Distortion of Flow Measurement and Cavitation Occurs Due to Orifice Inlet Velocity Profiles

This analysis investigates the distortion of flow measurement and the increase of cavitation along orifice flowmeter. The analysis using the numerical method (CFD) validated the distortion of flow measurement through the inlet velocity profile considering the convergence and grid dependency. Realizable k-e model was selected and y+ was about 50 in this numerical analysis. This analysis also estimated the vulnerability of cavitation effect due to inlet velocity profile. The investigation concludes that inclined inlet velocity profile could vary the pressure which was measured at pressure tab near pipe wall and it led to distort the pressure values ranged from -3.8% to 5.3% near the orifice plate and to make the increase of cavitation. The investigation recommends that the fully developed inlet velocity flow is beneficial to accurate flow measurement in orifice flowmeter.

Authors:

• Byung-Soo Shin
• Nam-Seok Kim
• Sang-Kyu Lee
• O-Hyun Keum

Keywords:

• Orifice
• k-e model
• CFD

References:

[1] http://en.wikipedia.org/wiki/Orifice_plate, Wikipedia, 2011.
[2] General Requirements for Fluid Metering: Installation. USA: ASME
PTC 19.5-72, 1972, pp. 179-181.
[3] Flow Conditioning and Meter Installation Requirements. USA: ASME
PTC 19.5-2004, 2004, pp. 64-66.
[4] Salim et al., "Wall y+ Stratagy for Dealing with Wall-bounded Turbulent
Flows", IMECS 2009, Vol II, Hong Kong, 2009
[5] M. Ishii, K. Mishima, Two-fluid model and hydraulic constitutive
relations, Nucl. Eng. Des., Vol. 82, 1984, pp. 107.
[6] CFX Manual, Theory, 2009