Home > Search Results: keywords:"momentum flux"
Search:
Search Tips :: Advanced Search
Search collections:
Sort by: Display results: Output format:
National Repository of Grey Literature 3 records found  Search took 0.01 seconds. 
Synthetic Jet Characteristic Velocity Estimated nn The Basis of Momentum Flux Measurement
 Kordík, Jozef ; Trávníček, Zdeněk
The paper compares two methods of evaluation of synthetic jet characteristic velocity. The first method of the characteristic velocity estimation is based on a simple measurement of the synthetic jet momentum flux (the jet thrust) by means of precision scales. The second method is a standard one, it is based on spatial-temporal integration of the velocity profile at the synthetic jet actuator nozzle exit. The velocity profile was obtained here using hotwire measurements in air. Comparison of the methods is based on dimensionless stroke length of the synthetic jet. It is confirmed that the results of both methods are nearly the same for higher dimensionless stroke length. On the other hand, if the jet regime approaches to the synthetic jet criterion threshold (i.e. to the dimensionless stroke length of 0.5) the results of both methods diverge. Using the current results a correction is suggested for the momentum-flux-based method to match the standard one.
Detailed record
Analysis of non-harmonic excitation of synthetic jet actuators
 Kordík, Jozef ; Trávníček, Zdeněk
Axisymmetric synthetic jet actuator based on a loudspeaker was tested experimentally. The actuator was driven by a voltage waveform, whose shape was derived from a pulse-width modulated signal. While the duty cycle and frequency of the excitation signal were varied the outlet velocities were measured by a hot-wire probe. Integral quantities such as characteristic velocity, momentum flux, and kinetic energy flux were evaluated from the outlet velocities. Their maxima were located as functions of frequency and the duty cycle. The found maximal values were compared with results obtained for harmonic excitation. The highest improvement (about 18%) was achieved for kinetic energy flux.
Detailed record
Analýza nestacionárního proudění uvnitř ulice a dvoru
 Kellnerová, Radka ; Jaňour, Zbyněk
Spatial distribution of momentum flux and moments of third order of velocity components obtained from one-point measurement are investigated. The area of interest covers an inner part of street canyon and adjacent intersection. Time-averaged momentum flux were divided into particular quadrants using Quadrant analysis method. Comparison between flux events and skewness provides some insight into the spatial distribution of strong intermittent tendency and explain better the spatially local dominance of sweep and ejection.
Detailed record

Interested in being notified about new results for this query?
Subscribe to the RSS feed.
Digital Repository :: Search :: Submit :: Personalize :: Help
Powered by Invenio v1.1.2
Maintained by admin.invenio@techlib.cz
This site is also available in the following languages:
Česky  English