Propellant Thruster Research Articles

Application of Laser Heating to Solid Propellant Thrusters for Restart and Variable Thrust

Application of Laser Heating to Solid Propellant Thrusters for Restart and Variable Thrust

Study of the Effect of Heat Supply on the Hydrodynamics of the Flow and Heat Transfer in Capillary Elements of Mixing Heads Jet Thrusters

The article presents the results of experimental studies of hydrodynamics and those of loobman single-phase and two-phase flows in capillary nozzle elements propellant thrusters and the proposed method of their calculation. An experimental study was performed in capillaries with a sharp entrance edge of the internal diameter of 0.16 and 0.33 mm and a relative length 188 and 161, respectively, in pouring distilled water and acetone in the following range of parameters Reynolds number Re = (0,3 ... 10) · 103, Prandtl number Pr = (2 ... 10), pressure p = (0,1 ... 0,3) MPa, the heat flux q = (0...2)×106 W/m2, the difference of temperature under-heating of liquid Δtn = (5 ... 80)K. The dependences for calculation of single phase boundaries, the undeveloped and the developed surface of the bubble and film key singing of subcooled liquid. It is shown theoretically and experimentally confirmed the virtual absence of areas of undeveloped nucleate boiling in laminar flow. The dependence for calculation of hydraulic resistance and heat transfer in the investigated areas of current. It is shown that in the region of nucleate boiling surface in the flow in capillary tubes, influence of the formed vapor phase on the hydrodynamics and heat transfer substantially higher than in larger diameter pipes.

MEMS 고체 추진제 추력기의 성능예측 및 분석

내탄도 모델 및 CFD 해석을 통해 MEMS 고체 추진제 추력기의 성능을 예측하고 분석하였다. 노즐목 지름이 <TEX>$416{\mu}m$</TEX>, 면적비가 1.85인 추력기의 내탄도 모델 해석 결과, 챔버 압력은 최대 197 bar까지 상승하였으며, 최대 추력은 3,836 mN이었다. CFD 해석에 내탄도 모델의 챔버 압력을 작동압력으로 적용하였으며, 해석 모델을 단열 모델과 열손실 모델로 구분하여 해석을 진행하였다. 해석 결과 점성 효과만이 고려된 단열 모델의 최대 추력은 내탄도 모델에 비해 14.92% 낮았으며, 짧은 작동 시간으로 인하여 열손실에 의한 추력 손실은 매우 작게 나타났다. The performance of a MEMS solid propellant thruster was predicted and analyzed through internal ballistics model and CFD analysis. The nozzle throat was <TEX>$416{\mu}m$</TEX>, and the area ratio of the nozzle was 1.85. As a result of the internal ballistics model, chamber pressure increased up to 197 bar and the maximum thrust was 3,836 mN. In CFD analysis, the chamber pressure of the internal ballistics model was applied as the operating pressure, and the CFD model was divided into an adiabatic and a heat loss model. As a result, the maximum thrust of the adiabatic model was 14.92% lower than that of the internal ballistics model, and the effect of heat loss was insignificant.

Development of a wall-climbing platform with modularized wall-cleaning units

Abstract This paper presents a wall-climbing platform equipped with new modularized wall-cleaning units. Instead of using such devices as winch systems or built-in guide rails, the proposed platform adopts a portable rope ascender for efficient wall-climbing. In order to keep in good contact with various types of walls, two propeller thrusters are optimally designed by the Taguchi method to ensure absorptive force of larger than 45 N per a propeller thruster. The compactness and lightness of proposed platform is successfully achieved so that its overall size, weight and load capacity are 1300 mm × 787 mm × 606 mm (length × width × height), 37 kg and 18 kg, respectively. Two types of modularized cleaning units are built by using the ball-screw mechanism to adjust the distance as well as the contact angle between the cleaning units and a wall. The dry type wall-cleaning unit is designed and its operating conditions are examined by the Taguchi method to remove more than 88.9% of contaminants on a glass. The semi-dry type wall-cleaning unit is constructed based upon the dry type wall cleaning unit to effectively remove solidified contaminants by rubbing the diatomite against the wall. The extensive experiments using the proposed wall-climbing platform equipped with the wall-cleaning units are carried out to demonstrate its stable climbing capability as well as excellent cleaning performance.

Use of Multibeam and Dual-Beam Sonar Systems to Observe Cavitating Flow Produced by Ferryboats: In a Marine Renewable Energy Perspective

With the prospect to deploy hydrokinetic energy converters in areas with heavy boat traffic, a study was conducted to observe and assess the depth range of cavitating flow produced by ferryboats in narrow channels. This study was conducted in the vicinity of Finnhamn Island in Stockholm Archipelago. The objectives of the survey were to assess whether the sonar systems were able to observe and measure the depth of what can be cavitating flow (in a form of convected cloud cavitation) produced by one specific type of ferryboats frequently operating in that route, as well as investigate if the cavitating flow within the wake would propagate deep enough to disturb the water column underneath the surface. A multibeam and a dual-beam sonar systems were used as measurement instruments. The hypothesis was that strong and deep wake can disturb the optimal operation of a hydrokinetic energy converter, therefore causing damages to its rotors and hydrofoils. The results showed that both sonar system could detect cavitating flows including its strength, part of the geometrical shape and propagation depth. Moreover, the boat with a propeller thruster produced cavitating flow with an intense core reaching 4 m of depth while lasting approximately 90 s. The ferry with waterjet thruster produced a less intense cavitating flow; the core reached depths of approximately 6 m, and lasted about 90 s. From this study, it was concluded that multibeam and dual-beam sonar systems with operating frequencies higher than 200 kHz were able to detect cavitating flows in real conditions, as long as they are properly deployed and the data properly analyzed.

Thermo-mechanical Design for On-orbit Verification of MEMS based Solid Propellant Thruster Array through STEP Cube Lab Mission

A MEMS solid propellant thruster array shall be operated within an allowable range of operating temperatures to avoid ignition failure by incomplete combustion due to a time delay in ignition. The structural safety of the MEMS thruster array under severe on-orbit thermal conditions can also be guaranteed by a suitable thermal control. In this study, we propose a thermal control strategy to perform on-orbit verification of a MEMS thruster module, which is expected to be the primary payload of the STEP Cube Lab mission. The strategy involves, the use of micro-igniters as heaters and temperature sensors for active thermal control because an additional heater cannot be implemented in the current design. In addition, we made efforts to reduce the launch loads transmitted to the MEMS thruster module at the system level structural design. The effectiveness of the proposed thermo-mechanical design strategy has been demonstrated by numerical analysis.

Performance of a green propellant thruster with discharge plasma

A discharge plasma was applied to initiate the combustion of a hydroxylammonium nitrate-based propellant as a substitute for the catalysts that are typically employed. The resulting thrust and thrust-to-power ratio during short interval firing tests as well as the chamber pressure with a single pulse discharge were evaluated. A 1.5-s firing test generated a maximum thrust of 322mN along with a thrust-to-power ratio of 0.95 mN/W. During the single-pulse discharge trials, pulsed discharge capacitor energies of 5.4, 10.8, and 16.4J were assessed, and the maximum chamber pressure was found to increase as the energy was raised. The maximum chamber pressures varied widely between experimental trials, and a 16.4-J energy value resulted in the highest chamber pressure of over 1 MPaG. The time spans between the pulsed discharge and the peak chamber pressure were in the range of 1–2ms, representing a chamber pressure increase rate much higher than those obtained with standard catalysts.

Verification of MEMS fabrication process for the application of MEMS solid propellant thruster arrays in space through launch and on-orbit environment tests

One of the most significant barriers encountered to the space application of MEMS technology is its lack of reliability and flight heritage in space environments. In this study a MEMS solid propellant thruster array was selected for the verification test of MEMS technology in space. The function and performance of MEMS solid thruster have been previously verified by laboratory-level research in universities. To ensure the successful operation of the MEMS thruster module before flight demonstration on-orbit, launch and on-orbit environment tests were performed at the qualification level. In the launch test, sine burst, and random vibration loads were applied to the MEMS thruster module. The thermal vacuum tests were carried out for the on-orbit environment test. As a result of the launch vibration test and on-orbit environment test, the variations of the characteristics were less than 0.7%, and all the functional requirements were successfully verified after the vibration tests. The tests successfully verified the manufacturing process because the thruster module showed stable normal function before the ignition. The test result outputs will be helpful in establishing MEMS fabrication guidelines for space applications.

Global model of an iodine gridded plasma thruster

Most state-of-the-art electric space propulsion systems such as gridded and Hall effect thrusters use xenon as the propellant gas. However, xenon is very rare, expensive to produce, and used in a number of competing industrial applications. Alternatives to xenon are currently being investigated, and iodine has emerged as a potential candidate. Its lower cost and larger availability, its solid state at standard temperature and pressure, its low vapour pressure and its low ionization potential make it an attractive option. In this work, we compare the performances of a gridded ion thruster operating separately with iodine and xenon, under otherwise identical conditions using a global model. The thruster discharge properties such as neutral, ion, and electron densities and electron temperature are calculated, as well as the thruster performance parameters such as thrust, specific impulse, and system efficiencies. For similar operating conditions, representative of realistic thrusters, the model predicts similar thrust levels and performances for both iodine and xenon. The thruster efficiency is however slightly higher for iodine compared with xenon, due to its lower ionization potential. This demonstrates that iodine could be a viable alternative propellant for gridded plasma thrusters.

큐브위성 STEP Cube Lab.의 임무 탑재체 인증모델의 열진공시험 및 열모델 보정을 통한 궤도 열해석

우주기반기술 검증용 극초소형 위성 STEP Cube Lab.(Cube Laboratory for Space Technology Experimental Project)의 주요 탑재체인 집광형 프레넬렌즈가 적용된 고효율 집광형 태양전력시스템, 열선 절단방식이 적용된 무충격 구속분리장치 그리고 MEMS 기반의 고체추력기에 대해 인증수준의 열진공 시험과 열평형 시험을 수행하였다. 이를 통해 열진공 환경 하의 인증수준의 시험온도규격에서 탑재체의 구조건전성 및 정상작동성을 검증하고, 열평형 시험 결과로부터 보다 신뢰성 높은 보정된 열해석 모델을 확립하였다. 본 논문에서는 주요 임무 탑재체의 인증수준의 열환경 시험에 대한 기능시험 결과 및 시험 결과로부터 수행된 열모델 보정과 최종 열모델의 궤도 열해석 결과에 대해 기술하였다. Qualification model(QM) of main payloads including concentrating photovoltaic system using fresnel lens, heating wire cutting type shockless holding and release mechanism, and MEMS-based solid propellant thruster have been developed for the STEP Cube Lab.(Cube Laboratory for Space Technology Experimental Project), which is a pico-class satellite for verification of core space technologies. In this study, we have verified structural safety and functionality of the developed payloads under a qualification temperature range through the QM thermal vacuum test. Additionally, a reliability of thermal model of the payloads has been confirmed by performing a thermal correlation based on the thermal balance test results.

Complementary control allocation for a Lagrangian seafloor imaging platform

Abstract: The depth controller for a Lagrangian imaging float is detailed, and performance results from simulation and field experiments are used to demonstrate the utility of a model based controller with a complementary control allocation approach. The float is an over actuated system in depth/altitude, which is the only degree of freedom controlled. Vertical control is accomplished using a combination of active buoyancy modulation and a conventional propeller thruster. The proposed depth control algorithm is designed to take advantage of the high authority, high bandwidth inputs available from the thruster, and the low bandwidth trim input available from the buoyancy controller. The float vertical dynamics are modeled as a double integrator in the input force, and empirically derived parameters are used to simulate actuator inputs and system response over pre-recorded bathymetry profiles. Simulation and preliminary experimental results indicate that significant reductions in actuator power can be achieved in field conditions, and that the combination of thruster and buoyancy control provide the altitude tracking performance required for benthic imaging.

Design and testing of low-cost miniature ion thruster for nanosatellites

Ion propulsion is a technology that offers low thrust but high specific impulse for small spacecraft. The propulsion system can be used for attitude control and deep-space missions. A disadvantage ion thrusters have is the high cost of the propellant. Xenon is a widely used propellant for ion thrusters; however, it is expensive. In addition, the manufacturing of the ion thruster can be costly. This paper presents a low-cost ion thruster that uses nitrogen and argon as its propellant. The thruster is named capacitive discharge ion thruster (CDIT) because the plasma is generated by a capacitive discharge. The force, specific impulse, mass efficiency, power efficiency, and thrust efficiency of the CDIT using nitrogen is 0.564 mN, 2 300 s, 0.44, 0.75, and 0.34, respectively, at a mass flow rate of 25 µg/s.

A quantitative optimisation model for a horizontal MEMS solid propellant thruster with experimental verification

This paper studies the effect of multiple geometric parameters of a micronozzle on a MEMS solid propellant thruster (MSPT) and establishes a quantitative optimisation model. Influences of the structural parameters of the micronozzle on performance are accurately calculated. The significance and contribution ratio of each parameter are evaluated by F distribution. Correspondingly, a horizontal MSPT is fabricated and tested to prove the optimisation model. In the implementation, a complete microigniter is formed by a single layer of Au, achieving an ultra-low ignition voltage of 2.1 V with an extremely low ignition resistance of 4 Ω.

Diagnostics of Air-Breathing Electric Thrusters

Air-Breathing Electric Thrusters (ABET) diagnostics is addressed, with on-ground prototypes in mind. It is based on detailed volume averaged Global Models and focuses on emission spectroscopy. Notably, the obtained optical emission spectroscopy diagnostics tools give important information about the thruster propellant constitution and also the ionization degree of each constituent. This allows for trade-off between various prototypes on the basis of their characterization and optimization.

Iodine as an alternative propellant for electrojet engines

In the article the analysis of iodine as a propellant electric propulsion for electric thruster with closed electron drift is provided. This compares the iodine thruster performance with the same parameters using the traditional propellant - xenon. Advantages of electro-propulsion on the iodine compared to installing, using xenon. Justified the use of iodine as a propellant for high power thrusters. Presents the preliminary design and the results of the first tests of stationary plasma thrusters on the iodine. The article provides information about the progress of RSC Energia corporate research, the purpose of which is to develop a bench-top system for the storage and supply of iodine. It is shown and described the system layout storage and supply for experimental testing electric propulsion on the iodine. Also shown plans of RSC Energia in further research on the development of electric propulsion on the iodine. The article presents a variant of the high power thrusters on a propellant of iodine, which offers the challenge of ensuring the life of the thruster and the use of thermionic cathode. This article provides an overview of Western achievements in the use of propellant iodine in electric thruster.

Investigation of 11D428А-22 thruster operation dynamics with bellows flow stabilizer

This paper presents the results of comparative fire test investigations of the bipropellant thruster 11Д428А-22 with both plate and bellows flow stabilizers. The direct-acting bellows flow stabilizer 11Д428А.410.00/-01 presented in this paper meets all current requirements and progress trends of such type of hardware. In the developed stabilizer the bellows is used as a sensitive element, which excludes any uncontrollable leakages of a working medium and improves the reliability by eliminating cramping and varying frictional forces typical for pistons and plungers. The use of bellows-expanding spring at an initial state of the stabilizer extends the regulation range of the latter and increases the maintenance accuracy of specified flow over the entire control range. The flow stabilizer provides the starting propellant flow at the expense of added mass; hence the negative regulator effect becomes the favorable one in respect of a feed pipeline of liquid propellant thruster to improve thruster operation dynamics. Novelty of the flow stabilizer configuration is combining functions of a regulator and a starting device and broadening a regulation range and accuracy due to the spring expands the bellows at the initial state. The development construction is easy to fabricate and it provides the agreement of calculated regulator parameters and those resulted at the tests.

MEMS 기반 고체 추력기의 마이크로 점화기를 이용한 궤도 열제어

MEMS based solid propellant thruster researched for the purpose of an academic research will be verified at space environment through CubeSat program. For this, the temperature of the MEMS thruster should be within allowable operating temperature range by proper thermal control to prevent the ignition failure caused by ignition time delay and to guarantee the structural safety of the MEMS thruster in the low temperature. In this study, we proposed an effective thermal control strategy, that is to use micro-igniter as a heater and temperature sensor for active thermal control instead of using additional heater. The effectiveness of the strategy has been verified through on-orbit thermal analysis of CubeSats with MEMS thruster.

An orthogonal analysis method for decoupling the nozzle geometrical parameters of microthrusters

This paper proposes an orthogonal analysis method for decoupling the multiple nozzle geometrical parameters of microthrusters, thus an reconfigured design can be implemented to generate a proper thrust. In this method, the effects of various nozzle geometrical parameters, including throat width Wt, half convergence angle ?in, half divergence angle ?out, exit-to-throat section ratio We/Wt and throat radius of the curvature Rt/Wt, on the performance of microthrusters are sorted by range analysis. Analysis results show that throat width seriously affects thrust because range value of 67.53 mN is extremely larger than the range value of other geometry parameters. For average specific impulse (ASI), the range value of exit-to-throat section ratio We/Wt and half divergence angle ?out are 4.82 s and 3.72 s, respectively. Half convergence angle with the range value of 0.39 s and throat radius with 0.32 s have less influence on ASI compared with exit-to-throat section ratio and half divergence angle. When increasing the half convergence angle from 10° to 40° and throat radius of the curvature from 3 to 9, average specific impulse initially decreases and then increases. A MEMS solid propellant thruster (MSPT) with the reconfigured geometrical parameters of nozzle is fabricated to verify the feasibility of the proposed method. The thrust of the microthruster can reach 25 mN. Power is estimated to be 0.84 W. This work provides design guideline to reasonably configure geometry parameters of microthruster.

Development of a dual-shaft propeller thruster equipped with rotational speed sensor for UVMS control

Majority of underwater robots utilize single propeller thrusters for navigation. A disadvantage of using a single-shaft propeller thruster is that the thrust force generated from a single propeller for reverse and forward thrust is asymmetric due to the disturbed flow caused by the thruster's body which may reduce thruster efficiency. Moreover, measurement procedures to precisely calculate propeller's rotation speed were also not available. To address these problems, this paper proposes a dual-shaft magnetic coupling-driven propeller thruster for underwater robot, equipped with sensors for measuring propeller's rotational speed. Numerical studies and experimental results on the position and orientation control of the proposed thruster are presented. Detail comparison of the rotational speed, thrust force and duty ratio between numerical calculation and actual experimental measurement results show the effectiveness of the proposed thruster. This paper also demonstrated that by using the proposed thruster, the control performance of an underwater robot can be improved significantly compared to commercially available thruster. The ability to determine propeller rotation directions is also a major advantage of this work.

Design and stability analysis of a novel wall-climbing robotic platform (ROPE RIDE)

This paper presents a novel robotic platform (ROPE RIDE: RObotic Platform Enabling Rope access In Dangerous Environment) to efficiently climb up various types of walls with the help of a rope ascender. A stability measure for a wall-climbing robotic platform is suggested in order to tactfully deal with detrimental effects of such disturbances on its mobile stability as obstacles on various types of walls or the interaction between its payload and environments. Based on the stability analysis, the wall-climbing robotic platform is systematically designed to ensure the mobile stability against external disturbances. The ROPE RIDE is subsequently constructed upon a rope ascender-based locomotion mechanism combined with the triangular tracks for smooth obstacle-climbing. In order to effectively maintain the adhesion to a wall during climbing up, two propeller thrusters are also adopted and a 1-DOF wall-cleaning unit using a ball–screw mechanism is installed as a payload to perform a cleaning task. The extensive experiments using the proposed ROPE RIDE on walls are carried out to demonstrate its superior capability of climbing up and cleaning walls of buildings.