Monopropellant Thruster Research Articles

Initial investigation of catalyst pack for 98 %+ hydrogen peroxide satellite monopropellant thruster

This study aimed to assess the decomposition rate of highly concentrated hydrogen peroxide on catalyst samples, based on the various materials and the geometry of the supporting structures. The drop test method was used and involved delivering a droplet of hydrogen peroxide to a catalyst sample in a sealed chamber, and then measuring the pressure rise. Different sample groups showed various pressure increase rates, indicating differences in catalytic performance. The drop tests were followed by a material investigation to compare the morphology of the active layer produced on various substrates and the effects of the high-test peroxide (HTP) interaction with the surface after the tests. Qualitative tests of phase composition and chemical composition were also performed. Different substrates resulted in varying morphology based on material type, chemical composition, and porosity. The study was treated as a screening test to choose the best catalytic pack option for testing under thruster-like conditions.

Development of hydrogen peroxide based micro thruster utilizing biomass-based catalyst bed

Micro thrusters, also referred to as micro-newton thrusters, are thrusters having a wide range of force capabilities in the micro-newton range. Micro thrusters are used in CubeSats, tiny robots and drones, micro- and nanosatellites, spacecraft attitude control, etc. The aim of the present study is to develop a monopropellant thruster (MPT) for 90 % concentrated hydrogen peroxide (H2O2). A rotatory evaporator was used to obtain a 90 % H2O2 form the available concentration of 50 % H2O2. The next stage involved the designing of the monopropellant thruster utilizing the NASA CEA rocket performance algorithm and the derived mathematical model. The test facility was constructed which includes a thruster, a feed line system, a static test firing platform, a data collecting system and the measuring sensors. To measure the thrust of the thruster, a pendulum thrust mechanism was constructed and fabricated into an experimental test stand. Lastly, the MPT chamber, which uses stainless steel mesh, was prepared and packed with the biomass-based catalyst. The 14 bar injection pressure conditions were used for the fire tests. With a mass flow rate of 5 g/s and a decomposition pressure of 10 bar, the theoretical specific impulse (Isp) was calculated to be 1993.2 Ns/kg at an O/F ratio of 0.002. The test firing with 90 % concentrated hydrogen peroxide gave an experimental specific impulse of 794.5 Ns/kg, which gives efficiency of 39.9 %.

Effect of Spherical Silver Particles Size of the Catalyst Bed on Hydrogen Peroxide Monopropellant Thruster Performance

Effect of Spherical Silver Particles Size of the Catalyst Bed on Hydrogen Peroxide Monopropellant Thruster Performance

Conceptual demonstration of a Lego-like modular fabrication method for an engineering model of a small monopropellant PCB thrusters

We present an innovative modular fabrication method for a green monopropellant thruster, employing printed circuit boards (PCB) as fundamental building blocks for rapid and efficient performance optimization. This PCB-based approach offers superior thermal and structural characteristics to conventional MEMS-based microthrusters. Furthermore, it streamlines mass production and facilitates the swift and reliable assembly of thrusters using well-established PCB surface mount technology. In this study, we present a conceptual demonstration of this pioneering materials and fabrication technique, exemplified by the development of a 200 mN thrust monopropellant thruster utilizing 90 wt% hydrogen peroxide. Subsequently, we conduct propulsion experiments and consistently observe identical patterns in pulse mode firing tests, demonstrating the repeatability of the system. The experimental results, including thrust and C* efficiencies, provide substantial evidence for the validity and feasibility of our proposed approach. The modular fabrication method presented in this study exhibits high potential for mass production of small satellite thrusters, effectively addressing the expanding thruster market.

Optimizing porosity of the catalyst for hydrogen peroxide based thrusters

The texture of the catalyst support is a crucial factor for H2O2 decomposition due to the expansion of H2O2 in monopropellant thrusters, which can lead to overpressure and catalyst breakage. Therefore, alumina supports with 5 wt%, 10 wt%, and 15 wt% microcrystalline cellulose templates were studied to create macropores. MIP and SEM analysis showed that microcrystalline cellulose template increases the macropore fraction. Low-concentration H2O2 decomposition experiments revealed that over 10 wt% microcrystalline cellulose prevented catalyst breakage. Additionally, the thermal durability of the catalyst was studied at different calcination temperatures. Alumina with 15 wt% microcrystalline cellulose and a 900 °C calcination temperature exhibited the highest fracture strength and suitable reaction kinetics. The catalysts were tested in high-concentration H2O2 monopropellant thruster. The results demonstrated enhancement in catalyst size retention, pressure stability, and pressure drop. Introducing macropores through microcrystalline cellulose addition overcomes unstable thruster performance and it extends catalyst lifespan in H2O2 monopropellant thrusters’ applications.

Numerical modeling and parametric analysis of performance of a monopropellant thruster using a single-part catalyst bed model

Monopropellant hydrazine thruster, depending on their thrust level, specific impulse, and unique functional regime, are widely used in situation control, orbital transmission, and position correction systems of satellites. In these thrusters, hydrazine decomposes by passing through the catalyst bed in a highly exothermic reaction to hot gas products. Hot gases generate thrust force by passing through a convergent-divergent nozzle. Pore scale analysis of catalytic reactions is very common in various industries and is of interest to researchers due to its accuracy. In this paper, the decomposition chamber of a monopropellant hydrazine thruster is numerically simulated with a single-part bed model at the pore-scale. The length of decomposition chamber was 2.48 cm. Then the effects of parameters such as catalyst granule diameter, catalyst bed porosity coefficient and also chamber inlet pressure on the performance of the decomposition chamber and thruster are investigated. Simulations have been performed for catalyst granules with diameters of 0.88, 1.00 and 1.15 mm in three porosity coefficients of 0.4, 0.55 and 0.65. The inlet pressure is also changed from 10 to 25 bar in four different levels. The results showed that the porosity coefficient is the most effective parameter and with its decrease, the specific impulse and temperature rise, while the thrust force and mass flow rate intensify. Also, the size of the catalyst granules affects the performance of the bed and thruster so that by increasing it (at a certain porosity coefficient), a trend similar to the effect of decreasing the porosity coefficient can be seen in the results. On the other hand, with enhancing inlet pressure, the thrust force increases significantly. In this paper, the effect of bed parameters on the thruster performance is discussed in detail, which contains helpful results for researchers that work on improving the decomposition chamber efficiency.

Compositionally complex catalytic oxide beds free of noble metals for H2O2 fuelled monopropellant thrusters

Compositionally complex catalytic oxide beds free of noble metals for H2O2 fuelled monopropellant thrusters

Green synthesis and catalytic activity assessment of bespoke nano-catalyst for eco-friendly green propellant systems based on hydrogen peroxide

AbstractMuch effort has been devoted to replace pollutant, toxic, cancerogenic hydrazine-based propellants. Hydrogen peroxide could secure promising characteristics as well as high density specific impulse. Effective catalysts with high durability are required to commence H2O2 decompositions, and to inherit hypergolic nature with different hydrocarbon fuels. Silver nanoparticles (18 nm) were synthesized via hydrogen gas evolved by water electrolysis. MnO2 (20 nm) was developed in a sustainable manner via green hydrothermal processing. High crystalline, mono-dispersed particles were developed. Catalytic activity was assessed via precise measurements of liquid temperature profile (LTP) up to the boiling point of hydrogen peroxide. Whereas silver demonstrated LTP peak within 20 s; MnO2 experienced LTP within 40 s. Catalyst survivability was recorded via precise measurement of life time mass loss rate upon catalyst addition to hydrogen peroxide. While silver nano-catalyst demonstrated high performance at the reaction start; silver was found to be poisoned with crystalline phase change to silver oxide within 20 s. On the contrary, manganese oxide experienced high durable catalytic action. Consequently, MnO2 could be candidate for H2O2 monopropellant thrusters as catalyst bed. On the other hand, silver nanoparticles could be candidate for a single use in bipropellant system to inherit hypergolicity. This study presents a pioneering report on facile synthesis of catalyst nanoparticles; comprehensive catalytic activity assessment of silver to manganese oxide for H2O2 decomposition was represented. Proper catalyst assortment for practical applications was represented.

Reactor Structure for the Decomposition of ADN-Based Monopropellant

Ammonia dinitramide (ADN)-based liquid monopropellants are considered to be environmentally friendly alternatives to the toxic and carcinogenic hydrazine-based propellants. Hence, Space Solutions Co., Ltd. is developing a 1N ADN-based liquid monopropellant thruster by conducting a combustion performance in different types of reactors. Various parameters, such as preheating temperature and the size of thermal and catalyst beds, were examined. The results showed that the decomposition of the propellant in a Pt-LHA catalyst bed, which was used in the Type-1 reactor, resulted in insufficient combustion at low preheating temperatures. Furthermore, increasing the preheating temperature led to partial reaction of the propellant, but resulted in low combustion efficiency due to disintegration of the catalyst. However, when a thermal bed (STS ball) was used in addition to the catalyst bed (Pt-LHA) in the Type-2 and Type-3 reactors, the combustion efficiency was improved, with a minimal pressure drop of 0.2 bar. It was also confirmed that the catalyst was not damaged even after repeated operations. In conclusion, this study suggests that the propellant needs to vaporize before decomposing on the catalyst bed to achieve optimal combustion efficiency.

Lunar descent and landing via two-phase explicit guidance and pulse-modulated reduced-attitude control

This work considers the three-dimensional descent path of a space vehicle, from periselenium of its operational orbit to the lunar surface. The trajectory is split in two arcs: (1) descent path, up to an altitude of 50 m, and (2) terminal approach and soft touchdown. For phase 1, a new, three-dimensional locally-flat near-optimal guidance is introduced that is based on the local projection of the position and velocity variables. A minimum-time problem is defined using the locally flat coordinates of position and velocity. This leads to identifying closed-form functions of time for the two thrust angles, which identify the commanded thrust direction. During terminal approach (phase 2), correct vertical alignment, modest velocity, and negligible angular rate at touchdown are pursued. With this intent, a predictive bang-off-bang guidance algorithm is proposed that is capable of guaranteeing the desired final conditions. In both phases, the attitude control system has the objective of aligning the actual thrust direction with the commanded one, provided by the guidance algorithm. The resulting reduced-attitude control problem is addressed through the use of a new quaternion-based nonlinear control algorithm, which is proven to enjoy asymptotic stability properties. The attitude actuation system is composed of 12 monopropellant thrusters, ignited using pulse width modulation. Monte Carlo simulations are run, assuming significant displacements from the nominal initial conditions and including several harmonics of the selenopotential. The numerical results unequivocally prove that the guidance and control architecture proposed in this study is effective to achieve lunar descent and safe touchdown in nonnominal flight conditions.

Effect of Structural Materials on Monopropellant Thruster Propulsion Performance in Micro Scale

This paper reports on the effect of structural materials on heat loss-associated propulsion performance degradation of monopropellant thrusters in the micro scale. In order to address the effect of fabrication materials on heat loss, propellant flow characteristics, and propulsion performance, a conjugate heat transfer numerical study has been conducted considering several practical substrate candidates for microthrusters. The results were analyzed with respect to the thermal diffusivity of the materials, which revealed different propulsion performance characteristics and inner nozzle flow characteristics due to varying amounts of heat loss, depending on the microfabrication materials used and propellant enthalpies. Regardless of propellant enthalpies, however, there was a dramatic degradation in the amount of the thrust produced with respect to thermal diffusivity, particularly in the range of low thermal diffusivity. Glass, among the material types compatible with fabrication processes in regard to microthrusters, exhibited a 4% degradation in thrust performance for the 50 mN class microthruster considered, with the least degradation, while copper, with 7% degradation, exhibited the greatest amount of degradation among the materials considered. With varying chamber pressure and Mach number at the nozzle exit depending on structural materials, the results also indicated the necessity of heat loss consideration in a microthruster design process.

The Experimental Investigation of a 98% Hydrogen Peroxide Monopropellant Thruster Comprising the Metal-Foam-Supported Manganese Oxide Catalyst

The article presents alternative metal-supported catalysts for decomposition of the highest-class hydrogen peroxide: 98%+ (Type 98 HP, according to MIL-PRF-16005F). The aim of this study was the experimental investigation of an alternative solution for decomposition of 98%+ hydrogen peroxide, strictly for chemical propulsion. High-porosity open cell metal foams have been identified as structures with great potential. Low density, good mechanical and thermal properties, availability of various materials and alloys as well as new technologies of manufacturing, make metal foam a potential solution for many different propellants, not only hydrogen peroxide. Open cell NiCrAl foam has been processed to prepare several catalysts, with different content and dispersion of the active phase. Cleaning and drying were performed to prepare carriers for further processing: wet impregnation, slow drying, and calcination. Simple drop tests with 98% hydrogen peroxide have been conducted to estimate activity level of catalysts, in a simplified scale: low, medium, high. Then, real-environment tests have been performed in a catalyst bed. Temperature, pressure along the bed and propellant mass flow rate were measured while testing. The analysis of the test results provided a general conclusion that metal foam supported manganese oxide catalyst is a promising solution for hydrogen peroxide propulsion.

Endurance characteristic affected by pressure drop across catalyst bed of hydrogen peroxide monopropellant thruster

Endurance characteristic affected by pressure drop across catalyst bed of hydrogen peroxide monopropellant thruster

Catalyst bed behavior of hydrogen peroxide/kerosene bipropellant thruster in monopropellant and bipropellant modes with cavitating venturi valve

For typical hydrogen peroxide/kerosene bipropellant thruster applications, hydrogen peroxide is injected into a catalyst bed prior to an injection of kerosene. During this period, the bipropellant thruster operates in a monopropellant mode. For ignition, kerosene is injected into hot oxygen gas and water vapor, which are the decomposition products of hydrogen peroxide. After ignition, the bipropellant thruster operates in a bipropellant mode. During this ignition sequence, the catalyst bed switches from the monopropellant mode to the bipropellant mode. The pressure drop in the catalyst bed differs between these modes. It is necessary to understand why this difference exists. In this study, I examined the cause of the difference in the pressure drop of the catalyst bed by catalyst bed modeling. The catalyst bed model was tuned according to the results of experiments conducted using a 40 N monopropellant thruster. Subsequently, the model prediction and experimental results of a 330 N bipropellant thruster were compared. Using the model prediction, the cause of the difference in the catalyst bed pressure drop was examined. A possible cause of the pressure drop difference between the two modes is the difference in gas density owing to the injection pressure difference of hydrogen peroxide.

Hydrogen peroxide decomposition in serpentine mini channel with silver catalyst

Micro thrusters were used to produce thrust in the order of a few Newtons to position satellites and other designed space objects. For such applications, monopropellant thrusters using hydrogen peroxide are preferred for their high maneuverability, accurate positioning, and attitude control. Hydrogen peroxide is a green monopropellant that forms the products (water and vapor) after it gets decomposed in contact with a catalyst. Complete catalytic decomposition of hydrogen peroxide is still a challenging task. In the present work, 30% of hydrogen peroxide concentration with silver catalyst (modified geometry) were used to increase reaction rate. The effect of silver placed at different locations in serpentine and straight mini channels (same dimensions) is analyzed. The analysis is done for a varied number of silver catalysts placed at different locations in serpentine and straight mini channels having a diameter of 0.25 cm. The serpentine mini channel shows better decomposition of hydrogen peroxide especially at shorter length of 10 cm than the straight mini channel with the same length of catalyst because of its better mixing capability due to non-uniformity in the flow field, especially at the bend sections. The results will be useful in determining the appropriate geometry and placement of the catalyst for efficient monopropellant decomposition.

Optimization of 10 N Monopropellant High Test Peroxide Thruster for Space Applications

Monopropellant thruster is one of the most propulsion system types developed in the space industry. This system uses a single type of propellant that reacts in porous medium catalytic packed bed to generate thrust in the form of hot gases. The last decade, green propellant hydrogen peroxide (H2O2), also known as High Test Peroxide (HTP), thanks to its low cost and easy to store as liquid, is used as an alternative solution of hydrazine which is very toxic and not environmentally friendly. In the current study, hydrogen peroxide monopropellant thruster is investigated for application in the future satellites. A numerical simulation is performed using the Computational Fluid Dynamics (CFD) software ANSYS Fluent in order to simulate fluid flow of hydrogen peroxide in thruster, and the finite volume method was employed for resolving the governing equation. Species transport model is applied in the single-phase reaction simulation using the Eddy Dissipation model (EDM) for turbulence-chemistry interaction. A mathematical approach based on the local thermal non-equilibrium (LTNE) model is used to describe the heat transfer through solid and fluid phases in the packed bed consisting of identical spherical silver particles. Several simulations performed allowed an optimal design of the injector, catalyst bed length and diameter and nozzle geometry, to achieve a 10N monopropellant thruster with hydrogen peroxide at 87.5% concentration.

Womersley's solution for the measurement of volume flow rates in transient laminar flow tubes

The characterization of transient flows within the Reynolds number range of Re = 10–100 and the Womersley number range α = 0.8–10 is required for the ongoing development of green monopropellant thrusters. However, at the ml/min scale flow rates of interest, these measurements are outside the capabilities of current commercial flow meters. It is proposed here that transient flows under the required dynamic conditions can be characterized via Womersley's solution for transient flow in a rigid tube. This solution method requires only the measured transient pressure gradient within a controlled laminar flow section and can be accomplished using existing commercial pressure measurement hardware. Experiments were performed where flow similarity was maintained with the ultimate thruster characterization application, but the radius of the flow passage was increased so that flows could be simultaneously characterized by both the proposed solution method and a commercial ultrasonic flow meter. It was shown that across the range of interest, applying Womersley's solution to a measured pressure gradient was an effective method of transient flow characterization. Additionally, it was shown that non-periodic flows can be characterized except for the initial flow startup transient with solution convergence times approximating the analytical solution to starting flow in a pipe. While these results were expected due to an experimental design matching the assumptions required for Womersley's analytic solution, this work demonstrates that this method is practically feasible as novel instrumentation enabling previously unobtainable measurements.

Preliminary design and study of 5N HTP monopropellant thruster for small satellites

In space propulsion hydrogen peroxide is a “green” solution that overcomes the problem of toxicity related to hydrazine-based systems. This work aims at designing, developing, and characterizing a monopropellant thruster for small satellites, based on hydrogen peroxide. The engine is intended for use on a 12-Unit CubeSat in Low Earth Orbit. Based on mission requirements a catalytic chamber and a nozzle were designed and a ground-test breadboard was manufactured. The prototype was assembled and tested on ground and measured engine performances are discussed highlighting their dependence on the nozzle throat diameter, that primarily affects the chamber pressure. Finally, effects of the mass flow rate on the system reactivity and steady state conditions are also investigated.

Design and Simulation of Single Capillary Injector and Circular Injector Plate for a Monopropellant Thruster

در این پژوهش ابتدا طراحی و شبیه‏سازی انژکتور کاپیلاری تک و سپس طراحی و شبیه‎سازی صفحه انژکتور دایروی سه سوراخه یک میکرورانشگر تک‎مؤلفه‌ای هیدرازینی 10 نیوتنی انجام گرفت. به منظور شبیه‏سازی انژکتور و صفحه انژکتور روش حجم سیال (VOF) بکار گرفته شد و آشفتگی جریان هم با استفاده از مدل k-ε شبیه‏سازی شد. با بررسی نتایج، مشخص گردید انژکتور و صفحه انژکتور طراحی شده توانایی تامین دبی جرمی مورد نظر میکرورانشگر را در اختلاف فشار معین طراحی دارند. از این رو ابعاد نهایی برای ساخت و استفاده در رانشگر تک مؤلفه‌ای هیدرازینی 10 نیوتنی انتخاب شدند. در نسخه قبلی این تراستر 10 نیوتنی، از انژکتور جریان پیچشی با پاشش چتری توخالی استفاده شده بود. اما در طرح جدید با انژکتور کاپیلاری به دلیل چتر کوچک و توپر انژکتور، طراح محفظه کاتالیستی قادر است تا ابعاد محفظه را به اندازه چشمگیری کاهش دهد که هم حجم کاتالیست مصرفی گران‎قیمت ایریدیوم کاهش می‏‎یابد و هم بالتبع ابعاد و وزن تراستر کاهش می‎یابد.

Investigation on Performance Characteristics of Hydrazine Monopropellant Thruster according to Reaction Chamber Adiabatic Temperature

Investigation on Performance Characteristics of Hydrazine Monopropellant Thruster according to Reaction Chamber Adiabatic Temperature