The focus of this review is to collect and compare research studies on hybrid rocket fuels and components produced via additive manufacturing. The use of hybrid rocket propulsion for launching ...applications is limited due to its inherently low regression rate and actual specific impulse. To address these limitations, various additive manufacturing methods have been employed so far to fabricate fuel grains with complex port geometries or composite fuel grains possessing intricate shaped, printed scaffolds into which a second fuel material is incorporated. In addition to the fuel grains, additive manufacturing technology has also proven to be beneficial for fabricating a considerable number of hybrid rocket components, thereby reducing the part count, production time and cost. In this review, the rationale, types of the materials used, methods and comparison of performance data are presented. Future directions that use additive manufacturing to enhance hybrid rocket propulsion are also provided.
•Hybrid Rockets suffer from low regression rates.•This may be overcome via certain modifications such as intricate fuel port geometries, or paraffin-based fuels.•Additive Manufacturing is suitable to achieve these modifications.
This paper presents the development of indigenous hybrid rocket technology, using 98% hydrogen peroxide as an oxidizer. Consecutive steps are presented, which started with interest in hydrogen ...peroxide and the development of technology to obtain High Test Peroxide, finally allowing concentrations of up to 99.99% to be obtained in-house. Hydrogen peroxide of 98% concentration (mass-wise) was selected as the workhorse for further space propulsion and space transportation developments. Over the course nearly 10 years of the technology’s evolution, the Lukasiewicz Research Network—Institute of Aviation completed hundreds of subscale hybrid rocket motor and component tests. In 2017, the Institute presented the first vehicle in the world to have demonstrated in-flight utilization for 98% hydrogen peroxide. This was achieved by the ILR-33 AMBER suborbital rocket, which utilizes a hybrid rocket propulsion as the main stage. Since then, three successful consecutive flights of the vehicle have been performed, and flights to the Von Karman Line are planned. The hybrid rocket technology developments are described. Advances in hybrid fuel technology are shown, including the testing of fuel grains. Theoretical studies and sizing of hybrid propulsion systems for spacecraft, sounding rockets and small launch vehicles have been performed, and planned further developments are discussed.
Data-driven fault detection using a bivariate time-series analysis was done for the maintenance of reusable liquid-propellant rocket engines. This method is based on the phase plane trajectory of ...feature vectors extracted from two sensor data by principal component analysis, and applied to all sensor pairs. System and sensor failures can be estimated by visualizing the state of all sensor pairs. The present method was applied to the static firing test results of a reusable rocket engine developed in Japan. Temperature sensor failure was successfully detected from 59 sensors in the 19 static firing tests. System failure caused by incorrect valve operation was also successfully detected. The ability to detect and estimate system and sensor failures was demonstrated, even if the engine's operational sequence changes dynamically due to ignition or cutoff or if there are deviations of the engine's operational sequence between tests.
•A bivariate time-series method is developed for data-driven fault detection.•Static firing test results of a reusable rocket engine is used for the validation.•The engine's operational sequence changes dynamically due to ignition or cutoff.•There are deviations of the engine's operational sequence between firing tests.•Detection and identification of system failures and sensor failures are realized.
We propose a fault detection and diagnosis (FDD) method for liquid-propellant rocket engine tests during startup transient based on deep learning. A numerical model describing the startup transient ...for the hot-firing test of the rocket engine allows to simulate normal and abnormal situations caused by various types of faults. Datasets containing potential fault types during the engine startup have been constructed using the numerical model to train deep neural networks targeting. Actual hot-firing ground test data of a liquid rocket have been used to determine the input parameters of the model and validate the simulation results. A numerical case study on FDD for the ground operation of an open-cycle liquid-propellant rocket engine demonstrates the effectiveness of the proposed method compared to the traditional red-line cutoff.
•Fault detection and diagnosis (FDD) is important during rocket engine startup.•We propose a deep neural network approach for this type of FDD.•A comprehensive engine model is derived to generate representative training data.•The model is validated using real data from hot-fire tests in normal/faulty cases.•The trained networks provide realistic, fast, and accurate FDD results.
Paper presents the results of numerical studies of hybrid rocket engines operating cycle including unsteady-state transition stage. A mathematical model is developed accounting for the peculiarities ...of diffusion combustion of fuel in the flow of oxidant, which is composed of oxygen-nitrogen mixture. Three dimensional unsteady-state simulations of chemically reacting gas mixture above thermochemically destructing surface are performed. The results show that the diffusion combustion brings to strongly non-uniform fuel mass regression rate in the flow direction. Diffusive deceleration of chemical reaction brings to the decrease of fuel regression rate in the longitudinal direction.
Ablative materials are at the base of entire aerospace industry; these sacrificial materials are used to manage the heat shielding of propulsion devices (such as liquid and Solid Rocket Motors ...(SRMs)) or to protect vehicles and probes during the hypersonic flight through a planetary atmosphere. Accordingly they are also known as Thermal Protection System (TPS) materials. Some non-polymeric materials have been successfully used as ablatives; however, due to their versatility, Polymeric Ablatives (PAs) represent the widest family of sacrificial TPS materials. In fact, when compared to non-polymeric ablatives such as high melting point metals, inorganic polymers (or metal oxides or carbides), PAs have some intrinsic advantages such as: tunable density, lower cost, and higher heat shock resistance. This review covers all main topics related to the science and technology of ablative materials with current and potential applications in the aerospace industry. After a short, yet comprehensive, introduction on non-ablative materials, this review paper summarizes fifty years of research efforts on polymeric ablatives, starting from the state of the art solutions currently used as TPS, up to covering the most recent efforts for nanostructuring their formulations.
Rocket based combined cycle (RBCC) engine is regarded as one of the most efficient propulsion systems for reusable space transportation vehicles and hypersonic cruise vehicles. It can perform ...excellently over a very broad range of Mach numbers and flight altitudes through multi-mode operations by effectively integrating high thrust-to-weight ratio of the rocket engine and high specific impulse of the airbreathing engine. The RBCC inlet, commonly operating in an extremely wide flight speed range covering static, subsonic, transonic, supersonic, and hypersonic, plays a vital role in the RBCC propulsion system and flight vehicles. This paper presents a comprehensive and systematical review of the research progress on the inlets for RBCC engines in different countries and different historical periods. A number of key technical and scientific issues specially concerning RBCC inlets are sorted out, including the wide range RBCC inlet design and optimization, inlet/embedded rocket/combustor matching and control, dynamic operation, etc. Several typical RBCC inlet applications and the corresponding research are discussed, including the Strutjet inlet, A5 inlet, GTX inlet, and the Astrox's inlet in the U.S., the RBCC inlet in JAXA, and a sidewall compression RBCC inlet in China. Finally, experience gained and some recommendations are summarized for future research of the RBCC inlet.
Catastrophic breakdown that occurs during the flight of supersonic vehicles demands more focused research in the insulation of rocket engines. At present, optimization of polymeric ablatives as ...viable insulation for solid rocket motor casing has a prominent role in the successful mission of rockets. Among polymers, elastomer serves an imperative part. Comprehensive investigations were disclosed, especially in the elastomeric heat shielding materials with various reinforcing agents. In this paper, research progress of mostly used elastomers is reviewed, and a circumstantial understanding about the features of ablation and insulation has been validated.
One of the issues of using a normal graphite nozzle for the hybrid rocket propulsion is the serious throat erosion due to combustion with a higher O/F ratio. This may undermine the throttling ...capability of the hybrid rocket engine. In this study, we would like to address how the propulsion performance changes under the conditions of different nozzle throat diameters and O/F ratios. We designed and tested a 40-kgf class single-port hybrid rocket motor with the swirling injection of oxidizer, which utilizes the 90 wt% hydrogen peroxide and polypropylene (PP) as oxidizer and fuel, respectively. Three different diameters of graphite nozzle throat (10, 11, and 12 mm) were used to approximate various conditions of nozzle erosion, while the mass flow rates of the injected oxidizer were kept the same. The hot-fire test results indicated that the thrust was nearly the same even the nozzle throat diameters and O/F ratios were different. Especially, the discrepancies among the measured thrusts and oxidizer ISP under various test conditions were found to be less than 1%, which is highly beneficial for the purpose of the thrust control using mass flow rate control of the oxidizer for a hybrid rocket engine with swirling injection of high-concentration hydrogen peroxide.
•A simple method is proposed for designing the plumbing system of a H2O2-PP hybrid rocket engine.•ISP of a H2O2-PP hybrid engine is not affected much by nozzle throat erosion in some O/F ratio shift.•Same ISP with O/F ratio shift in various nozzle throat diameters is explained through experiments.•Hybrid-engine thrust can be controlled by controlling the flow rate even with nozzle throat erosion.
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