Resistojet Thruster Research Articles

Dynamic Modeling, Fault Detection, and Fault Identification of Cold Gas and Resistojet Thrusters

Dynamic Modeling, Fault Detection, and Fault Identification of Cold Gas and Resistojet Thrusters

The Development of a Next-Generation Latticed Resistojet Thruster for CubeSats

CubeSat and small satellite resistojet heat exchanger designs are based on conventional concepts that have been used since the 1960s, being primarily limited to helical or twisted tape heat exchangers. The design flexibility enabled by new additive manufacturing technologies is yet to be properly harnessed. This study introduces a novel resistojet concept that incorporates a highly miniaturized lattice structure as the heat exchanger. A conjugate heat transfer analysis determined that the lattice with a diamond unit cell had superior thermal performance compared to the same lattice with a gyroid unit cell and increased the heat transfer rate by up to 11% compared to a helical heat exchanger of the same volume. Performance testing of the prototype thruster with integral diamond lattice indicated that specific impulses of up to 94 s were possible with a 30-Watt heater using nitrous oxide as the propellant. The prototype thruster weighed only 22 g and demonstrated a 67% reduction in the power required to achieve the same specific impulse as previous nitrous oxide resistojets designed for the small satellite platform. The development of highly miniaturized latticed resistojets is shown to be feasible and highly attractive for CubeSats, where mass and power are of the utmost importance.

Material selection based on joule heating simulation for resistojet thruster

Resistojets generate heat by passing an electric current through a resistive element, thereby heating a propellant at high pressure, which is subsequently expanded through a nozzle resulting in a supersonic exhaust jet. Specific impulse of a resistojet decides the performance of the thruster. Hence the goal here is to achieve highest specific impulse. The specific impulse of the resistojet is limited by the thermal design of the heater and the material selection. Since the design specifications on the resistojet model has been confirmed with calculated data points obtained from literature work, the material selection is done with the heat transfer simulation. Also, the materials selected as the simulation model is done on accordance with highest melting point and the factor of feasibility is taken into account. For achieving the heat transfer distributions among the flow channels through conduction allows the calculation of heat flux along the radial direction. The transient state condition of the turbulent fluid region is solved under the CFX solver. The simulation is done on different materials varying their thermophysical properties. The end result will be decided on the basis of the heat transfer rate and the residual obtained during higher iterations. Thus, this paper focuses on the choice of materials and the thermal analysis of the same to achieve the highest specific impulse and an efficient performance output.

Resistojet thruster with supercapacitor power source – design and experimental research

The paper presents the design of and experimental research on a resistojet thruster with a dedicated power supply system based on supercapacitors. First, the description of two research stands used in different stages of the research is presented. The experimental approach divides the research into two phases. The first part focuses on optimization of the heating chamber, which has a laboratory power supply as a power source. Seven configurations of the chamber – differing in the number of coaxial channels and spiral heaters – are presented together with the results of the optimization process. The second stage describes research into thruster-like conditions with both power supply systems – supercapacitor based and with a laboratory power supply – with the geometry chosen based on the optimization process. A comparison is presented of propulsion parameters for various pre-heating times, power levels and power supply types, with a cold gas system as a reference.

Endurance testing of the additively manufactured STAR resistojet

This paper reports the outcome of endurance tests performed on a proof-of-concept design of a high-temperature resistojet thruster. A high-performance resistojet could enable a fully all-electric spacecraft architecture providing all propulsion system functions. The thruster utilises a novel additive-manufactured heat exchanger, consisting of concentric thin-walled cylinders, which act as both a resistive heating element and regenerative heat exchanger. Two complete thruster assemblies were tested, with heat exchangers manufactured from 316L stainless steel using selective laser melting. The two test units were used to investigate the operational endurance and determine life-limiting failure modes of the design. The tests consisted of repeated operational cycling to known temperature limits while under vacuum. Degradation and failure was inferred from electrical characteristics of the thrusters, and X-ray computed tomography imaging was used for non-destructive inspection both pre- and post-testing. The analysis showed that the failure modes are due to thermally-induced stresses resulting from mechanical constraints and temperature gradients. The failures occurred after approximately 40 cycles in the first thruster operating with a current of 25 A, and, in the second thruster, after a total of 300 cycles at 15 A and 217 cycles at 20 A, resulting in two distinctly different failure locations.

Assessment of Micropropulsion System Unifying Water Ion Thrusters and Water Resistojet Thrusters

This study proposes a micropropulsion system unifying ion thrusters and resistojet thrusters and assessing that propulsive capability. The remarkable features of the system are the usage of water propellant and unification of the two types of thrusters by the single propellant. Water has been regarded as an attractive propellant in the view points of safety, availability, handling ability, low molecular mass, and future procurement in space. A multimode propulsion system is an attractive solution for the increasing demand for nano-/microsatellite missions. The proposal is to use microwave discharge water ion thrusters, tolerant for oxidization by water, and low-temperature water resistojet thrusters, enabling reuse of the waste heat. As a result of the assessment, it was expected that the propulsion system would have 3U size () and 3.70 kg mass, which realize in total a 6U and 10 kg satellite with 3U and 6 kg satellite bus system. The ion thruster would provide the maximum of by 47 W system power and the resistojet thruster would have 3.80 mN thrust and 72 s specific impulse by 19.4 W. Additionally, reuse of the waste heat from ion-thruster power supplies would enable the simultaneous operations of the two thrusters even at 50 W, which is almost the same power as the single ion thruster operation.

Numerical study of a novel monolithic heat exchanger for electrothermal space propulsion

Fully-coupled multiphysics simulations are applied to investigate a number of candidate heat exchanger materials in the Super-High Temperature Additively-Manufactured Resistojet (STAR) thruster. Two mission applications are considered: a low earth orbit (LEO) primary propulsion application and a secondary reaction control system (RCS) application of an all-electric geostationary (GEO) telecommunications platform. High-temperature operation provides a significant increase in specific impulse over the state-of-the-art Xenon-resistojets. Inconel 718 is investigated for moderate-performance for LEO applications, while pure tantalum and pure rhenium are examined for the extreme temperature high-performance GEO application. Simulations determine the attainable performance including heat transfer, Navier-Stokes continuum flow and Joule heating physics in both transient and steady state. Nozzle efficiency, heat exchanger efficiency, electrical characteristics and other key performance indicators are explored.

In orbit performance of butane propulsion system

The present work focuses on the determination of the in orbit performance of the Alsat-1 microsatellite propulsion system. The satellite mass is 90 kg, of which 6.2 kg is the propulsion system dry mass. The system is a butane propulsion system using low power resistojet thruster with 2.3 kg of propellant. The liquefied butane gas was selected due to its higher storage density and safety compared to the other propellants used for microsatellites. The purpose of this paper is the analysis of the firings performed after the launch of the satellite and to evaluate the system specific impulse and thrust level during the system lifetime. A total of 273 firings were performed on the Alsat-1 propulsion system in the period between the end of 2002 and mid 2009, the cumulated firing time is more than 12 h 49 min. The analysis of all the propulsion telemetry data shows that the system provides a total mission delta V of 25.3 m/s which is more than the 10 m/s specified for this mission. Furthermore, the mission average specific impulse and thrust are respectively 99.9 s and 48.8 mN.

Low-Cost Orbit Manoeuvres for Minisatellites using Novel Resistojet Thrusters

Electric propulsion using resistojets operating at low power (~100 W) and using liquid propellants have re-emerged as attractive propulsion options for small satellites. Compared to low-power pulsed plasma thrusters (PPT), the resistojet achieves 50 times the increase in thrust (~1–50 mN), which is necessary to overcome drag at solar maximum for small satellites in high drag obits (~200 km). Two resistojet thrusters have been developed at the Surrey Space Centre (SSC), which utilize a packed bed of silicon carbide (SiC) particles for the heat exchanger. A thermodynamic model has been developed to study and optimize the thruster design and a series of practical performance tests with both nitrous oxide and water as propellants has been completed at the USAF Research Lab (Edwards AFB) using the NASAJPL inverted pendulum thrust stand. Endurance tests (~300 h duration) were conducted to determine possible lifetime limitations or failure modes. The results are very encouraging and resistojet thrusters are now proposed as options for future USAF and SSC minisatellite missions. This paper describes the complete resistojet system, test results for the USAF Mighty Sat II. I and its flight performance, its performance and integration on the UoSAT-12 minisatellite and its launch in April 1999 where this novel technique was demonstrated for the first time in low Earth orbit on 26 July 1999.

Low-cost orbit manoeuvres for minisatellites using novel resistojet thrusters

Electric propulsion using resistojets operating at low power (~100 W) and using liquid propellants have re-emerged as attractive propulsion options for small satellites. Compared to low-power pulsed plasma thrusters (PPT), the resistojet achieves 50 times the increase in thrust (~1–50 mN), which is necessary to overcome drag at solar maximum for small satellites in high drag obits (~200 km). Two resistojet thrusters have been developed at the Surrey Space Centre (SSC), which utilize a packed bed of silicon carbide (SiC) particles for the heat exchanger. A thermodynamic model has been developed to study and optimize the thruster design and a series of practical performance tests with both nitrous oxide and water as propellants has been completed at the USAF Research Lab (Edwards AFB) using the NASAJPL inverted pendulum thrust stand. Endurance tests (~300 h duration) were conducted to determine possible lifetime limitations or failure modes. The results are very encouraging and resistojet thrusters are now proposed as options for future USAF and SSC minisatellite missions. This paper describes the complete resistojet system, test results for the USAF Mighty Sat II. I and its flight performance, its performance and integration on the UoSAT-12 minisatellite and its launch in April 1999 where this novel technique was demonstrated for the first time in low Earth orbit on 26 July 1999.

Computational and experimental investigations of rarefied flows in small nozzles

Detailed numerical and experimental studies are presented for unheated flows of hydrogen and nitrogen through a small nozzle. The nozzle geometry and flow conditions considered provide rarefied flows that are representative of resistojet thrusters employed on spacecraft for control. Computational results are obtained with the direct simulation Monte Carlo method. Experimental data are obtained using two different techniques. Measurements of axial velocity and translational temperature of hydrogen are performed using coherent anti-Stokes Raman scattering. Data are taken along the nozzle axis and in the exit plane of the nozzle. Measurements of thrust are obtained using a thrust stand for pure hydrogen, pure nitrogen, and for mixtures of the two. In all cases, the numerical predictions and experimental measurements are in excellent agreement.

Space Station propulsion system technology

Two propulsion systems have been selected for the space station: O/H rockets for high thrust applications and the multipropellant resistojets for low thrust needs. These thruster systems integrate very well with the fluid systems on the station. Both thrusters will utilize waste fluids as their source of propellant. The O/H rocket will be fueled by electrolyzed water and the resistojets will use stored waste gases from the environmental control system and the various laboratories. This paper presents the results of experimental efforts with O/H and resistojet thrusters to determine their performance and life capability.

Subsystems analyses for a Morl resistojet control system.

This article presents the results of the first phase of a program to define a resistojet control system for the manned orbiting research laboratory (MORL). 10-mlb hydrogen, ammonia, and biowaste thruster systems are defined to satisfy the impulse requirements arising from aerodynamic and gravity-gradient forces in orbit. Of the available biowastes (H2, CO2, and fecal water), the CO2 output alone was sufficient to provide the impulse requirements for the 10-mlb system; however, a combined CO2/H2 system permits greater growth capability at the expense of simplicity. The use of a resistojet thruster system to provide orbit injection and high-disturbance control impulse was also investigated. Orbit injection may be accomplished with a resistojet system at a thrust level of less than 1 Ib by means of a spiral transfer trajectory. High-disturbance events such as docking impact, logistic module stowage, and centrifuge operation may also be controlled satisfactorily by a resistojet system. No specific requirement was identified which requires the use of a separate high-thrust system.