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1

Eksperymentalna ocena długości odcinka stabilizacji strugi zaburzonej kolanem segmentowym 3x30°

100%

Pochwała S.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

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2012

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tom z. 100

91--94

EN

This paper presents results of experimental tests on a laboratory stand equipped with a lincar module equippcd with a stepper motor that allows traversing the test scction with a Prandtl tube in stcps of 2.00 mm. The study was conductcd for the vcrtical and horizontal positions and differential distances from a disturbing flow element, which was segment elbows 3x30°.

2

Wpływ deformacji profilu prędkości na wartość współczynnika przepływu przepływomierza z rurką uśredniającą ciśnienie dynamiczne

63%

Kabaciński M. , Pochwała S.

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tom R. 57, nr 2

157-160

PL

W pracy przedstawiono zasadę działania rurek uśredniających oraz stanowisko do ich wzorcowania. Zaprezentowano wyniki badań eksperymentalnych pomiaru strumienia powietrza przepływomierzami spiętrzającymi w strefie zaburzonego przepływu za pojedynczym kolanem. Określono profile prędkości w wybranych miejscach instalacji. Wyznaczono charakterystyki współczynnika przepływu K dla rurki o kształcie opływowym. Podano wartości współczynnika korekcyjnego umożliwiającego zmniejszenie niepewności pomiaru przepływu rurką uśredniającą. Wykazano, że lokalizacja przepływomierza poniżej 5D za kolanem powoduje istotny wzrost niepewności pomiaru.

EN

This paper presents experimental results of the air flow across an obstacle formed by a 90 degree segmented elbow. The internal diameter of the pipeline was D=152 mm, while the range of the mean velocities w = 10 30 m/s. The velocity profiles were determined (using Prandtl tube) both in the vertical and horizontal plane [12] in the relative distances L/D of the pipeline from 3 D to 20 D (Figs. 5 and 6). In the places of the established velocity profiles a streamlined flow averaging tube [7] was placed to determine the characteristics of the flow coefficient K (Figs. 8 and 9) as a function of the mean velocity (and Re number). The scope of this paper is also to present an automated test stand (equipped with a dedicated computer program - data acquisition) for calibrating flowmeters. The results of the experiments are given in the form of charts and compared. Analysis of the effect of changing the position of the averaging probe (vertical, horizontal) was conducted together with examination of the influence of the distance behind the obstacle (elbow) on the K-factor value. The realized experiment allowed shortening the distance between the obstacle and flowmeter installation place and informing about the correction factor value which can be used to minimise the uncertainty of the air flow rate measurement (Fig. 10). It was assumed that the horizontal plane is better for probe installation because of almost axi-symmetrical velocity profile and better repeatability of measurement points (K-factor changes by about 1%).

3

Eksperymentalne wyznaczanie profilu prędkości w kanale prostokątnym

51%

Pochwała S. , Rząsa M. , Pawłowski P.

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tom Nr 59

149--152

PL

Badania zrealizowane na potrzeby niniejszego artykułu miały na celu eksperymentalną ocenę wpływu typowego elementu armatury instalacyjnej oraz wartości turbulencji przepływu na wyznaczanie długość odcinka prostego pozwalającego na stabilizację strugi przepływającego płynu.

EN

The research reported in this article was concerned with experimental evaluation of the effect of installation of a typical element of armature and the level of flow turbulence on the length of the straight tube section needed for the development of fluid flow. In order to carry out the tests, an experimental setup was built, which main element consists of a steel channel through which ambient air is delivered inside the installation. The channel has a square cross-section and length of 160 mm. Along this channel, a system of three 30o elbows was installed and combined to form a single 90° segmented bend. With the purpose of assessing the flow disturbance at specified distances from the flow obstruction, it was necessary to determine the velocity profile of the fluid flow in the channel. This goal applied a measuring system comprising a Pitot tube connected to a linear module. This setup provided the measurements of the velocity along the entire section of the channel with the measurement space traversed with a step equal to 2mm.

4

Influence of typical flow disturbing elements on the flow rate in selected averaging Pitot tubes

51%

Pochwała S. , Kabaciński M. , Pospolita J.

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tom Vol. 16, No 3-4

219-228

EN

Flowmeters with averaging Pitot tubes are becoming more and more common in the industrial practice. It is often the case in long straight sections of channels with large diameters that the conditions regarding the adequately long sections of pipelines before and behind a flowmeter cannot be fulfilled. This is associated with the occurrence of an additional measurement uncertainty with an unknown value. Most of the information regarding this issue can be found for the case of Venturi probes. The amount of data regarding the flow averaging Pitot tubes is also limited. Hence, the decision to undertake the proposed subject. The conducted research made it possible to state recommendations regarding the metrology of testing. The results indicate that it is not only the distance from the flow disturbing element that plays a role but it is also the plane in which the sensor is located that affects the uncertainty of measurements of the flow averaging Pitot tubes.