Hongsheng Yu,Xiaodong Yu,Suhang Chen,Wei Zhang,Luigi T. DeLuca,Ruiqi Shen
The slow regression rate caused by the difficulty of pyrolysis can not meet the practical application requirements of hydroxyl-terminated polybutadiene (HTPB)-based fuels in hybrid rocket propulsion. Accelerating the decomposition of polymer matrix has become a new method to enhance the regression rate of HTPB fuels. For determining the difference of combustion performance between different acetylacetone (acac) complex loaded HTPB-based fuels, Fe(acac) 3 , Ni(acac) 2 , and Cu(acac) 2 are introduced into the HTPB matrix with 5 wt%, respectively. The experimental results reveal that the acetylacetone complexes can catalyze the pyrolysis of HTPB matrix hence increasing the regression rate of fuel grains: 5 wt% Fe, Ni, and Cu acetylacetone enhance the regression rate of HTPB fuels by 13.8%, 15.5%, and 11.4% at G ox = 50 kg/m 2 s. And the gap in regression rate between three complex loaded fuels is originated from the influence of many factors such as catalytic effect, combustion heat, and combustion products, etc. This study compares the regression rate of different acetylacetone complex loaded fuels for future catalyst selection, and explains the corresponding combustion mechanism.
Hongwei Gao,Hongsheng Yu,Yue Tang,Xiaodong Yu,Wei Zhang,Luigi T. DeLuca,Ruiqi Shen
ABSTRACT Low regression rate due to difficult pyrolysis is a major challenge in the practical application of terminated hydroxyl-terminated polybutadiene (HTPB)-based fuels in hybrid rocket propulsion. Accelerating the decomposition of the polymer matrix is an effective method to improve the regression rate of HTPB fuels. To determine the difference in combustion performance between different transition metal oxides loaded HTPB-based fuels, nickel oxide (NiO), ferric oxide (Fe 2 O 3 ), copper oxide (CuO) and manganese dioxide (MnO 2 ) were introduced into the HTPB matrix at 5% mass fraction. The experimental results showed that the metal oxides could significantly catalyze the pyrolysis of HTPB-based fuels and enhance the fuel regression rate, and the catalytic effect was mainly concentrated in the middle and late stages of the thermal decomposition process of polybutadiene components. Among the four transition metal oxides, CuO and MnO 2 showed better catalytic effects on the combustion performance of HTPB-based fuels in the high oxygen mass flux region, while NiO showed better catalytic effects in the low oxygen mass flux region. The present study compares the regression rate of fuel grains modified with different transition metal oxides, which provides a basis for the selection of future catalysts, verifies the catalytic effect of the transition metal oxides on the combustion of HTPB-based fuels and further analyzes the combustion reaction mechanism of the fuels.
Hongsheng Yu,Suhang Chen,Xiaodong Yu,Wei Zhang,Christian Paravan,Luigi T. DeLuca,Ruiqi Shen
The slow regression rate induced by the difficulty of pyrolysis has limited the practical application of hydroxyl-terminated polybutadiene (HTPB)-based fuels for hybrid rocket propulsion. A possible strategy is the use of suitable transition metal elements promoting polymer matrix thermal decomposition of fuels. This paper investigates the effects of nickel acetylacetonate, Ni(acac) 2 , on the thermal stability and combustion of HTPB-based fuel formulations. The presented experimental results show that the addition of Ni(acac) 2 can intensely decrease the thermal stability of HTPB thus enhancing the solid fuel regression rate even at a small additive mass fraction: under an oxygen mass flux of 50 kg/m 2 s, HTPB + 5 wt% Ni(acac) 2 shows a 25.5% increase over the non-loaded baseline. Kinetics analyses reveal that the catalytic effect is mainly induced by the Ni 2+ in Ni(acac) 2 at the early stage of decomposition, and by the NiO produced from the oxidative decomposition of Ni(acac) 2 in the fuel final degradation stage. On the other hand, the addition of Ni(acac) 2 decreases the combustion heat of HTPB-based fuels significantly and implies the accumulation of its decomposition products (much metal Ni, moderate elemental C, and a little NiO.) at the fuel regressing surface. Eventually, when the content of Ni(acac) 2 exceeds 5 wt%, the growth of regression rate slows down rapidly, and a performance detriment occurs at 40 wt%. This study verifies the catalytic effect of Ni(acac) 2 on polymer matrix for HTPB based fuels showing the attractive regression rate performance of this additive.
危险品化学品经营许可证（带存储）