EXPERIMENTAL STUDY OF AIR-WATER TWO-PHASE FLOW IN PARALLEL HELICALLY COILED PIPES

The air-water two-phase flow in a 12 mm inner diameter parallel helically coiled pipes is investigated with three different coils diameters. Void fraction, flow rate distribution and two-phase pressure drops along the pipes in the parallel channels are measured. The test two-phase pressure drops are compared with theoretical ones, in terms of multipliers and friction factors. The instabilities arisen during the experimental tests are investigated and are related to the void fraction and flow quality. The void fraction values corresponding to the onset of oscillations are compared with Relap5 code results at the same fluid dynamic conditions.