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  • AERODYNAMICS  (5)
  • ddc:330
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  • 1
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    Stockholm : Europ. Council for an Energy Efficient Economy | Wuppertal : Wuppertal Institut für Klima, Umwelt, Energie
    Publication Date: 2022-02-18
    Description: Iran is one of the largest oil producers and natural gas owners globally. However, it has to struggle with domestic energy shortages, economic losses through energy subsidisation and inefficient energy infrastructures. Furthermore, GHG and other energy related emissions are rapidly increasing and posing a growing threat to local environment as well as global climate. With current trends prevailing, Iran may even become a net energy importer over the next decades. Resource allocation is therefore a crucial challenge for Iran: domestic consumption stands versus exports of energy. The energy transformation sector clarifies Iran's dilemma: soaring electricity demand leads to blackouts, and power plant new builds are far from using most efficient technologies (e. g. CHP), therefore keeping energy intensive structures. But fossil fuels could be sold on international markets if spared by having more efficient energy infrastructures. As shown by the high energy intensity of its economy, Iran has large potentials for energy saving and efficiency. In order to highlight and better identify this potential the paper contrasts a high efficiency scenario in all sectors of energy transformation and consumption with a possible "business as usual" development. Using a bottom-up approach, the analysis provides a sector-by-sector perspective on energy saving potentials. These can be utilised on the demand side especially in the transport sector (fuels) and in households (electricity for appliances, natural gas for heating). Electricity generation bears efficiency potentials as well. We conclude that Iran, but also the international community, would benefit on various levels from a more energy-efficient Iranian economy: Energy exports could increase, generating more foreign currency and reducing the pressures on international oil and gas prices; energy consumption would decrease, leading to lower needs for nuclear energy and for subsidies to Iranian people, as well as to a reduction of the high external costs entailed by fossil fuels combustion (smog in cities, environmental stress).
    Keywords: ddc:330
    Repository Name: Wuppertal Institut für Klima, Umwelt, Energie
    Language: English
    Type: conferenceobject , doc-type:conferenceObject
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  • 2
    Publication Date: 2019-06-28
    Description: An existing cold-jet facility at NASA Lewis Research Center was modified to produce swirling flows with controllable initial tangential velocity distribution. Two extreme swirl profiles, i.e., one with solid-body rotation and the other predominated by a free-vortex distribution, were produced at identical swirl number of 0.48. Mean centerline velocity decay characteristics of the solid-body rotation jet flow exhibited classical decay features of a swirling jet with S - 0.48 reported in the literature. However, the predominantly free-vortex distribution case was on the verge of vortex breakdown, a phenomenon associated with the rotating flows of significantly higher swirl numbers, i.e., S sub crit greater than or equal to 0.06. This remarkable result leads to the conclusion that the integrated swirl effect, reflected in the swirl number, is inadequate in describing the mean swirling jet behavior in the near field. The relative size (i.e., diameter) of the vortex core emerging from the nozzle and the corresponding tangential velocity distribution are also controlling factors. Excitability of swirling jets is also investigated by exciting a flow with a swirl number of 0.35 by plane acoustic waves at a constant sound pressure level and at various frequencies. It is observed that the cold swirling jet is excitable by plane waves, and that the instability waves grow about 50 percent less in peak r.m.s. amplitude and saturate further upstream compared to corresponding waves in a jet without swirl having the same axial mass flux. The preferred Strouhal number based on the mass-averaged axial velocity and nozzle exit diameter for both swirling and nonswirling flows is 0.4.
    Keywords: AERODYNAMICS
    Type: NASA-CR-180895 , NAS 1.26:180895
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  • 3
    Publication Date: 2019-06-28
    Description: A propeller of an advanced turboprop testbed aircraft in pusher configuration is instrumented with 22 miniature blade-mounted transducers (BMTs) at two radii. Upstream pylon wake interaction with the propeller is the source of a one-per-cycle excitation for the blades in flight. The time history of fluctuating pressure signals over 26 flight conditions is statistically analyzed in the frequency domain. The rms amplitude of fluctuating pressure signals measured by suction surface BMTs indicates a very strong presence of the fundamental frequency over most of the upper surface. The pylon wake pressure signature on the propeller trailing edge, i.e., x/c not less than 0.80, shows predominantly random turbulence; hence, the amplitude of the fundamental frequency wave is fairly small. The resurgence of a large amplitude fundamental harmonic with coherent pylon wake signature further downstream, say at 90 percent chord, is unexpected behavior. The appearance of a dominating second propeller shaft order in the spectra of the rms pressure in transonic flight conditions identifies the presence of a two-per-cycle excitation source in the azimuthal direction. This is due to the presence of a shock wave, as evidenced by the pressure-time history plots.
    Keywords: AERODYNAMICS
    Type: In: Rotating machinery - Transport phenomena; Proceedings of the 3rd International Symposium on Transport Phenomena and Dynamics of Rotating Machinery (ISROMAC-3), Honolulu, HI, Apr. 1-4, 1990 (A93-54; p. 665-680.
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  • 4
    Publication Date: 2019-07-27
    Description: A reduced Navier-Stokes (RNS) initial value space marching solution technique was applied to vortex generator and separated flow problems and demonstrated good predictions of the engine face flow field. This RNS solution technique using FLARE approximations can adequately describe the topological and topographical structure flow separation associated with vortex liftoff, and this conclusion led to the concept of a subclass of separations which can be called vorticity separations: separations dominated by the transport of vorticity. Adequate near wall resolution of vorticity separations appears necessary for good predictions of these flows.
    Keywords: AERODYNAMICS
    Type: Symposium on Turbulent Shear Flows; Sept. 9-11, 1991; Munich; Germany
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  • 5
    Publication Date: 2019-08-28
    Description: As a building block in the development of smart lift-enhancement devices, a new concept for flow control using active vortex generators (AVGs) is presented. Ramp, wedge, and doublet wedge (Wheeler) VG configurations are investigated. The AVGs are designed to conform to the surface of the wing section at low alpha. As the section approaches the stall, they are deployed and accordingly, alpha(stall) and C(lmax) are increased. A qualitative analysis of the flow around the various VG configurations was conducted in a low speed wind tunnel at 1.6 ft/s and a Reynolds number of approximately 3400. The results demonstrate that ramp VGs produce vortices that have the longest distance at breakdown. The VGs were also applied to a 25-in. span, 8-in. chord NACA 4415 wing section. Optimization studies were conducted on the spanwise spacing, chordwise position, and size of statically deployed VGs. The test results demonstrate a 14-percent increase in C(lmax) while increasing alpha (stall) by up to 3.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 93-3447 , In: AIAA Applied Aerodynamics Conference, 11th, Monterey, CA, Aug. 9-11, 1993, Technical Papers. Pt. 1 (A93-47201 19-02); p. 376-386.
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  • 6
    Publication Date: 2019-07-13
    Description: A reduced Navier Stokes (RNS) initial value space marching solution technique was applied to vortex generator and separated flow problems and demonstrated good predictions of the engine face flow field. This RNS solution technique using FLARE approximations can adequately describe the topological and topographical structure flow separation associated with vortex liftoff, and this conclusion led to the concept of a subclass of separations which can be called vorticity separations: separations dominated by the transport of vorticity. Adequate near wall resolution of vorticity separations appears necessary for good predictions of these flows.
    Keywords: AERODYNAMICS
    Type: NASA-TM-104407 , E-6233 , NAS 1.15:104407 , Turbulent Shear Flow Symposium; Sep 09, 1991 - Sep 11, 1991; Munich; Germany
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