Effects of venturi length of swirl cup on carbon deposition

A research had been done to study the effects of venturi length of swirl cup on the carbon deposition of venturi by combustion experiments in quantification and numerical simulation analysis. Three variations of venturi lengths were made. The distances between venturi throat and nozzle exit of case A, B, C are 6mm, 8mm, 10mm respectively. Comparative analyses were conducted for above parameter in terms of the flow field, temperature field and carbon deposition characteristics in the swirl cup and the downstream. The experimental results show that the carbon amount on the inwall decrease with the increase of venturi length and the amount of reduction of case C can reach 99% by comparison to case A. Meanwhile, the numerical results indicate that the length of venturi has no discernable impact on the flow field and temperature field in the downstream of the swirl cup. However, the front stagnation points of the primary recirculation zone can be moved from the nozzle to the exit of the venture in path with the length increase. In addition, the peak value and distribution area of negative velocity and temperature near the venturi throat will have a dramatic reduction with the greatest amplitude between case A and C come to 99% and 35% respectively. Thus, increasing the length of venturi to a certain degree can lead to the carbon on the venturi sharply decrease, which has guiding significance for the structural design of the swirl cup.