scholarly journals Propelan Pepejal Kalium Nitrat Difabrikasi Kaedah Pengacuanan Mampat

2012 ◽  
Author(s):  
Mohammad Nazri Mohd. Ja’afar ◽  
Wan Khairuddin Wan Ali ◽  
Md Nizam Dahalan ◽  
Rizalman Mamat
Keyword(s):  
Burning Rate ◽  
Atmospheric Pressure ◽  
Solid Propellant ◽  
Strong Relationship ◽  
Potassium Nitrate ◽  
Experimental Results ◽  
Test Rig ◽  
Composite Propellant ◽  
Burning Rates ◽  
Different Characteristics

Propelan pepejal untuk kegunaan roket berbahan dorong pepejal yang telah dihasilkan di Universiti Teknologi Malaysia (UTM) adalah dari kumpulan propelan komposit kalium nitrat sebagai pengoksida dan sukros sebagai bahan api. Antara kaedah fabrikasi propelan adalah teknik pembentukan (forming), penyemperitan (extrusion), tuangan (casting) dan pengacuanan mampat (compressed moulding). Semua kaedah ini telah menghasilkan pelbagai propelan dengan sifat serta gaya laku yang berbeza–beza. Bergantung kepada bagaimana ia difabrikasi, propelan ini telah menunjukkan perkaitan sifat mekanikal yang begitu ketara. Dari setiap kaedah, propelan dibentuk mengikut satu bentuk serta dimensi yang piawai. Ujian kadar pembakaran dibuat ke atas setiap jalur propelan menggunakan alat uji kaji (test rig) yang telah direka bentuk. Ujian kadar pembakaran dilakukan pada tekanan atmosfera. Melalui ujian ini, kadar pembakaran propelan telah diperolehi. Hasil uji kaji menunjukkan kadar pembakaran propelan yang menggunakan teknik pembentukan dan teknik pengacuanan mampat masing–masing adalah 1.033 cm/s dan 0.429 cm/s. Manakala kaedah penyemperitan dan kaedah tuangan didapati tidak sesuai kerana sifat propelan kalium nitrat–sukros yang likat. Hasil uji kaji menunjukkan kaedah pengacuanan mampat ialah kaedah yang paling sesuai berbanding kaedah yang lain kerana dapat menghasilkan propelan yang seragam dan stabil. Kata kunci: Propelan; komposit; pengoksida; bahan api; kadar pembakaran Solid propellant used on solid fuel rocket developed at Universiti Teknologi Malaysia (UTM) is from the composite propellant group with potassium nitrate as the oxidizer and sucrose as the fuel. Among the propellant fabrication techniques are forming, extrusion, casting and compressed moulding. All of these techniques are used to fabricate several types of propellant with different characteristics and performances. Depending upon the technique of fabrication, these propellants have shown strong relationship with their mechanical properties. With every technique, the propellants are formed according to a standard shape and dimension. Burning rate tests were performed for each propellant strand fabricated using the test rig designed. The burning rate tests were performed at atmospheric pressure. Through this test, the propellant burning rates were obtained. Experimental results show that the burning rate for propellant developed using forming and compressed moulding are 1.033 cm/s and 0.429 cm/s, respectively. Meanwhile, the extrusion and casting methods were found not suitable due to the property of potassium nitrate–sucrose that is viscous. Experimental results show that the pressed moulding method is the most suitable method compared to the other techniques since it can produce propellant that is uniform and stable. Key words: Propellant; composite; oxidizer; fuel; burning rates

Burning Rate of Composite Propellants under the Conditions of Strain

2014 ◽  
Vol 31 (4) ◽  
Author(s):  
Songqi Hu ◽  
Jing Chen ◽  
Guanjie Wu ◽  
Yingji Liu ◽  
Yijin Hua
Keyword(s):  
Experimental Data ◽  
Burning Rate ◽  
Rate Ratio ◽  
Tensile Strain ◽  
Strain State ◽  
Poisson Ratio ◽  
Experimental Results ◽  
Exposed Area ◽  
Binder Component ◽  
Burning Rates

AbstractIn this work, a correlation between propellant burning rate and strain was established. In order to investigate the effects of strain and pressure, and to measure burning rate of composite propellants, a novel apparatus was designed and prepared. Burning rates of three formula composite propellants under different pressures and strains were measured using such device. Based on the measurements, a model for the analysis on the experimental results was proposed. It was demonstrated that the model corresponded with the experimental data if the propellant samples were under tensile strain increasing from 0 to 20%. Burning rate ratio and tensile strain obeyed the quadratic relationship, burning rate increased with strain, but there was no mutation in less than 20% deformation. Furthermore, burning rate ratio of composite propellants which had low Poisson ratio increased fast as tensile strain decreased. And the less binder component of composite propellants, the burning ratio changed more significantly under a given strain state. In addition, as the exposed area increased, the burning rate ratio became larger.

Ujian Pembakaran Propelan Roket Pepejal

2012 ◽  
Author(s):  
Mohammad Nazri Mohd Jaafar ◽  
Wan Khairuddin Wan Ali ◽  
Ahmad Saufi Mohamed Zahri
Keyword(s):  
Key Words ◽  
Burning Rate ◽  
Solid Propellant ◽  
Optimum Composition ◽  
Percentage Composition ◽  
Burning Rates ◽  
Solid Rocket

Komposisi laker dan bahan api yang digunakan dalam fabrikasi propelan pepejal mempengaruhi kadar pembakaran. Kajian ini melihat pengaruh mengubah peratusan komposisi kedua-dua bahan tadi. Hasil ujikaji yang diperolehi, menunjukkan bahawa kadar pembakaran berkurangan dengan pertambahan peratusan laker apabila bahan api dimalarkan pada 29%. Bagaimanapun, apabila laker ditetapkan kepada 22% dan komposisi bahan api diubah-ubah, kadar pembakaran menunjukkan plot parabola dengan komposisi optimum bahan api pada 28.6%. Kata kunci: Kalium nitrat; sulfur; aluminium; kadar pembakaran; roket pepejal The composition of lacquer and fuel used during fabrication of solid propellant affects the burning rates. This study shows the effect of varying the percentage composition of both items. Results obtained show that the burning rates reduce with increase in laker percentage when fuel was set constant at 29%. However; when lacquer was set constant at 22% and at varied fuel compositions, the burning rates show a parabolic plot with the optimum composition at 28.6% fuel. Key words: Kalium nitrate; sulfur; aluminium; burning rate; solid rocket

Withdrawal: Manufacture of solid propellant using epoxy resin and potassium nitrate

2020 ◽  
Author(s):  
Jose A. Rocco ◽  
Marcela G. Domingues ◽  
Rene F. Gonçalves ◽  
Ellen C. Rosa ◽  
Daniel Bontorin ◽  
...  
Keyword(s):  
Epoxy Resin ◽  
Solid Propellant ◽  
Potassium Nitrate

Review Summary Generation in Online Systems: Frameworks for Supervised and Unsupervised Scenarios

2021 ◽  
Vol 15 (3) ◽  
pp. 1-33
Author(s):  
Wenjun Jiang ◽  
Jing Chen ◽  
Xiaofei Ding ◽  
Jie Wu ◽  
Jiawei He ◽  
...  
Keyword(s):  
Decision Making ◽  
Real World ◽  
Text Summarization ◽  
Experimental Results ◽  
Product Review ◽  
Comprehensive Review ◽  
Online Systems ◽  
Real World Datasets ◽  
Different Characteristics

In online systems, including e-commerce platforms, many users resort to the reviews or comments generated by previous consumers for decision making, while their time is limited to deal with many reviews. Therefore, a review summary, which contains all important features in user-generated reviews, is expected. In this article, we study “how to generate a comprehensive review summary from a large number of user-generated reviews.” This can be implemented by text summarization, which mainly has two types of extractive and abstractive approaches. Both of these approaches can deal with both supervised and unsupervised scenarios, but the former may generate redundant and incoherent summaries, while the latter can avoid redundancy but usually can only deal with short sequences. Moreover, both approaches may neglect the sentiment information. To address the above issues, we propose comprehensive Review Summary Generation frameworks to deal with the supervised and unsupervised scenarios. We design two different preprocess models of re-ranking and selecting to identify the important sentences while keeping users’ sentiment in the original reviews. These sentences can be further used to generate review summaries with text summarization methods. Experimental results in seven real-world datasets (Idebate, Rotten Tomatoes Amazon, Yelp, and three unlabelled product review datasets in Amazon) demonstrate that our work performs well in review summary generation. Moreover, the re-ranking and selecting models show different characteristics.

scholarly journals Interactive Effects in Two-Droplets Combustion of RP-3 Kerosene under Sub-Atmospheric Pressure

Processes ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 1229
Author(s):  
Hongtao Zhang ◽  
Zhihua Wang ◽  
Yong He ◽  
Jie Huang ◽  
Kefa Cen
Keyword(s):  
Burning Rate ◽  
Atmospheric Pressure ◽  
High Speed ◽  
Ambient Pressure ◽  
Interactive Effects ◽  
Propagation Time ◽  
High Speed Camera ◽  
Single Droplet ◽  
Fuel Droplets ◽  
Spacing Distance

To improve our understanding of the interactive effects in combustion of binary multicomponent fuel droplets at sub-atmospheric pressure, combustion experiments were conducted on two fibre-supported RP-3 kerosene droplets at pressures from 0.2 to 1.0 bar. The burning life of the interactive droplets was recorded by a high-speed camera and a mirrorless camera. The results showed that the flame propagation time from burning droplet to unburned droplet was proportional to the normalised spacing distance between droplets and the ambient pressure. Meanwhile, the maximum normalised spacing distance from which the left droplet can be ignited has been investigated under different ambient pressure. The burning rate was evaluated and found to have the same trend as the single droplet combustion, which decreased with the reduction in the pressure. For every experiment, the interactive coefficient was less than one owing to the oxygen competition, except for the experiment at L/D0 = 2.5 and P = 1.0 bar. During the interactive combustion, puffing and microexplosion were found to have a significant impact on secondary atomization, ignition and extinction.

Burning Rate of Solid Propellant Ingredients, Part 1: Pressure and Initial Temperature Effects

1999 ◽  
Vol 15 (6) ◽  
pp. 740-747 ◽  
Author(s):  
A. I. Atwood ◽  
T. L. Boggs ◽  
P. O. Curran ◽  
T. P. Parr ◽  
D. M. Hanson-Parr ◽  
...  
Keyword(s):  
Burning Rate ◽  
Temperature Effects ◽  
Solid Propellant ◽  
Initial Temperature
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