PSI - Issue 71

Abhijit Parate et al. / Procedia Structural Integrity 71 (2025) 256–262

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Fig. 4. Variation of particle velocity (V p )-to-fluid velocity (U) ratio with the inlet velocity

3.3 Variation in Nozzle Area Ratio To investigate the effect of nozzle area ratio on the particle velocity, three different nozzles are designed of area ratio 0.4, 0.5 and 0.6. Simulations are conducted with all three nozzles with an acceleration tube length of 600 mm and a standoff distance of 17 mm for the inlet velocity of 25 m/s. Fig. 5 presents the obtained results of particle-to-fluid velocity ratio with the change in nozzle area ratio. The results demonstrate a consistent increase in particle impact velocity with an increase in nozzle exit area. For the 0.4 area ratio, particles have less time in the acceleration tube to extract energy from the entrained fluid, resulting in lower particle-to-fluid velocity. In contrast, for the 0.6 area ratio the particle-to-fluid velocity is more due to the less fluid velocity.

Fig. 5. Variation of particle velocity (V p )-to-fluid velocity (U) ratio with the nozzle area ratio.

3.4 Effect of Acceleration tube length The effect of tube length on both fluid and particle velocities is also investigated by varying the tube length to 400 mm, 600 mm, and 800 mm. Fig. 6 presents the obtained results of particle-to-fluid velocity ratio with the change in acceleration tube length. Particle velocity exhibited a monotonic increase with increasing tube length. Notably, the particle-to-fluid velocity ratio increased with longer tube lengths, suggesting that particles extract more energy from the entrained fluid over a greater distance. The observed changes in velocity ratios between tube lengths indicate that, although fluid remained stable, the extended residence time within the tube provided particles with more opportunity to accelerate, leading to higher particle-to-fluid velocity ratio.