666 USA Univ Illinois Champaign IL USA NASA Adv Supercomp Div Washington DC USA

ISBN: (数字)9781624105951

ISBN: (纸本)9781624105951

Arc-jets are essential facilities used in the research, development and evaluation of thermal protection systems for hypersonic vehicles since they can reproduce the high-enthalpy environments seen during planetary entry. A test campaign is underway in the Hypersonic Materials Environmental Test System arc-jet, in support of the oncoming Mars 2020 mission to screen the response of the PICA-NuSil system. High-fidelity thermochemical non-equilibrium computational fluid dynamics simulations have been carried out to assist the test campaign by simulating the complete test matrix for the facility. A novel approach using machine learning has been implemented in order to calibrate the numerical results to the experimental data available. In addition, three different specimens are analyzed to assess the effect of the geometry on the aerothermal environments and material response. Accurate computational modeling of hypersonic flow fields can help improve the design of thermal protection systems that may enable robot and human exploration of the Moon, Mars, and beyond.

关键词： Static Enthalpy computational fluid dynamics simulation Thermal Protection System Machine Learning Hypersonic Flows Mars Science Laboratory Numerical Analysis Hypersonic Vehicles Exploration of the Moon Robots

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Nuclear Thermal Rocket Engine with a Toroidal Aerospike Nozzle

Nuclear Thermal Rocket Engine with a Toroidal Aerospike Nozz...

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AIAA Propulsion and Energy Forum

作者： Stewart, Kyle Pollard, Jordan Papadopoulos, Periklis San Jose State Univ Aerosp Engn San Jose CA 95192 USA

ISBN: (数字)9781624106026

ISBN: (纸本)9781624106026

The following article describes the coupling of a nuclear thermal rocket engine with a toroidal aerospike nozzle. This coupling consists of two approaches to design. The first of these approaches being the top-level systems and subsystems analysis and design for the new engine. The second being the analysis and characterization of the major engine systems through the use of computational fluid dynamics simulations. With the coupling of the nuclear thermal rocket engine with the aerospike nozzle, the new system will be known as the Nuclear Thermal Propulsion System (NTPS). Due to the uniqueness of coupling a nuclear thermal rocket engine (NTR) with a toroidal aerospike nozzle, the traditional NTR design of a cylindrical nuclear core had to be abandoned. This change stems from the need for cooling of the aerospike nozzle and the inherent obstruction that the nozzle support structure would represent for such a system. The redesigned nuclear core is known as a hoop core because the nuclear core is fashioned into a hoop shape to allow for the integration with an aerospike nozzle specially configured for use with the annular core. This innovative design represents a significant improvement over conventional chemical rockets in both the means of providing energy for thrust generation as well as the expulsion and expansion of the related exhaust. The details of these engine components, as well as other systems, will be described in the subsequent chapters.

关键词： Aerospike Nozzle Nuclear Thermal Propulsion computational fluid dynamics simulation Chemical Rocket Propellant Coolant Altitude Compensating Nozzle Combustion Chambers Inlet Temperature Nuclear Propulsion

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