Spectrum Measurements with Laser Velocimeters

Mayo, W.

doi:10.1007/978-94-009-9565-9_46

Cited by 28 publications

(11 citation statements)

References 14 publications

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“…About 1,600 points per position were collected to estimate the mean velocity and turbulence intensity and over 50,000 points were collected for determining the turbulence spectrum. A correlation method ("slotting" technique), described by Mayo (1978) and Srikantaiah and Coleman (1985), was employed to obtain the spectral estimates.…”

Section: Methodsmentioning

confidence: 99%

Detection of a pulsed flow in an MHD environment by laser velocimetry

Srikantaiah

Wilson

1988

Experiments in Fluids

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Section: Methodsmentioning

confidence: 99%

Detection of a pulsed flow in an MHD environment by laser velocimetry

Srikantaiah

Wilson

1988

Experiments in Fluids

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“…The method of "discretized lag products," is used to form autocorrelation estimates. Mayo 17 shows that by this method alias free spectral estimates may be obtained, in principle, with any mean sample rate however slow. The length of each time block is 1 s, and 200 such blocks are used.…”

Section: Measurement Techniquementioning

confidence: 97%

Temperature and Velocity Measurements in Premixed Turbulent Flames

Dandekar

Gouldin

1982

AIAA Journal

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Turbulent flame-speed data for premixed flames of methane-air, propane-air, and ethylene-air mixtures stabilized in grid turbulence are reported and discussed. It is shown that turbulence effects on flame speed cannot be correlated fully by the turbulence length scale and rms velocity in the cold flow. Rather there appear to be significant flame-flow turbulence interactions affecting both turbulence level in the reaction zone and measured flame speeds. Results of detailed velocity measurements, including autocorrelations, by laser velocimetry are used to elucidate the nature of these interactions. It is concluded that flame-speed experiments must be designed and conducted to provide sufficient information (e.g., boundary conditions) to allow for reconstruction of the flowfield and these interactions by modelers if the data are to be of value in turbulent combustion model development and evaluation. Nomenclature ? = integral scale of turbulence P = pressure R ( = turbulence Reynolds number, uV/v R x = microscale turbulence Reynolds number, u\/v S L = laminar flame speed S T = turbulent flame speed u = rms velocity, = vw 77 u" = U-U U = instantaneous velocity U = Favre average velocity U = Reynolds average velocity e = Favre average energy dissipation rate X =Tay lor's microscale p = gas density p(r) = autocorrelation coefficient, =

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“…These measurements are used to compute mean velocities, Reynolds stresses and triple products. To compute the autocorrelation function, Mayo's (1978) discretized lag products technique is used. Twenty-five sets of 10000 points are recorded along with the time between data points to be used in the time series analysis.…”

Section: Data Acquisition and Analysismentioning

confidence: 99%

“…The autocorrelation function is estimated from 25 blocks of continuous velocity data consisting of 10000 samples each, using Mayo's discretized lag products technique (Mayo 1978) as discussed in §2.2. One-sided power spectral density estimates are computed by Fourier transforming the autocorrelation function, after the autocorrelation is extended to negative lag times making use of the symmetry of the autocorrelation.…”

Section: Autocorrelations and Spectramentioning

confidence: 99%

Turbulent flow normal to a triangular cylinder

Heist

Gouldin

1997

J. Fluid Mech.

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Laser Doppler Velocimetry (LDV) measurements are presented for a nominally two-dimensional constant-density flow over a surface-mounted triangular cylinder. The thickness of the boundary layer approaching the triangular cylinder is much less than the height of the triangle. Momentum and turbulent kinetic energy balances are presented and comparisons are made with other separated and reattaching flows. Also, time domain information is presented in the form of autocorrelations and spectra. From the energy balances, the importance of the pressure transport term at the high-speed edge of the shear layer is seen. Observations of the relationships between the shapes of the spectra and the details of the energy balance are made. For example, the slope of the velocity spectra varies from the free-stream value of −5/3 to a value of −1 in the middle of the recirculation region. Concurrent with this increase in slope is a decrease in the role of shear production in the turbulent kinetic energy balance and an increase in the role of advection and turbulent transport. From the two-component LDV measurements, a very low-frequency unsteadiness is shown to contribute energy preferentially to different components of the velocity fluctuations depending on the location in the flow.

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Spectrum Measurements with Laser Velocimeters

Cited by 28 publications

References 14 publications

Detection of a pulsed flow in an MHD environment by laser velocimetry

Detection of a pulsed flow in an MHD environment by laser velocimetry

Temperature and Velocity Measurements in Premixed Turbulent Flames

Turbulent flow normal to a triangular cylinder

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