Particle-laden swirling flow

Application Challenge AC3-12 © copyright ERCOFTAC 2013

Description of Test Case Experiments

For the detailed study of particle-laden, swirling two-phase flows, a vertical test section with downward flow was chosen (Figure 2). In order to allow good optical access, a simple pipe expansion was selected as test section. Such a configuration has the advantage that the inlet conditions can be measured easily, which is important for performing numerical calculations. The complete test rig consists of two flow circuits (Figure 1) for the primary (6) and secondary annular flows (5), respectively. A blower (1) with a variable flow rate supplies these two pipe systems via a T-junction and a throttle valve (2) is used to adjust the flow rate at the primary inlet. The mass flow rates through the primary and annular inlets were obtained from two orifice flow meters (3). The secondary flow circuit is split into four smaller pipes which are connected radially to the swirl generator. The upper part of the swirl generator is constructed as a settling chamber, and the air passes over a number of screens and then moves radially inward across the radial swirl vanes. The swirl intensity of the annular flow may be adjusted continuously by turning the swirl vanes in the radial swirl generator (8). The primary flow circuit is connected to a pipe passing straight through the centre of the swirl generator. The dust particles are injected into the primary flow above the swirl generator by a particle feeder (4) with a variable-speed motor. Above the particle feeder, a reservoir (7) for the dust particles is installed.

The inlet configuration and the dimensions of the test section are shown in Figure 1. The test section consists of a 1.5 m long Plexiglas tube with an inner diameter of 194 mm. The end of the test section is connected to a stagnation chamber (11). As a result, an annular type of central recirculation bubble was established in the upper part of the test section.