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The main aim of this paper is to analysis of chemical performance of hydrogen peroxide based on numerical and parametric methods. The proper chemical function of the catalytic bed, as one of the components of monopropellant thruster, plays a significant role in achieving the two design main goals in (minimizing mass and maximizing the specific impulse). To this end, the effect of catalyst diameter (granules) on the bed chemical performance, optimal length and pressure drop, simulations for beds with different catalytic pellet diameters have been made to 0.4-0.9 cm diameters. Hydrogen peroxide with a concentration of 90% is defined as an inlet fluid at 0.014 m/s in simulations. The calculation of flow pressure drop across the catalyst bed is one of the activities undertaken in this study. The results of this study indicate that with increasing the pellet diameter, the reaction effective surface is reduced and the catalyst bed length is increased for complete decomposition of the propellant. In addition to the required length for complete decomposition of hydrogen peroxide, the pressure drop in various catalyst beds have also been calculated and evaluated. The results of the catalytic bed drop evaluation indicate that at a specific flow rate, a minimum pressure drop will be made in a specific diameter. The reason for this is the interaction of reaction surface and catalyst bed lengths on the pressure drop generated during the propellant decomposition process. Verification and validation of achieved results was conducted by comparing with experimental results.

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In most airbag systems, the gaseous mixture that fills up the airbag is produced by the fast combustion of a propellant in a combustion chamber called inflator. Since the process of gas production in the airbag inflator is a high-temperature combustion process, having a right understanding and precise control over the combustion in the airbag inflator has always been a challenge. In this paper, the numerical study of combustion process in a pyrotechnic inflator was carried out based on a Zero-Dimensional Multi Zones model. The parametric study show that the performance of inflator is more affected by the propellant characteristics such as mass, combustion index, and propellant temperature coefficient and is not significantly influenced by hardware elements of inflator. In order to simulate hybrid pyrotechnic inflator, the initial pressure of gas plenum was increased by 25 to 50 times. As a result, the performance both in combustion chamber and in discharge tank decreased. This lower temperature leads to a higher thermal efficiency.

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In this work, governing equations of the feed line, cut-off valve, and the starter system are analyzed mathematically and numerically. In the mathematical solution, the stability of the valve system is considered using the Laplace transform along with the linearization of the equations of the system. According to parameter design of the feed pipe–valve system, the system demonstrates the stable behavior in the effective parameter of the valve system on the basis of the Nyquist and Bode stability criterion. In the numerical solution, the steady state behavior of the cut-off valve is simulated during the cut-command. Then the rate of the pressure variation, mass flow rate through of the valve, gas pressure of the starter system, and the upstream pressure of the valve (water hammer) are considered based on the valve's poppet motion. The comparison of the simulation results with the experimental data depicts only 13 percent error in the mass flow rate through of the valve. In the last time of the closing valve, there is no variation in the mass flow rate in the valve due to the excessive loss factor of the valve when the valve approximately is closed. The results show that the closure of the cutoff valve shall be provided in accordance with allowable maximum pressure of the hydraulic shock on the established

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Burning rate is a determinate Parameter in Performance Prediction of Solid Propellant motors. Any error in determining the burning rate directly affects the prediction of thrust and burning time. Small-scale rocket motors are widely used by space and military industries to carry out burning rate measurement. The use of Subscale motors has many advantages over more simplistic, such as strand burners. Effects like: Two phase flow, radiation, and erosive burning effects are present within a subscale test whereas strand burns are not capable of capturing these parameters. The biggest problem with subscale burning rate motors however is determining appropriate times for when the propellant grain has lit and burned out. Accurate and consistent selection of start and end points is crucial to determining the burning rate of a given propellant. Investigation of Developed and modern methods to obtain burning rate from motor test according to the primary methods in Iran's aerospace industries is the main objective of this study. In this study, using designed laboratory solid rocket motor, 26 tests was Performed. Reproducibility of the methods available in universities and defense companies worldwide has been considered and with Common Tangent bisection method has been compared. Results show the high quality of industrial Methods subset the Thickness-time Method, Hessler-Glick, and mass balance method with comparing to low reproducibility of tangent bisection method

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In this paper, a new method for preliminary design of feed system (FS) in a cryogenic liquid propellant rocket engine (LPRE) has been developed. The cycle type of LPRE is pump-fed system and staged combustion. Engine cycle consists of main turbopump with reactive gas turbine, a fuel booster pump with hydro turbine and an oxidizer booster pump with active gas turbine. This method based on four specifications, proper cavitation number in pumps especially in oxidizer component, power balance between pumps and turbines, strength of material in main rotor of turbopump and mass evaluation of FS determine the type of FS components and calculate initial requirements for preliminary design of each of them. Calculation shows that employing of booster pumps improve the cavitation characteristic of main pumps and consequently decrease FS mass, but causes added mass to fed-system. Optimum point could be achieved through using genetic algorithm, in which all involving parameters could be considered. Results of the method compared with the same engine scheme. Comparison of the results confirms the correctness of the method and enhancement of FS characteristic parameters.

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This research discuss about the effect of simultaneous usage of Propellant Utilization (PU) system and Flight Apparent Velocity Regulation (AVR) system. These systems were used for sending OBC commands to engine for adapting the engine working regime with flight conditions and fame to active control systems. Each of PU and AVR systems has an effective roll in access to final parameters such as mass and velocity at the end of active phase and simultaneous usage of these systems lead to increase the range accuracy and payload mass. We study these effects on final parameters in this paper. Therefore, with dynamic simulation of liquid propellant engine in during of active phase in flight simulator, sending commands of these systems to change the engine working regime is provided. For a specific mission results show that with working of the PU, range increased and presence of AVR, is assist to reach this range in front of disturbance during the flight. Another main result of this research is, increasing of payload mass for a specific mission with simultaneous usage of PU and AVR systems.

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The purpose of this paper is to introduce a design and fabrication procedure for a solid propellant gas generator. Based on this procedure a gas generator was designed to supply the required operating fluid of a controllable flying object’s gaseous actuator of control surface which results of that design is presented in this paper as well. Supplying required pressure during the mission and gas flow rate with expected chemical characteristics are requirements of the design. At first the amount of necessary parameters like flow rate and pressure were specified. Then the design calculations were done according to proposed approach. In order to evaluate the design process and achieved data, a full scale gas generator set was built. Since this study includes specifying a proper formula for solid propellant of gas generator, a lab scale motor was used to qualify the propellant’s characteristics experimentally. After doing tests and comparing the results with output data of gas generator design procedure, convenient consistency was observed. Besides by doing several tests it was found that PSAN as oxidizer, HTPB as binder and chromium oxide as catalyst is a proper composition for solid propellant of gas generator. Finally, covering basic requirements of a solid propellant gas generator such as uniform flow rate and less presence of solid phase and corrosive components in combustion products by means of designed gas generator is an approval to show the validity of presented design method.

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The purpose of this article is to design the optimum method of Propellant Management Device (PMD) of hydrazine fuel tank which used in zero-gravity conditions. To this end, numerical methods are used to analysis of the tank and the fuel behavior inside the tank with PMD to optimize system design parameters. Hence, Ansys version 17 software used to finalize modelling, analysis, meshing and consideration of fuel behavior in PMD by utilizing the Volume Of Fluid (VOF) method. Also Solid Works software version 2016 is used to primary PMD and tank modeling. Then, numerical simulation is performed to consider PMD's performance and to illustrate the capillary phenomenon for continues fuel transferring in zero-gravity conditions. The design variables in tank and PMD optimization respectively are: minimizing the tank weight to safety factor ratio; dimensional specifications of tank and PMD (height, diameter, length and width dimensions). The objectives of PMD optimization are to achieve maximum volumetric and mass flow rate values. On the other hands, to achieve the most desirable amount of fuel to PMD, that at the end of the time of simulation used by flow rates curves. Numerical analysis results that are obtained include: optimal system parameters related to the specifications of the tank with minimum weight and maximum safety factor and also optimal system parameters related to specifications of PMD with maximum performance of mass and volume flow rates in zero gravity. In conclusion, by comparing the existing systems with the optimal system parameters results will be verified.

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The purpose of this article is to system design methodology of Propellant Management Device (PMD) for hydrazine fuel tank which used in low (zero) gravity conditions. To this end, the suggestion system design flowchart has three main steps that concluded: step one, Tank design and modeling; step two, PMD design and modeling and step three, stored fuel treatment simulation and analysis. In the design flowchart has performed the result of each step based on mission inputs. Therefore, rejected results in each step led to vary the related parameters. Thus Solid Works software is used to primary PMD and tank modeling. Then, numerical simulation is performed to consider PMD's performance and to illustrate the capillary phenomenon for continues fuel transferring in zero-gravity conditions.Also, numerical methods are used to analysis of the tank and the fuel behavior inside the tank with PMD to optimize system design parameters. Hence, Ansys software used to finalize modelling, analysis, meshing and consideration of fuel behavior in PMD by utilizing the Volume Of Fluid (VOF) method. The optimal system parameters related to specifications of PMD with maximum performance of mass and volume flow rates in zero gravity. In conclusion, by comparing the results (PMD performance) with experimental and existing results will be verified.

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Evaluation of pressure oscillation of solid rocket motors in actual conditions requires static tests. These test have a large application in evaluation of motor various parameters effect on its operation. Using of these tests are very limited due to their high costs and so, evaluation of various parameters is nearly impossible. To solve this problem, sub scaled solid rocket motor must be designed. In this paper, designing process of space shuttle sub scaled solid boosters, called 1881, with scale 1:31 has been proposed. Space shuttle and ariane 5 boosters have been argued to modeling and simulation. Sub scaled motor modeling and design parameters using Buckingham’s Pi theorem and then, operation and dimensional properties have been presented. Three tests for evaluation of designed motor were done successfully and pressure and thrust history and its oscillations have been evaluated. Results show that for facility of fitting and reduction of test cost in subscale motors, using of Tan-Cu in throat instead of graphite and flange design of joints are very useful. Despite of using Buckingham’s Pi theorem in solid motor scaling, propellant chemistry and its burning rate are affected of Crawford bomb and real flow of combustion products and in many case, error correction between Crawford and motor data is inevitable. On the other hand, existence of empty volume in forward segments and others, plays an important role in pressure oscillations and after end of burning or reducing, oscillations will be uniform.

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The idea of designing new geometries for catalytic bed in the decomposition chamber of monopropellant thrusters is introduced with numerical simulations of pore-scale turbulent flows. The LES numerical technique is used for simulation of turbulent structures in the flow-field. The efficiency and reliability of the results obtained from numerical simulation have been determined by solving a benchmark problem of turbulent flow over the pack of cubes. The results show very good agreement with the experimental data, indicating the accuracy of the used model and numerical solution process. The characteristics of turbulent flow over two different geometries have been investigated using the numerical method. The results have been analyzed to evaluate the effectiveness of geometrical changes on the parameters associated with the catalytic reaction. All simulations have been conducted for cold flow, and the exact effects of the geometrical design of porous bed on reactive flow have not been quantified. The eddy dissipation and length scales of turbulence have been considered as the main parameters, because of their effect on rates of turbulent mixing and rate of reaction. The difference between the turbulent dissipation and length scales in the investigated flows in two different geometries indicates the effectiveness of the geometrical changes of the porous bed on the flow characteristics. Coherent structures are seen in the new geometry and the wall shear stress is reduced significantly, which increases the life of the catalytic coating.

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The role And place of rural development in Economic, social and political processes in local, regional, national , international and the consequences of undeveloped in rural areas such as widespread poverty, rising inequalities, rapid population growth, unemployment, immigration and urban margins the cause is attention to rural development and even its priority to urban development. In this regard, the present study is to Future approach, to offer influential propellants in the development of rural areas of Iran. The research method is based on the Delphi technique. At first, by using Porter's five forces analysis for micro environment and analysis STEEP (social, technological, economic, environmental and political) for the macro environment, Events and effective propellants in the rural development were selected by experts of Delphi Group. Then, for determining the main drivers of the importance, the impact and the lack of certainty of cross-impact analysis propellants and hierarchical analysis model is used. According to the Finding results, the most important key factors regarding to degree of importance importance; respectively are partnership, investment and entrepreneurship, training skilled manpower, natural resources, income generation, the rural guide plan, ownership of resources, technology, services and tourism. According to the opinion of experts the first five factors are very important in rural development. That certainty and uncertainty of propellants is discussed to planning appropriate actions for controlling and directing them towards Iran rural development.