Shehna Sagaria | Luleå University of Technology (original) (raw)

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Literature Research by Shehna Sagaria

This paper presents the details of space propulsion by mini magnetospheric plasma propulsion. Min... more This paper presents the details of space propulsion by mini magnetospheric plasma propulsion. Mini magnetospheric plasma propulsion is one of the most recently proposed methods of space propulsion. It is primarily based on space propulsion by magnetic sail. Magnetic sail propulsion is a method of propelling the spacecraft by using the momentum obtained by the reflection of the high speed solar wind by a magnetic field around the spacecraft, which is produced by a solenoid in the spacecraft. This gives high thrust to the spacecraft. But for effective propulsion, the strength of the magnet has to be high. Mini magnetospheric propulsion is proposed as a better alternative to this by Prof. Robert Winglee. In this method the size and weight of the magnet of the magnetic sail is reduced by expanding the magnetic field using plasma. This plasma creates mini magnetospheres around the spacecraft and stretches the magnetic field to a few kilometres in diameter. This results in very high effective rate of reflection of the solar wind by the magnetospheres around the spacecraft. This imparts high momentum and very high thrust to the spacecraft.

Journal Publications by Shehna Sagaria

The boundary-layer flow of a nano-fluid over a moving surface, is simulated, by solving the gover... more The boundary-layer flow of a nano-fluid over a moving surface, is simulated, by solving the governing equations, using an efficient implicit finite difference scheme called the Keller’s box scheme. This scheme is second order accurate even on a non-uniformly spaced grid. Surface injection or suction is considered through appropriate boundary conditions. The effect of nano-particles is taken into account by incorporating the thermo-physical property models. The effect of wall injection or suction, as well as the moving surface velocity, affects the wall shear stress and heat transfer rates in a complex manner inducing flow separation in certain cases. These results are very useful in assessing the effectiveness of the use of different nano-fluids for practical engineering applications.

Papers by Shehna Sagaria

Space missions are always cost depended and one of the effective ways for cost control is to reus... more Space missions are always cost depended and one of the effective ways for cost control is to reuse the launch system completely or partially. DLR, the German Aerospace Center, is currently developing a flight experiment called Reusability Flight Experiment (ReFEx), which is a winged re-entry launch system. One of the main features of this vehicle is its Hybrid Navigation System (HNS), an autonomous navigation system that is vital to vehicle re-entry. The main goal of this thesis is to develop a highly integrated, compact, and self-contained mechanical enclosure to accommodate all the components of the hybrid navigation system, except the external sensors and antenna. The enclosure is to be integrated within the ReFEx, close to the Guidance and Control system. The mechanical design is considered based on the different requirements of the HNS components, like, the orientation, the accessibility for electrical connections and reconnections, and ease of integration. Based on the component and system requirements, an initial outline of the HNS box (HNS dummy) is created. The HNS components are then designed and included into the HNS dummy. Following this, different configurations are studied for the HNS components’ accommodation in the box. A final flight accommodation configuration is chosen based on the structural rigidity and accessibility to different components. Based on the configuration chosen, an initial design is generated through various design iterations using CATIA V5, with proper component supports. This is followed by the preliminary enclosure design, considering the different loads that are subjected to it during flight. This design is checked with the ReFEx outer structure to ensure proper mechanical clearance margins. After finalizing the design of the HNS enclosure, a detail enclosure design is generated where the individual enclosure parts are defined. This enclosure model is then integrated with the HNS sensors and electronic component models to produce a detailed HNS mechanical model. The mechanical fitting and physical attributes of the detailed HNS model is tested by producing a prototype though 3D printing technology. The enclosure prototype is assembled in house with all the HNS components using different mechanical fasteners. Based on the observations from the prototype, a HNS production model was created. The production model was used to generate subsequent part drawings for the mechanical production processes. An assembly process flow for the HNS integration is developed based on the prototype assembly for the flight model. The developed HNS model and the corresponding part drawings would be used for the HNS development. The HNS assembly and integration would be according to the assembly process plan developed.

The boundary-layer flow of a nano-fluid over a moving surface is simulated, by solving the govern... more The boundary-layer flow of a nano-fluid over a moving surface is simulated, by solving the governing equations, using an efficient implicit finite difference scheme called the Keller’s box scheme. This scheme is second order accurate even on a non-uniformly spaced grid. Surface injection or suction is considered through appropriate boundary conditions. The effect of nano-particles is taken into account by incorporating the thermo-physical property models. The effect of wall injection or suction, as well as the moving surface velocity, affects the wall shear stress and heat transfer rates in a complex manner inducing flow separation in certain cases. These results are very useful in assessing the effectiveness of the use of different nano-fluids for practical engineering applications.