Joseph Ranalli

Assessing the impact of video game based design projects in a first year engineering design course

Introductory engineering design courses are an opportunity to engage and encourage first-year engineering students. In one such course, we implemented a novel student design project using a commercial video game. The game, Kerbal Space Program, is a simulation of rocket travel and provides a reasonably realistic representation of rocket propulsion and orbital mechanics. Teams of students were tasked with designing a rocket that could fly to the home planets moon and return safely. The efficacy of the project was assessed using a pre- and post-activity survey, and results are compared with those from a larger-focus research project on the effectiveness of toys in the classroom.

Field testing the Raman gas composition sensor for gas turbine operation

A gas composition sensor based on Raman spectroscopy using reflective metal lined capillary waveguides is tested under field conditions for feed-forward applications in gas turbine control. The capillary waveguide enables effective use of low powered lasers and rapid composition determination, for computation of required parameters to pre-adjust burner control based on incoming fuel. Tests on high pressure fuel streams show sub-second time response and better than one percent accuracy on natural gas fuel mixtures. Fuel composition and Wobbe constant values are provided at one second intervals or faster. The sensor, designed and constructed at NETL, is packaged for Class I Division 2 operations typical of gas turbine environments, and samples gas at up to 800 psig. Simultaneous determination of the hydrocarbons methane, ethane, and propane plus CO, CO2, H2O, H2, N2, and O2 are realized. The capillary waveguide permits use of miniature spectrometers and laser power of less than 100 mW. The capillary dimensions of 1 m length and 300 μm ID also enable a full sample exchange in 0.4 s or less at 5 psig pressure differential, which allows a fast response to changes in sample composition. Sensor operation under field operation conditions will be reported.

Field tests of the Raman gas composition sensor

A gas composition sensor based on Raman spectroscopy using reflective metal lined capillary waveguides is tested under field conditions for feedforward applications in combustion control. The capillary waveguide enables effective use of low powered lasers and rapid composition determination, for computation of required parameters to pre-adjust burner control based on incoming fuel. Tests on high pressure fuel streams show sub-second time response and better than one percent accuracy on natural gas fuel mixtures. Fuel composition and Wobbe constant values are provided at one second intervals or faster. The sensor, designed and constructed at NETL, is packaged for Class I Division 2 operations typical of gas turbine and boiler environments, and samples gas at up to 800 psig. Simultaneous determination of the hydrocarbons methane, ethane, and propane plus CO, CO2, H2O, H2, N2, and O2 are realized. The capillary waveguide permits use of miniature spectrometers and laser power of less than 100 mW. The capillary dimensions of 1 m length and 300 μm ID also enable a full sample exchange in 0.4 s or less at 5 psig pressure differential, which allows a fast response to changes in sample composition. Sensor operation under field operation conditions will be reported.

Simple Analysis of Flame Dynamics via Flexible Convected Disturbance Models

DOI: 10.2514/1.B34405 Flame sheet modeling is a common approach for the determination of flame transfer functions for prediction and modeling of thermoacoustic combustion instabilities. The dynamics of the flame-sheet model for simple flame geometries can be shown to be equivalent to a basic model of convective disturbances interacting with a steady heat release region. This framework shows that the flame transfer functions predicted by linearized flame-sheet models are the Fourier transform of the steady heat release rate profile for the flamesheet geometry transformed into a Lagrangian convective time reference frame. This result is significant relative to existing flame-sheet modeling approaches in allowing the prediction of dynamic behaviors on the basis of steady information only. Multiple perturbations on the flame can be treated simply via superposition of individual perturbations. Analysis of results from these convective disturbance models illuminates the existence of two independent length scales governing the flame transfer function dynamics. Magnitude is governed by the tip-to-tail length of the flame, whereas phase is governed by the heat release rate profile center of mass calculated from the disturbance origin. The convective disturbanceapproachshowspromiseinitspotentialtoderive flametransferfunctionpredictionsfromasteady flame heat release rate profile.

Compressive sensing for spatial and spectral flame diagnostics

Combustion research requires the use of state of the art diagnostic tools, including high energy lasers and gated, cooled CCDs. However, these tools may present a cost barrier for laboratories with limited resources. While the cost of high energy lasers and low-noise cameras continues to decline, new imaging technologies are being developed to address both cost and complexity. In this paper, we analyze the use of compressive sensing for flame diagnostics by reconstructing Raman images and calculating mole fractions as a function of radial depth for a highly strained, N2-H2 diffusion flame. We find good agreement with previous results, and discuss the benefits and drawbacks of this technique.

Targeted flipped classroom technique applied to a challenging topic

The significant initial time commitment to create online content required for flipped classrooms may pose an obstacle to their implementation, despite the known learning benefits. We hypothesize that flipping only specific, problematic topics may still provide benefits to students with less instructor preparation. In this study, we targeted a flipped classroom toward a single, difficult course unit (the Reynolds Transport Theorem in fluid mechanics) to reduce the total time required for course preparation. Six lectures on this topic were converted to online videos and in-class time was used for group-based problem solving. Comparisons were made between a traditional lecture section (n=8) and flipped classroom sections (n = 15). A statistically significant improvement was seen when comparing exam performance on a question-by-question basis. Student survey responses about the method were unanimously positive, and students specifically noted the ability to rewatch sections of the video as a benefit to their learning. The interview responses also produced an unanticipated result. Students indicated that they preferred the partial approach to a hypothetical full course flip, stating they felt “it would get old.” While the use of a targeted flipped classroom was investigated here to reduce the initial faculty time commitment, this finding may warrant future investigation on reaction to partial versus full course flipped classrooms.

Characterization of Instabilities in a Low-Swirl Injector with Exhaust Gas Recirculation

There is an international effort to reduce greenhouse gases, including carbon dioxide emissions. In terms of addressing CO2 emission from power plants, post-combustion carbon capture is viewed as a near term solution, as it does not require redesign of the entire plant. Various post-combustion carbon absorption strategies are available. In implementing this type of device, Exhaust Gas Recirculation has been proposed, because it offers cost reduction benefits for absorption hardware by reducing the total flow rate that needs to be processed, and by increasing the concentration of CO2 in the exhaust gas. However, EGR represents a change in the reactant gases, for which the effect on the combustion process needs to be understood. Changes in fuel composition may be especially have an impact on flame dynamics. Tests will be performed in a lean-premixed combustor with High and Low Swirl Injectors. Methane and Methane/Hydrogen blends will be tested with EGR simulated by dilution with nitrogen and carbon dioxide. Instabilities will be characterized by the velocity oscillation amplitude and frequency, to draw conclusions about the impact EGR has on combustor operation.