Abstract
Hybrid rocket engines (HREs) are a chemical propulsion system that nominally combine the advantages of liquid-propellant rocket engines (LREs) and solid-propellant rocket motors (SRMs). HREs in some cases can have a higher specific impulse and better controllability than SRMs, and lower cost and engineering complexity than LREs. For HREs and SRMs, both kinds of rocket engine employ a solid fuel grain, and the chosen grain configuration is a crucial point of their design. Different grain configurations have different internal ballistic behavior, which in turn can deliver different engine performance. A cylindrical grain design is a very common design for SRMs and HREs. A non-cylindrical-grain is a more complex grain configuration (than cylindrical) that has been used in many SRMs, and is also a choice for some HREs. However, while an HRE and an SRM can employ the same fuel grain configuration, the resulting internal ballistic behavior would not be expected to be the same. Pressure-dependent burning tends to dominate in SRMs, while axial flow-dependent burning tends to dominate in HREs. To help demonstrate in a more direct manner the influence of the differing combustion processes on the same fuel grain configuration used by an HRE and SRM, a number of internal ballistic simulations are undertaken for the present study. For the reference SRM cases looked at, an internal ballistic simulation program that has the capability of predicting head-end pressure and thrust as a function of time into a simulated firing is utilized for the present investigation; for the corresponding HRE cases, a simulation program is used to simulate the burning and flow process of these engines. For the present investigation, the two simulation programs are used to simulate the internal ballistic performance of various HREs and SRMs employing comparable cylindrical and non-cylindrical fuel grain configurations. The predicted performance results, in terms of pressure and thrust, are consistent with expectations that one would have for both propulsion system types.
Highlights
With the development of propulsion technology, a combination of features incorporated in liquid rocket engines (LREs) and solid rocket motors (SRMs) can be judiciously implemented into hybrid rocket engines (HREs)
Grain configurations have a significant influence on the internal ballistic behavior of solid-propellant rocket motors (SRMs), which in turn sets the performance of these rocket motors
In order to observe the influence of different oxidizer mass flows on the three grain designs, a number of simulations were done, and the results presented
Summary
With the development of propulsion technology, a combination of features incorporated in liquid rocket engines (LREs) and solid rocket motors (SRMs) can be judiciously implemented into hybrid rocket engines (HREs). HREs can have a higher specific impulse than SRMs, which can help give HREs better mission flexibility and performance than SRMs. At the same time, HREs have lower engineering complexity than LREs. At the same time, HREs have lower engineering complexity than LREs This means that HREs are easier and cheaper to manufacture. Another important advantage of HRE is the safety. Different to SRMs, the grain in HREs commonly only contain the fuel, while the oxidizer is loaded in the separate oxidizer tank. The separation of fuel and oxidizer mitigates the risk of accidental firing, while in pre-firing status, i.e., in storage
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
