Wyniki wyszukiwania - BazTech

1

Flow averaging tube geometry improvement for K-factor stability increase

Kabaciński M., Pospolita J.

Measurement Automation Monitoring

|

2017

|

Vol. 63, No. 1

2--5

EN

Fluid flow around two-profile averaging differential pressure sensor was investigated in this paper. Research concentrated particularly on fluid movement direction and velocity over the investigated flow sensor. Analysis was conducted experimentally in low velocity wind tunnel. Because of large number of measuring points placed very close to each other, it was decided that velocity profile measurement will be performed by means of fully automated test stand. Due to a recirculation of the stream in the vicinity of the probe tested in the wind tunnel, an original two-direction probe was used. A linear module with a stepper motor formed an integral part of the measurement system. The location of the measuring probe, the possibility of adjusting stream mean velocities and data acquisition was undertaken by means of a dedicated program. The above mentioned investigation method helped to improve the metrological properties of the flowmeter applying non symmetrical probe cross-section forced air stream to be redirected in the desired direction. This modification significantly increased K-factor value and stability of air flow through the contraction of the flowmeter.

2

Injection Effects on Sediment Transport in Closed-Conduit Flows

Cao D., Chiew Y.-M., Yang S.-Q.

Acta Geophysica

|

2016

|

Vol. 64, no. 1

125--148

EN

Experiments were conducted to investigate injection effects on sediment transport in closed-conduit flows. The results show that the sediment transport rate essentially remains unchanged when the ratio of the injection velocity and that at boiling, Vi/Vcr < 10. However, significant sediment transport rate is observed when Vi/Vcr increases beyond this limit. In the literature, three semi-empirical models have been developed to relate seepage effects on the sediment transport rate. The experimentally measured data in the pre- and post-boiling condition (Liu and Chiew 2014, and the present study, respectively) are compared with these models. The results show that the models of Francalanci et al. (2008) and Nielsen et al. (2001) perform poorly in predicting injection effects on the sediment transport. Although Yang’s (2013) model could reasonably predict the influence of injection on the sediment transport rate in the post-boiling condition, it similarly fails when applied to the pre-boiling condition.

3

Experimental research on velocity profiles in selected flow systems

Kabaciński M.

TASK Quarterly : scientific bulletin of Academic Computer Centre in Gdansk

|

2012

|

Vol. 16, No 3-4

185--201

EN

A problem of measuring of velocity profiles with the use of a fully automated test stand is presented in this paper. Due to the installed measurement equipment and various software alternatives it is possible to assess the inlet effect and distribution of velocities in the vicinity of averaging Pitot tubes in order to determine the phenomena occurring in their vicinity (recirculation, main stream direction) and verify the numerical models of turbulence. Due to the stream recirculation in the vicinity of the probes tested in a wind tunnel, a two-way probe was used instead of a Pitot tube. A linear module with a stepper motor formed an integral part of the measurement system whereby it was possible to determine the position of the measurement probe with a precision of 0.1mm. The measuring anemometer location, the possibility of adjusting the stream mean velocities and data acquisition were established by means of an original program. As far as the research in pipelines is concerned - the resulting characteristics allow the uncertainty of measurement to be precisely determined, which should be accounted for during the determination of air fluxes at locations which are not included in the technical documentation of a flowmeter.

4

Opracowanie efektywnej metody obliczania niestacjonarnego tarcia cieczy podczas turbulentnego przepływu w przewodach zamkniętych

Kudźma S.

Zeszyty Naukowe Katedry Mechaniki Stosowanej / Politechnika Śląska

|

2005

|

z. 29

273-278

PL

W pracy przedstawiono procedurę obliczania strat tarcia w przewodach ciśnieniowych w przypadku niestacjonarnego przepływu turbulentnego. Jest ona wykorzystana do symulacji stanów przejściowych metodą charakterystyk. Opiera się ona o nową aproksymowaną postać funkcji wagowej i jej implementacji do uzupełnionej i poprawionej metody Trikha'ego obliczania niestacjonarnych strat tarcia podczas przepływu laminarnego. Przy zastosowaniu tej metody uzyskano znaczące skrócenie czasu obliczeń, przy pomijalnie małym spadku dokładności rozwiązania w porównaniu do rezultatów obliczeń z wykorzystaniem metody tradycyjnej.

EN

The paper presents a procedure of calculations of unsteady friction losses by a new efficient method. This procedure concerns turbulent condition calculated by method of characteristics. It is based on a new approximation of weighting function and an improved implementation of Trikha's method used in calculation of transient laminar flow. Results of simulation obtained using the new efficient method of simulation are nearly indistinguishable from results obtained using the exact (traditional) expressions whereas time of computation is much more shorter.