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1

Pumping capacity of pitched blade multi – stage impellers

Jirout T.

Chemical and Process Engineering

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2014

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Vol. 35, nr 1

47--53

EN

This paper extends knowledge about flow in an agitated batch with pitched blade multi-stage impellers. Effects of various geometrical parameters (blade number, distance between impellers) of pitched blade multi-stage impellers on pumping ability have been investigated. Axial velocity profiles were measured by LDA (Laser Doppler Anemometry). Axial pumping capacities were obtained by integration of measured axial velocity profiles in outflow from impellers. Main attention was focused on the effect of the distance between impellers in multi-stage configurations, on their pumping capacity and flow in the mixing bath in comparison with an independently operating pitched blade impeller with the same geometry. In case of a relatively close distance between Impellers H3/d= 0.5 - 0.75, the multi-stage impeller creates only one circulation loop and the impellers itself behave identically as pumps in series. However for relative higher distance of impellers than H3/d= 1.25, the multi-stage impeller creates two separated circulation loops.

2

Differences in the perilymph fluid stimulation before and after experimental stapedotomy

Kwacz M., Mrówka M., Wysocki J.

Acta of Bioengineering and Biomechanics

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2012

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Vol. 14, no. 2

67-73

EN

A stapedotomy surgery using a piston stapes prosthesis significantly modifies the perilymph fluid stimulation level and always leads to alteration of conditions in sound transmission through the cochlea. This paper shows the results of non-contact measurements of the stapes head velocity, a Teflon piston stapes prosthesis velocity and round window velocity conducted in freshly harvested human cadaver temporal bone specimens. The vibration patterns were measured within the frequency range of 0.4-10 kHz at the sound pressure level of 90 dB administered to the external auditory canal in the same specimen before and after experimental stapedotomy. It was shown that the vibrations of the stapes Teflon piston prosthesis and the physiological stapes are similar and approximately five-fold lower amplitude of the round window membrane vibrations compared to a physiologic situation is caused by piston shape of the stapes prosthesis. The results in this report are the part of a larger study designed to develop a new type of chamber stapes or whole middle ear prosthesis.

3

Round window membrane motion before and after stapedotomy surgery - an experimental study

Kwacz M., Mrowka M., Wysocki J.

Acta of Bioengineering and Biomechanics

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2011

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Vol. 13, no. 3

27-33

EN

This paper presents the results of non-contact measurements of the human ear round window (RW) membrane motion in freshly harvested human cadaver temporal bone specimens. A PSV 400 Scanning Laser Vibrometer system (Polytec, Waldbronn, Germany) was used to determine the effect of stapedotomy on the sound-induced displacement amplitude of the RW membrane. The vibration patterns were measured in the frequency range of 0.4–10 kHz in four specimens with air conduction stimulation at 90 dB SPL applied to the external auditory canal. It was shown that the vibration amplitude of the RW membrane after stapes piston prosthesis implantation, in comparison with a physiological specimen, was reduced several times. The motion of the RW membrane can be used to determine the cochlear stimulation for the evaluation of middle ear ossicle reconstruction, especially in the case of otosclerosis surgery.