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![Passive techniques for controlling the flow in supersonic wing-body junctions için kapak resmi Passive techniques for controlling the flow in supersonic wing-body junctions için kapak resmi](/client/assets/d79c3e4af2b6d196/ctx/images/no_image.png)
Passive techniques for controlling the flow in supersonic wing-body junctions
Başlık:
Passive techniques for controlling the flow in supersonic wing-body junctions
Yazar:
Blank, S. C., author.
ISBN:
9780355894646
Yazar Ek Girişi:
Fiziksel Tanımlama:
1 electronic resource (211 pages)
Genel Not:
Source: Dissertation Abstracts International, Volume: 76-08C.
Özet:
Executive Summary Junction flows are common to all flight speeds and they are associated with undesirable features such as increases in drag, limitations on performance and at supersonic speeds high heat transfer rates. Junction flows are associated with performance losses in turbomachinery (around 30% of the total pressure losses in an axial turbine) and they can lead to premature detection of military underwater vessels. Junction fairings are widely used at subsonic speeds and correct fairing of the C-141 wing alone, could have resulted in potential fuel savings of approximately US $40,000 per year per aircraft which can be roughly translated into a $600,000 saving during the lifetime of each airframe. Typically, for a modern transport type of aircraft the wing juncture accounts for between 1 and 2 % of cruise drag and therefore, careful design of the wing junction is necessary. At supersonic speeds, by far the most disadvantageous feature associated with juncture design is high heat transfer rates due to shock / shock interaction. These heat transfer rates are sufficient to cause severe structural damage leading to component burn-off. Typical leading edge temperatures during re-entry for an aerospaceplane, like HOTOL, are around 2000 K, exclusive of increases in temperature caused by the interaction. Although drag reduction may not be so relatively critical at these flight speeds, the potential loss of control components, like stabilising fins, needs to be carefully examined and some configuration re-design may be necessary as a consequence. This research project is aimed at developing a technique through which the disadvantageous features associated with supersonic junction designs can be alleviated. It was found that through re-design of the wing / body junction the maximum mean static pressure local to the fin leading edge could be halved, the strength of the junction vortices could be lowered and the amount of separated flow reduced. The applications of the technology span all vehicles operating within the supersonic flight regime and therefore, the markets to which the technology is applicable are military aircraft, defence systems, aerospaceplanes and commercial supersonic transports. As the technology is, in principle, applicable to the design of commercial supersonic transport aircraft (HSCT) and the market for these vehicles is forecast to be worth up to $200 billion (FY 1987) an examination of the issues behind marketing this type of vehicle is presented in the nontechnical section. The presently available data produced by the major manufacturers were found to be lacking in the following areas (a) evaluations of market elasticity, (b) distribution techniques, (c) the availability of acquisition finance and financing techniques, (d) political sensitivity analysis (d) product life cycle analysis and (f) the relationship marketing of the venture. Technical Summary An experimental investigation of glancing shock wave / turbulent boundary layer interaction produced by hemi-cylindrically blunted fins was conducted in two test facilities. The majority of the tests were made in the large 9" x 9" continuous supersonic wind tunnel at a Mach number of 2.45 and at a Reynolds number (Reg) of 4.1 x 10e4. Additionally some flow visualisation tests, in which blunt leading edge strake design parameters were investigated, were conducted at a Mach number of 2.43 and Reg of 5.8 x 10e4 in the smaller 2.5" x 2.5" short duration facility. The investigation's primary aim was to assess the potential of using passive techniques, namely fillets and strakes, to eliminate or alleviate the amount of separated flow and the flow field's unsteadiness, and to reduce the pressure levels experienced around the fin. Swept (45) and unswept fins of D/g =1.6 and unswept fins of D/g = 0.6 were tested in the larger wind tunnel, and straight models of D/g = 0.682 were used in the smaller facility. A number of different types of modification were investigated including ramp-type fillets, sharp leading edge strakes and blunt leading edge strakes. The study involved mean static pressures measured on the side wall, surface oil flow pictures taken over the side wall and the fin, and schlieren pictures taken in two planes normal to each other. In addition, laser light sheet flow visualisation and high speed cine films were taken of the shock systems produced by some of the models. It was found that filleting the junction did not improve the flow field characteristics whilst the addition of a sharp leading edge strake to the junction showed some beneficial effects on the mean surface static pressure distributions. The blunt leading edge strakes were found to possess the greatest potential for minimising the interaction. The incorporation of either blunt or sharp strakes into the junction helped to minimise the unsteadiness of the interaction.
Notlar:
School code: 0719
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Yer Numarası | Demirbaş Numarası | Shelf Location | Lokasyon / Statüsü / İade Tarihi |
---|---|---|---|
XX(683159.1) | 683159-1001 | Proquest E-Tez Koleksiyonu | Arıyor... |
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