Search Results

The paper describes a numerical study, supported by experiments, on light aircraft 2-Stroke Direct Injected Diesel engines, typically rated up to 110 kW (corresponding to about 150 imperial HP). The engines must be as light as possible and they are to be directly coupled to the propeller, without reduction drive. The ensuing main design constraints are: i) in-cylinder peak pressure as low as possible (typically, no more than 120 bar); ii) maximum rotational speed limited to 2600 rpm. As far as exhaust emissions are concerned, piston aircraft engines remain unregulated but lack of visible smoke is a customer requirement, so that a value of 1 is assumed as maximum Smoke number. For the reasons clarified in the paper, only three cylinder in line engines are investigated. Reference is made to two types of scavenging and combustion systems, designed by the authors with the assistance of state-of-the-art CFD tools and described in detail in a parallel paper.

A hydrogen economy is an increasingly popular solution to lower global carbon dioxide emissions. Previous research has been focused on the economic conditions necessary for hydrogen to be cost competitive, which tends to neglect the effectiveness of greenhouse gas mitigation for the very solutions proposed. The holistic carbon footprint assessment of hydrogen production, distribution, and utilization methods, otherwise known as “well-to-wheels” carbon intensity, is critical to ensure the new hydrogen strategies proposed are effective in reducing global carbon emissions. When looking at these total carbon intensities, however, there is no single clear consensus regarding the pathway forward. When comparing the two fundamental technologies of steam methane reforming and electrolysis, there are different scenarios where either technology has a “greener” outcome.

Bioregenerative systems for removal of gaseous contaminants are desired for long-term space missions to reduce the equivalent system mass of the air cleaning system. This paper describes an innovative design of a new biofiltration test lab for investigating the capability of biofiltration process for removal of ersatz multi-component gaseous streams representative of spacecraft contaminants released during long-term space travel. The lab setup allows a total of 24 bioreactors to receive identical inlet waste streams at stable contaminant concentrations via use of permeations ovens, needle valves, precision orifices, etc. A unique set of hardware including a Fourier Transform Infrared (FTIR) spectrometer, and a data acquisition and control system using LabVIEW™ software allows automatic, continuous, and real-time gas monitoring and data collection for the 24 bioreactors. This lab setup allows powerful factorial experimental design.

The Sabatier reactor is an exothermic, heterogeneous catalytic reactor that has the function of reducing carbon dioxide to methane and water vapor. Sabatier reactor operation is affected by gravity through the effects of buoyant forces. The buoyant forces affect the transfer of heat and can be significant in determining the temperatures of the various portions of the reactor. The temperatures then affect the fundamental processes such as the chemical reaction rate. This paper presents the results of zero “G” computer model simulations of Sabatier reactor operation. Groundbase experiments were made for various manned loadings under normal ambient and gravity (l-G) conditions and were correlated with normal gravity simulations. The zero “G” simulations show the reactor will run significantly hotter in a zero “G” environment if cooling air flow is not increased to compensate for the loss of natural convections.

The kinetics of the Sabatier methanation reaction, the reduction of carbon dioxide with hydrogen to methane and water, was investigated for 58 percent nickel on kieselguhr catalyst and 20 percent ruthenium on alumina catalyst. Differential rate data from an experimental program were correlated with a power function rate equation both for forward and reverse reactions. The kinetic parameters of activation energy, frequency rate constant and reaction order were determined for the rate equation. The values of these parameters were obtained from an Arrhenius plot of the experimental differential rate data. Also the carbon monoxide side reaction effect was measured and included in the correlation of parameters. The reaction was found to fit the rate equation experimentally within the temperature range 421°K, where the reaction effectively begins, to 800°K where the reaction rate drops and departs from the rate equation form.

The feasibility of a near-complete and biosafe conversion of human- and food waste into biogas was investigated in the context of ESA’s MELiSSA loop (Micro Ecological Life Support System Alternative). The treatment comprises of a series of processes, i.e. a mesophilic lab-scale CSTR (continuously stirred tank reactor), an upflow biofilm reactor, a fibre liquefaction reactor containing the rumen bacterium Fibrobacter succinogenes and a hydrothermolysis system in near-critical water. In the one-stage CSTR, a biogas yield of 75% with a specific biogas production of 0.37 L biogas g-1 added VS (volatile suspended solids) at a HRT (hydraulic retention time) of 15 to 25 days was obtained. When the SRT (solid retention time) was uncoupled from the HRT, and all solids were completely retained in the methane reactor, a more complete biogas conversion was observed at a SRT of above 20 days, corresponding to a 10% increase of degradation on a total COD basis.

This specification covers requirements for a self-propelled, boom type aerial device, equipped with an aircraft deicing fluid spraying system. The unit shall be highly maneuverable for deicing all exterior surfaces of wide-body and intermediate size aircraft, e.g., B-747 and B-737. The vehicle will also be used for aircraft maintenance and inspection. The vehicle shall be suitable for day and night operations.

This aerospace recommended practice covers requirements for a self-propelled, boom type aerial device, equipped with an aircraft deicing fluid spraying system. The unit shall be highly maneuverable for deicing all exterior surfaces of intermediate size aircraft, e.g. DC-9, B-727 and B-737. The vehicle will also be used for aircraft maintenance and inspection. The vehicle shall be suitable for day and night operations.

This document is reissued for application to helicopters. It is primarily intended to apply to the engine or engines, but it shall also apply to fire protection of lines, tanks, combustion heaters, and auxiliary powerplants (APU). Post-crash fire protection is also discussed.

This document is reissued for application to helicopters.

After the launch to the ISS (International Space Station) with The Space Shuttle flight STS 118 13A.1 on August 9th 2007 and the accommodation in the US lab Destiny, the air quality monitor ANITA (Analysing Interferometer for Ambient Air) has been successfully put into operation. ANITA is a technology demonstrator flight experiment being able to continuously monitor with high time resolution the air conditions within the crewed cabins of the ISS. The system has its origin in a long term ESA technology development programme. The ANITA mission itself is an ESA-NASA cooperative project. ESA is responsible for the provision of the HW, the data acquisition and data evaluation. NASA's responsibilities are launch, accommodation in the US Lab Destiny, operation and data download. The ANITA air analyser is currently calibrated to detect and quantify online and with high time resolution 33 gases simultaneously with down to sub-ppm detection limits.

The innovations in aircraft propulsion have been identified as the key parameter towards the progress in transportation. Continuous advancement in the performance and efficiency of propulsion has enabled aircraft to travel over larger distances with higher speed. Aviation is also responsible for approximately 2% of total greenhouse gas emission and is expected to grow around 3% by 2050. The present article aims to use the exergetic analysis of a turboprop engine which should be helpful in designing of such engines and also helps these engine users to regulate and select the operation modes. A gas turbine with film air cooling of turbine blades has been proposed to be the turboprop engine. The engine is analyzed on exergy point of view at different power loading operation modes and the performance is studied.

The numerical simulation of internal aerodynamic of automotive combustion chamber is characterised by complex displacements of moving elements (piston, intake/exhaust valves…) and by a strong variation of volume that cause some problems with classical numerical based mesh methods. With those methods (FEM, FVM) which use geometric polyhedral elements (hexaedron, tetrahedron, prismes…), it is necessary to change periodically the mesh to adapt the grid to the new geometry. This step of remeshing is very fastidious and costly in term of engineer time and may reduce the precision of calculation by numerical dissipation during the interpolation process of the variables from one mesh to another. Recently, the researcher community has renewed his interest for the development of a generation of numerical to circumvent the drawbacks of the classical methods.

This SAE Aerospace Information Report (AIR) is a review of the general characteristics of power sources that may be used to provide secondary, auxiliary, or emergency power for use in aircraft, space vehicles, missiles, remotely piloted vehicles, air cushion vehicles, surface effect ships, or other vehicles in which aerospace technology is used. The information contained herein is intended for use in the selection of the power source most appropriate to the needs of a particular vehicle or system. The information may also be used in the preparation of a power source specification. Considerations for use in making a trade study and an evaluation of the several power sources are included. More detailed information relating to specific power sources is available in other SAE Aerospace Information Reports or in Aerospace Recommended Practices.

This SAE Aerospace Information Report (AIR) is a review of the general characteristics of power sources that may be used to provide secondary, auxiliary, or emergency power for use in aircraft, space vehicles, missiles, remotely piloted vehicles, air cushion vehicles, surface effect ships, or other vehicles in which aerospace technology is used. The information contained herein is intended for use in the selection of the power source most appropriate to the needs of a particular vehicle or system. The information may also be used in the preparation of a power source specification. Considerations for use in making a trade study and an evaluation of the several power sources are included. More detailed information relating to specific power sources is available in other SAE Aerospace Information Reports or in Aerospace Recommended Practices.

This SAE Aerospace Information Report (AIR) is a review of the general characteristics of power sources that may be used to provide secondary, auxiliary, or emergency power for use in aircraft, space vehicles, missiles, remotely piloted vehicles, air cushion vehicles, surface effect ships, or other vehicles in which aerospace technology is used. The information contained herein is intended for use in the selection of the power source most appropriate to the needs of a particular vehicle or system. The information may also be used in the preparation of a power source specification. Considerations for use in making a trade study and an evaluation of the several power sources are included. More detailed information relating to specific power sources is available in other SAE Aerospace Information Reports or in Aerospace Recommended Practices.