NUMERICAL STUDY OF CRITICAL FLOW IN SMALL ORIFICES
Abstract
This paper presents a numerical investigation of critical flow in small cylindrical orifices. Microorifices with diameters ranging from 16 to 423mm with length to diameter ratios (L/D) ranging from 0,6 to 16 were simulated using a numerical solver. Flow simulations were carried out under several back to upstream pressure ratios (<i>P</i><sub>b</sub> / <i>P</i><sub>0</sub>) under pressurized (increasing upstream pressure <i>P</i><sub>0</sub>) and vacuum (decreasing back pressure <i>P</i><sub>b</sub>) modes of operation. Numerical results were validated by comparing calculated flow rates with experimental data. This comparison showed a good agreement between simulation and experimental data. Results also showed that, when operating with small diameter orifices under vacuum conditions, both the Reynolds number and the volumetric flow rate remain constant at critical flow regime. However, when operating under pressure, the volumetric flow rate refered to the upstream stagnation conditions does not stabilise even at critical flow conditions, and the Reynolds number increases by decreasing the back to upstream pressure ratio.
Event details
- Event
- FLOMEKO 2000
- Technical Committee
- TC9
- Place
- Salvador, Bahia, BRAZIL
- Time
- 4 June 2000 - 8 June 2000