Vantage Partners LLC
Vantage Partners LLC
Ashpis D.E.,NASA |
Laun M.C.,HX5 Sierra LLC |
Griebeler E.L.,Vantage Partners LLC
AIAA Journal | Year: 2017
The accurate measurement of power consumption by dielectric barrier discharge plasma actuators is a challenge due to the characteristics of the actuator current signal. Microdischarges generate high-amplitude, high-frequency current spike transients superimposed on a low-amplitude, low-frequency current. A high-speed digital oscilloscope was used to measure the actuator power consumption using the shunt resistor method and the monitor capacitor method. The measurements were performed simultaneously and compared to each other in a time-accurate manner. Itwas foundthat lowsignal-to-noiseratiosof theoscilloscopesused,incombinationwiththe highdynamicrangeof the current spikes, make the shunt resistor method inaccurate. An innovative, nonlinear signal compression circuit was applied to the actuator current signal and yielded excellent agreement between the two methods. The paper describes the issues and challenges associated with performing accurate power measurements. It provides insights into the two methodsincludingnewinsightintotheLissajouscurveof themonitorcapacitormethod.Extension to abroadrangeof parameters and further development of the compression hardware will be performed in future work.
Wright W.B.,Vantage Partners LLC |
9th AIAA Atmospheric and Space Environments Conference, 2017 | Year: 2017
A research project is underway at NASA Glenn to produce computer software that can accurately predict ice growth under any meteorological conditions for any aircraft surface. This report will present results from the newest LEWICE, version 3.5. This program differs from previous releases in its ability to model mixed phase and ice crystal conditions such as those encountered inside an engine. It also has expanded capability to use structured grids and a new capability to use results from unstructured grid flow solvers. A quantitative comparison of the results against a database of ice shapes that have been generated in the NASA Glenn Icing Research Tunnel (IRT) has also been performed. This paper will extend the comparison of ice shapes between LEWICE 3.5 and experimental data from a previous paper. Comparisons of lift and drag are made between experimentally collected data from experimentally obtained ice shapes and simulated (CFD) data on simulated (LEWICE) ice shapes. Comparisons are also made between experimentally collected and simulated performance data on select experimental ice shapes to ensure the CFD solver, FUN3D, is valid within the flight regime. The results show that the predicted results are within the accuracy limits of the experimental data for the majority of cases. © 2017, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.
Rigby D.L.,Vantage Partners Ltd |
Ameri A.A.,Ohio State University |
Veres J.,NASA |
9th AIAA Atmospheric and Space Environments Conference, 2017 | Year: 2017
Viscous three-dimensional simulations of the Honeywell ALF502R-5 low pressure compressor (sometimes called a booster) using the NASA Glenn code GlennHT have been carried out. A total of ten simulations were produced. Five operating points are investigated, with each point run with two different wall thermal conditions. These operating points are at, or near, points where engine icing has been determined to be likely. In the future, the results of this study will be used for further analysis such as predicting collection efficiency of ice particles and ice growth rates at various locations in the compressor. A mixing plane boundary condition is used between each blade row, resulting in convergence to steady state within each blade row. The k-omega turbulence model of Wilcox, combined with viscous grid spacing near the wall on the order of one, is used to resolve the turbulent boundary layers. For each of the operating points, heat transfer coefficients are generated on the blades and walls. The heat transfer coefficients are produced by running the operating point with two different wall thermal conditions and then solving simultaneously for the heat transfer coefficient and adiabatic wall temperature at each point. Average Nusselt numbers are calculated for the most relevant surfaces. The values are seen to scale with Reynolds number to approximately a power of 0.7. Additionally, images of surface distribution of Nusselt number are presented. Qualitative comparison between the five operating points show that there is relatively little change in the character of the distribution. The dominant observed effect is that of an overall scaling, which is expected due to Reynolds number differences. One interesting aspect about the Nusselt number distribution is observed on the casing (outer diameter) downstream of the exit guide vanes (EGVs). The Nusselt number is relatively high between the pairs of EGVs, with two lower troughs downstream of each EGV trailing edge. This is of particular interest since rather complex ice shapes have been observed in that region. © 2017, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.
Williams J.C.,NASA |
Meador M.A.B.,NASA |
McCorkle L.,Ohio Aerospace Institute |
Mueller C.,QinetiQ |
Wilmoth N.,Vantage Partners LLC
Chemistry of Materials | Year: 2014
We report the first synthesis of step-growth aromatic polyamide (PA) aerogels made using amine end-capped polyamide oligomers cross-linked with 1,3,5-benzenetricarbonyl trichloride (BTC). Isophthaloyl chloride (IPC) or terephthaloyl chloride (TPC) were combined with m-phenylenediamine (mPDA) in N-methylpyrrolidinone (NMP) to give amine-capped polyamide oligomers formulated with up to 40 repeat units. Addition of the cross-linker, BTC, typically induces gelation in under 5 min. Solvent exchange of the resulting gels into ethanol followed by supercritical CO2 drying gives colorless aerogels with densities ranging from 0.06 to 0.33 g/cm3, compressive moduli between 5 and 312 MPa, and surface areas as high as 385 m2/g. Dielectric properties were also measured in the X-band frequency range. It was found that relative dielectric constant decreased with density as seen with other aerogels with the lowest relative dielectric constant being 1.15 for aerogels with densities of 0.06 g/cm3. Because of their superior mechanical properties, these aerogels can be utilized in a number of aerospace related applications, such as insulation for rovers, habitats, deployable structures, and extravehicular activity suits, as well as low dielectric substrates for antennas and other electronics. Because of potentially lower cost relative to polyimide and other polymer aerogels, they also have potential for use in more terrestrial applications as well, such as insulation for refrigeration, building and construction, and protective clothing. © 2014 American Chemical Society.
Okojie R.S.,NASA |
Lukco D.,Vantage Partners LLC |
Nguyen V.,Sienna Technologies, Inc. |
Savrun E.,Sienna Technologies, Inc.
IEEE Electron Device Letters | Year: 2015
Uncooled MEMS-based 4H-SiC Wheatstone bridge configured piezoresistive pressure sensors were demonstrated from 23 °C to 800°C. The full-scale output (FSO) voltage exhibited gradual decrease with increasing temperature from 23 °C to 400 °C, then swung upward as temperature increased further to where the values measured at 800 °C were nearly equal to or higher than the room temperature values. This newly observed FSO behavior in 4H-SiC contrasts sharply with the FSO behavior of silicon piezoresistive sensors that decrease continuously with increasing temperature. The increase in the sensor output sensitivity at 800 °C implies higher signal to noise ratio and improved fidelity, thereby offering promise of further insertion into >600 °C environments without the need for cooling and complex signal conditioning. © 2014 IEEE.
Meador M.A.B.,NASA |
McMillon E.,NASA |
Sandberg A.,NASA |
Barrios E.,NASA |
And 3 more authors.
ACS Applied Materials and Interfaces | Year: 2014
The dielectric and other properties of a series of low-density polyimide block copolymer aerogels have been characterized. Two different anhydride-capped polyimide oligomers were synthesized: one from 2,2-bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) and 4,4′-oxidianiline (ODA) and the other from biphenyl-3,3′,4,4′-tetracarboxylic dianhydride and ODA. The oligomers were combined with 1,3,5-triaminophenoxybenzene to form a block copolymer networked structure that gelled in under 1 h. The polyimide gels were supercritically dried to give aerogels with relative dielectric constants as low as 1.08. Increasing the amount of 6FDA blocks by up to 50% of the total dianhydride decreased the density of the aerogels, presumably by increasing the free volume and also by decreasing the amount of shrinkage seen upon processing, resulting in a concomitant decrease in the dielectric properties. In this study, we have also altered the density independent of fluorine substitution by changing the polymer concentration in the gelation reactions and showed that the change in dielectric due to density is the same with and without fluorine substitution. The aerogels with the lowest dielectric properties and lowest densities still had compressive moduli of 4-8 MPa (40 times higher than silica aerogels at the same density), making them suitable as low dielectric substrates for lightweight antennas for aeronautic and space applications. © 2014 American Chemical Society.
Raju M.S.,Vantage Partners LLC
52nd AIAA/SAE/ASEE Joint Propulsion Conference, 2016 | Year: 2016
The open national combustion code (Open- NCC) is developed with the aim of advancing the current multi-dimensional computational tools used in the design of advanced technology combustors. In this paper we provide an overview of the spray module, LSPRAY-V, developed as a part of this effort. The spray solver is mainly designed to predict the flow, thermal, and transport properties of a rapidly evaporating multi-component liquid spray. The modeling approach is applicable over a widerange of evaporating conditions (normal, superheat, and supercritical). The modeling approach is based on several well-established atomization, vaporization, and wall/droplet impingement models. It facilitates large-scale combustor computations through the use of massively parallel computers with the ability to perform the computations on either structured & unstructured grids. The spray module has a multi-liquid and multi-injector capability, and can be used in the calculation of both steady and unsteady computations. We conclude the paper by providing the results for a reacting spray generated by a single injector element with 60° axially swept swirler vanes. It is a configuration based on the next-generation lean-direct injection (LDI) combustor concept. The results include comparisons for both combustor exit temperature and EINOX at three different fuel/air ratios. © 2016, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.
Wright W.B.,Vantage Partners LLC
8th AIAA Atmospheric and Space Environments Conference | Year: 2016
A research project is underway at NASA Glenn to produce computer software that can accurately predict ice growth for many meteorological conditions for any aircraft surface. This report will present results from the latest LEWICE release, version 3. 5. This program differs from previous releases in its ability to model mixed phase and ice crystal conditions such as those encountered inside an engine. It also has expanded capability to use structured grids and a new capability to use results from unstructured grid flow solvers. An extensive comparison of the results in a quantifiable manner against the database of ice shapes that have been generated in the NASA Glenn Icing Research Tunnel (IRT) has also been performed. This paper will show the differences in ice shape between LEWICE 3. 5 and experimental data. In addition, comparisons will be made between the lift and drag calculated on the ice shapes from experiment and those produced by LEWICE. This report will also provide a description of both programs. Quantitative geometric comparisons are shown for horn height, horn angle, icing limit, area and leading edge thickness. Quantitative comparisons of calculated lift and drag will also be shown. The results show that the predicted results are within the accuracy limits of the experimental data for the majority of cases. © 2016, American Institute of Aeronautics and Astronautics Inc, AIAA.
Simon D.L.,NASA |
Rinehart A.W.,Vantage Partners LLC
Proceedings of the ASME Turbo Expo | Year: 2014
This paper presents a model-based anomaly detection architecture designed for analyzing streaming transient aircraft engine measurement data. The technique calculates and monitors residuals between sensed engine outputs and model predicted outputs for anomaly detection purposes. Pivotal to the performance of this technique is the ability to construct a model that accurately reflects the nominal operating performance of the engine. The dynamic model applied in the architecture is a piecewise linear design comprising steady-state trim points and dynamic state space matrices. A simple curve-fitting technique for updating the model trim point information based on steady-state information extracted from available nominal engine measurement data is presented. Results from the application of the model-based approach for processing actual engine test data are shown. These include both nominal fault-free test case data and seeded fault test case data. The results indicate that the updates applied to improve the model trim point information also improve anomaly detection performance. Recommendations for follow-on enhancements to the technique are also presented and discussed. Copyright © 2014 by ASME.
Wey C.,Vantage Partners LLC |
Proceedings of the ASME Turbo Expo | Year: 2013
A 9-Point Lean Direct low emissions combustor concept was utilized to evaluate gaseous emissions performance of two bio-derived alternative jet fuels and a JP-8 fuel for comparison. Gaseous emissions were measured in a flame tube operating at inlet temperatures from 650 up to 1030 F, pressures of 150, 250, and 350 psia, and a range of fuel/air ratios. The alternative fuels consisted of a Hydroprocessed Esters and Fatty Acids Fuel made from tallow and a second bio derived fuel produced from direct fermentation of sugar. Copyright © 2013 by ASME.