Comparison of Traditional Two-Spool and Three-Spool with Vaneless Counter-Rotating Low-Pressure Turbine for Aircraft Propulsion Power Extraction

abstract: In previous work, the effects of power extraction for onboard electrical equipment and flight control systems were studied to determine which turbine shaft (i.e. high power shaft vs low power shaft) is best suited for power extraction. This thesis will look into an alternative option, a three-spool design with a high-pressure turbine, low-pressure turbine, and a turbine dedicated to driving the fan. One of the three-spool turbines is designed to be a vaneless counter-rotating turbine. The off-design performance of this new design will be compared to the traditional two-spool design to determine if the additional spool is a practical alternative to current designs for high shaft horsepower extraction requirements. Upon analysis, this thesis has shown that a three-spool engine with a vaneless counter-rotating stage has worse performance characteristics than traditional two-spool designs for UAV systems.Dissertation/ThesisMasters Thesis Aerospace Engineering 201

A review of NASA's propulsion programs for aviation

A review of five NASA engine-oriented propulsion programs of major importance to civil aviation are presented and discussed. Included are programs directed at exploring propulsion system concepts for (1) energy conservation subsonic aircraft (improved current turbofans, advanced turbofans, and advanced turboprops); (2) supersonic cruise aircraft (variable cycle engines); (3) general aviation aircraft (improved reciprocating engines and small gas turbines); (4) powered lift aircraft (advanced turbofans); and (5) advanced rotorcraft

Overview of NASA Electrified Aircraft Propulsion Activities

No abstract availabl

Techno-economic environmental risk analysis of sustainable power systems.

Sustainable engine systems are undoubtedly one of the main topics at the centre of the recent scientific debate. A significant number of novel thermodynamic concepts, partly based on gas turbine engines, are available in the open scientific literature and have been scarcely investigated. Cranfield University has developed an integrated, modular, multi-disciplinary framework of computational software called Techno-economic Environmental Risk Analysis (TERA) to assess complex, thermodynamic cycles from an integrated point of view. The present study completes a TERA work on sustainable power systems in two steps. Initially, the entire TERA methodology is applied to the aviation field with the integration of a set of modules to investigate three novel, turbofan, aircraft engines. Namely, the mentioned concepts are featured by: a counter-rotating core for short range (GTCRSR), an active core for short range (GTACSR), and an inter-cooler for Long Range (GTICLR). The optimised design specifications of the GTCRSR engine show a reduction of more than 7% of block fuel in comparison to the reference engine, more than 6% for the GTACSR and almost up to 5% for the GTICLR. Subsequently, a library of electric power generation future technology concepts has been built to be merged in the TERA for energy framework, developing the relevant computational codes. The power plants chosen encompass different domains of the field and are: the Advanced Zero Emissions Power plant — AZEP (carbon capture and storage concept); a supercritical steam turbine power plant (for nuclear applications); a land-based wind farm working in synergy with a conventional power plant. Multiple, specific control strategies for the fossil fuel and nuclear power plant have been identified to handle the power output down to 60% of the design point for the AZEP and slightly below 80% for the nuclear cycle. Hourly performance simulations of typical days representative of each season of the wind farm in combination to conventional gas turbine engines have been investigated for different size (from 223 MW to 5 MW at full load).Engineering and Physical Sciences (EPSRC)PhD in Aerospac

Conceptual design of battery energy storage for aircraft hybrid propulsion system

The paper presents a conceptual design approach for Energy Storage (ES) devices in advanced hybrid propulsion system for small aircrafts. The study targets operational improvement and reduction of fuel consumption for different flight missions. Power sharing strategies for ES and the engine are proposed for cruise flight phase aiming to maximise the range and/or endurance for the available amount of fuel in the tank. The ES size is designed against the engine performance and the proposed power sharing strategy by optimizing the flight altitude

Air plasma sprayed thermal barrier coatings on titanium alloy substrates

Titanium alloys as lightweight structure materials have been shown more interest in the use at moderately elevated temperatures. However, their poor oxidation resistance at temperature above 600 °C limits a wide application. Consequently, thermal protection becomes a concern. 8 wt. % yttria partially stabilized zirconia thermal barrier coatings (TBCs) were air plasma sprayed on titanium alloy substrates (Ti–6.6Al–3.61Mo– 1.69Zr–0.28Si in wt.%). The microstructures and mechanical properties of the coating system were studied by using SEM, XRD, MIP, tensile test and Vickers microhardness. The results show that the as-sprayed ceramic coating consists of the non-transformable tetragonal t′ phase of zirconia. The microstructure of the internal substrate keeps unchanged, no reaction and interdiffusion happen obviously at the bond coat/substrate interface during plasma spraying. However, there exists a thin layer of plastic deformation zone in the substrate beneath the bond coat/substrate interface. The surface connected porosity of the as-sprayed ceramic coating shows a typical bimodal pore size distribution. The adhesive strength of the TBCs decreases with increasing the thickness of the as-sprayed ceramic coatings, which is attributed to the residual stresses induced during thermal spraying. The anisotropy in the mechanical properties between the cross section and the top surface of the ceramic coatings is examined. © 2007 Elsevier B.V. All rights reserved

Effect of structural flexibility on the design of vibration-isolating mounts for aircraft engines

Previous analyses of the design of vibration-isolating mounts for a rear-mounted engine to decouple linear and rotational oscillations are extended to take into account flexibility of the engine-mount structure. Equations and curves are presented to allow the design of mount systems and to illustrate the results for a range of design conditions

Personal Rotorcraft Design and Performance with Electric Hybridization

Recent and projected improvements for more or all-electric aviation propulsion systems can enable greater personal mobility, while also reducing environmental impact (noise and emissions). However, all-electric energy storage capability is significantly less than present, hydrocarbon-fueled systems. A system study was performed exploring design and performance assuming hybrid propulsion ranging from traditional hydrocarbon-fueled cycles (gasoline Otto and diesel) to all-electric systems using electric motors generators, with batteries for energy storage and load leveling. Study vehicles were a conventional, single-main rotor (SMR) helicopter and an advanced vertical takeoff and landing (VTOL) aircraft. Vehicle capability was limited to two or three people (including pilot or crew); the design range for the VTOL aircraft was set to 150 miles (about one hour total flight). Search and rescue (SAR), loiter, and cruise-dominated missions were chosen to illustrate each vehicle and degree of hybrid propulsion strengths and weaknesses. The traditional, SMR helicopter is a hover-optimized design; electric hybridization was performed assuming a parallel hybrid approach by varying degree of hybridization. Many of the helicopter hybrid propulsion combinations have some mission capabilities that might be effective for short range or on-demand mobility missions. However, even for 30 year technology electrical components, all hybrid propulsion systems studied result in less available fuel, lower maximum range, and reduced hover and loiter duration than the baseline vehicle. Results for the VTOL aircraft were more encouraging. Series hybrid combinations reflective of near-term systems could improve range and loiter duration by 30. Advanced, higher performing series hybrid combinations could double or almost triple the VTOL aircrafts range and loiter duration. Additional details on the study assumptions and work performed are given, as well as suggestions for future study effort

Next Generation Aircraft Electrical Power Systems and Hybrid/All Electric Aircraft

Presentation to Aerospace Electrical Systems Expo, providing an overview of NASA's work on hybrid electric and all electric propulsion and projecting technology needs