Space systems design (spacecraft, satellites, space stations and their equipment)
Amirhamzeh Farajollahi; Reza Firuzi; Mohammad Reza Salimi; Mohsen Rostami
Volume 15, Issue 4 , December 2022, , Pages 107-121
Abstract
In this study, the effects of geometry and spiral rifling like guides inside the injection nozzle on the performance of an engine are investigated, using AVL Fire software. To do so, firstly injectors with different nozzle geometries and their resultant spray patterns were simulated. Numerical results ...
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In this study, the effects of geometry and spiral rifling like guides inside the injection nozzle on the performance of an engine are investigated, using AVL Fire software. To do so, firstly injectors with different nozzle geometries and their resultant spray patterns were simulated. Numerical results of this step show that creation of spiral rifling like guides inside the nozzle increases the spray cone angle and improves fuel atomization quality. In the next step, effects of using forgoing nozzle geometries on sample engine characteristics were studied and the related results compared to those of common cylindrical injectors. Numerical results of this step clearly show the superior performance of nozzles with spiral rifling like guides. In this case, SFC reduces up to 32 percent while the engine power and it's torque rises more than 63 percent. Also the amount of pollutants like NOx reduces 12 percent with respect to common cylindrical nozzles.
Space systems design (spacecraft, satellites, space stations and their equipment)
Mostafa Jafari; Alireza Toloei
Volume 15, English Special Issue , May 2022, , Pages 35-44
Abstract
A numerical dynamic-aerodynamic interface for simulating the separation dynamics of constrained strap-on boosters jettisoned in the atmosphere is presented. Two commercial solvers: a 6DOF multi-body dynamic solver and a numerical time-dependent flow solver are integrated together with an interface code ...
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A numerical dynamic-aerodynamic interface for simulating the separation dynamics of constrained strap-on boosters jettisoned in the atmosphere is presented. Two commercial solvers: a 6DOF multi-body dynamic solver and a numerical time-dependent flow solver are integrated together with an interface code to constitute a package that presents real-time dynamic/aerodynamic coupled analysis. Dynamic unstructured mesh approach is employed using local remeshing methods in respect of bodies motion with a second-order upwind accurate 3D Euler solver. This interface can simulate multi body separation dynamics interaction with aerodynamic effects to complete separation mechanisms like springs, thrusters, joints and so on. The flow solver is validated by the Titan IV launch vehicle experimental data. The separation integration is used for a typical launch vehicle with two strap-on boosters using spring ejector mechanism and spherical constraint joints acting in the dense atmosphere. Hence, the aim of the presented interface is to facilitate the integration of complicated separation mechanisms with a full numerical CFD aerodynamic solver.
Space systems design (spacecraft, satellites, space stations and their equipment)
Mohammad Reza Salimi
Volume 15, Issue 1 , March 2022, , Pages 93-105
Abstract
In present study, a hydrazine based monopropellant thruster decomposition chamber is simulated numerically. The catalyst bed separated in two sides, the particles size in upstream side is larger than those in downstream side. Effects of upstream side length and its particles diameter on catalyst bed ...
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In present study, a hydrazine based monopropellant thruster decomposition chamber is simulated numerically. The catalyst bed separated in two sides, the particles size in upstream side is larger than those in downstream side. Effects of upstream side length and its particles diameter on catalyst bed characteristics were investigated. To this end, three standard particles sizes of mesh: 16.5, 25 and 30 for the upstream side and two standard particles diameter of 1/8 and 1/16 (in) for downstream side were analyzed. Additionally, three upstream side lengths of 2.5, 5 and 7.5 (mm) were used while the length of bed is 6.5 (cm). Simulations were performed in three bed loading coefficients of 16.5, 25 and 35 (kg/m2s). The related results showed the effectiveness of upstream side on flow and thermal fields are strongly depends on the ration of particles sizes in upstream and downstream sides. Moreover, the upstream side length and bed loading are two important factors affecting the upstream side effectiveness.
Mohammad Hossein Tirandaz; Milad َAzimi
Volume 13, Issue 2 , June 2020, , Pages 37-50
Abstract
This paper aims to use H2 and H∞ norms to optimally place sensor/actuator patches on a flexible structure. Unlike most existing optimization methods, the proposed approach not only increases the norms of the controlled modes of the system but also it can reduce the system's spillover problems by ...
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This paper aims to use H2 and H∞ norms to optimally place sensor/actuator patches on a flexible structure. Unlike most existing optimization methods, the proposed approach not only increases the norms of the controlled modes of the system but also it can reduce the system's spillover problems by taking into account the residual modes and reducing systems H2 and H∞ norms. The residual vibration of the system is captured considering sandwich structures and the finite element analysis. In order to show the optimal placement effect of piezoelectric patches, the vibrational behavior of the closed-loop system is controlled using strain rate feedback controller. Numerical simulation is performed to study the debonding effects between the sandwich layers.
Fathollah Ommi; Dooman Poorrajab Sufinai; Davood Doomiri Ganji; Seyed Hossein Moosavi
Volume 13, Issue 1 , March 2020, , Pages 1-11
Abstract
In this research, it is attempted to determine the diameter and velocity distribution according to the flow characteristics of the upstream and without needing experimental measurements.Firstly, Fluent software has been used to simulate the turbulent flow of inside nozzle by k-? model to obtain the nozzle ...
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In this research, it is attempted to determine the diameter and velocity distribution according to the flow characteristics of the upstream and without needing experimental measurements.Firstly, Fluent software has been used to simulate the turbulent flow of inside nozzle by k-? model to obtain the nozzle turbulence energy at the nozzle outlet. Then, nonlinear growth rate analysis of instability is used to determine spray breakup length and the frequency of maximum instability and the mean diameter of primary breakup. Four equation maximum entropy model has been developed according to the inlet of upstream flow. Subsequently, the terms of momentum source as well as the energy of maximum entropy model has been determined using the results of simulated nozzle turbulence flow and instability analysis. In the following, first the results of maximum entropy model have been evaluated with the experimental input and then determined with upstream input. The obtained results which have been compared with experimental tests show well agreement.
Mohammad Amin Eskandari; Hasan Karimi; Davood Ramesh; Mohammda Reza Alikhani
Volume 13, Issue 1 , March 2020, , Pages 39-48
Abstract
Expansion cycle rocket engines have unintelligible and sensitive dynamic behavior. Contrary to other types of rocket engine which have gas generator, Expansion cycle rocket engines utilizes mass flow of fuel propellant to provide power for rotating turbo pump. Which contributes to a complicated and difficult ...
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Expansion cycle rocket engines have unintelligible and sensitive dynamic behavior. Contrary to other types of rocket engine which have gas generator, Expansion cycle rocket engines utilizes mass flow of fuel propellant to provide power for rotating turbo pump. Which contributes to a complicated and difficult ignitions process in these engines. Priority and delay process in opening of control valves is important to prevent aforementioned phenomena. As opening and closing of control valves cause dynamic process in rocket engine, whose effects are expensive and difficult to predict by experimental tests. Therefore, dynamic modelling plays a key role in development of expansion cycle rocket engines and may decrees future expenses. In this article RL-10 rocket engine with sufficient data for validation has been chosen. The main goal of this article is dynamic modelling of expansion cycle rocket engine using mathematical non-linear models. Modelling results yield that the presented non-linear model is valid.
Mehran Nosratollahi; Ahmad Soleimani
Volume 13, Issue 1 , March 2020, , Pages 49-60
Abstract
In this paper, the performance of fluid momentum controller (FMC) actuators in satellite temperature management is investigated based on two pyramidal and 3-axis proposed configurations. In this regard, the temperature of different satellite surfaces with fluid actuators and without actuators in an orbital ...
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In this paper, the performance of fluid momentum controller (FMC) actuators in satellite temperature management is investigated based on two pyramidal and 3-axis proposed configurations. In this regard, the temperature of different satellite surfaces with fluid actuators and without actuators in an orbital period of satellite is investigated and the results are compared to each other. For FMC actuators that are closed as a loop, a Moving Reference Frame (MRF) is used and the flow inside the actuators is laminar. The effect of fluid angular velocity of actuators on the temperature of satellite surfaces with two different angular velocity has been investigated and time-dependent heat flux is applied to the satellite surfaces. The results indicate that in the pyramidal configuration, the decrease in the temperature of the satellite wall surfaces is influenced by two parameters: fluid angular velocity and orbital period of satellite, but in the critical conditions, the 3-axis configuration can carry out this temperature management more quickly.
