Type Of Propulsion System Research Articles

Engines for Commercial Aircraft

CHARACTERISED by fierce competition among the major producers, the civil powerplant market has recently had to come to terms with a new type of propulsion system which, if all its claims are fully realised, will bring large benefits in terms of fuel efficiency and economy of operation. The most effective size of these engines, whether of the unducted fan or geared fan configuration, has yet to be proved but it appears that they will not be produced for applications requiring very high thrust, at least not for the foreseeable future.

ENERGY CONSIDERATIONS STUDY ON NAVAL SHIP FUEL CONSUMPTION VARIATIONS

ABSTRACTSpeed‐power margins are applied during the preparation of powering performance estimates for new U.S. Navy ship designs. This paper describes a study which was carried out in support of the U.S. Navy's Energy Conservation Program. The primary purpose of the study was to estimate, for new naval ships, the savings in ship fuel consumption and ship acquisition costs which might be achieved by the use of design power margin values which are smaller than those in the current NAVSEA margin policy. A second, related purpose was to determine the risks, in terms of reduced probabilities of achieving design speed, which would be associated with the use of reduced power margin values. The results of the study indicate that reductions in fuel consumption and acquisition cost can be achieved if a projected new naval ship is redesigned with a smaller value of power margin. However, the results are shown to be dependent upon ship size constraints and on the type of propulsion system. The results of the study also indicate that, for a projected new naval ship, the use of a reduced design power margin value will be accompanied by a substantial decrease in the probability of achieving the design speed.

Optimal Control of Flywheel Hybrid Transmissions

Selection of variable transmission ratio in a vehicle with a flywheel energy storage element to maximize the kinetic energy transfer for specified vehicle accelerations is formulated as an optimal control problem. Models for single and parallel power-flow path configurations are presented as generic hybrid propulsion system types. For both systems variation of the ratio of the continuously variable transmission results in inherently nonlinear control, with velocity trajectories found by the solution of two-point boundary value problems. For the single power-flow path system a closed loop controller is synthesized which tracks acceleration command. For the parallel path system, which is representative of conventional power split transmissions, the open loop control yields useful information, indicating tradeoffs between system energy recovery efficiency and component design parameters. Maximum energy recovery during regenerative braking is achieved by minimizing power losses to vehicle drag and transmission elements. Planetary gear geometry is shown to have the strongest influence on efficiency, maximum transmission component loading, and CVT ratio range.

A brief review of air transport noise

Flight vehicles are characterized according to their manner of operation and type of propulsion system; and their associated sources of noise are identified. Available noise reduction technology as it relates to engine cycle design and to power plant component design is summarized. Such components as exhaust jets, fans, propellers, rotors, airflow-surface interactions and reciprocating engine exhausts are discussed, along with their noise reduction potentials. Significant aircraft noise reductions are noted to have been accomplished by the application of available technology in support of noise certification rules. Further noise reductions to meet more stringent future noise regulations will require substantial additional technology developments. Improved analytical prediction methods, and well controlled validation experiments supported by advanced design aeroacoustic facilities, are required as a basis for an effective integrated systems approach to aircraft noise control.

A Brief Review of Air Transport Noise

Abstract Flight vehicles are characterized according to their manner of operation and type of propulsion system; and their associated sources of noise are identified. Available noise reduction technology as it relates to engine cycle design and to power plant component design is summarized. Such components as exhaust jets, fans, propellers, rotors, airflow-surface interactions and reciprocating engine exhausts are discussed, along with their noise reduction potentials. Significant aircraft noise reductions are noted to have been accomplished by the application of available technology in support of noise certification rules. Further noise reductions to meet more stringent future noise regulations will require substantial additional technology developments. Improved analytical prediction methods, and well controlled validation experiments supported by advanced design aeroacoustic facilities, are required as a basis for an effective integrated systems approach to aircraft noise control.

A discussion on ship technology in the 1980s - Future propulsion systems for merchant ships

The paper is primarily from an individual shipowner’s viewpoint. The first part of the paper considers the likely trends with regard to main propulsion systems arising from that viewpoint. It takes into account the emphasis on reliability and safety, pollution problems, and the combination of capital and operating costs of the system. Consideration is given to the various fuels used with prices and price trends. This is related to an analysis of the various types of propulsion systems presently available including gas turbine and nuclear power systems. In the second part of the paper, the individual views are compared with those derived from a statistical investigation of trends in machinery installations related to ship types and sizes based on published data. The conclusions drawn from the two approaches are in close agreement that in the 1980s the most widely used propulsion systems will be the slow speed diesel and the geared steam turbine with the main contenders being the medium speed diesel engine and the gas turbine. Nuclear propulsion is ruled out for this period because of pollution hazards and high capital costs.

Aquatic animal propulsion of high hydromechanical efficiency

Aquatic animal propulsion of high hydromechanical efficiency

Evaluation of noise problems anticipated with future vtol aircraft. AMRL-TR-66-245.

Abstract : The potential noise problems anticipated with future VTOL aircraft are analyzed and discussed in general terms, and a brief review of the basic principles of noise generation of various types of propulsion systems proposed for VTOL is included. Primary consideration is given to the noise environments produced in areas adjacent to VTOL sites, since they could cause the most serious noise problem limiting the usefulness of VTOL aircraft. Contours of perceived noise levels are compared for different takeoff and landing profiles of 3-4 passenger, 60 passenger, and 25 ton-lift-crane VTOL aircraft. Criteria and methods for assessing the response of communities to noise from V-port operations are discussed along with the problem of detection of military VTOL aircraft by means of noise. Recommendations are given on the requirements for future research on these noise problems with emphasis on the need for considering noise as an integral part of the design, selection, and test of VTOL aircraft.

Advanced Propulsion Concepts

The scale of space exploration and utilization which is likely to become possible as a result of advances in space transportation technology during the next two or three decades is discussed. The idealized energy costs for a variety of missions, variables which determine hardware costs, operational costs, and developmert costs are summarized. Specific types of propulsion systems which are likely to make possible large scale, economic space explorations are described. (M.C.G.)