A review of the performance and structural considerations of paraffin wax hybrid rocket fuels with additives

Nanoaluminum powder (nAl, nominal size of particles 50 nm and 100 nm), obtained by electrical explosion of wires, was passivated by air and coated by several different protective organic reagents to assess the effects on ballistics of nAl-loaded hydroxyl-terminated polybutadiene (HTPB)-based solid fuel with respect to pure HTPB baseline. The nAl samples were characterized by transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET), and chemical analysis on active aluminum content (Al°) content and added to HTPB-based solid fuels for hybrid propulsion. Combustion tests were carried out burning central-perforated single-port cylindrical samples in a 2D radial burner. Data analysis was performed to obtain a continuous time-resolved regression rate. Coated nAl particles may significantly improve the ballistics of HTPB + nAl formulations burning in gaseous oxygen, with respect to pure HTPB. All investigated formulations with nAl exhibit increase of instantaneous regression rate (up to 89% maximum),...

Combustion of HTPB-Based Solid Fuels Loaded with Coated Nanoaluminum

Thermal characterizations of the paraffin wax/low density polyethylene blends as a solid fuel

This paper describes computational fluid dynamics applied to the analysis of a hybrid rocket motor with a diaphragm in the combustion chamber to enhance rocket performance. This work follows the last author’s experiments: An engine was tested with nitrous oxide and paraffin wax as propellants. Several of the tests have been used as references for numerical simulations. The following approximations have been made: steady-state conditions, eddy dissipation model with one-step reaction, gaseous injection of fuel and oxidizer, and no droplets entrainment (typical of a paraffin grain). First of all, a single geometry without a diaphragm has been analyzed with different turbulence models (k-ω, k-ω shear stress transport, k-e, k-e renormalization group). It has been shown that the k-ω model predicts a lower flame temperature and chamber pressure than the k-e model. Then, five geometries have been studied to compare two different types of diaphragms (one hole and four holes) in two positions (24 and 33% of the to...

Investigation of Effect of Diaphragms on the Efficiency of Hybrid Rockets

Solid fuels for hybrid rockets were characterized in the framework of a research project aimed to develop a new generation of solid fuels, combining at the same time good ballistic and mechanical properties. A rheological, mechanical and ballistic characterization of paraffin-based hybrid rocket solid fuels was performed, considering pure wax-based fuels and fuels doped with suitable metal additives. Nano-Al powders and metal hydrides (Magnesium hydride (MgH2), Lithium Aluminum hydride (LiAlH4)) were used as fillers in paraffin matrices. Results of this investigation show a strong correlation between the measured viscosity of the melted paraffin layer and the regression rate: a decrease of viscosity increases the regression rate. This trend is due to the increasing development of entrainment phenomena, which strongly increase the regression rate. Addition of Lithium Aluminum Hydride (mass fraction 10%) can further increase the regression rate up to 378% with respect to the pure HTPB regression rate, taken as baseline reference fuel. The highest regression rates were found for the Solid Wax (SW) composition, added with 5% MgH2 mass fraction; at 350 kg/m 2 s oxygen mass flux, the measured regression rate, averaged in space and time, was 2.5 mm/s, which is approximately five times higher than that of the pure HTPB composition. Compositions added with nano-sized Aluminum powders were compared with those added with MgH2, using gel or solid wax.

Ballistic and rheological characterization of paraffin-based fuels for hybrid rocket propulsion

A novel paraffin-based blends fuel prepared from pure paraffin wax of the alkane family with polyethylene of the alkene family is proposed and tested in a slab motor to visualize the droplet entrainment mechanism followed by a hybrid rocket motor test to analyze its combustion characteristics. The mechanical strength of the proposed blended fuel is investigated by increasing the polyethylene weight percent. The overall regression rate of 5 wt % of polyethylene with 95 wt % of pure paraffin is found to be 3.9 factors higher than that of a pure polyethylene. Improved combustion efficiency under the condition of a similar oxidizer mass flow rate range is achieved with respect to pure paraffin fuel in which performance gain is comparable to that of the SP-1a fuel of Stanford University. Spectrum analysis of the chamber pressure shows no critical instability mode for the range of this study. The blend fuel is found to be comparatively effective for the hybrid rocket fuel in terms of mechanical strength, combus...

Evaluation of Paraffin–Polyethylene Blends as Novel Solid Fuel for Hybrid Rockets

A Novel blended solid fuel which mixes paraffin wax of alkane and LDPE of alkene is invented and tested in a slab motor and hybrid rocket motor to visualize droplet entrainment and to analyze combustion characteristics. The mechanical strength of blended fuel was investigated increasing the LDPE wt%. Overall regression rate of PR95PE05 is found to be 3.9 factors higher compared to that of HDPE. Improved combustion efficiency was achieved with respect to pure paraffin fuel where performance gain was comparable to that of SP-1a fuel of Stanford University. Analysis of the spectrum of the chamber pressure revealed no critical instability for the range of this study. The PR95PE05 blended fuel can be regarded comparatively effective for the hybrid rocket fuel in terms of mechanical strength, combustion performance, and combustion instability.

Effect of Paraffin-LDPE Blended Fuel in Hybrid Rocket Motor

This study aimed to evaluate the prevalence and associated factors of involutional blepharoptosis in a nationwide representative sample in Korea. Cross-sectional study 20 941 Korean men and women 40 years of age and older who participated in last 2 years (2008 and 2009) of the 4th wave of the Korean National Health and Nutrition Examination Survey (KNHANES) IV and the first 2 years (2010 and 2011) of KNHANES V. Ocular examinations were performed by ophthalmologists trained in procedure and grading methods, and blepharoptosis was defined as a marginal reflex distance <2 mm on either eye. The prevalence of involutional blepharoptosis in the Korean adult was 13.5% (95% CI: 12.1%, 14.9%). It was increasing along with aging (5.4% among 40’s and 32.8% in people over 70 years old). A statistically significant negative association between levator function and blepharoptosis was found. With right eye, while only 5.4% (95% CI: 4.5%, 6.2%) had blepharoptosis among people whose levator function was excellent (≥12 mm), 71.4% (95% CI: 60.0%, 85.9%) of people whose levator function was poor (≤4 mm) had blepharoptosis. Hypertension, diabetes, higher body mass index (BMI), and lower education had statistically significant association with blepharoptosis adjusting all other confounders. The distribution and proportional changes of levator function and marginal reflex distance 1 (MRD1) with aging implicate a contributory role of muscular degeneration. Strong association with hypertension, diabetes, BMI, and education level suggests that etiology of involutional blepharoptosis would be multifactorial and further investigation would be necessary to determine precise mechanism and contribution of factors.

/pdf/prevalence-and-associated-factors-of-blepharoptosis-in-1umb0f2qq9.pdf

Prevalence and associated factors of blepharoptosis in Korean adult population: The Korea National Health and Nutrition Examination Survey 2008-2011

The purpose of this experimental research is to investigate combustion characteristics of cylindrical multi-port grain of a hybrid rocket motor. The physical model of concern includes an oxidizer supply system, a multi-port fuel grain, and a combustor with preand post chamber. Gaseous oxygen and polymer (PE and PMMA) are applied as the oxidizer and the fuel, respectively. In geometric points of view, the effects of the port number and the distance between ports on a regression rate are taken into account. Internal combustion performance was analyzed using smalland large scale motors: one is motor diameter of 50 mm and the other is 96 mm, with oxidizer mass flux ranging from 10 kg/m-sec to 300 kg/msec for both cases. The port number positively shifts the O/F ratio to near its optimum value as well as the oxidizer mass flux to the typical range influenced by pressure effects so that the fuel regression rate becomes fast as the port number increases to a typical number up to 4 ports. Emphasis was placed on merging effects among fuel gain ports having 4 and 5 port to analyze how port geometrical configuration may influence the chamber pressure and thrust drop.

http://enu.kz/repository/2009/AIAA-2009-5112.pdf

Combustion Characteristics of the Cylindrical Multi-port Grain for Hybrid Rocket Motor

The experimental study on paraffin wax/LDPE blended fuel for hybrid rocket was performed. Various combustion characteristics of blended fuel were compared with pure paraffin, HTPB, HDPE and SP-1a fuel in order to evaluate the performance of blended fuel. The regression rate of lab-scale and large-scale motor using pure paraffin fuel was increased by 10.2 and 9.8 factor when respectively compared to that of HDPE. The regression rate factor of blended fuel was 3.4 in which the regression rate of blended fuel was higher than that of HTPB and HDPE, but lower than that of pure paraffin, SP-1a fuel. The values of characteristic velocity and specific impulse of blended fuel was higher than those of pure paraffin, HTPB and HDPE, and almost the same as SP-1a fuel. As these results, it was confirmed that blended fuel can be an effective solid fuel for hybrid rocket.초 록 하이브리드 로켓을 위한 파라핀 왁스/LDPE 혼합 연료에 관한 실험적 연구를 수행하였다. 혼합 연료의 성능 평가를 위해 혼합 연료의 다양한 연소 특성을 순수 파라핀, HTPB, HDPE, SP-1a 연료와 비교하였다. 순수 파라핀의 후퇴율은 HDPE에 비해 large-scale과 lab-scale 모터에서 각각 10.2, 9.8배 증가하였다. Lab-scale 혼합 연료의 후퇴율은 HDPE에 비해 3.4배 증가하여 HTPB, HDPE 연료보다는 높은 후퇴율을 나타냈으나 순수 파라핀, SP-1a에 비해서는 낮은 후퇴율을 나타냈다. 혼합 연료의 특성속도와 비추력은 순수 파라핀, HTPB, HDPE 보다 높았고 SP-1a 연료와 대등하였다. 이로부터 혼합 연료가 효과적인 하이브리드 로켓 연료가 될 수 있음을 확인하였다.Key Words: Hybrid Rocket(하이브리드 로켓), Paraffin Wax(파라핀 왁스), LDPE(저밀도 폴리에틸렌), Regression Rate(후퇴율), Characteristic Velocity(특성 속도), Specific Impulse(비추력)Nomenclature

Jungtae Cho

Papers

Evaluation of Paraffin–Polyethylene Blends as Novel Solid Fuel for Hybrid Rockets

Effect of Paraffin-LDPE Blended Fuel in Hybrid Rocket Motor

Prevalence and associated factors of blepharoptosis in Korean adult population: The Korea National Health and Nutrition Examination Survey 2008-2011

Combustion Characteristics of the Cylindrical Multi-port Grain for Hybrid Rocket Motor

A Study on the Combustion Characteristics of Paraffin wax/LDPE Blended fuel