Aerospace Science and Technology
Mohammad Hassan Pachenari
Abstract
Flexible ropes have wide-ranging applications in aerospace engineering, yet accurately measuring their motion state without disrupting dynamic characteristics remains a challenge. This study introduces a visual measurement method aimed at precisely assessing flexible rope motion to support the development ...
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Flexible ropes have wide-ranging applications in aerospace engineering, yet accurately measuring their motion state without disrupting dynamic characteristics remains a challenge. This study introduces a visual measurement method aimed at precisely assessing flexible rope motion to support the development and validation of an accurate cable dynamics model. Addressing non-uniform movement speeds attributed to the rope's large length-diameter ratio, a novel tether edge segmentation operator is proposed to delineate motion blur regions into exposure beginning and ending time tethers. This operator enhances accuracy over existing centerline extraction methods, particularly in asymmetric motion blur regions. The proposed approach not only resolves accuracy issues during high-speed motion but also leverages the camera's inherent image acquisition frame rate, reducing system complexity and cost. Validation of the material point tracking algorithm through mathematical and physical simulations underscores its effectiveness in monitoring any point on the tether. Furthermore, verifying the tether dynamics model through the absolute nodal coordinate method highlights the novelty and significance of this research in advancing aerospace engineering applications.
Aerospace Science and Technology
Hamid reza Ali mohamadi; Hassan Naseh; Fathollah Ommi
Abstract
The present paper strives for optimization of the Liquid-Propellant Engine (LPE)’s feed system. To this end, the new hybrid meta-model methodology by utilizing the Design of Experiment (DOE) method and the Response Surface Method (RSM) were developed and implemented as two effective means of designing, ...
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The present paper strives for optimization of the Liquid-Propellant Engine (LPE)’s feed system. To this end, the new hybrid meta-model methodology by utilizing the Design of Experiment (DOE) method and the Response Surface Method (RSM) were developed and implemented as two effective means of designing, analyzing and optimizing. The input design variables, constraints, objective function, and their surfaces were identified. Then, the design and development strategy was clarified by utilizing the combination of RSM, DOE and regression analysis. Hence, 64 different experiments were carried out on the RD-253 propulsion system. The response surface curves were drawn and the related objective function equation was obtained. The Analysis of Variance (ANOVA) results indicate that, the developed hybrid model is capable to predict the responses adequately within the limits of input parameters. In addition, the precision of the model was assessed by comparing with the existing samples and the output was interpreted and analyzed that shown highly accuracy. Therefore, desirability function analysis has been applied to LPE’s feed system for achieving to maximize the power and minimize the weight, simultaneously. Finally, confirmatory tests have been conducted with the optimum parametric conditions to validate the optimization techniques. In conclusion, the methodology capability is to optimize the LPE system, an 11% increase in the power to feed system weight ratio and a 2% increase the thrust to engine weight ratio. These values are considerably large for LPE design.
Aerospace Science and Technology
Fatemeh Amozegary; Amir reza Kosari; Mahdi Fakoor
Abstract
The ever increasing demand for placing satellites in the geostationary orbit has caused the revision and change of the conventional mechanism of allocating orbital slots. Therefore, collocation approaches and station keeping of several satellites with a common position have been developed to improve ...
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The ever increasing demand for placing satellites in the geostationary orbit has caused the revision and change of the conventional mechanism of allocating orbital slots. Therefore, collocation approaches and station keeping of several satellites with a common position have been developed to improve the utilization of the capacity of the geostationary orbit. This, in turn, leads to an increase in the complexity and sensitivity of the modeling, guidance, and control processes. However, new restrictions are added to the problem of maintaining a common location, such as maintaining the minimum separation distance between satellites to prevent possible interference. Employing a collocation strategy is essential, especially for effective control of high-demand orbital regions that will lead to space congestion.Controlling the relative motion of satellites by maintaining a safe distance between them is the main rule in collocation. This article investigates the problem of the relative motion of satellites corresponding to collocation strategies. Then, the results are implemented and compared using a solution based on geometrical modeling of relative orbit and the concepts of spherical geometry. In this regard, the relative orbital elements of the two satellites are calculated using the presented relative motion modeling. Also, the relative position of the satellites is obtained. The case studies and evaluations confirmed that the inclination and eccentricity separation strategies are suitable options for meeting the fuel consumption requirements and providing more space for collocated satellites than other strategies.
Aerospace Science and Technology
Hassan Naseh; Mehran MirShams; Hamid Reza Fazeley
Abstract
Recently, engineering systems are quite large and complicated. Conceptual design process of Space Transportation Systems (STSs) is a multidisciplinary task which must take into account interactions of various disciplines and analysis codes. Current approach for the conceptual design of STSs requires ...
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Recently, engineering systems are quite large and complicated. Conceptual design process of Space Transportation Systems (STSs) is a multidisciplinary task which must take into account interactions of various disciplines and analysis codes. Current approach for the conceptual design of STSs requires the evaluation of a large number of different configurations and concepts. With existing legacy codes, estimating the performance of all design combinations becomes very time consuming and computationally expensive. A possible solution to this problem could be employing of surrogates during design tasks. This paper describes an effort to optimize the design of an entire STS to achieve a low Earth orbit, consisting of multiple stages using an efficient surrogate-based Multidisciplinary Design Optimization (MDO) framework with the goal of minimizing vehicle weight and ultimately vehicle cost. Furthermore, a combination of Response Surface Methodology (RSM) and Kriging surrogates has been used for building surrogate models. The disciplines of aerodynamics, propulsion, trajectory simulation, geometry, and mass properties, have been integrated to produce an engineering system model of the entire vehicle. In addition, the system model has been validated using the existing design data of STS’s trajectory and their subsystems. For the design optimization, in order to ensure that the payload achieves the desired orbit, a hybrid algorithm has been used to minimize the deference between the actual and desired orbital parameters. The objective function of the optimization problem is to minimize the overall system mass, thus minimizing the system cost per launch. The proposed design and optimization methodology provides designers with an efficient and powerful approach in computation during designing space transportation systems and can also be developed for more complex industrial design problems with comparable characteristics.
Aerospace Science and Technology
Sam Mohamad Hassan Pouryoussefi; Sohrab Gholamhosein Pouryoussefi
Abstract
Importance of study of pulsating heat pipes (PHPs) behavior and limitations in conducting experimental studies, the necessity of numerical simulations is getting critical in this area. In present work, numerical simulations are carried out for pulsating heat pipes. Thermal performance of closed loop ...
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Importance of study of pulsating heat pipes (PHPs) behavior and limitations in conducting experimental studies, the necessity of numerical simulations is getting critical in this area. In present work, numerical simulations are carried out for pulsating heat pipes. Thermal performance of closed loop pulsating heat pipes is investigated at different operating conditions such as evaporator heating power and filling ratio. Water, ethanol, methanol and acetone are employed as working fluids. A two-dimensional single loop PHP is used for present study. Computational Fluid Dynamics (CFD) video technique is employed for flow visualization purpose. Perfect match was observed between the present CFD video clip and previous experimental video-based studies in terms of flow pattern and behavior. Present study shows how researchers can benefit from developments of numerical tools to test pulsating heat pipes behavior at different operating conditions or different working fluids without facing difficulties and limitations of applying laboratory thermal measurement equipment or high-speed cameras. The CFD video clip as result of numerical simulation was found very informative for flow visualization purpose. The simulated clip made it much easier to capture phenomena occur in a pulsating heat pipe. The thermal performance investigation at different operating conditions and working fluids was found very informative in terms of application and design purposes especially for experimental studies. By increasing heating power greater than 60 W, circulation velocity was increased for most cases. Phase contour videos are inserted at the bottom of the article.
Aerospace Science and Technology
Mohammad Hossein Khalesi
Abstract
Unmanned Aerial Vehicles (UAVs) have numerous applications in military, commercial and hobby fields. Among these vehicles, drones with vertical take-off and landing (VTOL) capability have attracted more attention due to their specific capabilities such as better maneuverability and hover flight. In recent ...
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Unmanned Aerial Vehicles (UAVs) have numerous applications in military, commercial and hobby fields. Among these vehicles, drones with vertical take-off and landing (VTOL) capability have attracted more attention due to their specific capabilities such as better maneuverability and hover flight. In recent years, numerous concepts emerged which trying to propose new configurations to enhance UAVs performance. In this paper, we propose a novel concept which integrates single main rotor helicopter and quadrotor structure to overcome some difficulties exist in those applications. This suggested configuration, include a variable pitch main rotor equipped with four smaller counterrotating rotors to overcome its opposite torque (instead of a tail rotor in helicopters) and also sustain a portion of the UAV weight which make it possible to use a smaller main rotor. This design preserves maneuverability of helicopters, while eliminates tail rotor power loss and its asymmetric lateral force and also enhances the flight stability and maneuverability by properly using other four rotors’ thrusts. Preliminary dynamic modeling and control system design are presented in the text and the results show that this idea can be investigated further. The next steps are planned to be studied in next researches.
Aerospace Science and Technology
Asad Saghari; Amirreza Kosari; Masoud Khoshsima
Abstract
This paper deals with the problem of optimal selection of orbital parameters for an Earth observation mission in the absence of the possibility of injection into sun-synchronous orbit by considering the requirements and limitations of the mission and the satellite platform. By modeling the existing relationships ...
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This paper deals with the problem of optimal selection of orbital parameters for an Earth observation mission in the absence of the possibility of injection into sun-synchronous orbit by considering the requirements and limitations of the mission and the satellite platform. By modeling the existing relationships between each of the three areas of orbit, mission and platform, the effects of changes in each of the parameters have been analyzed and tracked. One of the important advantages of the proposed solution is that in the process of optimal selection of relevant parameters, all aspects of the orbit, mission and platform are considered simultaneously. This, in turn, can lead to an implementable and operational option for accomplishing the mission. In evaluation of effects of changing orbital parameters on the mission characteristics and requirements of the satellite platform, a developed computer code has been used.
