Convective Nonlinearity in Non-Newtonian Fluids

In the limit of infinite yield time for stresses, the hydrodynamic equations for viscoelastic, Non-Newtonian liquids such as polymer melts must reduce to that for solids. This piece of information suffices to uniquely determine the nonlinear convective derivative, an ongoing point of contention in the rheology literature.Comment: 4 page

The Gas Turbine Heat Cycle and its Influence on Fuel Efficiency and Emissions

This paper discusses the application of heat exchangers to aircraft engines. At first the thermodynamic cycles with and without heat recovery and intercooling will be compared in a parameter study and the most suitable heat cycle for aircraft application will be selected. Next, heat exchangers of different kind and geometry and their off-design behaviour will be described. One of them will be selected for an intercooled and recuperated (ICR) aircraft engine. The results of an engine performance simulation program for this engine will be presented, the simulation will cover several operating points at sea level static (SLS) and in flight. The data base of the simulation corresponds to real engines and heat exchangers and therefore represents today's' technology. The results of the simulation will be compared with data of a modern high-bypass turbofan, which has been simulated by the same program. Finally the behaviour of the intercooled, recuperative and the conventional engine on a flight mission will be compared, which has been calculated by a flight performance program coupled with the engine simulation program. The results will be summarised and evaluated regarding fuel consumption, NOx and soot production as well as weight assumptions

The Gas Turbine Heat Cycle and its Influence on Fuel Effiency and Emissions

This paper discusses the application fo heat exchangers to aircraft engines. At first the thermodynamic cycles with and without heat recovery and intercooling will be compared in a parameter study and the most suitable heat cycle for aircraft application will be selected. Next, heat exchangers of different kind and geometry and their off-design behaviour will be described. One of them will be selected for an intercooled and recuperated (ICR) aircraft engine. The results of an engine performance simulation program for this engine will be presented, the simulation will cover several operating points at sea level static (SLS) and in flight. The data base of the simulation corresponds to real engines and heat exchangers and therefore represents todays' technology. The results of the simulation will be compared with data of a modern high-bypass turbofan, which has been simulated by the same program. Finally the behaviour of the intercooled, recuperative and the conventional engine on a flight mission will be compared, which has beein calculated by a flight performance program coupled with the engine simulation program. The results will be summarised and evaluated regarding fuel consumption, NOx and soot production as well as weight assumptions

Estimates of the climate impact of future small-scale supersonic transport aircraft – results from the HISAC EU-project

The climate impacts of three fleets of supersonic small-scale transport aircraft (S4TA) are simulated. Based on characteristic aircraft parameters, which were developed within the EU-project HISAC, emissions along geographically representative trajectories are calculated and in addition the resulting changes in the atmospheric composition (carbon dioxide, ozone layer, water vapour) and climate (near surface global mean temperature) are deduced. We assume a fleet development with an entry in service in 2015, a full fleet in 2050. The results show a temperature increase of 0·08mK (0·07-0·10mK) with only small but statistically significant variations between the configurations, leading to a minimum climate impact for a weight optimised and hence lower flying aircraft. A climate impact ratio of 3·0 ± 0·4 between a S4TA and its subsonic counterpart is calculated, which is considerable less than for previous supersonic fleets because of a lower flight altitude, leading to smaller water vapour impacts

Abstract 1

We consider a model for immiscible three-phase (e.g., water, oil, and gas) flow in a porous medium. We allow the relative permeability of the gas phase to exhibit hysteresis, in that it varies irreversibly along two extreme paths (the imbibition and drainage curves) that bound a region foliated by reversible paths (scanning curves). By numerically solving one-dimensional flow problems involving simultaneous and alternating injection of water and gas into a rock core

Predicting Take-Off Noise, Sonic Boom, and Landing Noise of Supersonic Transport Aircraft Concepts

In 2023, the German Aerospace Center (DLR) has launched the STORMIE (Supersonic Transport Open Research Models and Impact on Environment) project. Focus of the project is the prediction and minimization of environmental and human impacts of civil supersonic transport. Data generated in the project will be used to inform national and European authorities in order to discuss certification standards for supersonic aircraft within the International Civil Aviation Organization’s Committee on Aviation Environmental Protection (CAEP). In order to assess the environmental impacts, representative civil supersonic business-jet and airliner concepts will be designed. This paper will present an overview of past and ongoing activities conducted at DLR to assess and minimize landing and take-off noise as well as the sonic boom of supersonic aircraft. Numerical methods at different levels of fidelity are applied and will be complemented by listening experiments in a later project stage. First noise-related activities within the STORMIE project are summarized