Trends in aeropropulsion research and their impact on engineering education

This presentation is concerned with the trends in aeropropulsion both in the U.S. and abroad and the impact of these trends on the educational process in our universities. In this paper, we shall outline the new directions for research which may be of interest to educators in the aeropropulsion field. Awareness of new emphases, such as emission reductions, noise control, maneuverability, speed, etc., will have a great impact on engineering educators responsible for restructuring courses in propulsion. The information presented herein will also provide some background material for possible consideration in the future development of propulsion courses. In describing aeropropulsion, we are concerned primarily with air-breathing propulsion; however many observations apply equally as well to rocket engine systems. Aeropropulsion research needs are primarily motivated by technologies required for advanced vehicle systems and frequently driven by external requirements such as economic competitiveness, environmental concern and national security. In this presentation, vehicle based research is first described, followed by a discussion of discipline and multidiscipline research necessary to implement the vehicle-focused programs. The importance of collaboration in research and the training of future researchers concludes this presentation

Modeling and Simulation of a Microturbine Generator to be Coupled With a Molten Carbonate Fuel Cell for Distributed Generation

Distributed generation is desired when the individual energy requirements ranging from 25-75 kW of office buildings, restaurants, hospitals and apartments can not be met by the current electric utility grid. Microturbine generators as stand alone power generation systems have been designed to meet these requirements. For power requirements up to 50 MW, hybrid fuel cell systems offer higher efficiency and lower levels of pollutant emissions with more advanced fuel energy savings than non-hybrid systems. The objective of this project is to develop a simulation of a microturbine generator as a stand alone power generation system to validate a microturbine generator as part of a hybrid power generation system designed to produce 250 kW of usable power in MATLAB/Simulink®. The stand alone power generation system will be modeled using a 1-Dimensional approach. The hybrid power generation system is modeled as three major sub-systems; a hybrid microturbine generator, a molten carbonate fuel cell with catalytic oxidizer, and a shell-and-tube heat exchanger. The hybrid power generation system will be analyzed by two different models; a 0-Dimensional hybrid model where all the components are 0-Dimensional and a 0-Dimensional model with 1-Dimensional zooming for the hybrid microturbine generator. The analysis of the stand alone system is used for validation of the hybrid system at the operating design point of the microturbine generator. A control system was placed on the hybrid microturbine generator power generation system and an analysis was completed on the temperature response of the 0-Dimensionl hybrid system as the microturbine generator power was ramped from 0-30 kW over six different time intervals. A second controller was placed on the fuel cell power generation system to further analyze the hybrid system\u27s controllability. The three MATLAB/Simulink® models developed provide an initial design methodology for modeling and simulation of a hybrid power generation system

Efficiency and Pressure Loss Characteristics of an Ultra-Compact Combustor with Bulk Swirl

Research was conducted on a novel combustor design using a highly centrifugal loaded circumferential cavity to enhance flame speeds and lower mixing time to lower overall combustion time achieving improved efficiency and stability. This Ultra-Compact Combustor (UCC) is fed air with a bulk swirl, resembling gas leaving a compressor without the final set of compressor guide vanes to straighten the flow, at higher than normal Mach numbers for a combustor. The larger Mach numbers in the combustor do not cause a total pressure loss in excess of what Rayleigh theory would dictate for the given heat addition taking place within the combustor. Tests were conducted on the UCC with a clockwise or counter-clockwise swirl direction in the circumferential cavity using JP-8 and natural gas derived Fischer-Tropsch synthetic jet fuel with each direction. The results for lean blow out stability, combustion efficiency, and emissions proved that the best configuration uses counterclockwise swirl. The two fuels performed equally with no noticeable differences between JP-8 and the synthetic Fischer-Tropsch fuel

Design and Analysis of a Disk-oriented Engine Combustor

In a novel approach to gas-turbine power production, an engine was designed and analyzed to use both a single-stage centrifugal compressor and single-stage radial in- ow turbine configured back-to-back. This air path reduced the axial length of the engine up to 60%, providing additional modularity in a gas-turbine engine that could be used to improve mobility of ground-based power units or increase the survivability of aircraft through the use of distributive propulsion. This increased modularity was made possible by the use of a circumferential ow combustor that substantially decreased the axial length of the burner and negated the need to return compressor radial ow to the axial direction, as found in conventional combustion approaches. The Disk-Oriented Engine was designed to incorporate swirling inlet ow from a centrifugal compressor and exhaust directly into a radial in-ow turbine, while still maintaining the initial swirl pattern out of the compressor. The configuration of the combustion cavity was evaluated through computational fluid dynamics. An iterative design approach was used to achieve desired ow characteristics and combustion dynamics through geometry shaping and placement of air supply holes. The result of this design process was a computational combustor model that accepted swirling inlet ow, dispersed that air and fuel about a unique u-bend circumferential combustion cavity, and exhausted in the radial direction to feed a radial in-ow turbine. Sustained combustion was simulated at design conditions with a 3% total pressure loss in the combustor and a turbine inlet pattern factor of 0.24, indicating that such a design could operate as a gas-turbine engine, while reducing axial length up to 60% compared to traditional systems of similar size and performance. Computational results were compared to experimental tests on fuel-air swirl injectors, providing qualitative and quantitative insight into the stability of the flame anchoring system. From this design, a full-scale physical model of the Disk-Oriented Engine Combustor was designed and built for combustion analysis and characterization

Progettazione multidisciplinare ottimizzata nelle microturbine a gas

Optimized multidisciplinary design in micro-gasturbine

Design and Analysis of a Compact Combustor for Integration with a JetCat P90 Rxi

Ultra Compact Combustors are a novel approach to modern gas turbine combustor designs that look to reduce the overall combustor length and weight. A previous study integrated an Ultra Compact Combustor into a JetCat P90 RXi turbine engine and achieved self-sustained operation with a length savings of 33% relative to the stock combustor. However, that combustor could not operate across the full stock engine performance range due to flameout at increased mass ow rates as reactions were pushed out of the primary zone. To ensure reactions stayed in the primary zone, a new design with a larger combustor volume was conceived maintaining the same axial dimensions. The primary zone\u27s volume was increased without changing the length by utilizing bluff body stabilization, which resulted in a space savings when compared to the previous backward-facing step stabilized configuration. A new design was investigated computationally for generalized ow patterns, pressure losses, exit temperature profiles, and reaction distributions at three engine power conditions. The computational results were compared to stock combustor experimental results to show the validity of this new Ultra Compact Combustor, with a turbine inlet temperature of 1080 K and a pattern factor of 0.67. The combustor was then built and tested in the JetCat P90 RXi without rotating turbomachinery. The engine was force fed air and the combustor ignited at an air mass ow rate of 30 g/s and an equivalence ratio of 0.21. The combustor responded well to changes in air and fuel ow rates, maintaining a stable flame from ignition through the idle condition. Rotating turbomachinery was added and the combustor operated with an air assist of 3,000 RPM up to a maximum engine speed of 25,000 RPM, 19% of the maximum engine speed, at an exit gas temperature of 982 K, a 19 K increase over the stock

Aeronautical Engineering: A special bibliography with indexes, supplement 54

This bibliography lists 316 reports, articles, and other documents introduced into the NASA scientific and technical information system in January 1975

Aeronautical Engineering. A continuing bibliography with indexes, supplement 156

This bibliography lists 288 reports, articles and other documents introduced into the NASA scientific and technical information system in December 1982

Novel Thermal Energy Conversion Technologies for Advanced Electric Air Vehicles

Future air vehicles will increasingly incorporate electrical powertrains that require very tight integration of power, propulsion, thermal, and airframe technologies. This paper provides an overview of a new category of thermal energy conversion technologies that can be used to provide highly efficient turbo-generation and electric propulsion, while synergistically managing and recycling both the low grade waste heat from electrical components and the high grade waste heat from engine components

Energy- and Aerodynamic Examination of Slightly Backward Leaning Impeller Blading of Small Centrifugal Compressors

Last decade, turbochargers with maximum 50-60 mm diameter, are more and more frequently designed with slightly backward leaning impeller blading. These kind of impeller blading, comparing to the radial blading, produces higher stress and assuming the same compressor pressure ratio it needs higher tangential speed due to the impeller exit flow slip (hereafter slip). These two disadvantages are surely compensated by some kind of thermal or aerodynamic advantages. By the authors’ examination, using backward leaning impeller blading, the disadvantages are compensated by the small, but the definite increase of compressor efficiency and the positive effect on compressor characteristics.This paper, examining and comparing the above- mentioned advantages and disadvantages, tries to clear the reasons of this design trend and hopefully contributes to the further improvement of these compressor