[en] This article describe the results of experimental observations in pulsating simple shear flows. A uniform-mean-gradient shear flow was generated within the best test section od an open circuit wind tunnel. Transverse arrays of honeycomb channels with differing resistances were used to generated shear flow at low shear rates (less than 20 s-¹⁾ A set of rotating vanes pulsated the flow field at 8.5 Hz and 18 Hz. Instantaneous velocity was measured by employing a two-component hot wire anemometry technique. The experimental credibility of the facility was established in stationary simple shear flows. In pulsating flows the pulsation effects on mean shear rate, the kinetic energy of turbulence, Reynolds stresses and the probability dentist y of stream-wise velocity fluctuations were studied. It was found that division form stationary turbulence with pulsation at 8.5 Hz was more significant than at 18 Hz. The modified form of the governing equations for pulsating flows was derived. The emphasis of the analysis was placed on the production and dissipation mechanisms in pulsating simple shear flows. The results are discussed in connection with the modified equations and physically plausible explanations are offered to interpret the laboratory observations. It is concluded that the anisotropic dissipation mechanism may be responsible for the observed experimental results

[en] In the month of March, 1967, a cooperative study was conducted at the AEC Hanford Reservation, Richland, Washington, by personnel from the Pacific Northwest Laboratories, the University of British Columbia, and the University of Washington. Presented here are results of a sequence of observations made during one day using a three dimensional sonic anemometer - thermometer for fluctuation measurements, sensitive cup anemometer for wind profiles, and thermocouples for temperature profiles. Other measurements using an ultra-fast response thermal probe and a hot-wire anemometer were made simultaneously but will not be reported here. The electronic and acoustic components of the sonic device are capable of responding to fluctuations up to hundreds of cycles per second but the length of the sound paths used, 30 centimeters, limits the meaningful response to about 10 cycles per second, more or less, depending on the wind speed. The sonic instrument was mounted at a height of four meters; mean winds and temperatures were measured at six heights from .75 to 24 meters. The runs, here numbered from 5 to 11, were spaced one hour apart and each lasted for about one half hour. Run number five began in the early afternoon. The early runs show unstable temperature stratification, run nine was approximately neutral; ten and eleven show stable stratification. The average wind speed varied throughout the day hut the trend was towards higher speeds: run five had the lowest and run eleven the highest average speeds. Data for the profiles were recorded on punched tape, sonic data was recorded in FM format on magnetic tape. (author)

[en] Variations in wind velocity and direction due to the mounting structure are studied using Gill anemometers mounted on 1.8m long arms of a 232m high tower. The tower 'shadowing' effect for the observed range, from 0 to 20 m/s, is in linear correlation with the velocity. The polar diagrams of the variations in wind speed and direction are presented as a funciton of the wind's direction. The horizontal component decreases by 15% when the anemometer is on the windward side of the tower, and by a maximum of 80% on the lee side. In the letter case the decrease is highly sensitive to wind direction. Variations in direction do not exceed 15 degrees

No abstract available

[en] Published in summary form only

[en] This paper describes the design and manufacture of a novel system to measure low water velocities in the range of 0.5-2.5 cm/s. Measurements had to be conducted inside horizontal slots which were 7 mm wide, 220 mm long and 6 mm deep. Results of the measurements are discussed

[en] Two thermally-coupled hot wires form a detector for measuring the smallest gas-streams or velocities. The performance of these sensors in respect to small, sinusoidal gas-streams is analysed. Furthermore, the natural fluctuations acting upon the system are investigated. As a quality criterion, an expression of the signal to noise ratio in dependence on constructive data is given. (orig.)

No abstract available

[en] Short communication

No abstract available