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1

Flow Velocity Measurement by Means of Spherical Probe on the Basis of Potential Flow Theory

Wierciński Z.

Zeszyty Naukowe. Cieplne Maszyny Przepływowe - Turbomachinery / Politechnika Łódzka

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2005

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nr 128, vol. 2

573--580

EN

Basing on the potential flow around a sphere the analysis of the velocity measurement by means of the sphere probe is presented. Solving the system of five nonlinear equations with four unknowns the simple theoretical characteristics of the five hole probe is found and compared with the experimental one. [...] Next, the analysis of the four hole sphere probe is considered. Only the rhombic and triangle point sets give the unique solution of the problem, and the quadratic set gives non-unique solution.

2

Theoretical foundation for velocity measurement by means of the five holes sphere probe

Wierciński Z.

Transactions of the Institute of Fluid-Flow Machinery

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2005

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nr 117

3-15

EN

The measurement of the local velocity belongs to the most common in the fluid dynamics and power engineering. This measurement is mostly done by the five hole sphere probe. In this paper, basing on the potential flow past the sphere, the analysis of the velocity measurement by means of the sphere probe is presented. The transformation relation between the spherical and the probe coordination i.e. yaw and pitch angle alfa and beta is found. Solving next the system of five nonlinear equations with four unknowns the simple theoretical characteristics of the five hole probe is found and compared with the experimental one. There is a quite good agreement in the angle ranges of - 10°< alfa < 10° and _10° < beta< 10°. The discrepancies between theoretical and experimental characteristics outside this region are probably caused by the inaccuracies in manufacturing of the sphere probe and differences between potential past a sphere and real How past a sphere probe.

3

On capability of using a four point sphere probe to flow velocity measurement

Wierciński Z.

Technical Sciences / University of Warmia and Mazury in Olsztyn

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2005

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nr 8

5-25

EN

Measurement of the velocity is, next to the pressure measurement, among the most frequent measurements in mechanics of fluids and power engineering. That measurement is taken using, among others, the five-hole sphere probe. This paper presents the analysis of velocity measurement using a sphere probe showing that positioning of four measurement holes on the surface of the sphere is sufficient for measurement of the velocity direction and module. As a result we obtain a system of four nonlinear algebraic equations, which, however, not always possesses a solution. The paper presents four selected configurations of measurement holes on the sphere surface, three of which assure unequivocalness of problem solution. Additionally, the theoretical characteristic of five-hole sphere probe and its comparison with the experimentally obtained characteristic is presented.

PL

Pomiar wektora prędkości należy, oprócz pomiaru ciśnienia, do najczęściej wykonywanych w mechanice płynów i w eksploatacji maszyn i urządzeń energetycznych. Pomiaru tego dokonuje się m.in. za pomocą sondy kulowej pięciootworowej. W pracy przedstawiono analizę pomiaru wektora prędkości za pomocą sondy kulowej, wykazując, że do pomiaru kierunku i modułu wektora prędkości wystarcza umieszczenie czterech otworów pomiarowych na powierzchni kuli. W rezultacie otrzymujemy układ czterech równań nieliniowych, który jednak nie zawsze ma rozwiązania. Przedstawiono cztery wybrane konfiguracje czterech otworów pomiarowych na powierzchni kuli, z których trzy zapewniają jednoznaczność rozwiązania problemu. Ponadto zaprezentowano teoretyczną charakterystykę pięciootworowej sondy kulowej i jej porównanie z charakterystyką otrzymaną eksperymentalnie.