Name: improving the combustion performance of a hybrid rocket engine using a novel fuel grain with a nested helical structure
Uploaded: 2021-01-18T12:30:00
Description: Watch this Scientific Journal Video about Improving the Combustion Performance of a Hybrid Rocket Engine using a Novel Fuel Grain with a Nested Helical Structure at JoVE.com

This work was supported by the National Natural Science Foundation of China (Grant Nos. 11802315, 11872368 and 11927803) and Equipment Pre-Research Foundation of National Defense Key Laboratory (Grant No. 6142701190402).

1. Experimental setup and procedures
<ol>
	<li>Preparation of fuel grain 
	NOTE: The fuel grain with novel structure consisted of two parts, which are shown in Figure 4. As the main part of the novel grain, the paraffin-based fuel accounts for more than 80% of the total mass. The ABS substrate is used as an additional fuel. The preparation of this fuel grain was realized by combining 3D printing and centrifugal casting.
	<ol>
		<li>Substrate preparation
		<ol>
			<li>Open 3D software ...

<ol>
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J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Fundamentals of Hybrid Rocket Combustion and Propulsion. , (2007).</li><li>Boardman, T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> 33rd Joint Propulsion Conference and Exhibit. , (1997).</li><li>Connell, T. 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The technique presented in this paper is a novel approach using a fuel grain with a nested helical structure. There are no difficulties in setting up the necessary equipment and facilities. The helical structure can be easily produced by 3D printing, and nesting of paraffin-based fuels can be easily carried out by centrifugal casting. Fused deposition molding (FDM) 3D printers are not expensive and the cost of centrifuges is low.
When the inner surface of the shaped fuel grain was found to hav...

A technique to improve the combustion performance of a hybrid rocket engine is urgently required. To date, practical applications of hybrid rocket engines are still far less than those of solid and liquid rocket engines1,2. The low regression rate of traditional fuels limits the improvement of thrust performance for the hybrid rocket engine3,4. In addition, its combustion efficiency is slightly lower than that of other chemical energy rockets due to internal diffusion combustion5, as shown in Figure 1. Although various techniques have been studied and developed, such as the use of multi-ports6, enhancing additives7,8,9, liquefying fuel10,11,12, swirl injection13, protrusions14, and bluff body15, these approaches are associated with problems in volume utilization, combustion efficiency, mechanical performance, and redundancy quality. Thus far, structural improvement of the fuel grain, which does not have these shortcomings, has attracted more attention as an effective means of improving combustion performance16,17. The advent of three-dimensional (3D) printing has brough an effective way to increase the performance of hybrid rocket engines through the ability to rapid and inexpensively produce either complex conventional grain designs or nonconventional fuel grains18,19,20,21,22,23,24,25,26,27,28,29,30. However, during the combustion process, these improvements in combustion performance diminishes with the characteristic structure burning, resulting in a decrease in combustion performance23. We have demonstrated that a novel design is useful in improving performance of hybrid rocket engines31. The detail for this technique and representative results is presented in this paper.
The fuel grain consists of a helical substrate made by acrylonitrile-butadiene-styrene (ABS) and a nested paraffin-based fuel. Based on centrifugal and 3D printing, the advantages of the two fuels with different regression rates were combined. The special helical structure of the fuel grain after combustion is shown in Figure 2. When gas passes through the fuel grain, numerous recirculation zones are simultaneously created at grooves between blades, which is shown in Figure 3. This characteristic structure on the inner surface increases the turbulence kinetic energy and swirl number in the combustion chamber, which increase the exchanges of both matter and energy in the combustion chamber. Ultimately, the regression rate of the novel fuel grain is effectively improved. The effect of improving the regression rate has been well proven: in particular, the regression rate of the novel fuel grain was demonstrated to be 20% higher than that of the paraffin-based fuel at the mass flux of 4 g/s&#183;cm2,32.
One advantage of the fuel grain with a nested helical structure is that it is simple to manufacture. The molding process mainly requires a melt mixer, a centrifuge, and a 3D printer. The ABS substrate formed by 3D printing greatly reduces the manufacturing cost. Another significant and unique advantage is that the enhancement effect does not disappear during the combustion process.
This paper presents the experimental system and procedure for improving the combustion performance of a hybrid rocket engine using the novel fuel grain structure. Additionally, this paper presents three representative comparisons of combustion performance parameters to prove the feasibility of the technique, including oscillation frequency of combustion chamber pressure, regression rate, and combustion efficiency characterized by characteristic velocity.

<table>
	<tbody>
		<tr>
			<td>3D printer</td>
			<td>Raise3D</td>
			<td>N2 Plus</td>
			<td>305 &#215; 305 &#215; 605 mm</td>
		</tr>
		<tr>
			<td>3D drawing software</td>
			<td>Autodesk</td>
			<td>Inventor</td>
			<td></td>
		</tr>
		<tr>
			<td>ABS</td>
			<td>Raise3D</td>
			<td>ABS black</td>
			<td>1.75 mm</td>
		</tr>
		<tr>
			<td>Camera</td>
			<td>Sony</td>
			<td>A6000</td>
			<td></td>
		</tr>
		<tr>
			<td>Carbon</td>
			<td>Aibeisi</td>
			<td>ATP-88AT</td>
			<td></td>
		</tr>
		<tr>
			<td>Centrifugal machine</td>
			<td>Luqiao Langbo Motor Co.Ltd</td>
			<td>Custom</td>
			<td>&#8804;1450 rpm</td>
		</tr>
		<tr>
			<td>Data processing software</td>
			<td>OriginLab</td>
			<td>Origin 2020</td>
			<td></td>
		</tr>
		<tr>
			<td>EVA</td>
			<td>DuPont Company</td>
			<td>360</td>
			<td>binder</td>
		</tr>
		<tr>
			<td>Mass flow controller</td>
			<td>Bronkhost</td>
			<td>F-203AV</td>
			<td>0-1500 ln/min</td>
		</tr>
		<tr>
			<td>Melt mixer</td>
			<td>Winzhou Chengyi Jixie Co.Ltd</td>
			<td>Custom</td>
			<td></td>
		</tr>
		<tr>
			<td>Multi-function data acquisition card</td>
			<td>NI</td>
			<td>USB-6211</td>
			<td></td>
		</tr>
		<tr>
			<td>Paraffin</td>
			<td>Sinopec Group Company</td>
			<td>58#</td>
			<td>Fully refined paraffin, Melting point&#8776;58&#8451;</td>
		</tr>
		<tr>
			<td>PE wax</td>
			<td>Qatar petroleum chemical industry Company</td>
			<td>Custom</td>
			<td></td>
		</tr>
		<tr>
			<td>Slicing software</td>
			<td>Raise3D</td>
			<td>ideaMaker</td>
			<td></td>
		</tr>
		<tr>
			<td>Spark plug</td>
			<td>NGK</td>
			<td>PFR7S8EG</td>
			<td></td>
		</tr>
		<tr>
			<td>Stearic acid</td>
			<td>ical Reagent Company</td>
			<td>Custom</td>
			<td>hardener</td>
		</tr>
	</tbody>
</table>

improving the combustion performance of a hybrid rocket engine using a novel fuel grain with a nested helical structure

A technique to improve the combustion performance of a hybrid rocket engine using a novel fuel grain structure is presented. This technique utilizes the different regression rates of acrylonitrile butadiene styrene and paraffin-based fuels, which increase the exchanges of both matter and energy by swirl flow and recirculation zones formed at the grooves between the adjacent vanes. The centrifugal casting technique is used to cast the paraffin-based fuel into an acrylonitrile butadiene styrene substrate made by three-dimensional printing. Using oxygen as the oxidizer, a series of tests were conducted to investigate the combustion performance of the novel fuel grain. In comparison to paraffin-based fuel grains, the fuel grain with a nested helical structure, which can be maintained throughout the combustion process, showed significant improvement in the regression rate and great potential in improvement of combustion efficiency.

Figure 7 shows the changes in combustion chamber pressure and oxidizer mass flow rate. To provide the necessary time for flow regulation, the oxidizer enters the combustion chamber in advance. When the engine builds pressure in the combustion chamber, the oxygen mass flow rate drops rapidly and then maintains a relatively steady change. During the combustion process, the pressure in the combustion chamber remains relatively stable.
Images showing a comparison of c...

Watch this Scientific Journal Video about Improving the Combustion Performance of a Hybrid Rocket Engine using a Novel Fuel Grain with a Nested Helical Structure at JoVE.com

Improving the Combustion Performance of a Hybrid Rocket Engine using a Novel Fuel Grain with a Nested Helical Structure

A technique utilizing a solid fuel grain with a novel nested helical structure to improve the combustion performance of a hybrid rocket engine is presented.

A technique to improve the combustion performance of a hybrid rocket engine using a novel fuel grain structure is presented. This technique utilizes the ...

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