Browse Topic: Fuel economy
Composite materials have become widely adopted in commercial aviation, as aerospace manufacturers look to use them to drive weight reduction and improved fuel efficiency in new aircraft designs. In the case of aircraft rotary blades, the poor wear properties of these materials have necessitated the development of metal leading edge guards that can provide critical protection against erosion and impact damage during flight. Electroforming has been a leading process for the manufacture of these protective guards, with nickel parts providing excellent wear resistance that significantly extends the service life of the rotary blade assembly. Currently there has not been a focus on utilizing direct electrodeposition of metal on to carbon filled epoxy composite structures, as traditional plating-on-plastics approaches require considerable effort in surface preparation and normally do not provide adequate adhesion to the underlying structure. Alpha Metalcraft Group has been working in cooperation with aerospace suppliers in the design of an electroplating ready composite structure that would allow for direct nickel deposition, provide excellent adhesion, and significantly reduce both the time and cost for the manufacture of ready-to-assembly rotary blade structures. Test panels were constructed of commercially available prepreg materials or by resin infusion of dry fabrics that incorporated different metal containing conductive layers to allow for the direct deposition through a nickel sulfamate electrodeposition process. Different surface modification strategies were investigated to expose the metal conducting layer and thereby provide the metal-to-metal bonding surfaces required for successful electrodeposition.
This paper presents experimental research aimed at developing novel low lubrication methods for rotorcraft and jet engines, focusing on sustaining minimal lubrication to prevent catastrophic bearing failure during loss of lubrication (LoL) events or to increase fuel consumption performance on once-through, fuel-oil bearing lubrication engines. Utilizing two high-speed bearing test rigs simulating low and high thrust class engine conditions, the study establishes lower bounds for oil flow rates necessary to maintain thermal stability and prevent thermal runaway in hybrid ball bearings. These findings inform the design of the Zulu Pod (ZPod), a passively driven, self-contained oil delivery system that uses engine compressor bleed air to precisely meter lubricant flow. Engine test stand results demonstrate that replacing traditional fuel-oil lubrication with the ZPod system reduces thrust specific fuel consumption (TSFC) by an average of 7%, with up to 11% savings, without compromising engine thrust or bearing health. The ZPod offers a simplified, efficient alternative to fuel-lubricated systems by eliminating fuel diversion for lubrication, enhancing fuel efficiency, and maintaining bearing performance in attritable or single-use engines. Additionally, the study highlights the potential of minimal lubrication supplied by the ZPod to extend operational life during LoL scenarios, enabling safer aircraft recovery. Future work will focus on extending testing to higher thrust classes and optimizing ZPod designs for broader applications.
ABSTRACT The US Army is seeking improvements in the fuel efficiency of their military vehicles.. They have initiated a number of R&D projects aimed at advancing the state-of-the-art of powertrain efficiency including demonstration in a laboratory environment. This effort will set a benchmark for the vehicle integrators, allowing them to improve future vehicle offerings. The SAIC, AVL, Badenoch, QinetiQ and Ker-Train Research team offered powertrain solutions from 7 Tons to 40 Tons that achieved the goal of 44% thermal efficiency and the stringent flexible fuel and emissions requirements. In each of these offerings the team was able to identify modifications to existing engines that allowed dramatic improvements in the thermal efficiency. These efficiency improvements were achieved through a combination of techniques, combustion cycle adjustments using in-cylinder pressure monitoring and precise control of fuel injector timing, and turbo-compounding. For the R&D project, the fuel injector timing will be controlled using commercial engine development hardware and software. The high speed hardware emulates the engine control module but allows the developer to finely tune the fuel injection to maximize the 50% Maximum Fuel Burn point (MFB50) with only limited NOx production. This will be accomplished using a variety of fuels and maintaining the output power to within 2% of the engine’s nominal rating. This paper will describe the fundamental diesel combustion process that must be controlled and techniques for usable power extraction from the waste exhaust gases to provide this performance. It will describe the engine development tools that enable these controls changes to be realized within a vehicle development cycle and retain the baseline engine maturity.
This paper presents a comprehensive decision-making algorithm for highway overtaking maneuvers, one of the highest risk maneuvers. For such, an overtaking scenario is divided into four phases: approach phase in which the host or overtaking vehicle (HV) detects a slow-moving lead vehicle (LV) in the same lane; left lane change and passing phase in which the HV performs a left lane change and passes the LV; right lane change phase in which the HV comes back to its original lane and free-flowing phase in which the HV maintains its lane and the initially set velocity. Depending on the phase-wise safety zones, the decision-making algorithm makes two decisions: change lane (1 = left lane change, 0 = maintain the same lane, -1 = right lane change) and adjust speed (1 = accelerate, 0 = maintain the current speed, -1 = decelerate). The proposed decision-making algorithm complements the human driver’s decision-making process and can be easily adapted for individual users. Safety and comfort constraints used for defining safety zones and reference trajectories are verified using the highD dataset, consisting of naturalistic vehicle trajectories on German highways. The decision-making algorithm is coupled with a trajectory planner and an operational controller to develop an automated overtaking system. The developed overtaking system is verified in a virtual environment (a combination of Simcenter Prescan and Matlab) by performing many simulations. The results demonstrate the robustness of the decision-making algorithm.
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