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Drawing on all of the prior subject matter, this chapter provides an integrated forecast for the most likely development paths to sustainable green aviation. Required technology development for aircraft design/operation and alternative fuel production are highlighted, both for the short and long term. Land use and other feedstock issues are examined on a regional basis. The essential features of the move towards green aviation are delineated on the basis of projected public policy.

© 2016 Elsevier Inc. Objective To determine the effects of late surfactant on respiratory outcomes determined at 1-year corrected age in the Trial of Late Surfactant (TOLSURF), which randomized newborns of extremely low gestational age (≤28 weeks' gestational age) ventilated at 7-14 days to late surfactant and inhaled nitric oxide vs inhaled nitric oxide-alone (control). Study design Caregivers were surveyed in a double-blinded manner at 3, 6, 9, and 12 months' corrected age to collect information on respiratory resource use (infant medication use, home support, and hospitalization). Infants were classified for composite outcomes of pulmonary morbidity (no PM, determined in infants with no reported respiratory resource use) and persistent PM (determined in infants with any resource use in ≥3 surveys). Results Infants (n = 450, late surfactant n = 217, control n = 233) were 25.3 ± 1.2 weeks' gestation and 713 ± 164 g at birth. In the late surfactant group, fewer infants received home respiratory support than in the control group (35.8% vs 52.9%, relative benefit [RB] 1.28 [95% CI 1.07-1.55]). There was no benefit of late surfactant for No PM vs PM (RB 1.27; 95% CI 0.89-1.81) or no persistent PM vs persistent PM (RB 1.01; 95% CI 0.87-1.17). After adjustment for imbalances in baseline characteristics, relative benefit of late surfactant treatment increased: RB 1.40 (95% CI 0.89-1.80) for no PM and RB 1.24 (95% CI 1.08-1.42) for no persistent PM. Conclusion Treatment of newborns of extremely low gestational age with late surfactant in combination with inhaled nitric oxide decreased use of home respiratory support and may decrease persistent pulmonary morbidity. Trial registration ClinicalTrials.gov: NCT01022580

This paper presents a brief overview of air-breathing propulsion research conducted at the National Aeronautics and Space Administration (NASA) Glenn Research Center (GRC) over the last 70 years. It includes a historical perspective of the center and its various stages of propulsion research in response to the country’s different periods of crises and growth opportunities. The GRC’s research and technology development covered a broad spectrum, from a short-term focus on improving the energy efficiency of aircraft engines to advancing the frontier technologies of high-speed aviation in the supersonic and hypersonic speed regimes. This paper highlights major research programs, showing their impact on industry and aircraft propulsion, and briefly discusses current research programs and future aeropropulsion technology trends in related areas.

An overview of research efforts at NASA Glenn Research Center (GRC) in low-emission combustion technology that have made a significant impact on the nitrogen oxides (NOx) emission reduction in aircraft propulsion is presented. The technology advancements and their impact on aircraft emissions are discussed in the context of NASA’s Aeronautics Research Mission Directorate (ARMD) high-level goals in fuel burn, noise and emission reductions. The highlights of the research presented here show how the past and current efforts laid the foundation for the engines that are flying today as well as how the continued technology advancements will significantly influence the next generation of aviation propulsion system designs.

A three-dimensional viscous flow analysis is performed using a time-marching Reynolds-averaged Navier-Stokes code for a 3:1 rectangular nozzle with two delta tabs located at the nozzle exit plane to enhance mixing. Two flow configurations, a subsonic jet case and a supersonic jet case using the same tab configuration, which were previously studied experimentally, are computed and compared with the experimental data. The experimental data include streamwise velocity and vorticity distributions for the subsonic case, and Mach number distributions for the supersonic case, at various axial locations downstream of the nozzle exit. The computational results show very good agreement with the experimental data. In addition, the effect of compressibility on vorticity dynamics is examined by comparing the vorticity contours of the subsonic jet case with those of the supersonic jet case which were not measured in the experiment.

Gas-turbine engines are widely used for aircraft propulsion because of their high efficiency in the power range of interest. This chapter presents an overview of gas-turbine engines, including a discussion of the thermodynamic cycle and definitions of component and system efficiencies relevant to the performance of the engines. Also presented is how gas-turbine engines are classified as turbojet, turbofan, turboprop, propfan, and ramjet based on how thrust is generated for propulsion. For each of these types of gas-turbine engines, the distinguishing features are highlighted. Finally, application of supersonic combustion in a ramjet, known as a scramjet, for propulsion in hypersonic speed regime is outlined. Keywords: gas turbines; thrust; propulsion; thermodynamic cycle; efficiency; impulse turbines; turbojet; turbofan; turboprop; propfan; ramjet; scramjet; combined cycle engine

Acceleration of plasma by area expansion is an area of significant interest to the high power inspace propulsion research. This paper verifies the applicability of a diverging channel to designing practical self-field magnetoplasmadynamic (MPD) thruster for higher specific impulse. Theoretical development for the expanding annular geometry is documented and analyzed for a partially ionized two temperature computational model that addresses potential understanding of effect of geometric scales, and predictions of self-field magnetic effects.

A three-dimensional viscous flow analysis is performed using a time-marching Reynolds-averaged Navier-Stokes code for a 3:1 rectangular nozzle with two delta tabs located at the nozzle exit plane to enhance mixing. Two flow configurations, a subsonic jet case and a supersonic jet case using the same tab configuration which were previously studied experimentally, are computed and compared with the experimental data. The experimental data include streamwise velocity and vorticity distributions for the subsonic case, and Mach number distributions for the supersonic case, at various axial locations downstream of the nozzle exit. The computational results show very good agreement with the experimental data. In addition, the effect of compressibility on vorticity dynamics are examined by comparing the vorticity contours of the subsonic jet case with those of the supersonic jet case which were not measured in the experiment.