Solid-Fuel Regression Rates and Flame Characteristics in an Opposed Flow Burner

Abstract

An opposed flow burner is examined as an instrument to screen and characterize fuel before full-scale hybrid rocket testing. This device requires small amounts (∼10 g) of solid fuels, and it can save time and material in early phases of fuel characterization. Although impinging jet configurations have been investigated in the past, the full range of operation of these systems in terms of hybrid rocket motor flowfield conditions has not been fully explored. The regression rate, flame structure, and flame temperature in an opposed burner configuration is investigated, and an analysis to relate the results to hybrid rocket applications is developed. Hydroxyl-terminated polybutadiene, dicyclopentadiene, and paraffin are investigated via an opposed flow burner over an oxidizer mass flux range of 4 to 25 kg∕s∕m 2 . Results show solid-fuel regression rate sensitivity to laminar and turbulent flow regimes. Aluminized hydroxyl-terminated polybutadiene regresses ∼34% slower than neat fuel in the opposed flow burner. Infrared spectroscopy reveals peak flame temperatures of the samples tested, ranging from 1850 to 2100 K. Although the opposed flow burner is not a perfect representation of hybrid rocket motor operation, it may prove useful in smallscale screening of fuels.

Experimental Observation and Characterization of B−HTPB‐based Solid Fuel with Addition of Iron Particles for Hybrid Gas Generator in Ducted Rocket Applications

“…It is observed that particle loaded samples consume less mass during combustion compared to SF1. In this context, similar observation has been reported by previous researchers with paraffin-wax or polymeric fuels loaded with metal particles which were examined by using OFB [28,36,[38][39][40]. Actually, the required temperature for HTPB pyrolysis is below 500°C whereas boron ignition occurs above 500°C (Figure 4).…”

“…Therefore, a very old testing tool which was introduced in 1950s called opposed flow burner (OFB) has been used in the present study which can minimize the effort as well as cost for rapid screening of fuel. Recently OFB has been employed by many researchers for formulation and selection of different types of solid fuel combinations [28,[35][36][37][38][39][40]. In OFB the burning environment on the fuel surface can be digitally captured and analysed which is not possible in a rocket motor.…”

Electron spins coupling of coconut shell activated nanocarbons in solid propellant on improving to the thrust stability and specific impulses

“…This gas pressure in the nozzle has direct effect on the thrust such as Equations (3) and (4). The specific impulse of rockets such as described in Equations (5) and (…”

“…As shown by the result in Table 2, the addition of NCCS to the stoichiometric propellant fuel mixture produces the highest rocket thrust. Equations (5) and 6shows g0 is the standard gravity (9.8 m/s 2 ), Isp (specific impulse) measured in seconds is the amount of time a rocket engine can generate thrust, given a quantity of propellants whose weight is equal to the engine has thrust. The total impulse (I) of a rocket is defined as the average thrust times the total time of firing.…”

“…Nanoscale aluminum has the same effect, but it has a much lower ignition temperature due to its high specific surface area, resulting in the energy release being closer to the fuel surface [4]. Energetic nanoscale aluminum has been proven to be an effective catalyst in the composite solid propellant containing hydroxyl terminated polybutadiene (HTPB) and hybrid propellants with solid HTPB grains [5]. The combustion quality can be increased using HTPB on hybrid motors with the addition of nanoscale aluminum as a catalyst [6].…”