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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Experiments in fluids 12 (1992), S. 385-393 
    ISSN: 1432-1114
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract This paper presents new experimental results on thermal field and heat transfer in a two-dimensional annulus between horizontally eccentric cylinders. The study is conducted by means of optical techniques, for 1.07×104≤Ra L≤8.27×104 and a wide eccentricity range. The horizontal eccentricity of the inner cylinder substantially alters the thermal field and the geometry of the plume, but, in analogy to the behaviour for vertical eccentricity, the average Nu is slightly affected in the investigated range of eccentricity. The concentric geometry is also considered mainly to validate the experimental technique and evaluate the accuracy of the adopted methodology by comparison with available results. Both shearing interferometer and reference beam interferometer are obtained by means of Wollaston prisms with appropriate splitting angles, so that the temperature and local Nu distributions may be evaluated quantitatively from the original pictures via digital image processing.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Experiments in fluids 22 (1997), S. 268-270 
    ISSN: 1432-1114
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The statistical properties of the velocity differences are experimentally investigated in a turbulent jet-flow at moderate Re λ by X-probe hot wire anemometry measurements. It is found that the traverse velocity components show a more intermittent behavior with respect to the longitudinal ones. This result is obtained by the analysis of the longitudinal and transverse intermittency exponents measured by the Extended Self-Similarity form of scaling, and by the comparison of the longitudinal and transverse velocity difference Probability Distribution Functions.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 8 (1996), S. 1181-1191 
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The statistical properties of the velocity fluctuation components at moderate Reλ are studied in homogeneous and non-homogeneous turbulence by an experimental technique. Measurements are performed by means of a hot-wire anemometer with X-probe downstream of a screen for several positions, x/M=9 up to 109, where M is the screen mesh size, with Reλ ranging from 37 to 82. The homogeneity of the flow is analyzed by means of velocity measurements in different transverse positions and a direct evaluation of the local isotropy of the flow is performed by means of velocity spectra. The scaling properties of the statistical moments of the structure functions up to the order of six, are investigated in the extreme positions by means of the extended self-similarity (ESS) method and the intermittency exponents are detected for both homogeneous and non-homogeneous flow conditions. A comparison of the longitudinal and transverse intermittency exponents as functions of the position is then performed and discussed in addition to the analysis of the transition from the anomalous to a regular scaling for small spatial separation. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 11 (1999), S. 423-431 
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Experimental data obtained in the near region of a turbulent jet flow (from x/D=0 up to x/D=19, where D is the jet diameter and x is the axial coordinate) are processed through wavelet decomposition. A wavelet based technique for coherent structures identification is applied to the longitudinal and transverse velocity data series obtained by X probe hot wire anemometry measurements. This methodology permits the evolution with x of the time signature of coherent structures to be analyzed. The statistics of the local turbulent energy magnitude is also discussed and the temporal dynamics is studied by the analysis of the time of appearance of the most energetic structures evolving with x/D. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Journal of Computational Physics 106 (1993), S. 286-298 
    ISSN: 0021-9991
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Computer Science , Physics
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Experiments in fluids 26 (1999), S. 161-168 
    ISSN: 1432-1114
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  An experimental investigation of the statistical properties of the velocity difference in an anisotropic turbulent cylinder wake at moderate Re λ is conducted by a triple hot-wire anemometer (HWA) probe. The energy spectra show a clear large scale anisotropy due to the presence of the Von Karman vortices. In spite of the low Re λ and the large scale anisotropy, the extended-self-similarity (ESS) allows location of broad scaling ranges and the calculation of the scaling exponents of the three velocity structure function components in order to examine the intermittency anomalies. More intermittent behavior of the transverse velocity components with respect to the longitudinal one is found both by ESS and by comparison of the longitudinal and transverse velocity difference probability distribution functions (PDF).
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-1114
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A unified methodology for the application of reference beam and shearing interferometry to measure axisymmetric temperature fields within flames is proposed. Sensitivity and accuracy of the techniques are analyzed basing on interferograms of reference temperature profiles and CARS measurements obtained in test laminar flames. The rapid decay of temperature measurements accuracy with increasing both intensity of errors sources and uncertainty on independent parameters is assessed. The spatial variation of mixture composition in diffusive combusting flows requires the application of complementary methods to obtain a satisfactory accuracy, while flow fields with lean premixed combustion can be treated as optically-homogeneous media. The temperature maps resulting from the investigation of the test laminar flames are presented and discussed. The capability to disclose the thermal structure and to provide reliable quantitative data is demonstrated.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Experiments in fluids 20 (1996), S. 199-209 
    ISSN: 1432-1114
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract An experimental investigation of scaling laws in turbulence generated by a biplane grid for low Reynolds numbers (Re λ) is presented. The present study covers a wide range of flow field conditions (from Re λ∼2.5 to Re λ∼36) that have not been analyzed from this point of view. It is shown that following the Kolmogorov theory a scaling range can not be observed since the separation between the energy production scales and the dissipative scales is too short. On the other hand, an extended form of scaling, the Extended Self-Similarity (ESS), permits the identification of a range of scales characterized by the same scaling exponent much wider than the one previously examined. Thus the scaling laws for the first six moments of the velocity structure function are accurately calculated by means of the ESS and an anomalous scaling with respect to the Kolmogorov theory is observed for Re λ down to the order of 10. As a matter of fact the scaling exponents are in good agreement with the ones that were determined at higher Re λ by previous experimental and numerical investigations. For Re λ≤6 a regularization of the scaling exponents is observed as an effect of the dissipation. We also present an analysis of the universality properties of the ESS form of scaling by means of the form function and an analysis of the sensitivity of the scaling range to the Re λ.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Experiments in fluids 28 (2000), S. 1-10 
    ISSN: 1432-1114
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  Two phase sampling techniques are developed for the analysis of the propellers wake by means of LDV. The first one (TTT) uses the detection of Doppler signal as trigger condition; each LDV sample, tagged with the blade angular position at the measurement time, is arranged inside angular slots. The other technique (ATT) follows an angular triggering method, with some enhancements to reduce measurement time. The implemented techniques are complementary from the accuracy and efficiency point of view. The TTT enables to quickly analyze the propellers wake, in view of the minimization of data acquisition time, particularly in poor flow seeding conditions. The ATT is instead suitable for accurate investigations of space-limited and highly turbulent flow regions.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Meccanica 30 (1995), S. 719-725 
    ISSN: 1572-9648
    Keywords: Turbulence ; Self-similarity ; Fluid dynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Description / Table of Contents: Sommario Nel presente lavoro viene presentato uno studio riguardante le proprietà della cosiddetta funzione di forma $$f\left( {\frac{r}{\eta }} \right)$$ che caratterizza le leggi di scala delle fluttuazioni di velocità in un flusso turbolento. L'analisi é basata su precedenti misure sperimentali effettuate in flussi turbolenti generati da griglie a bassi Reλ ed in condizioni omogenee e non omogenee. Le proprietá di universalitá della funzione di forma sono studiate nell'ambito della cosiddetta Extended Self-Similarity.
    Notes: Abstract In this work some investigations on the properties of the so calledform function $$f\left( {\frac{r}{\eta }} \right)$$ which characterizes the scaling behavior of the small scales fluctuations in a turbulent flow are presented. The present analysis is based on previous experimental measurements in homogeneous and non-homogeneous grid-generated turbulence at low Reλ. The universality properties of the form function are investigated in the frame of the Extended Self Similarity (ESS) form of scaling.
    Type of Medium: Electronic Resource
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