Abstract
It is well known that the precession movement of the helical vortex core generated in the swirl flow from the runner exit of Francis turbine causes the pressure oscillation in the draft tube. This phenomenon which occurs in the part-load operation have been investigated in detail for a long time. At the part-load operation, flow from the runner exit has the swirl in the same direction as that of the runner rotation. On the other hand, when the turbine operates at over-load, flow from the runner exit has the swirl against the runner rotation and the characteristics of the pressure oscillation in such a situation as this is very different in quality from that at the part-load operation. Sometimes this phenomenon raises a hard problem in the actual plant. In the present paper, the behavior of the vortex core and the basic characteristics of pressure oscillation under the conditions of reverse swirl flow are investigated using a small Francis turbine test rig with a cone-type draft tube.
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Abbreviations
- a :
-
guide vane opening (GVO) [m]
- D e :
-
exit diameter of runner [m]
- Q :
-
discharge [m3/s]
- Δ h :
-
surge amplitude [m]
- Q 11 :
-
unit discharge,EquationSource% MathType!MTEF!2!1!+- % feaagCart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbWexLMBbXgBd9gzLbvyNv2CaeHbl7mZLdGeaGqiVu0Je9sqqr % pepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9vqaqpepm0xbba9pwe9Q8fs % 0-yqaqpepae9pg0FirpepeKkFr0xfr-xfr-xb9adbaqaaeGaciGaai % aabeqaamaabaabauaakeaacaWGrbGaai4laiaacIcacaWGebWaa0ba % aSqaaiaadwgaaeaacaaIYaaaaOWaaOaaaeaacaWGibaaleqaaOGaai % ykaaaa!459A!</EquationSource><EquationSource Format="TEX"><![CDATA[$$Q/(D_e^2\sqrt H )$$
- q :
-
injecting air quantity [m3/s]
- n :
-
runner speed [rpm]
- H :
-
effective head [m]
- f :
-
surge frequency [Hz]
- n 11 :
-
unit speed, = EquationSource% MathType!MTEF!2!1!+- % feaagCart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbWexLMBbXgBd9gzLbvyNv2CaeHbl7mZLdGeaGqiVu0Je9sqqr % pepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9vqaqpepm0xbba9pwe9Q8fs % 0-yqaqpepae9pg0FirpepeKkFr0xfr-xfr-xb9adbaqaaeGaciGaai % aabeqaamaabaabauaakeaacaWGUbGaamiramaaBaaaleaacaWGLbaa % beaakiaac+cadaGcaaqaaiaadIeaaSqabaaaaa!4397!</EquationSource><EquationSource Format="TEX"><![CDATA[$$n{D_e}/\sqrt H$$
- f 11 :
-
unit frequency, = EquationSource% MathType!MTEF!2!1!+- % feaagCart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbWexLMBbXgBd9gzLbvyNv2CaeHbl7mZLdGeaGqiVu0Je9sqqr % pepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9vqaqpepm0xbba9pwe9Q8fs % 0-yqaqpepae9pg0FirpepeKkFr0xfr-xfr-xb9adbaqaaeGaciGaai % aabeqaamaabaabauaakeaacaWGUbGaamiramaaBaaaleaacaWGLbaa % beaakiaac+cadaGcaaqaaiaadIeaaSqabaaaaa!4397!</EquationSource><EquationSource Format="TEX"><![CDATA[$$f{D_e}/\sqrt H$$
References
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Hosoi, Y., Characteristics of pressure surge due to whirling water from exit of water turbine runner, Bulletin of the.ISME, Vol. 16, No. 99 (1973), pp. 1324–1335.
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© 1996 Springer Science+Business Media Dordrecht
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Furuie, Y., Mita, H., Hosoi, Y. (1996). Experimental Investigation of Vortex Core in Reverse Swirl Flow From Francis Runner. In: Cabrera, E., Espert, V., MartÃnez, F. (eds) Hydraulic Machinery and Cavitation. Springer, Dordrecht. https://doi.org/10.1007/978-94-010-9385-9_85
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DOI: https://doi.org/10.1007/978-94-010-9385-9_85
Publisher Name: Springer, Dordrecht
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