Toxic Propellants Research Articles

Predesign of a Radial Inflow Turbine That Uses Supercritical Methane for a Mid-Scale Thruster for Upper Stage Application

The worldwide concern regarding the harmful effects of old polluting and toxic propellants has led to increased interest in new, green propellants and higher efficiency thrusters. This fact requires that a new generation of turbopumps, fit for these propellants, is developed. This paper focuses on the design of a radial inflow turbine, which was developed to power a single-shaft turbopump system for a 30 kN upper stage expander cycle thruster engine. The objective was to create a high-efficiency, compact, cheap-to-manufacture, 3D-printable turbine suitable to simultaneously power the methane and Oxygen pumps that feed the thruster. The total power consumed by the pumps for which this turbine was designed is 152 kW. The solution proposed in this paper includes measures such as elimination of the bladed diffuser, which was carried out to reduce the weight and the overall dimensions of the turbine. Comparing it with an axial turbine with the same power output, it has lower overall dimensions because it does not require a direction change at the inlet to the turbine bladed components, it does not require a stator to work, and its casing has a conical shape and is not cylindrical like the axial construction one. The proposed design has been analysed by CFD, which revealed that it can power the pumps. Analysis performed in off-design conditions indicated that the turbine has the best efficiency if the rotation speed and mass flow are varied at the same time. A breadboard model of the turbopump for which the turbine in this paper has been designed has been built using plastic and tested at pressures up to 6 bars using compressed air. The results indicate that above 1.5 bars of inlet pressure the turbine can overcome the internal resistances of the components and the rotor starts to spin. No indication of imbalance of the rotor was observed at maximum test pressure. Two configurations of the seals between the turbine and the adjacent pump have been tested, indicating that labyrinth seals must be doubled by floating ring seals.

Development of Polyamine/Alkanolamine-based Hypergolics with hydrogen Peroxide: A new route to N-methylimidazole with MDEA as a promising green fuel

A novel non-ionic liquid fuel based on a mixture of N-methylimidazole (MIm) and N-methyldiethanolamine (MDEA) called PAHyp 2 which reacts hypergolically with hydrogen peroxide is presented in this work. To study the hypergolic behaviors, a drop test setup able of capturing simultaneous high-speed schlieren, infrared and visible imaging was used. While infrared images capture the temperature history of the ignition process, schlieren images offer advantages of capturing the pressure waves as well as providing better visualization of the morphological description of the liquid dynamics. PAHyp 2 with hydrogen peroxide has specific impulse 6% lower than hydrazine-based fuels but because of its higher density it requires smaller propellant tanks for a given mission. In order to meet the requirements of good chemical stability and low viscosity of<30 cP, the proportion of MIm should range between 40 and 50% (or 60 to 50% of MDEA) and the amount of catalyst should be no more than 3 wt%. FTIR spectra showed no chemical degradation. By adding 3 wt% catalyst, the shortest ignition delay time of 8.8 ms was recorded. Based on these preliminary results, we believe that just like the other polyamiane/akanolamine-based fuels recently reported by our group, this new recipe is also a promising candidate to replace conventional toxic propellants and as such should be further studied.

Development and coupled thruster / electrolyser tests of a water propulsion system

Green propulsion is a key element of future Space propulsion because being environmentally friendly is not just a legal obligation but it can significantly reduce the hazards to people involved in the handling and thus also the overall lifecycle cost. This reduction is due to the easier handling of propellants compared to state-of-the-art toxic propellants based on Hydrazine.When it comes to a replacement of classical, toxic propellants for long term orbital missions current replacement candidates still have handling limitations because these propellants contain chemical energy. Water is the greenest of all possible propellants with no hazard potential because the energy is added in orbit via solar power. The Water Electrolysis Propulsion (WEP) is a system where gaseous oxygen and hydrogen are produced via electrolysis from pure water over a long period with low electric power and burnt with a high thrust and high Specific Impulse (ISP) when needed. Compared to classical Electric Propulsion Systems in this system the energy generation and usage are decoupled.With own R&T support, German (DLR) and European (ESA) funding this technology and the two key technology bricks (Electrolyser, stoichiometric thruster) have been further matured within ArianeGroup. This paper describes the latest development tests of the space grade electrolyser, the stoichiometric thruster and a coupled test series.

Memories and safety lessons learned of an Apollo Electrical Engineer

This article documents lessons learned from experiences in NASA's Apollo and Skylab Programs. These lessons are valuable for future missions, NASA exploration, and commercial flights. The article describes the author's experiences as an electrical engineer supporting design, testing, and mission operations during various Apollo, Skylab, and Apollo Soyuz Test Project missions. Incidents include the Apollo 13 oxygen tank explosion, the Apollo 14 docking close call, the Apollo 15 propulsion system electrical short, the Apollo 10 inadvertent lunar module abort, the Skylab 4 loss of control for entry, the Apollo Soyuz Test Project crew ingestion of toxic propellant, the Apollo 7 AC bus short, and the Apollo 16 Lunar Rover Vehicle anomalies. Lessons from two incidents on uncrewed flights, the Apollo 4 launch pad instrumentation electrical noise and the Mars Viking test stand electrical noise problem, are also included because of their direct relevance to human spaceflight.

Development of China's New Generation Launch Vehicles

In the past 2 years, China's new generation launch vehicles, such as the LM-6, LM-7, LM-5 and LM-11 launch vehicles, successfully made the maiden flights, which marked Chinese Long March series launch vehicles having many achievements such as the diameter of launch vehicles increased from 3.35 m to 5 m and the toxic propellants replaced with non-toxic and pollution-free propellants. This paper will introduce the features and new technology of LM-7, LM-5 and LM-11 launch vehicles, which are China's new typical generation Launch vehicles.

Response characteristics of H2O2 monopropellant thrusters with MnO2-mixed PbO catalyst

As environmental concerns increase, rocket-grade hydrogen peroxide has been considered as one of the candidates for replacing toxic propellants. Various components for the development of monopropellant thrusters using hydrogen peroxide have been studied, including catalysts, catalytic supports, and design parameters in monopropellant thrusters. As a part of these efforts, an experimental investigation, including design parameters, for a catalyst bed is performed with MnO2-mixed PbO catalysts in a hydrogen peroxide monopropellant thruster. In addition to basic performance of the monopropellant thruster, the response characteristics of rising time and tail-off time are compared with respect to two different catalysts. From the experimental results, it is found that a catalyst with high reactivity is much more preferable for reducing not only rising time but also tail-off time. Tail-off time in case of MnO2-mixed PbO is considerably shortened compared to that of MnO2. Moreover, design parameters, such as catalyst capacity and catalyst bed loading, for designing a catalyst bed in a monopropellant thruster can be suggested from an analysis of all experimental results.

Mixing and combustion modeling of hydrogen peroxide/kerosene shear-coaxial jet flame in lab-scale rocket engine

H2O2/kerosene bipropellants are effective alternatives for toxic propellants currently in use. The complex H2O2/kerosene turbulent flow and combustion chemical reaction are modeled, the atomization, evaporation and mixing are investigated, the characteristics of the complex chemical reaction path of kerosene at different stages in combustion chamber are analyzed, and the profiles of static pressure, temperature and Mach number of exhaust plume are provided. During the kerosene injection, the spray angle is 13°, the atomization and evaporation occur and complete simultaneously, the lasting time of atomization is about 1 ms, and the maximal vaporization rate reaches 1.5×10−6 kg/s. The combustion chamber can be divided into the following three zones: rapid high-temperature pyrolysis zone, oxidization zone and equilibrium flow zone. The initial excitation of kerosene reactions is crucial link, and the hydrogen abstraction reactions are the dominant reactions in the high pyrolysis. These peak values of static pressure, temperature, Mach number along plume axis almost evenly distribute, and the interval distances are about 32 mm along the centerline of axis.

Demonstration of 500 N scale bipropellant thruster using non-toxic hypergolic fuel and hydrogen peroxide

While shedding light on green space propulsion, the development of non-toxic hypergolic bipropellants has provided alternatives to the conventional, highly toxic propellants. Non-toxic energetic hydrocarbon fuels promoted by sodium borohydride were produced, and their hypergolicity with rocket grade hydrogen peroxide was confirmed. Ignition delays ranged from 4 ms to 17 ms, depending on the oxidizer concentration. A 500 N scale thruster utilizing a non-toxic hypergolic bipropellant combination was also developed. With an oxidizer-to-fuel ratio of 5.48, the injector was designed with pentad unlike-impinging jets, one fuel jet orifice and four oxidizer jet orifices for enhancing the mix and atomization of the hypergolic propellants. The operation test was performed, and burning time was established to be 3.5 s. For the demonstrator, the rising time was approximately 158 ms, and the pressure oscillation inside the combustion chamber was approximately ±7.69%. These results indicate the feasibility of this novel concept engine for future space missions.

Advances in Hypergolic Propellants: Ignition, Hydrazine, and Hydrogen Peroxide Research

A review of the literature pertaining to hypergolic fuel systems, particularly using hydrazine or its derivatives and hydrogen peroxide, has been conducted. It has been shown that a large effort has been made towards minimizing the risks involved with the use of a toxic propellant such as the hydrazine. Substitution of hydrazines for nontoxic propellant formulations such as the use of high purity hydrogen peroxide with various types of fuels is one of the major areas of study for future hypergolic propellants. A series of criteria for future hypergolic propellants has been recommended, including low toxicity, wide temperature range applicability, short ignition delay, high specific impulse or density specific impulse, and storability at room temperature.

One-Newton class thruster using arc discharge assisted combustion of nitrous oxide/ethanol bipropellant

This paper discusses a 1-N class thruster using nitrous oxide (N2O)/ethanol bipropellant thruster using arc discharge assisted combustion. Bipropellant thruster, which is mainly used in spacecraft for orbit transfer and station keeping, utilizes toxic propellants: hydrazine and nitrogen tetroxide despite relatively high specific impulse. Then a new bipropellant thruster with arc plasma assisted combustion was proposed to develop a non-toxic eco-friendly bipropellant thruster. Both N2O and ethanol, which can be stored in a liquid form, have neither toxicity nor reactivity to materials such as metal and polymer. Arcjet was utilized to initiate and sustain N2O/ethanol chemical reaction at 0.4 MPa thrust chamber pressure. A prototyped thruster shows that combustion was successfully started and sustained with the assistance of a 1-kW arc discharge. Thrust measurements at atmospheric ambient pressure yielded a specific impulse of 55 s with a characteristic exhaust velocity efficiency of 60%.

Assessment of Catalysts for Hydrogen-Peroxide-Based Thrusters in a Flow Reactor

Hydrogen peroxide is a candidate propellant for rocket-propulsion applications with the potential to replace highly toxic propellants currently used. Decomposition of hydrogen peroxide yields a high-temperature oxygen-steam mixture, which can be used as monopropellant or as oxidizer in a bipropellant configuration. This work examines different types of cellular ceramic-based catalysts for hydrogen-peroxide decomposition at miniature scale of nominal mass flows of . An exhaustive investigation of different catalysts in a flow reactor configuration similar to a propulsion application is conducted. The test matrix includes honeycomb monoliths with different channel geometries, densities, lengths, different carrier materials, and wash-coating procedures, as well as different types of catalysts such as pellets and foams. Thirty nine catalyst configurations with a total of 121 catalysts have been experimentally investigated based on their transient and stationary performance at design mass-flow levels of .

Lead Free Ammunition without Toxic Propellant Gases

AbstractEnvironmental and health considerations have encouraged the development of ammunition with substitutes for lead and other heavy metals. In general, the emission products from munitions containing nitro‐based propellants are highly complex mixtures of gases, vapors, and solid particles. The major combustion products are H2O, CO, CO2, H2, and N2. In addition, compounds including hydrogen cyanide (HCN), ammonia (NH3), methane (CH4), nitrogen oxides, benzene, acrylonitrile, toluene, furan, aromatic amines, benzopyrene, and various polycyclic aromatic hydrocarbons are detected in minor concentrations. Many of the identified chemical species have severe toxicological properties, and some of the compounds do even have mutagenic effects. Gun smoke emission is a concern because its exposure to humans may be substantial during military and civilian police training, as respiratory protection equipment is not routinely worn. In this work we study the compositions of some of the main decomposition products, experimentally as well as theoretically. The concept of frozen equilibrium at around 1500–2000 K appears to apply for CO, CO2, and H2. However, the trace species in the combustion mixtures appear theoretically to be present in negligible concentrations. Our measured results are many orders of magnitude higher than theoretical results in open space. We forecast that future development of gun powder will focus on reducing the amount of toxic trace species.

Environmental Life Cycle Criteria for Propellant Selection Decision-Making

A system of previously undefined environmental life cycle cost elements were developed for use in the propellant selection processes for spacecraft launch propulsion systems, with input from the National Aeronautics and Space Administration (NASA), the Swedish Space Corporation, and stakeholders in industry and academia. These environmental life cycle cost elements were incorporated into a life cycle cost analysis of toxic propellant (hydrazine) versus green (High Performance Green Propellant) through a modified cost benefit analysis. Environmental cost element line items within the life cycle were identified as costs or benefits (cost reductions or avoided costs). A case study was also implemented to further illustrate these findings, resulting in a real-world 66% reduction in Phase E (operational) mission cost for High Performance Green Propellant (HPGP) compared with hydrazine. Based on the analysis, the largest environmental cost drivers were facility operations and maintenance, end of life disposal, and transportation, with the major costs being associated with health and human safety protection.

Experimental Evaluation of the freezing of MON-3 Released into a Vacuum Chamber

In order to prevent hazardous contamination inside satellite stations by the sediment action of frozen toxic liquid propellant on the space suits of astronauts, it is necessary to understand the phase changes of the leaked liquid propellant in case of valve breakdown. Using MON-3 as the liquid propellant, the minimum flow rate of MON-3 released without freezing to the vacuum chamber was investigated. For all the experimental flow rates tested in this study (0.347×10−5−4.45×10−5 g/s), MON-3 was found to freeze when released into the vacuum chamber. Freezing may be caused by the loss of latent heat to the surroundings in the vicinity of the orifice outlet where vaporization occurs.

Strategy of Biological Reclamation of Chemically Polluted Ecosystems

The strategy of biological reclamation of ecosystems in the zones of chemical pollution with asymmetrical dimethylhydrazine (ADMH), a highly toxic propellant, is proposed. The strategy is based on the results of comprehensive studies on trends in the interactions of soils, plants, and accompanying microorganisms with ADMH at rocket stage drop sites and in specially established test areas, under natural and controlled conditions.

Propulsive Performance of Hypergolic H202/Kerosene Bipropellant

Hydrogen peroxide (H2O2)/kerosene is a prospective bipropellant due to its high-energy content, high storage density, and environmentally benign properties. The possibility of making it hypergolic renders this option even more attracting. Self-ignitable H2O2/kerosene bipropellants were prepared by combining different candidate catalysts and promoters. Preliminary screening evaluations were conducted by using a dropping-test method. Propulsive performances of the combinations having passed satisfying dropping-test requirements were then investigated on a specially designed thrust engine. The results revealed that short ignition delay and reliable propulsion performances could be acquired in both steady-state and pulse-mode operations, and the combination of kerosene with additives and H2O2 of 90% concentration could still have good performances after 3 months storage time. It is expected that the combination of H2O2 and kerosene can be an efficacious alternative for storable toxic propellants used currently.

Nontoxic Orbital Maneuvering and Reaction Control Systems for Reusable Spacecraft

Toxic propellants have a high ground operations cost because of the potential hazards that require extensive safety precautions, particularly for reusable spacecraft. Nontoxic propellants for orbital maneuvering and reaction control systems have received periodic attention since the late 1960s as new reusable vehicles and upgrades to existing vehicles are proposed. This paper discusses the spacecraft requirements that drive propellant selections, the viable candidates for nontoxic propellants, and the system concepts and technologies required. Options for nontoxic propellants are also discussed, which are categorized as monopropellants, storable bipropellants, and cryogenic oxygen-based bipropellants. Monopropellants provide inherently simple systems and are most suited to low total impulse systems. Hydrogen peroxide and kerosene is a promising storable bipropellant in terms of its density, specie c impulse, and low toxicity for long-duration spacecraft on-orbit propulsion systems. This combination can be made hypergolic, which renders it a very effective replacement for currently used storable propellants. The hypergolic characteristics of kerosene with additives and high-concentration hydrogen peroxide are presented in detail. Higher-performance liquid oxygen and alcohol or hydrocarbon fuels are advantageous for reusable propulsion systems that emphasize e uid commonality with other spacecraft systems and for human exploration missions where in-situ propellant production is foreseen. The prospects for further research work on all of these propellants are also discussed.

Cardiopulmonary Toxicity of Propellants for Aerosols

Some of the propellants used in aerosols have the potential to produce bronchoconstriction, reduce pulmonary compliance, depress respiratory minute volume, reduce mean blood pressure, and accelerate heart rate. The most toxic propellant is trichlorofluoromethane (FC 11), which exerts all of these undesired effects except bronchoconstriction and a reduction of pulmonary compliance. Coincidentally, FC 11 is the most widely used low-pressure propellant. The least toxic propellant is difluoroethane (FC 152a), which is rarely used in aerosols. Additional investigation is needed to determine which toxic effects are the important ones in deciding on the future use of these propellants. It will also be necessary to examine the influence of pathological lesions in the heart and lung on the sensitivity of these organs to the various aerosols. 5 references, 2 figures, 1 table.

Toxicity of aerosol propellants in the respiratory and circulatory systems IV. Cardiotoxicity in the monkey

The 15 fluorocarbons which can be used to propel aerosols have been grouped into 4 classes, depending on their potential to elicit cardiac arrhythmia and depression of myocardial contractility. The most toxic propellant, trichlorofluoromethane (FC 11) produces both forms of cardiotoxicity when inhaled in concentrations of 2.5–5%. The minimal proarrhythmic concentration in the monkey is reduced by i.v. infusion of epinephrine or by production of myocardial ischemia. The combination of the two effects reduced the minimal proarrhythmic concentration to 0.5%. This phenomenon suggests that the hazard of exposure to aerosol propellants is increased in persons with heart disease.

Air pollution control at Cape Kennedy.

Abstract Larger missiles and the increased use of toxic propellants require effective planning and operations to prevent the development of major air pollution problems. At Cape Kennedy Air Force Station, large-scale air-borne sources are of an instantaneous rather than a continuous nature. Significant air contamination sources include missile exhaust, aborts, spills of volatile propellants, disposal of toxic materials, and normal industrial or transportation activities. Abatement techniques incorporating equipment design, operations support, and environmental studies are discussed. Special emphasis is given controls, test data, and problems associated with the Titan II missile program.