| 1. |
- Bergenblock, Tobias, 1972, et al.
(författare)
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Averaging of particle data from phase Doppler
- 2006
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Ingår i: International Journal of Multiphase Flow. ; 32, s. 248-268
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Tidskriftsartikel (refereegranskat)abstract
- A novel post-processing algorithm is proposed to correct statistical bias observed in the treatment of time seriesobtained by a phase Doppler anemometer (PDA) at flow locations with variable particle velocity and concentration.Extensive properties of each validated particle are weighted with their inverse measuring (validation) volume to accountfor the procedure of particle sampling and fluctuations in the particle concentration. To compensate for the short characteristiclength of the validation volume, the properties of particles are expressed by properties of fields of particle groups,using a local averaging time. A window shift and a decorrelation scheme are applied on the fields to increase their frequencyresolution. This algorithm has been tested on numerical time series, provided by an Eulerian/Lagrangian code representinga gas/solids flow past a bluff body. Moments and spectral estimates of concentration and velocity of particlegroups were successfully validated by the numerical simulation using the PDA data algorithm and control volume averaging.The control volume was much larger than the PDA validation volume, but the centre positions of the two volumeswere identical.
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| 2. |
- Bergenblock, Tobias, 1972, et al.
(författare)
-
Experimental estimation of particle flow fluctuations in dense unsteady two-phase flow using phase Doppler anemometry
- 2007
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Ingår i: International Journal of Multiphase Flow. ; 33, s. 849-872
-
Tidskriftsartikel (refereegranskat)abstract
- A recently proposed and successfully validated post-processing algorithm is extended to treat particle data obtained by a phase Doppler anemometer (PDA) in dense, fluctuating, low-speed, two-phase flow. In such a flow, Doppler signals may be noisy and split, since particles have long residence times in the measurement volume. A novel time average based on the measured burst lengths is proposed to estimate the cross-sectional area of the measurement volume. This time average accounts for the possible split of a noisy Doppler burst, and it provides a more general description of the measurement volume than the conventional ensemble average. The extended post-processing algorithm was tested on experimental time series obtained in a circulating fluidized bed and the algorithm was compared to conventional treatment of the particle data by a commercial PDA processor. The conventional processing strongly overestimates the vertical mass flux integrated over the cross-section. In contrast, time-mean and fluctuations of mass flux, particle volume concentration, and particle velocity are reliably estimated employing the proposed algorithm, with continuity check parameters in succeeding particle data, as well as with a particle velocity filter to estimate the size of the probe volume, applying a two-component PDA in a three-dimensional flow.
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