Applied aerodynamics : papers presented at the AIAA SciTech Forum and Exposition 2020 : Orlando, Florida, USA, 6-10 January 2020. AIAA SciTech Forum and Exposition (2020 : Orlando, Fla.)最新文献

{"title":"Ground-State Atomic Nitrogen Measurements using fs-TALIF in High-Pressure NRP Discharges","authors":"C. Dumitrache, A. Gallant, G. Stancu, C. Laux","doi":"10.2514/6.2020-1745","DOIUrl":"https://doi.org/10.2514/6.2020-1745","url":null,"abstract":"Measurements of ground state atomic nitrogen inside of a nanosecond repetitively pulsed (NRP) discharge operating at pressures between 0.1-5 bar are performed using a femtosecond two-photon absorption laser induced fluorescence (fs-TALIF) technique. The main goal of this work is to develop a quench-free diagnostic technique which would allow measurements at elevated pressures with high spatial and temporal resolution. Quantitative information is extracted from the TALIF signal via a novel calibration technique based on direct absorption measurements performed in a low-pressure DC discharge. The VUV measurements were done at the Soleil synchrotron facility using their unique high-resolution Fourier-transform spectrometer ( (cid:1) (cid:2)(cid:1)⁄ = (cid:5)(cid:6) (cid:5)(cid:7) ). During this preliminary work, fs-TALIF measurements of N( 4 S) are demonstrated in the post-discharge of the NRP between 1-500 µs after the nanosecond pulse. A maximum number density of N-atoms of (cid:8) × (cid:5)(cid:6) (cid:5)(cid:7) (cid:11)(cid:12) (cid:13)(cid:14) was measured at 1 µs after the pulse when the discharge was operated at 1 bar in pure nitrogen. Importantly, the limit of detection of the fs-TALIF technique was determined to be (cid:15) (cid:16)( (cid:18) (cid:19) ) ~ (cid:5)(cid:6) (cid:5)(cid:22) (cid:11)(cid:12) (cid:13)(cid:14) . This is approximately two orders of magnitude lower than previously reported by ns-TALIF. The main goal of this work is to present a new diagnostic technique, based on femtosecond two-photon absorption laser-induced fluorescence (fs-TALIF), that enables spatially and temporally resolved measurements of ground-state population of atomic nitrogen in an NRP discharge at high pressures (p ≥ 1 bar). The first nitrogen TALIF experiment was performed by Bischel et al. 10 inside a flow discharge in which atomic nitrogen was obtained by N 2 dissociation in a He+SF 6 buffer gas mixture at ~10 Torr. Their proposed scheme involved the two-photon excitation of the 3p 4 D multiplet state at λ = 2 × 211 nm with fluorescence collection taking place in the NIR at 868 nm following the radiative decay: 3p 4 D ← 3s 4 P 5/2 . In our experiments, we are using a different TALIF excitation scheme involving the 3p 4 S 3/2 level at λ = 2 × 206.6 nm. This scheme was first proposed by Adams et al. and it has been shown in the past to present some distinct advantages compared to the scheme proposed by Bischel. Despite the higher photon energy, the 3p 4 S 3/2 state benefits from a lower quenching rate of the upper state by N 2 11 . Moreover, the collection of fluorescence takes place in the visible spectrum ( λ = 745 nm) where the quantum efficiency of the most detectors is notably higher. Previous work on ns-TALIF showed that it can be successfully employed for studying low pressure discharges ( below several tens of milibars 12 ). Above this pressure, quenching of the excited state becomes a major loss mechanism with a time scale even faster than the ","PeriodicalId":93413,"journal":{"name":"Applied aerodynamics : papers presented at the AIAA SciTech Forum and Exposition 2020 : Orlando, Florida, USA, 6-10 January 2020. AIAA SciTech Forum and Exposition (2020 : Orlando, Fla.)","volume":"9 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83663998","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"New Impeller Shrouds to Improve Hydrodynamic Performance of Centrifugal Pumps: Experimental and Numerical Evaluations","authors":"H. Bozorgasareh, M. Jafari, Javad Khalesic, Heshmat Olah Gazori, M. Hassanalian","doi":"10.2514/6.2020-1800","DOIUrl":"https://doi.org/10.2514/6.2020-1800","url":null,"abstract":"","PeriodicalId":93413,"journal":{"name":"Applied aerodynamics : papers presented at the AIAA SciTech Forum and Exposition 2020 : Orlando, Florida, USA, 6-10 January 2020. AIAA SciTech Forum and Exposition (2020 : Orlando, Fla.)","volume":"10 3 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82705697","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Lagrangian simulations of spray interaction with a surface using a stochastic multi-regime impingement model","authors":"W. Ge, V. Ramanuj, R. Sankaran","doi":"10.2514/6.2020-0910","DOIUrl":"https://doi.org/10.2514/6.2020-0910","url":null,"abstract":"","PeriodicalId":93413,"journal":{"name":"Applied aerodynamics : papers presented at the AIAA SciTech Forum and Exposition 2020 : Orlando, Florida, USA, 6-10 January 2020. AIAA SciTech Forum and Exposition (2020 : Orlando, Fla.)","volume":"59 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89008565","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Assured Multi-Mode Navigation for Urban Operations of Small UAS","authors":"Christoph Struempfel, E. Schuster, Svenja Huschbeck, Christiane Berth, M. Haag","doi":"10.2514/6.2020-1945","DOIUrl":"https://doi.org/10.2514/6.2020-1945","url":null,"abstract":"The paper discusses the preliminary analysis of an urban availability tool required for preflight flight planning. In this tool, areas in an urban environment are assessed with respect to GNSS availability, separation to traffic and obstacles, impact of UAS noise, and various other criteria. GNSS availability will drive the necessity to include alternative navigation sensors such as laser scanners, vision sensors and altimeters in the navigation mechanization to meet the required navigation performance necessary for urban operations. This paper shows the initial results of the GNSS availability tool and discusses the sensor integration strategy when GNSS-only availability is not sufficient.","PeriodicalId":93413,"journal":{"name":"Applied aerodynamics : papers presented at the AIAA SciTech Forum and Exposition 2020 : Orlando, Florida, USA, 6-10 January 2020. AIAA SciTech Forum and Exposition (2020 : Orlando, Fla.)","volume":"77 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90349165","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Solution of Maxwell's Equations Using Fourth-Order Modified Runge-Kutta Scheme on Transformed Coordinates","authors":"Vishal Sharma, K. Hoffmann","doi":"10.2514/6.2020-2155","DOIUrl":"https://doi.org/10.2514/6.2020-2155","url":null,"abstract":"","PeriodicalId":93413,"journal":{"name":"Applied aerodynamics : papers presented at the AIAA SciTech Forum and Exposition 2020 : Orlando, Florida, USA, 6-10 January 2020. AIAA SciTech Forum and Exposition (2020 : Orlando, Fla.)","volume":"2 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88816411","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Development of a Thermal Management System for Electrified Aircraft","authors":"Jeffryes W. Chapman, Sydney L. Schnulo, M. Nitzsche","doi":"10.2514/6.2020-0545","DOIUrl":"https://doi.org/10.2514/6.2020-0545","url":null,"abstract":"This paper describes the development and optimization of a conceptual thermal management system for electrified aircraft. Here, a vertical takeoff and landing (VTOL) vehicle is analyzed with the following electrically sourced heat loads considered: motors, generators, rectifiers, and inverters. The vehicle will employ liquid-cooling techniques in order to acquire, transport, and reject waste heat from the vehicle. The purpose of this paper is to threefold: (1) Present a potential modeling framework for system level thermal management system simulation, (2) Analyze typical system characteristics, and (3) Perform optimization on a system developed for a specific vehicle to minimize weight gain, power utilization, and drag. Additionally, the paper will study the design process, specifically investigating the differences between steady state and transient sizing, comparing simulation techniques with a lower fidelity option and quantifying expected error.","PeriodicalId":93413,"journal":{"name":"Applied aerodynamics : papers presented at the AIAA SciTech Forum and Exposition 2020 : Orlando, Florida, USA, 6-10 January 2020. AIAA SciTech Forum and Exposition (2020 : Orlando, Fla.)","volume":"70 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88908087","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mid Lift-to-Drag Rigid Vehicle 6-DoF Performance for Human Mars Entry, Descent, and Landing: A Fractional Polynomial Powered Descent Guidance Approach","authors":"Breanna J. Johnson, P. Lu, R. Sostaric","doi":"10.2514/6.2020-1513","DOIUrl":"https://doi.org/10.2514/6.2020-1513","url":null,"abstract":"Defining a feasible vehicle design and mission architecture capable of reliably delivering a payload of 20 metric tons (mt) or more is a great challenge for landing humans on Mars. The Mid Lift-to-Drag Rigid Vehicle (MRV), a rigid decelerator studied in NASA’s Entry, Descent, and Landing Architecture Study (EDLAS), has shown to be a viable vehicle candidate for future human Mars missions. As the vehicle concept matures, models of increasing fidelity are added to the six-degree-of-freedom (6DoF) EDL simulation. This paper presents 6DoF simulation results using model updates for vehicle mass properties, fineness ratio, and aerodynamic-propulsive interactions. Additionally, an assessment of the Fractional-Polynomial Powered Descent Guidance (FP 2 DG) performance is presented, and the vehicle performance is compared with the Tunable Apollo Powered Descent Guidance (TAPDG). Finally, Monte Carlo results of the vehicle design trades are presented.","PeriodicalId":93413,"journal":{"name":"Applied aerodynamics : papers presented at the AIAA SciTech Forum and Exposition 2020 : Orlando, Florida, USA, 6-10 January 2020. AIAA SciTech Forum and Exposition (2020 : Orlando, Fla.)","volume":"35 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83132440","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Thermal-Chemical Plasma Instability in a Reacting Flow","authors":"Hongtao Zhong, M. Shneider, M. Mokrov, Y. Ju","doi":"10.2514/6.2020-1661","DOIUrl":"https://doi.org/10.2514/6.2020-1661","url":null,"abstract":"","PeriodicalId":93413,"journal":{"name":"Applied aerodynamics : papers presented at the AIAA SciTech Forum and Exposition 2020 : Orlando, Florida, USA, 6-10 January 2020. AIAA SciTech Forum and Exposition (2020 : Orlando, Fla.)","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83147240","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental study of energy delivered to the filaments in high pressure nanosecond surface discharge","authors":"C. Ding, A. Jean, S. Shcherbanev, I. Selivonin, I. Moralev, N. Popov, S. Starikovskaia","doi":"10.2514/6.2020-1662","DOIUrl":"https://doi.org/10.2514/6.2020-1662","url":null,"abstract":"of energy delivered to the filaments in high pressure discharge. discharges driven by repetitive high frequency (typically at least tens of kHz) nanosecond pulses; constriction of the discharges corresponding to sharp increase of the electron density in a nanosecond time scale has been experimentally observed. Filamentary surface dielectric barrier discharge provides similar plasma properties in the filaments but instead of a single shot channel, multiply equidistant filaments (30-50 in our case) appear along the edge of the high-voltage electrode. A regular \"grid\" of the filaments results in efficient and stable ignition of combustible mixtures. Our recent experiments shown high, more than 7 eV/particle, specific delivered energy for the filaments in air initiated by pulses of negative polarity 30-45 kV on the electrode at gas pressure equal to 8 bar. Developed physical model of the filamentary nanosecond surface DBD suggests extra-raid fast gas heating (tens of kK during parts of nanoseconds) in discharges at high electric field and high energy density at elevated pressures. In this case the efficiency of ignition is explained by high temperature and quasi-equilibrium plasma formed in the filaments; high density of O-atoms and high hydrodynamic perturbations in the vicinity of each filaments. One of open questions is the initial stage, namely how streamer-to-filament transition happens and what is a physical reason of sub-nanosecond single-shot construction. The aim of the present work is an experimental study of appearance of the filaments using microimaging; of the value of specific delivered energy and study of character of hydrodynamic perturbations for the filamentary nSDBD discharge of positive polarity. negative polarity streamers. During the a few channels move faster than the surrounding streamers; the distribution of these channels around the edge of the electrode is arbitrary. At higher voltages, a regular set of filaments is developed. Difference in morphology is linked to the different polarities of the","PeriodicalId":93413,"journal":{"name":"Applied aerodynamics : papers presented at the AIAA SciTech Forum and Exposition 2020 : Orlando, Florida, USA, 6-10 January 2020. AIAA SciTech Forum and Exposition (2020 : Orlando, Fla.)","volume":"85 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81053376","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Multiple Shaker Placement for Ground Vibration Test of X-59 Aircraft using Topology Optimization","authors":"Chan-gi Pak","doi":"10.2514/6.2020-1901","DOIUrl":"https://doi.org/10.2514/6.2020-1901","url":null,"abstract":"A multiple shaker placement methodology is developed and tested using a topology optimization technique. Current multiple shaker placement methodology requires optimum accelerometer placement and optimum single-shaker placement techniques. The proposed methodology is tested using a finite element model of the X-59 Low Boom Flight Demonstrator aircraft. The effective independence and the driving point acceleration transfer function (DPATF) methods are used for the accelerometer placement study. In this study, four shakers are used to excite each mode more effectively during the ground vibration test; all the modes of interest thus are separated into four groups. Each shaker takes care of a separate group of modes. Grouping the modes of interest is performed utilizing topology optimization. The number of modes for each group therefore will be automatically decided during grouping. For each group of modes, perform the following two steps to determine optimal location of four shakers: 1) At each accelerometer location, compare the magnitude of DPATF values at natural frequencies, select the minimum value, and make a vector with these minimum values of the DPATF magnitudes for each group; and 2) Select the degrees of freedom corresponding to the maximum value of this vector. The objective function value is the maximum value of the vector with minimum value of the magnitude of the superposed acceleration transfer function. This objective function value is maximized by changing the modes for each group. Forty accelerometers are enough to have good correlation between mode shapes obtained from the reduced order model and the simulated ground vibration test.","PeriodicalId":93413,"journal":{"name":"Applied aerodynamics : papers presented at the AIAA SciTech Forum and Exposition 2020 : Orlando, Florida, USA, 6-10 January 2020. AIAA SciTech Forum and Exposition (2020 : Orlando, Fla.)","volume":"55 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84768556","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}