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Home>Products>Journal and Reviews>I.RE.AS.E.>Latest issue International Review of Aerospace Engineering - February 2010 - Papers
International Review of Aerospace Engineering - Papers
Vol. 3. n. 1, pp. 1-8
Abstract - The effect of tabs placed at the exit of a circular nozzle of 10 mm exit diameter on the near flow field characteristics of the jet was investigated experimentally for subsonic and sonic Mach numbers. The tab used was a semi- circular arc of diameter 1.5 mm and length 2 mm. The near field characteristics of the jet was studied for two configurations of the tab, namely, the concave surface facing the flow exiting the nozzle (arc-tab facing-in), convex surface facing the flow (arc-tab facing-out) and flat rectangular tab, for the blockage ratio of 7.64%. The centerline Mach number decay shows that, for the jet with arc-tab facing-in, a maximum reduction in core length of about 80% of the core of the plain jet was achieved at all subsonic and correctly expanded sonic conditions. Arc-tab facing-out and rectangular tab configurations reduce the core length by about 50%. The decay of arc-tab controlled jet was compared with that obtained for rectangular tab of same blockage and a plain circular nozzle. The jet was found to decay at a faster rate in the case of arc-tab facing-in configuration as compared to the facing-out and rectangular tab configurations. Mach number profiles show that, the arc-tab facing-in distorts the jet effectively by spreading the jet wider in the plane normal to the tab compared to arc-tab facing-out. Iso-Mach contours show that, the jet spread is wider in the plane normal to the tab and the effect of spread is more pronounced in the jet with arc-tab facing-in as compared to arc-tab facing-out. The effect of the tab orientation and its shape seem to have a profound influence on the evolution of the jet. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Arc-Tab Facing-In, Arc-Tab Facing-Out, Streamwise Vortices, Mach Number Decay.
Vol. 3. n. 1, pp. 9-18
Abstract - This paper describes how the House of Quality matrix has been quantified for use in conceptual design. The House of Quality matrix is used for visualizing the relationships between subsystem design parameters and top-level requirements. The idea is then to insert quantified values of the subsystems’ characteristics as coupling elements, thus visualizing both the requirements-subsystems relationship and system performance. Here, a spreadsheet program (MS Excel) with a built-in modeling/solver tool has been used to model the subsystems. This makes the matrix interactive, thus facilitating trade studies between requirements and system design. By adding probabilistic analysis it is possible to explore the entire range of system behavior early on, rather than just focusing on one or more worst case scenarios as has previously often been the case, and thus promoting the selection of more optimal solutions. The quantitative approach also opens up for mathematically formal optimization which has been exploited by deriving Pareto fronts for visualization of conflicting objectives, one such objective being. The design application used as illustrative example is conceptual design of an aircraft fuel system. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Relationship Matrix, Conceptual Design, Optimization, Aircraft, Fuel System.
Vol. 3. n. 1, pp. 19-26
Abstract - In earlier analogue avionic systems the number of cables used to transfer information between the various system components was considerable. With these systems, at least one pair of wires has been required for each signal and so a typical installation requires several pairs of wires. With the equivalent digital systems, all the analogue signals are converted into their equivalent and are assigned unique address labels to ensure there are no conflicts. These signals are then transmitted down a single pair of wires, which makes up a data bus. Aircraft data bus systems allow a wide variety of avionics equipment to communicate with one another and exchange data. The type of language used on an aircraft data bus is known as the protocol.There are currently different data bus standards (protocols) that currently account for most of the avionics data interchange on today’s aircraft, and these are: ARINC 429, ARINC 629, MIL-STD 1553, MIL-STD 1773, CSDB and ASCB. ARINC 429 is the most commonly used data bus for commercial-transport aircaft and MIL-STD 1553 for miltary aircraft. In this study after evaluating the main characteristics of data transmission and data bus used aircraft systems, ARINC 429 standard examined in detail. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Aircraft Data Bus, ARINC 429.
Vol. 3. n. 1, pp. 27-34
Abstract - A numerical simulation for an oscillating sub-boundary layer vortex generator (SBVG) with co-rotating and counter-rotating has been carried out. The device was attached and tested on a flat plate with zero pressure gradient condition. The simulation adopted a fully turbulent flow, having a Reynolds number of 1x106. The SBVG is oscillated in a sinusoidal motion between -180 and 180. It was observed that oscillated (unsteady) vortex generator resulted in a better performance in comparison with the static (steady) SBVG. This investigation also shows that the vortices for counter rotating SBVG persists far downstream compared to the co-rotating. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Oscillating SBVG, Flow Control, CFD.
Vol. 3. n. 1, pp. 35-40
Abstract - In this paper the results are published of post-doctorate research undertaken at the Brazilian Aeronautics Technological Institute (ITA) in 2006. The purpose of this paper is to evaluate and to discuss the operational performance of the main Brazilian carriers in the period from 2000-2005, by comparing their productivity growth and operational performance metrics with those of full service airlines (FSA), regional airlines (RA) and low-fare/low-cost airlines (LCA), chosen from among benchmarks in this industry. The research focused on the productivity analysis of the main production factors: labor, capital, energy and also in the processes directly managed by the airlines. A Multifactor Productivity (MFP) Index, which included the production factors labor and capital, was used to measure the airlines’ productivity. In the survey, 45 international carriers were selected in North and South American, European and Asian markets, and whose data availability and previous studies indicated a good operational performance and productivity. The research showed that there was widespread and accentuated improvement in productivity among Brazilian airlines in the period following deregulation and a best operational performance of the low cost/low fare companies that can be explained by the better use of their aircraft in terms of hours flown per airplane and day. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Airlines Productivity, Airlines Efficiency, Air Transport Productivity.
Vol. 3. n. 1, pp. 41-50
Abstract - An improved inverse design method has been presented for the solid wall optimization in the internal and cascade flows for aeronautical applications. Direct, inverse and geometry modification algorithms follow each other in the procedure till the target conditions are reached. Generally, the design process is completed within 6 iterations without relaxation factor. The direct and inverse solvers are based on the two dimensional Euler equations for modeling inviscid compressible flow. Roe’s approximated Riemann method with MUSCL approach and MinMod limiter has been implemented in the cell centred finite volume approach. The 4th order Runge-Kutta method has been used to solve the time derivatives of the conservative variables. The numerical boundary conditions are based on the method of characteristics at the inlet and the outlet. Soft solid wall technique has been used at the corresponding boundaries to improve the convergence properties. Opening wall concept and local flow direction based geometry modification algorithm have been applied in the inverse mode and the blade modification sub module respectively in the iterative marching scheme. The direct solver is validated by NACA 65-410 wing and cascade flows. The inverse design method is tested over a sinusoidal bump in a channel flow and over the sinusoidal profiles in a symmetrical cascade flow. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Inverse Design, CFD, Optimization, Cascade and Internal Flows.
Vol. 3. n. 1, pp. 51-58
Abstract - Wind tunnel experiments were conducted on NACA-0015 airfoil model to investigate the effect of the reduced frequency & Reynolds Number on the aerodynamic characteristics and hysteresis behavior associated with the pitching motion of the airfoil. Pressure measurements were conducted on the mid span of the airfoil for quantitative results. The hysteresis behavior was observed in aerodynamic characteristics as strong function of reduced frequency in form of a loop which gets enlarged with the increase in the value of reduced frequency. The present investigation of oscillating sinusoidal motion of airfoil, α=10°+15°sin (ωt) showed that, under the operating conditions studied, the airfoil was allowed to execute oscillating motion from almost steady(quasi-steady) conditions to unsteadiness with the incremental increase in the reduce frequency. Static conditions show distinct characteristics as compared to dynamic mode. But at extremely low reduced frequency of oscillation even in the dynamic mode the quasi-steady conditions do prevail. This results in a value of reduced frequency up to which the quasi-steady characteristics are preserved. Normal force defect is derived from the surface pressure distribution and the value of reduced frequency within 5% of normal force defect is obtained for varied range of Re to determine and validate the quasi-steady conditions. Re effect is dominant at very low reduced frequency. Also as reduced frequency increases causes decrease in the Re effect and increase in the normal force defect up to certain limiting value. Further increase in the reduced frequency reduces the normal force defect. Effect of Leading edge contamination is also depicted to cause incremental shift in the static stall angle. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Oscillating Airfoil, Dynamic Stall, Hysteresis, Quasi-Steady Characteristics.
Vol. 3. n. 1, pp. 59-66
Abstract - The use of a model rocket as a platform for scientific research into the behavior of liquid slosh is presented. A slosh event caused by the multi-axial acceleration of the rocket during flight is characterized by 6-DOF inertial measurements (accelerations and rates of rotation in three axes) synchronized with images acquired from a partially filled model fuel tank using an infrared camera. The proof-of-concept, high-powered solid-motor sounding rocket was also used to gather data for the verification of rocket dynamics simulation software. The rocket motor’s thrust was characterized in a thrust stand using a six degree of freedom torque-force load cell, and the electronic payload was qualified for electromagnetic and radio frequency compatibility following MIL-STD 461F. The advent of low-cost, high-quality motors, sensors and electronic components has made possible to build sounding rockets and payloads for scientific studies for costs much lower than conventional sounding rockets. The proposed platform can be used in slosh research to fill the gap between ground-based liquid slosh experiments and more costly experiments flown on special aircraft to achieve reduced gravity conditions. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Liquid Slosh, Sounding Rocket, Cfd, Inertial Measurement Unit.
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