Variable Cycle Powerplants for a Mach 2.7 Supersonic Civil Transport

1996 ◽  
Author(s):  
Louay Aleid ◽  
Pericles Pilidis
Keyword(s):  
Fuel Consumption ◽  
Preliminary Analysis ◽  
Point Of View ◽  
Variable Geometry ◽  
Jet Engine ◽  
Preliminary Results ◽  
Variable Stator ◽  
Size Variable

The aim of the work outlined in this paper is to compare three different variable cycle jet engine concepts for future SSTs. These engines are: the Turbofan-Turbojet, the Mid-Tandem Fan engine and the Double Bypass Engine. The comparison is carried out on a basis of performance, handling and sizing issues. This preliminary analysis compares S.F.C., size, variable geometry and cycle changes, and the effect of variable stator on the running lines of each compressor for each engine. The fuel bill, for two standard missions, is estimated as well. These preliminary results indicate that the three engines are quite similar in terms of general suitability. The Mid Tandem Fan appears to be an attractive proposition from the point of view of sizing, however this comes with a small penalty in fuel consumption.

Variable Cycle Installation for a Mach 2.7 Supersonic Civil Transport

1998 ◽  
Author(s):  
Louay Aleid ◽  
Pericles Pilidis
Keyword(s):  
Fuel Consumption ◽  
Wave Drag ◽  
Point Of View ◽  
Variable Geometry ◽  
Jet Engine ◽  
Performance Variable ◽  
Preliminary Results ◽  
Preliminary Comparison

A preliminary comparison of the installed performance of three variable cycle jet engine concepts for future Supersonic Transports is outlined in this paper. These engines, are: the Turbofan-Turbojet, the Mid-Tandem Fan engine and the Double Bypass Engine. The comparison of the uninstalled performance, variable geometry, cycle changes, the effect of variable compressor stators on the running lines of the compressors and sizing assessments for each engine were carried out in Reference 4. An estimate is now made of the installed performance by calculating the air friction, the pre-entry and the afterbody drags, plus the wave drag. A sizing calculation was carried out for the nacelles of all the engines. The uninstalled and installed fuel bills, for two standard missions, are also estimated. These preliminary results indicate that the Turbofan-Turbojet and the Mid Tandem Fan engines are quite similar in terms of general suitability. The Mid Tandem Fan appears to be an attractive proposition from the point of view of sizing, however this comes with a small penalty in fuel consumption. The Double Bypass engine was found to be the least attractive of the powerplants investigated. The differences, however appear to be small.

scholarly journals A New Measure of Complementarity in Market Basket Data

2021 ◽  
Vol 16 (4) ◽  
pp. 670-681
Author(s):  
Radosław Puka ◽  
Stanislaw Jedrusik
Keyword(s):  
Large Data ◽  
Point Of View ◽  
Detailed Data ◽  
Market Basket ◽  
Economic Theories ◽  
Empirical Verification ◽  
Preliminary Results ◽  
Research Fields ◽  
It Systems ◽  
Real Market

Modern IT systems collect detailed data on each activity, transaction, forum entry, conversation and many other areas. The availability of large data volumes in the business, industry and research fields opens up new opportunities for the empirical verification of various economic theories and laws. The analysis of big datasets in turn allows us to look at many issues from a new point of view and see the dependencies that are otherwise difficult to derive. In this paper, we propose a new measure for dependencies between goods in market basket data. The introduced measure was inspired by the well-known microeconomic concept of complementarity. Due to its similar properties to those of complementarity, the new measure was called basket complementarity (b-complementarity). B-complementarity not only measures the strength of dependencies between goods but also measures the direction of these dependencies. The values of the proposed measure can be relatively easily calculated using market basket data. This paper also presents a simple example illustrating this new concept, areas of possible application (e.g., in e-commerce) and preliminary results of searching for goods that meet the criteria of basket complementarity in real market basket data.

Navigation of the S.S.T.

1967 ◽  
Vol 20 (2) ◽  
pp. 176-187
Author(s):  
J. Villiers
Keyword(s):  
Fuel Consumption ◽  
Traffic Control ◽  
Air Traffic Control ◽  
General Rule ◽  
Air Traffic ◽  
Flight Path ◽  
Point Of View ◽  
Optimum Trajectory ◽  
Flight System ◽  
Actual Position

As a general rule the navigational function is aimed at determining the position of the aircraft in order to resolve three types of problem:(1) To subject the aircraft's flight path to an optimum trajectory calculated before departure or progressively adapted in course of flight to the circumstances encountered.(2) To choose at each point of the selected flight path the flight system best adapted to the safety and economy of the flight.(3) Taking into account the presence of other aircraft in the airspace, to know and make known the actual position and the information allowing provision to be made for future positions, so as to permit effective air traffic control.Departures of the actual from the chosen flight path penalize the flight by a lowering of economy (in flying time or fuel consumption). It does not seem, however, that the problems raised from this point of view by S.S.T. are by nature or in difficulty any different from those which affect conventional aircraft. Taking into account the present-day precision of navigational aids there is every reason to believe that departures of the actual flight path from the optimum flight path will introduce a penalization which it is possible to ignore when compared with the penalization due to the inaccuracy of the knowledge of the elements (winds, temperatures, pressures) which have, in fact, served to determine this optimum flight path.

Approaches to Functional, Structural and Security SOA Testing

2012 ◽  
pp. 381-401 ◽  
Author(s):  
Cesare Bartolini ◽  
Antonia Bertolino ◽  
Francesca Lonetti ◽  
Eda Marchetti
Keyword(s):  
Web Services ◽  
Point Of View ◽  
Structural Testing ◽  
Combined Approach ◽  
Security Testing ◽  
Preliminary Results ◽  
Important Concern ◽  
Is Security

In this chapter, we provide an overview of recently proposed approaches and tools for functional and structural testing of SOA services. Typically, these two classes of approaches have been considered separately. However, since they focus on different perspectives, they are generally non-conflicting and could be used in a complementary way. Accordingly, we make an attempt at such a combination, briefly showing the approach and some preliminary results of the experimentation. The combined approach provides encouraging results from the point of view of the achievements and the degree of automation obtained. A very important concern in designing and developing web services is security. In the chapter we also discuss the security testing challenges and the currently proposed solutions.

scholarly journals Gears Galore!

2013 ◽  
Vol 135 (04) ◽  
pp. 51-54 ◽  
Author(s):  
Lee S. Langston
Keyword(s):  
Fuel Consumption ◽  
Gas Turbines ◽  
Historical Analysis ◽  
Jet Engines ◽  
Efficient Operation ◽  
Jet Engine ◽  
The Status ◽  
The 1960S ◽  
A Company ◽  
Bypass Ratio

This paper presents a review of gas turbines and Honeywell, a company based in Phoenix, history. The article through the review and historical analysis intends to provide perspective on the status of geared fan engines. The addition of a fan to a jet engine, first proposed by Frank Whittle, one of the inventors of the jet engine, increases thrust and reduces fuel consumption. Pratt & Whitney and Rolls Royce were the first to develop a dual spool engine for more efficient operation over a range of flight conditions. Work started on the geared fan TFE731 at the Garrett AiResearch Phoenix Division in 1968. The TFE731 gearbox resulted in a gear reduction of 1.8:1, to power the fan for a 2.5 bypass ratio, which was very high for the 1960s. Honeywell also has another geared turbofan engine, the ALF502. It was developed by AVCO Lycoming in Stratford, Connecticut, and has a 6000–7000 lbt thrust range. Honeywell’s successful 45-year record of producing geared fan small gas turbines gives promise of a bright future for geared fans on large commercial jet engines, providing lower fuel consumption and less noise.

Diagnosing chromospheric magnetic field through simultaneous spectropolarimetry in Hα and Ca II 854.2 nm

2019 ◽  
Vol 15 (S354) ◽  
pp. 46-52
Author(s):  
K. Nagaraju ◽  
K. Sankarasubramanian ◽  
K. E. Rangarajan
Keyword(s):  
Magnetic Field ◽  
Time Evolution ◽  
Opposite Polarity ◽  
Point Of View ◽  
Current Understanding ◽  
Small Scale ◽  
Preliminary Results

AbstractMeasurement of magnetic field in this layer is challenging both from point of view of observations and interpretation of the data. We present in this work about spectropolarimetric observations of a pore, simultaneously in Ca ii (CaIR) at 854.2 nm (CaIR) and H α (656.28 nm). The observed region includes a small scale energetic event (SSEE) taking place in the region between the pore and the region which show opposite polarity to that of pore at the photosphere. The energetic event appears to be a progressive reconnection event as shown by the time evolution of the intensity profiles. Closer examination of the intensity profiles from the downflow regions suggest that the height of formation of CaIR is higher than that of Hi α, contrary to the current understanding about their height of formation. Preliminary results on the inversion of Stokes-I and V profiles of CaIR are also presented.

Optimizing Separate Exhaust Turbofans for Cruise Specific Fuel Consumption

2017 ◽  
Vol 139 (12) ◽  
Author(s):  
Syed J. Khalid
Keyword(s):  
Fuel Consumption ◽  
Control Algorithm ◽  
Velocity Ratio ◽  
Transmission Efficiency ◽  
Specific Fuel Consumption ◽  
Variable Geometry ◽  
Nozzle Throat ◽  
Propulsive Efficiency ◽  
Turbofan Engines ◽  
Bypass Ratio

Cruise specific fuel consumption (SFC) of turbofan engines is a key metric for increasing airline profitability and for reducing CO2 emissions. Although increasing design bypass ratio (BPR) of separate exhaust turbofan configurations improves cruise SFC, further improvements can be obtained with online control actuated variable geometry modulations of bypass nozzle throat area, core nozzle throat area, and compressor variable vanes (CVV/CVG). The scope of this paper is to show only the benefits possible, and the process used in determining those benefits, and not to suggest any particular control algorithm for searching the best combination of the control effectors. A parametric cycle study indicated that the effector modulations could increase the cruise BPR, core efficiency, transmission efficiency, propulsive efficiency, and ideal velocity ratio resulting in a cruise SFC improvement of as much as 2.6% depending upon the engine configuration. The changes in these metrics with control effector variations will be presented. Scheduling of CVV is already possible in legacy digital controls; perturbation to this schedule and modulation of nozzle areas should be explored in light of the low bandwidth requirements at steady-state cruise conditions.

scholarly journals Exhaust Energy Recovery with Variable Geometry Turbine to Reduce Fuel Consumption for Microcars

2018 ◽  
Author(s):  
Fernando Ortenzi ◽  
Antonino Genovese ◽  
Martina Carrazza ◽  
Franco Rispoli ◽  
Paolo Venturini
Keyword(s):  
Fuel Consumption ◽  
Energy Recovery ◽  
Variable Geometry ◽  
Reduce Fuel Consumption ◽  
Variable Geometry Turbine ◽  
Exhaust Energy

A Model for Solid Production and Transport for Small Urban Catchments: Preliminary Results

1992 ◽  
Vol 25 (8) ◽  
pp. 29-35 ◽  
Author(s):  
J.-L. Bertrand-Krajewski
Keyword(s):  
Conceptual Model ◽  
Suspended Solids ◽  
Point Of View ◽  
Transfer Model ◽  
Storm Events ◽  
Preliminary Results ◽  
Sewer Systems ◽  
Urban Catchments

A conceptual model for solid production and transfer in sewer systems is proposed. It has been established for small urban catchments of less than 100 ha, which can be considered from a global point of view. Hydrological and hydraulic phenomena are simply represented with a cascade of two linear reservoirs. The first part of the solid transfer model has been established to reproduce daily and hourly suspended solids loads during dry weather periods. The second part of the model deals with solid transfer during storm events, including sediment build-up over the catchment, washoff, erosion, deposition and transport. Two classes of particles are introduced to distinguish between deposits in pipes and solids transported in suspension. The objectives are the calculation of suspended and bed loads and the evolution of the deposits. Preliminary results are satisfactory but further research is needed in order to test and verify the model for other catchments and rainfalls.

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