Gas Propulsion System Research Articles

An Analytical Study on the Performance and Feasibility of Converting a Combined Gas or Gas Propulsion System to a Combined Gas Turbine–Electric and Steam System for a Type 22 Frigate

An Analytical Study on the Performance and Feasibility of Converting a Combined Gas or Gas Propulsion System to a Combined Gas Turbine–Electric and Steam System for a Type 22 Frigate

Design optimization of cubic-shaped pressurant tank for CubeSat propulsion system

From a technical and economic point of view, cold gas propulsion for nanosatellites is one of the more rational systems. There is a problem, however: the optimal spherical shape for a high-pressure vessel only takes up half the cubic volume of the CubeSat unit. To increase the volume, it is proposed to switch to a cubic-shaped tank. The aim of this work is to synthesize the more rational structural design of a pressurant tank that fits within a cubic constraint, which provides the perfect balance between the mass of the structure and the delta-V budget available for the propulsion system. The proposed variants are as follows: a set of four cylinders with spherical bottoms; 14 equal spheres arranged in a face-centered cubic packing; a thin-walled cube supported by ribs, the location and parameters of which provide the smallest mass of the structure; a cube, the reinforcement scheme of which is calculated using topology optimization method; an original polyspheric and bypass design schemes where the filling of the volume of the cube is created by a set of spherical and cylindrical shells of different radii. All the considered vessel variants can be obtained using additive technologies, such as selective laser sintering. For each variant, the internal volume and mass of the vessels were obtained, as well as the delta-V budget, taking into account the mass of the tank and the mass of the stored gas. The analysis of the results reveals that there are two structures that are more rational. The new bypass scheme provides the largest delta-V budget, but it has a 1.6 times larger mass than the initial spherical vessel design. It should be noted that the difference in vessel mass is not crucial for CubeSat form factor satellites. Choosing a rational design may require a larger delta-V budget. The possibility of increasing the reserve delta-V of the CubeSat cold gas propulsion system by 25–35 % due to the transition from a spherical to a cube-shaped tank has been demonstrated. At the same time, the mass of the tank structure increases by 1.6–6.3 times, which can be considered an acceptable price for increasing the efficiency of the propulsion system. The new bypass scheme offers the optimal balance of mass and delta-V reserve.

On the selection of propellants for cold/warm gas propulsion systems

Cold/warm gas spacecraft propulsion systems generate thrust by accelerating a cold or moderately heated gas through a nozzle. Despite their simplicity compared with typical chemical or electric propulsion systems, the choice of propellant nonetheless represents an important consideration that affects the design, operation, and performance of such thrusters. Here we review different propellants that have been used or proposed for cold/warm gas propulsion systems, and we perform a study investigating almost 5000 other possible alternatives. Propellants include organic and inorganic substances that can be stored in solid, liquid, gaseous, and multi-phase states at ambient conditions, and which undergo a phase change to a pure gaseous state (where needed) by heating before being ejected from the thruster. The different propellants are assessed by considering important evaluation factors, such as propulsive performance, storage requirements and storage density, mission suitability, safety, and cost. While conventional thruster performance metrics like the specific impulse are low for some propellants, the design and operational advantages they offer, together with a higher total impulse mass density (i.e. the impulse per propulsion system wet mass), make them superior choices for many missions.

Simulation and developments for large pellet formation and acceleration for shattered pellet injection of the ITER DMS

Amongst the technological developments needed for ITER, the disruption mitigation system (DMS) is one of the most challenging since it has to mitigate the consequences of high-energy plasma disruptions to ensure the lifetime of ITER's structure and in-vessel components. ITER DMS is using Shattered Pellet Injection, whose technology needs to be developed for ITER specific requirements.In the framework of the “Technology Fundamental Studies for DMS” contract with ITER Organization, as part of the ITER DMS Task Force activities, and CEA, the DSBT (Low Temperature Systems Department) designed and operates a pellet injection test bench to produce and accelerate large cryogenic pellets with diameters from 10 to 28.5 mm and length/diameter ratios up to two. The objective of this activity is to study and to optimise the pellet formation and acceleration process using pure Protium, Deuterium, Neon and mixtures of these gases.Analytic and numerical studies were used to define the geometrical and cryogenic parameters for the pellet desublimation in the in-situ condensation cell of the cryostat. An analytical model has also been developed for the pellet acceleration in the single stage gas gun to validate the propellant valve design aiming at achieving velocities of up to 500 m/s for 28.5 mm protium pellets and 200 m/s for neon pellets.The complete test bench is composed of the gas propulsion system, the cryostat with its key component the pellet formation cell, the flight tube and the target chamber with viewing ports. The mechanical assembly is completed with specific instrumentation and fast data acquisition systems for the observation of the pellet formation and acceleration. The pellet integrity and trajectory are characterised by shadowgraphy with high resolution, high-speed cameras located at 1 m and 3 m after the barrel exit and with an accelerometer and a target foil in the target chamber.This document details the simulation studies, the selected test bench design and first obtained results.

Petri net-based reliability and availability analysis to support asset management: a CODOG propulsion system case study

It is common sense that reliability and availability analysis is an appropriate technique to support proper physical asset management. However, this task can become very complex in face of a dynamic demand during the operational course of the analyzed assets. That is the case when considering military missions since operational conditions are not as steady as in the manufacturing industry for instance, and different operational scenarios are expected in short periods. In these cases, advanced tools for reliability and availability analysis such as Petri nets are expected to be applied. Accordingly, this paper presents a Petri net-based reliability and availability analysis to support maintenance decision-making for asset management. It addresses a reliability and availability analysis in a dynamic demand scenario that is demonstrated through an application case study for a Combined Diesel Or Gas (CODOG) propulsion system that is used in military ships.

Use of Genetic Programming for the Estimation of CODLAG Propulsion System Parameters

In this paper, the publicly available dataset for the Combined Diesel-Electric and Gas (CODLAG) propulsion system was used to obtain symbolic expressions for estimation of fuel flow, ship speed, starboard propeller torque, port propeller torque, and total propeller torque using genetic programming (GP) algorithm. The dataset consists of 11,934 samples that were divided into training and testing portions in an 80:20 ratio. The training portion of the dataset which consisted of 9548 samples was used to train the GP algorithm to obtain symbolic expressions for estimation of fuel flow, ship speed, starboard propeller, port propeller, and total propeller torque, respectively. After the symbolic expressions were obtained the testing portion of the dataset which consisted of 2386 samples was used to measure estimation performance in terms of coefficient of correlation (R2) and Mean Absolute Error (MAE) metric, respectively. Based on the estimation performance in each case three best symbolic expressions were selected with and without decay state coefficients. From the conducted investigation, the highest R2 and lowest MAE values were achieved with symbolic expressions for the estimation of fuel flow, ship speed, starboard propeller torque, port propeller torque, and total propeller torque without decay state coefficients while symbolic expressions with decay state coefficients have slightly lower estimation performance.

SU2 REAL GAS MODELS’ PERFORMANCE PREDICTIONS ON A COLD GAS THRUSTER

Cold gas propulsion systems are preferred, especially for the altitude and trajectory control for satellites, since the 1960s. Both depressurizing the propellant in the propellant tank throughout the mission and the expansion occurring in the divergent part of the thruster nozzle are the reasons for observing very low temperatures and pressure at the outlet section. We have decided to use an open-source compressible CFD tool, SU2, in order to predict the performance of the propulsion system in the early design phase. The scope of this study is the comparison of the results of the vacuum chamber performance tests and the outcomes of unsteady simulations with SU2 using different gas models, including ideal gas, van-der Waals, and Peng-Robinson models. Then, the accuracy and performance of these models are evaluated for the extremely low temperature and pressure conditions. Thruster performance tests have been conducted in the thermal vacuum chamber test campaign at the specially built testing facilities. In order to simulate nominal and low-temperature operation conditions, a propellant tank is thermally conditioned to the predetermined values, and performance test parameters are used as the input for the CFD simulations. The obtained results showed that the van der Waals gas model is the most appropriate gas model for both cases and provides the most realistic results in terms of performance parameters.

Estimation of gas turbine shaft torque and fuel flow of a CODLAG propulsion system using genetic programming algorithm

In this paper, the publicly available dataset of condition based maintenance of combined diesel-electric and gas (CODLAG) propulsion system for ships has been utilized to obtain symbolic expressions which could estimate gas turbine shaft torque and fuel flow using genetic programming (GP) algorithm. The entire dataset consists of 11934 samples that was divided into training and testing portions of dataset in an 80:20 ratio. The training dataset used to train the GP algorithm to obtain symbolic expressions for gas turbine shaft torque and fuel flow estimation consisted of 9548 samples. The best symbolic expressions obtained for gas turbine shaft torque and fuel flow estimation were obtained based on their R2 score generated as a result of the application of the testing portion of the dataset on the aforementioned symbolic expressions. The testing portion of the dataset consisted of 2386 samples. The three best symbolic expressions obtained for gas turbine shaft torque estimation generated R2 scores of 0.999201, 0.999296, and 0.999374, respectively. The three best symbolic expressions obtained for fuel flow estimation generated R2 scores of 0.995495, 0.996465, and 0.996487, respectively.

Optimization of Micro-Thruster Cold Gas Propulsion System Design for Space Applications

Comparing the complexity of the hardware and the control system, cold gas micro thrusters are much more simplified than other propulsion thrusters. Numerical calculation was carried out for mass requirement, mass flow rate, valves, feed system and computational fluid dynamics with finite element analysis was used for tank, pipe and nozzle design. Four different materials: Structural steel, Stainless steel, Aluminum and Titanium, were considered for tank design. They were subjected to the same conditions for four different tank geometries. The propulsion system was designed to be able to produce between 1 and 2 minutes of continuous thrust and the sudden impulses of between 0.8 and 1 seconds of gas expulsion, with over 20 impulses as desired thrust time. The mass and the volume needed for multiple tank geometries, concepts, and materials were determined. The main performance characteristics of the micro thrusters evaluated were Pressure Distribution, Velocity Profile, Temperature Distribution, Nozzle Efficiency and the corresponding Mach Number Distribution. This work is to provide a stable and controllable platform for testing equipment that can be ultimately applied to space applications.

On a New Type of Combined Solar–Thermal/Cold Gas Propulsion System Used for LEO Satellite’s Attitude Control

This paper presents the development, construction and testing of a new type of solar–thermal propulsion system which can be used for low earth orbit (LEO) satellites. Currently, the vast majority of LEO satellites are fitted with a cold gas propulsion system. Although such a propulsion system is preferred, the service duration of an LEO satellite is limited by the amount of cold gas they carry onboard. In the case of the new type of solar–thermal propulsion system proposed in this paper, the cold gas is first transferred from the main tank in a cylindrical service tank/buffer tank which is placed in the focal line of a concave mirror. After the gas is heated by the solar light focused on the service tank by the concave mirror, it expands by opening the appropriate solenoid valve for the satellite’s attitude control. In this way the service duration of LEO satellite on orbit can increase by 2.5 times compared with a classic cold gas propulsion system. This is due to the propellant’s internal energy increase by the focused solar light. This paper also presents the results achieved by carrying out tests for the hot gas propulsion system in a controlled environment.

Trend analysis of domestic and international regulations for electric propulsion system

ABSTRACT While regulations are being strengthened to prevent air pollution from ships in Korea and other countries, the Korean government has passed the Eco-Friendly Ship Act, which is effective from 1 January 2020. Therefore, for coastal ships constructed in Korea, the emission of air pollutants should be reduced by alternative fuel and improving their propulsion system. Accordingly, the Ministry of Oceans and Fisheries in Korea has announced a plan to promote the conversion of all 140 government ships into eco-friendly ships using liquefied natural gas or electric propulsion systems by 2030. To apply these propulsion systems, rules, and regulations of the Korea government must first be reorganized. In this study, the type and development trend of electric propulsion systems are reviewed, and trends in regulations for installing electric propulsion systems on ships in various countries, including the United States and Europe, and institutions, including the IEC, IEEE, and International Maritime Organization, are analyzed. Finally, the standardization of the regulation system is discussed to facilitate the introduction of eco-friendly ships to Korea, and relevant implications will be presented.

Use of Artificial Neural Network for Estimation of Propeller Torque Values in a CODLAG Propulsion System

An artificial neural network (ANN) approach is proposed to the problem of estimating the propeller torques of a frigate using combined diesel, electric and gas (CODLAG) propulsion system. The authors use a multilayer perceptron (MLP) feed-forward ANN trained with data from a dataset which describes the decay state coefficients as outputs and system parameters as inputs – with a goal of determining the propeller torques, removing the decay state coefficients and using the torque values of the starboard and port propellers as outputs. A total of 53760 ANNs are trained – 26880 for each of the propellers, with a total 8960 parameter combinations. The results are evaluated using mean absolute error (MAE) and coefficient of determination (R2). Best results for the starboard propeller are MAE of 2.68 [Nm], and MAE of 2.58 [Nm] for the port propeller with following ANN configurations respectively: 2 hidden layers with 32 neurons and identity activation and 3 hidden layers with 16, 32 and 16 neurons and identity activation function. Both configurations achieve R2 value higher than 0.99.

Design and development of prototype carpal wrist cold gas propulsion system for attitude control applications

In recent years, the Philippine space program has launched several small-scale satellites, and lately has commissioned its own space program. Research on improving the subsystems of these satellites would be beneficial to future space programs in the Philippines. This paper will detail the process of designing, validating, fabricating, and testing a prototype Carpal Wrist Cold Gas Propulsion System (CW-CGPS). By making use of a carpal wrist’s (CW) hemispherical movement capabilities, the sixteen thrusters could theoretically be replaced by four mounted on opposite ends. Optimization of the propulsion system is based on finding the nozzle design with the most adequate values for thrust, Mach number, and specific impulse while the CW design is validated when it can be calibrated to move as the program dictates. This study uses multiple programs to simulate and verify the design. The conditions of the testing environment are established by resources from international space organizations. Assembly and feasibility are assessed based on the results of the research. It was found that the final optimized system had a model torque of 0.247 N-m, more than enough to overcome the maximum combined influence of the gravity gradient torque of 2.34E-06 N-m and aerodynamic torque of 1.57E-25 N-m. The design, development, and test campaign for the thruster system is presented.

Orbital Maintenance of a Constellation of CubeSats for Internal Gravity Wave Tomography

The advent of radio occultation (RO) instruments aboard CubeSats leads to the possibility of a mission to sound atmospheric internal gravity waves if such satellites are deployed in close-flying constellation. The satellites in the constellation must have slightly perturbed orbital inclinations in order to spread the RO soundings within clusters in two horizontal dimensions, and consequently the satellites will disperse because they will experience different rates of regression of nodes. This dispersion must be countered by propulsive maneuvering in order to maintain the close formation of the constellation. Here, a theoretical approach to the necessary propulsive maneuvering is presented and simulations using comprehensive orbit propagators are performed to analyze four propulsive systems: two cold gas propulsion systems and two electrospray propulsion systems. Cold gas propulsion permits greater separations in inclination between satellites in a constellation by virtue of the greater thrust they can exert on a spacecraft: cold gas propulsion can permit inclination separations of 1 to 10 $^\circ$ while electrospray limits separations to less than 0.2 $^\circ$ . On the other hand, electrospray propulsion provides much longer mission lifetime by virtue of the greater total thrust it offers: cold gas propulsion expends all of its fuel in maintaining the constellation formation in less than approximately 100 days while electrospray propulsion can maintain formation for greater than 1000 days before expending all of its fuel. Mission lifetime is the most critical consideration for a mission, thus electrospray propulsion is recommended for the constellation-flying of CubeSats, but the accelerations that they offer must be greatly increased to enable spacecraft separations useful for tomography of internal gravity waves. Note that any close-flying constellation involving satellites with slightly perturbed inclinations will experience the same dispersing effect as the constellations described herein and, thus, require the same propulsive maneuvering to maintain formation.

Fabrication and Testing of the Cold Gas Propulsion System Flight Unit for the Adelis-SAMSON Nano-Satellites

Adelis-SAMSON is a nano-satellite mission aimed at performing geo-location of target signals on Earth using a tight three-satellite formation in space. To maintain formation, each nano-satellite is equipped with a cold gas propulsion system. The design, qualification, and integration of the Adelis-SAMSON nano-satellite propulsion system is presented in this paper. The cold gas propulsion system mass is approximately 2 kg, takes a volume of 2U, and generates a thrust of 80 mN from four thrusters using krypton as a propellant. We first present the propulsion system requirements and corresponding system configuration conceived to meet the mission requirements. Subsequently, we present the system architecture while listing all the components. We overview the particular role and qualification process of four of the propulsion system’s components: the propellant tank, thruster assembly, pressure regulators, and fill and vent valve. We detail the tests performed on each component, such as proof pressure tests, vibration tests, and external leak tests. Finally, we present the propulsion system level tests before delivery for satellite integration and discuss the propulsion system’s concept of operations.

Design, development, and performance of an ammonia self-managed vaporization propulsion system for micro-nano satellites

An ammonia self-managed vaporization propulsion (ASVP) system for micro-nano satellites is presented. Compared with a normal cold gas or liquefied gas propulsion system, a multiplex parallel sieve type vaporizer and related vaporization control methods are put forward to achieve self-managed vaporization of liquefied propellant. The problems of high vaporization latent heat and incomplete vaporization of liquefied ammonia are solved, so that the ASVP system takes great advantage of high theoretical specific impulse and high propellant storage density. Furthermore, the ASVP operation procedure and its physical chemistry theories and mathematical models are thoroughly analyzed. An optimal strategy of thrust control is proposed with consideration of thrust performance and energy efficiency. The ground tests indicate that the ASVP system weighs 1.8 kg (with 0.34-kg liquefied ammonia propellant) and reaches a specific impulse of more than 100 s, while the power consumption is less than 10 W. The ASVP system meets multiple requirements including high specific impulse, low power consumption, easy fabrication, and uniform adjustable thrust output, and thus is suitable for micro-nano satellites.

Development of a Laval nozzle for a cold gas propulsion system

This paper presents a study regarding the calculation and design of a Laval nozzle, and its influence on the performances obtained. For this research, numerical simulation were conducted using the commercial software ANSYS CFX to verify the geometry and to compare it with the analytical results. This study is part of a research project that develops an advanced solar thermal propulsion system; the main purpose is to increase the operation life of a satellite using focused solar light. Two geometries are analyzed in this paper: one with a cone shape and the other generated using the characteristics method. The working fluid is nitrogen gas, which was used due to its inert properties and high molar mass. For the numerical simulations an exterior domain has been taking into account, to capture the jet and to observe how is evolving into the atmosphere. Several cases were studied; temperature was the main parameter varied from one case to another. As a result of the numerical simulations, it was found that the nozzle shape and temperature at the inlet to the convergent section influences performance of the propulsion system in a significant manner. Mach diamonds form because of the supersonic exhaust of the nozzle, and can be seen how their intensity is decreasing in magnitude near the domain outlet.

Cold gas propulsion microthruster for feed gas utilization in micro satellites

Micro spacecraft, which have gained huge popularity in the last decade, are termed as “CubeSats”, a well-known class of small satellites. The fast growing functionality and popularity of CubeSats have helped researchers push technology demonstration towards efficient performance and reliability needed for commercial and governmental applications. Keeping in mind the increasing space debris, dependence of satellite life on fuel, and the use of fossil fuels as propellants, recent efforts are being made to develop a cold gas propellant-based (CGP) micro propulsion system. The CGP system has various merits, namely, non-toxicity, easy to use, and low leakage concerns over other propulsion systems. Liquid propellant-based propulsion requires a liquid feed system, which uses pressurized gas (such as helium, argon and nitrogen) to pressure-feed liquid to the combustion or vaporization chamber so as to produce thrust. But once the liquid propellant is depleted, the pressurized gas is unusable while the system runs out of fuel. Thus, the proposed CGP system being studied, apart from being used as a normal cold gas propulsion system, also offers the advantage of being used as a propulsion system for a liquid fueled system, in the event the liquid fuel runs out. The present work reports on cold gas micro thruster development, utilization of feed gas in a liquid fueled thruster, and the experimental study on the CGP system in simulated vacuum conditions and under a range of pressure conditions. Pressure in the pressure feed gas system for a 1–50 kg category of satellites varies from 4 to 8 bar depending on the mission requirement. The pressure reduces as the liquid propellant gets exhausted. The experimental results are used to validate a computational fluid dynamics model of the system. Thrust values are obtained between the micro to milli-Newton range so as to fulfil the requirements of attitude and station keeping for CubeSats in the 1–50 kg dry mass range. Under vacuum conditions, we obtained thrust values of 0.8 mN at 1 bar feed pressure to 2.24 mN at 4 bar feed pressure. These thrust values are nearly twice those achieved for sea level tests for the corresponding feed pressure. Furthermore, the parameters such as Mach number, velocity vector, pressure, temperature, specific impulse, and nozzle efficiency are studied and reported for atmospheric and vacuum conditions.

Identification of S VIII through S XIV emission lines between 17.5 and 50 nm in a magnetically confined plasma

43 spectral emission lines from F-like to Li-like sulphur ions have been identified in the wavelength range from 17.5 to 50 nm in spectra obtained following tracer injection into plasmas created in a magnetically confined plasma device, the stellarator TJ-II. Plasmas created and maintained in this heliac device with electron cyclotron resonance heating achieve central electron temperatures and densities up to 1.5 keV and 8 × 1018 m−3, respectively. Tracer injections were performed with ≤6 × 1016 atoms of sulphur contained within ∼300 μm diameter polystyrene capsules, termed tracer encapsulated solid pellets, using a gas propulsion system to achieve velocities between 250 and 450 m s−1. Once ablation of the exterior polystyrene shell by plasma particles is completed, the sulphur is deposited in the plasma core where it is ionized up to S+13 and transported about the plasma. In order to aid line identification, which is made using a number of atomic line emission databases, spectra are collected before and after injection using a 1 m focal length normal incidence spectrometer equipped with a CCD camera. This work is motivated by the need to clearly identify sulphur emission lines in the vacuum ultraviolet range of magnetically confined plasmas, as sulphur x-ray emission lines are regularly observed in both tokamak and stellarator plasmas.

Time Optimal State Feedback Control with Application to a Spacecraft with Cold Gas Propulsion

A cold gas propulsion system is well suited to provide the required thrust for a small surveyor spacecraft operated near an asteroid or planetary surface. The cold gas propellant can obtained in-situ from local surface or atmospheric constituents. For small spacecraft, the cold gas system may be limited to only on-off control of the main tank where the generated thrust is directly dependent on the tank pressure. As such the thrust will slowly decrease as the propellant is expended. A state feedback, time optimal, control law is developed for a vehicle with decreasing thrust in translational motion. The success of the control law is shown in simulation.