Hosein Mansori-Nezhad; Kamran Daneshjoo; Majid Shahravi
Volume 9, Issue 3 , December 2016, , Pages 53-71
Abstract
The mechanism is a set of mechanical components that are connected and can move relative to each other. If it can be used in space, it is called space mechanism. The space mechanisms are widely used in space missions. Many space missions have been failed due to malfunction of space mechanisms. This clears ...
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The mechanism is a set of mechanical components that are connected and can move relative to each other. If it can be used in space, it is called space mechanism. The space mechanisms are widely used in space missions. Many space missions have been failed due to malfunction of space mechanisms. This clears the importance in research and development of space mechanism. The deployable mechanisms are categorized based on geometry and performance. A variety of space deployable mechanisms are investigated and their advantages and limitations are introduced in this paper. All types of space mechanisms which have been used since the beginning of space travels are covered in this paper, hence this paper is a thorough review paper on this topic. This feature of paper, makes it unique in the field of information about new space mechanisms and usable in the country space industry.
Hojat Taei; Mansour Hozuri; Amirhossain Adami
Volume 10, Issue 2 , September 2017, , Pages 53-63
Abstract
The hydrazine propulsion system is one of the most widely used monopropellantpropulsion systems. This low-cost and low mass system is used for the attitude control ofsatellites due to its high specificity and rapid response.For this purpose, in the presentstudy, an optimal design of a hydrazine monopropellant ...
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The hydrazine propulsion system is one of the most widely used monopropellantpropulsion systems. This low-cost and low mass system is used for the attitude control ofsatellites due to its high specificity and rapid response.For this purpose, in the presentstudy, an optimal design of a hydrazine monopropellant propulsion system with the aim ofminimization of total mass and maximization of total impulse in the framework ofmultidisciplinary design optimization and sequential design method is considered. Inaddition, the principles of multidisciplinary and sequential design are described in thispaper. It has been tried to examine the impact of different elements on design goals andcompare the optimal value obtained in each of the design structures from differentaspects. It should be noted that the design process is accomplished in two ways, i.e.single-objective and multi-objective, and the optimal multidisciplinary design method iscompared with the sequential design method for the hydrazine monopropellant propulsionsystem.
Mehrn Mirshams; Asad Saghari; Ehsan Zabihian
Volume 8, Issue 3 , October 2015, , Pages 55-63
Abstract
This paper proposes a supplementary method for conceptual design of satellite electrical power subsystem(EPS). Each of represented methods for satellite electricalpower subsystemconceptual design in different references have some advantages and also disadvantages, besides in each of the methods a determined ...
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This paper proposes a supplementary method for conceptual design of satellite electrical power subsystem(EPS). Each of represented methods for satellite electricalpower subsystemconceptual design in different references have some advantages and also disadvantages, besides in each of the methods a determined part of this subsystem has been in focused. In this research, first advantages and disadvantages of existing approaches for the conceptual design of electrical power subsystemwere reviewed, continued with combining of previous methods, improved relationships and using some of the simulation methods plus the using of statistical databases, a complementary method with more ascendency and less disadvantages in comparison with other approaches was presented. Finally, using a data from a specific satellite and the results of the statistical design, the complementary method has been validated.
Mehrdad Khosravi; Saeid Salehy; Mohsen Abedi
Volume 12, Issue 1 , April 2019, , Pages 55-68
Abstract
Decreasing satellite solar arrays temperature, results in increasing electrical efficiency. Efficiently and subsequently power generation enhancements have several advantages. One of the modern techniques for balancing temperature conditions is employing heat pipes. In the present paper, design optimization ...
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Decreasing satellite solar arrays temperature, results in increasing electrical efficiency. Efficiently and subsequently power generation enhancements have several advantages. One of the modern techniques for balancing temperature conditions is employing heat pipes. In the present paper, design optimization of heat pipes configuration attached to the solar arrays of a sun-pointing satellite is conducted using multiobjective genetic optimization algorithm. The objective of optimization is to reduce solar cells temperature and utilized heat pipes mass simultaneously. Thermal simulations of the satellite are carried out with SINDA/FLUINT and Thermal Desktop softwares. The numerical simulations are validated against experimental measurements of the satellite thermal model in a vacuum chamber. Afterwards, the multiobjective genetic algorithm produced the optimal configurations of the heat pipes using the optimal Pareto concept. Six different designs on the Pareto front are selected and their corresponding results are discussed.
Space systems design (spacecraft, satellites, space stations and their equipment)
Sajjad Davari; Hadiseh Karimaei; Mohammad Reza Salimi; Hassan Naseh
Volume 16, Issue 2 , June 2023, , Pages 55-61
Abstract
In this paper, the catalyst bed of a 10 N hydrazine monopropellant thruster was designed. The catalyst bed is including iridium granules, which is used to decompose the hydrazine in monopropellant thruster. Hydrazine must be decomposed almost completely in the catalytic chamber, because it is a carcinogenic ...
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In this paper, the catalyst bed of a 10 N hydrazine monopropellant thruster was designed. The catalyst bed is including iridium granules, which is used to decompose the hydrazine in monopropellant thruster. Hydrazine must be decomposed almost completely in the catalytic chamber, because it is a carcinogenic chemical fuel and on the other hand, achieving the maximum power from the thruster is also an important goal. As a result, the effect of change in catalytic chamber length on the mass fraction of chemical species including hydrazine, ammonia, nitrogen, and oxygen was studied. Also, after determining the length of the catalytic chamber, the diameter of the nozzle throat corresponding to the same length was determined.
Mohammad Hosein Shafiei; negin vazirpour
Volume 12, Issue 3 , September 2019, , Pages 55-61
Abstract
In this paper, the approach of discrete-time partial stabilization is employed to design a robust three-dimensional guidance law against maneuvering targets. In the partial stabilization method, the considered system is divided into two sub-systems which achieving to asymptotic stability is desirable ...
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In this paper, the approach of discrete-time partial stabilization is employed to design a robust three-dimensional guidance law against maneuvering targets. In the partial stabilization method, the considered system is divided into two sub-systems which achieving to asymptotic stability is desirable only for the first one. One of the advantages of this paper is to design a discrete-time guidance law even with limitations and difficulties in discrete-time Lyapunov theorem. The Lyapunov function has been chosen based on the physics of the guidance problem (making the rate of line of sight (LOS) rotation close to zero). In this paper, it is shown that there is no possibility for asymptotic stabilization of the guidance problem in the case of maneuvering targets. Thus, it has been sufficed to limit the rotation rate of LOS to a small value which will guarantee the missile hit to the target in a short time. Simulations results show the appropriate performance of the proposed guidance law.
Vahid Bohlouri; Hosein Haghighi; Samane Kaviri; Marzieh Taghinezhad; ehsan maani; Soheil Seyedzamani
Volume 12, Issue 2 , September 2019, , Pages 55-70
Abstract
In this paper, the design and implementation of hardware-in-the-loop (HIL) test-bed for spacecraft attitude control are presented with respect to the practical consideration. This test-bed includes an air bearing 3-DOF table, Helmholtz coil, sun simulator, orbit simulator, reaction wheels and torqrods ...
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In this paper, the design and implementation of hardware-in-the-loop (HIL) test-bed for spacecraft attitude control are presented with respect to the practical consideration. This test-bed includes an air bearing 3-DOF table, Helmholtz coil, sun simulator, orbit simulator, reaction wheels and torqrods as actuators, gyro, GPS, AHRS, magnetometer, and processing board. In addition, online monitoring of attitude and orbit position in LabVIEW and Celestia software, data telemetry, battery package and power distribution board are developed in this case. Using this test-bed, different operational modes are evaluated and verified for satellite attitude control. The experimental results of damping mode show that the capability of decreasing the angular velocity to the desired value (0.3 deg/s). Moreover, a torque simulator to apply the disturbances and test of propulsion scenarios, online telemetry with ground station, near-optimal design of Helmholtz coil are the advantages of this test-bed.
Space systems design (spacecraft, satellites, space stations and their equipment)
Vahid Bohlouri; Hossein Haghighi; Soheil Seyedzamani
Volume 12, Issue 4 , December 2019, , Pages 57-67
Abstract
In this paper, damping mode of a satellite attitude control is designed and implemented using magnetic actuators in software /hardware-in-the-loop testbed. To this end, the equivalent of Earth’s magnetic field is designed using Helmholtz coil, frictionless is made by air-bearing, and algorithms ...
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In this paper, damping mode of a satellite attitude control is designed and implemented using magnetic actuators in software /hardware-in-the-loop testbed. To this end, the equivalent of Earth’s magnetic field is designed using Helmholtz coil, frictionless is made by air-bearing, and algorithms are developed on designed control board. By measuring the Earth’s magnetic field, actuator commands are generated by the damping algorithm then braking torque is produced. Some applied restrictions and special requirements such as non-simultaneous operation between magnetic sensor and magnetic actuators, air-bearing friction, initial angular velocity are considered. By identifying the air-bearing frictional model, the results are compared in software/hardware-in-the-loop. The compared results show that the ability of the designed system to perform damping mode.
space law
Negar Mofakham Naser Eslami; Ahmad Momeni rad; S. Ahmad Tabatabai
Volume 15, Issue 4 , December 2022, , Pages 57-70
Abstract
Today, one of the main concerns of the Committee for the Peaceful Use of Outer Space (COPUOS) and its subcommittees is the issue of militarization in space law. Top space countries such as the United States, Russia and China have added to this concern by using advanced space military equipment. Therefore, ...
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Today, one of the main concerns of the Committee for the Peaceful Use of Outer Space (COPUOS) and its subcommittees is the issue of militarization in space law. Top space countries such as the United States, Russia and China have added to this concern by using advanced space military equipment. Therefore, the international community must look for desirable and practical solutions to solve this problem in order to prevent militarization and the creation of an arms race in space. Based on this, the present article tries to investigate the military prohibitions governing space activities in order to prohibit such activities in outer space by analyzing the military use of space and legal documents and explaining the conventional and customary system governing space treaties and by examining some dual-use space-based weapons; Conduct a descriptive analysis and reveal more about the negative aspects of the military use of space.
GPS and navigation GPS)، GLONASS، GALILEO
Mona Zahednamazi; Alireza Toloui
Volume 16, Issue 4 , December 2023, , Pages 57-70
Abstract
One of the attitude sensors for the spacecraft is the star sensor. The attitude calculation by the star sensor includes several steps: image processing, star identification, database search, and implementation of the attitude determination algorithm. This paper presents analysis and improvements on the ...
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One of the attitude sensors for the spacecraft is the star sensor. The attitude calculation by the star sensor includes several steps: image processing, star identification, database search, and implementation of the attitude determination algorithm. This paper presents analysis and improvements on the star identification algorithm based on singular value decomposition. To improve the identification results, modifications have been made to the algorithm. Also, analysis and simulation are presented to investigate the effect of field of view dimensions and the number of stars used on the identification results, and the rate of duplicate sets in the database. In addition, identification has been considered a two-step process based on singular values and vectors. The results show the superiority of the improved algorithm in increasing the identification rate and reducing the rate of duplicate sets in the database. The identification rate of the improved algorithm in 〖10〗^°×〖10〗^° and 〖12〗^°×〖12〗^° fields of view dimension is always more the %97. The simulations were performed based on the Hipparcos star catalog for stars brighter than magnitude 6.5 and using MATLAB software.
Hadiseh Karimaei; seyed mostafa hosseinalipour
Volume 10, Issue 3 , December 2017, , Pages 59-65
Abstract
The droplet formation stage of a spray, which enjoys a great diversity in size and droplet velocity, is predictable through a statistical approach. Since the available methods require experimental data such as mean droplet diameter and mean droplet velocity as inputs to estimate the distribution of the ...
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The droplet formation stage of a spray, which enjoys a great diversity in size and droplet velocity, is predictable through a statistical approach. Since the available methods require experimental data such as mean droplet diameter and mean droplet velocity as inputs to estimate the distribution of the droplets, this study attempts to propose a consistent theoretical model based on the energy conservation equation for the estimation of mean droplet diameter to be used in the predictive models of droplet size distribution, such as maximum entropy model. Therefore, those models can be independent of experimental data. The parameters needed in the model, such as atomization efficiency and the Weber number are provided using a CFD model. Then, a parametric study to evaluate the relationship between the atomization efficiency and spray velocity, and mean droplet diameter is carried out. This new proposed model entitled energy-based model (EBM) can provide a very good prediction of mean droplet diameter in comparison with the available experimental data.
investigating space radiation
Majid Mokhtari; Hamideh Daneshvar; Morteza Bahmani nejad; Shahryar Malekie; Armin Mosayebi,; Amir Torabpoor-Isfahani,; Iman Aryanian
Volume 15, Issue 2 , June 2022, , Pages 59-69
Abstract
Sandwich panels are used in various industries due to their high special strength. It is used in ultra-light aerospace structures. In this paper the protective effect of sandwich structures used in ultralight space structures against gamma rays is investigated. Eight structures of the most widely used ...
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Sandwich panels are used in various industries due to their high special strength. It is used in ultra-light aerospace structures. In this paper the protective effect of sandwich structures used in ultralight space structures against gamma rays is investigated. Eight structures of the most widely used structures used in space structures such as telecommunication antennas and satellite bodies are exposed to radioisotopic sources of gamma rays (Amercium barium and cesium) with energies of 60 kV, 80 kV, 382 and 66 kV, have been compared to each other. Surface material (aluminum and carbon), surface thicknesses and honeycomb cell dimensions are the most important evaluation parameters. In this paper, different structures have been compared using the "special protection" parameter and the best structure from a protection perspective has been identified and reported.
Space subsystems design: (navigation, control, structure and…)
Abdolmajid khoshnood; Ali Aminzadeh; Peyman Nikpey
Volume 15, Issue 1 , March 2022, , Pages 63-71
Abstract
This paper is dedicated to modeling of fuel sloshing dynamics and its effect on the stability and control of the space vehicle. Sloshing due to the liquid movement in the fuel tank of a space vehicle's propulsion system can be effective on the vehicle’s control and stability. Force and moment interaction ...
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This paper is dedicated to modeling of fuel sloshing dynamics and its effect on the stability and control of the space vehicle. Sloshing due to the liquid movement in the fuel tank of a space vehicle's propulsion system can be effective on the vehicle’s control and stability. Force and moment interaction between fuel sloshing and space vehicle’s control system will be appeared as a feedback in the control system. With respect to simplicity of analyzing of a rigid body's equations of motion in comparison with a fluid dynamics equations and as a result reducing computational efforts, it is possible to apply a mechanical model instead. So in this paper fuel sloshing is modelled as a linear mechanical system to investigate its effect on the stability and control of the vehicle. For this purpose, two mechanical models, mass-spring and pendulum systems, are applied to model dynamics of a space vehicle with fuel sloshing and each system’s parameters are evaluated for simulat
space sciences and exploration
Ebrahim Amiri; Masoome Khani Chamani; Mahdi Jafari-Nodoshan; Sajjad Ghazanfarinia; Masoud Khoshsima
Articles in Press, Accepted Manuscript, Available Online from 16 December 2023
Abstract
The economic model generally expresses the mechanisms used to earn money from a business, and if it doesnot generate income, its failure will be certain. Therefore, the decision to carry out a mission isnot only based on technical specifications, and besides that, economic profitability is another part ...
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The economic model generally expresses the mechanisms used to earn money from a business, and if it doesnot generate income, its failure will be certain. Therefore, the decision to carry out a mission isnot only based on technical specifications, and besides that, economic profitability is another part of decision-making and will be one of the main factors for commercial investments. Space projects, as wellas moon-mining projects, are no exception to this rule and require an all-round approach to compare financial and technical feasibility. Analyzing the economic feasibility of any project can be summed up in the evaluation of its economic model. In this regard, a model is needed to compare, rank and determine the available options, which is economically justified. In this paper, the economic evaluation of moon-mining based on the materials available on the moon and sending them to the earth is discussed. Materials with economic priority are categorized and selected in a fuzzy evaluation and using an economic model suitable for space mining, an economic evaluation for the business of selling materials on the Earth is carried out and according to economic efficiency, the type of material and also the high-level specifications of the project has been extracted.
S. A. Fazelzadeh; Gh. A. Varzandian
Volume 1, Issue 2 , December 2008, , Pages 43-50
Abstract
In this study, optimal low-thrust spacecraft trajectories are obtained by time-domain finite element method. Equations of motion are expressed in state-space form. The performance index is considered as minimum time. The problem has been formulated through the variational approach. The time-domain finite ...
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In this study, optimal low-thrust spacecraft trajectories are obtained by time-domain finite element method. Equations of motion are expressed in state-space form. The performance index is considered as minimum time. The problem has been formulated through the variational approach. The time-domain finite element discretized form of the performance index, state equation constraints and the related boundary conditions are presented. By setting out the discrete equations, a set of nonlinear algebraic equations is generated and by using Newton–Raphson method, optimum answer is attained. The effects of the number of time segments on the performance index are examined. Furthermore, the influences of effective exhaust velocities on the optimal trajectory are demonstrated.
A. Vafaeesefat; S. H. Tabatabai
Volume 2, Issue 3 , December 2009, , Pages 43-50
Abstract
Weight optimization is one of important parameters in space structure design. Size optimization is usually performed using gradient or genetic algorithm. Gradient algorithm is based on derivation of objective function and constraints of problem. The performance of gradient method is depended on start ...
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Weight optimization is one of important parameters in space structure design. Size optimization is usually performed using gradient or genetic algorithm. Gradient algorithm is based on derivation of objective function and constraints of problem. The performance of gradient method is depended on start point and do not search all design domain. Genetic algorithm searches all design domains, but it cannot get close to the global optimum. In this paper, a new method is presented for size optimization. The algorithm starts with genetic algorithm and result of genetic algorithm is then used as start point for gradient algorithm. The presented method is used for size optimization of two trusses with three and ten elements. It is also applied on for optimization of a lattice structure of parabolic antenna. The results show that the present algorithm can perform better results compared to genetic algorithm alone.
M. S. Mohammadi; M. Mortazavi; M. Malekan
Volume 6, Issue 4 , January 2014, , Pages 43-52
Abstract
According to mission requirements in many of space missions, an exact time should be assigned for launch date namely launch window. Among various parameters influencing launch window, in this article a couple of most mission related ones are being researched. First is some constraints on handling satellite ...
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According to mission requirements in many of space missions, an exact time should be assigned for launch date namely launch window. Among various parameters influencing launch window, in this article a couple of most mission related ones are being researched. First is some constraints on handling satellite power and the second is the imaging mission constraintsfor a remote sensing satellite. Then after this study on mission requirements a conceptual method for launch window estimation is presented and supported by a case study on sample micro-satellite IRSAT.
Mehdi Fathi; ali mohammadi; Nemat Ollah Ghahramani
Volume 8, Issue 4 , January 2016, , Pages 45-51
Abstract
In this paper the feasibility of rapid alignment and calibration of a static strapdown inertial navigation system (INS) is evaluated. Resting conditions including zero-velocity update and a known initial heading direction as virtual external measurement data are integrated with INS data. By comparing ...
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In this paper the feasibility of rapid alignment and calibration of a static strapdown inertial navigation system (INS) is evaluated. Resting conditions including zero-velocity update and a known initial heading direction as virtual external measurement data are integrated with INS data. By comparing the virtual external measurements with the estimates of those generated by the aligning INS, estimates of the velocity and heading errors can be obtained and these errors will be propagated in the INS as a result of alignment inaccuracies. An extended Kalman filter based on an augmented process model and a measurement model is designed to estimate alignment attitudes and biases of inertial sensors. Monte Carlo simulation results show that the integration of INS with rest conditions is very effective in rapid and fine leveling and azimuth alignment of INS, but this type of data fusion due to poor acceleration and angular rates of static condition has no chance of valuable calibration of all inertial sensor biases.
Mohammad Saberi-Tavakoli; Fariborz Saghafi
Volume 5, Issue 4 , January 2013, , Pages 47-60
Abstract
This paper has tried to control for multiple satellite formation flight under a method called Virtual structure. First the algorithm was implemented in the reference coordinate system has no gradient and then we have developed the same algorithm for a circular orbit around the earth within a set of satellites ...
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This paper has tried to control for multiple satellite formation flight under a method called Virtual structure. First the algorithm was implemented in the reference coordinate system has no gradient and then we have developed the same algorithm for a circular orbit around the earth within a set of satellites that are in circulation. Then for each of the satellites we have added collision avoidance controller to the system. And then the control system on the satellites such as SPHERES taking into account the constraints operators has control over their implementation.
Hassan Naseh; Mehran Mirshams; Elyas Fadakar; Mehdi Jafari Nadoushan
Volume 11, Issue 2 , September 2018, , Pages 47-53
Abstract
The main goal of this paper is to introduce the Moon exploration mission design based on existing technology.The Moon exploration mission design entailsoptimal maneuvering orbit, payload and launch vehicle design. Optimal maneuvering orbit is designed with respect to Circular Restricted Three Body Problem ...
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The main goal of this paper is to introduce the Moon exploration mission design based on existing technology.The Moon exploration mission design entailsoptimal maneuvering orbit, payload and launch vehicle design. Optimal maneuvering orbit is designed with respect to Circular Restricted Three Body Problem (CRTBP) to model the motion of a spacecraft in the Earth/Moon system. To this end, optimal maneuvering orbitadopted CRTBP as dynamical model and obtained three-dimensional Earth to Moon transfers with low cost. This method is more preferable and flexible than Hohmann transfer because of its lower cost and its access to various inclinations in departure and arrival.The optimal Launch Vehicle Conceptual Design (LVCD) algorithm is based on optimization of major design parameters. LVCD algorithm is coded in a software to let the design engineer explore the design space and to reduce the cost and time of the conceptual design phase that is developed by the authors.The optimization process is performed subject to the restrictions and the performance index is optimized in a mutual iteration mechanism. Consequently, the designed launch vehicle ability to satisfy the mission objectives and its requirements is evaluated.
Jamal Asgari; Ali Reza Amiri -Simkooei; Farzane Zanganeh-nejad
Volume 5, Issue 3 , October 2012, , Pages 49-57
Abstract
Inertial Navigation System (INS) and Global Positioning System (GPS), are used in various navigation and positioning applications. Because each of the INS and GPS technologies has some limitations and advantages, during last two decades, the systems integration has been widely used for accurate and reliable ...
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Inertial Navigation System (INS) and Global Positioning System (GPS), are used in various navigation and positioning applications. Because each of the INS and GPS technologies has some limitations and advantages, during last two decades, the systems integration has been widely used for accurate and reliable navigation and positioning. In an integrated system, accurate GPS observations are used to estimate the high rate INS errors and state vector (including INS error vector, position, velocity and other optional parameters). A field test results are presented in this paper. The goal of this test is to compare the coordinates of a relatively low cost INS, GPS RTK coordinates, and the integrated GPS/INS results. The decentralized approach has been used for this integration.
J. Roshanian; S. M. M. Hassani; M. M. Nazari; M. Aliyari
Volume 6, Issue 2 , July 2013, , Pages 49-56
Abstract
Aerospace Launch Vehicles (ALV) are generally designed with high reliability to operate in complete security through fault avoidance practices. However, in spite of fault avoidance, fault occurring is inevitable. Hence there is a requirement for on-board fault detection and isolation (FDI) without significant ...
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Aerospace Launch Vehicles (ALV) are generally designed with high reliability to operate in complete security through fault avoidance practices. However, in spite of fault avoidance, fault occurring is inevitable. Hence there is a requirement for on-board fault detection and isolation (FDI) without significant degradation in the ALV performance. The robust observers are widely used in FDI due to reduction of the effect of disturbances in the FDI process. In this paper, the robust fault diagnosis observer is designed for an ALV subject to uncertainties. The linear sliding mode technique is used to design the observer for a linear time varying model of an ALV. The parameter estimation from the sliding mode scheme is compared with those generated by a nonlinear simulation and are found to provide good correlation. Then, a proposed linear sliding mode observer is employed to generate the residual as an indicator of predefined gyroscope faults.
A. Imani; M. Bahrami
Volume 7, Issue 1 , April 2014, , Pages 49-56
Abstract
The problem of relative motion control for spacecraft formation flying in eccentric orbits is considered in this paper. Due to the presence of nonlinear dynamics and external disturbances, a robust fuzzy sliding mode controller is developed. The slopes of sliding surfaces of the conventional sliding ...
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The problem of relative motion control for spacecraft formation flying in eccentric orbits is considered in this paper. Due to the presence of nonlinear dynamics and external disturbances, a robust fuzzy sliding mode controller is developed. The slopes of sliding surfaces of the conventional sliding mode controller are tuned according to error states using a fuzzy logic and reach the pre-defined slopes. The controller is designed based on the nonlinear model of relative motion and perturbation and atmospheric drag are considered as external disturbances. Using the Lyapunov second method, the stability of the closed-loop system is guaranteed. The performance of the presented controller in tracking the desired reference trajectory is compared to a sliding mode controller in which simulation results confirm the superior performance of the proposed controller.
F. Ommi; A. Kargar; S. M. Hosseinalipour
Volume 2, Issue 1 , April 2009, , Pages 51-57
Abstract
Optimized injectors spray and consequently their proper fluid distribution is one of the most important factors determining the thrust force and combustion stability. Reaching a stable combustion with a high specific impulse needs a proper fuel distribution and atomization. Asymmetric distribution of ...
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Optimized injectors spray and consequently their proper fluid distribution is one of the most important factors determining the thrust force and combustion stability. Reaching a stable combustion with a high specific impulse needs a proper fuel distribution and atomization. Asymmetric distribution of fuel spray droplets lead to asymmetric spray cone and incomplete combustion that cause the chamber broken. Regarding to the numerous advantages of swirl double-based injectors, 25 number of this injector type are manufactured to be mounted on a circular injector plate. To ensure that they have enough accuracy, macroscopic spray characteristic of all injectors are measured and examined in cold test lab and PDA lab.Having checked the quality of each injector, two types of injector plates are designed and manufactured precisely. Having manufactured a circular and a hexagonally arranged injector plate, their spray characteristics are examined.Results show that the circular injector plate has satisfactory spray characteristics like droplet distribution and desirable spray cone and could be ready for warm test.
A.R. Aghalari; A. Kalhor; S. M. M. Dehghan; S. H. Cheheltani
Volume 7, Issue 3 , October 2014, , Pages 51-67
Abstract
The Agile Satellite Attitude Control System Simulator (ASACSS) is a laboratory system designed for the purpose of developing and testing attitude control algorithms in a low-risk, low-cost environment. In this paper, the design and development of the ASACSS is described, including hardware and software. ...
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The Agile Satellite Attitude Control System Simulator (ASACSS) is a laboratory system designed for the purpose of developing and testing attitude control algorithms in a low-risk, low-cost environment. In this paper, the design and development of the ASACSS is described, including hardware and software. There are many papers that present a new mathematical technique or prove a new theory, but this study presents the design and development of a new experimental system. This simulator consists of four main components: 1) power supply system 2) on-board control system 3) supporting equipments and 4) monitoring computer. On-board control system includes a industrial computer, four single gimbal control moment gyros and a sensor for attitude determination. Supporting equipments include a platform for installing simulator subsystems, a semi-spherical air bearing and a pedestal. A high-speed wireless LAN connection enables remote command initiation, monitoring and data collection for post-experimental analysis. In this paper, The design and construction process of the simulator are described. More over some experimental results presented from the application of a simple PID attitude controller on the spacecraft simulator. Finally, experimental results are compared with those obtained from simulation.
