Abstract Droplet entrainment offers high regression rate of HTPB/paraffin fuels, but also leads to more complicated mass and heat transfer mechanisms during combustion. The droplet entrainment of the fuels in a windowed two-dimensional (2D) slab burner were investigated by using a high-speed camera, and the convective heat transfer coefficient was modified. The results indicated that the entrained droplets could be easily generated below 1.29 MPa of combustion pressure (p c), which was dominant in the regression of fuels, whereas the regression rate decreased by approximately 0.9 mm when p c increased from 0.32 MPa to 1.29 MPa due to the negative correlation of droplet entrainment rate with p c. However, the regression at higher p c mainly depended on weak evaporation and thermal decomposition rather than droplet entrainment, which was insensitive to p c and decreased by only about 0.05 mm s−1 with the increase in p c from 1.85 MPa to 2.52 MPa. The carbonized layer could be easily formed on the burning surface at higher p c, which hindered the droplet entrainment. Additionally, the improvement of convective heat transfer coefficient with the presence of droplet entrainment was evaluated, and the blocking effect was weakened, especially under high oxidizer mass flux.
Highlights The generation of entrained droplets is studied for the combustion of HTPB/paraffin fuels. The dominant position of droplet entrainment for the high regression rate characteristics of HTPB/paraffin fuels is confirmed. The presence of characteristic combustion chamber pressure is found for the droplet entrainment process of HTPB/paraffin fuels. The correlation of convective heat transfer coefficient considering droplet entrainment during HTPB/paraffin fuels regression is established.
Droplet entrainment and its role in the combustion of HTPB/paraffin fuels
Acta Astronautica ; 204 ; 107-115
2022-12-26
9 pages
Aufsatz (Zeitschrift)
Elektronische Ressource
Englisch
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