Modelling and experimental investigations of a bi-modal unmanned underwater/air system

Guo, D 2019, Modelling and experimental investigations of a bi-modal unmanned underwater/air system, Masters by Research, Engineering, RMIT University.


Document type: Thesis
Collection: Theses

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Title Modelling and experimental investigations of a bi-modal unmanned underwater/air system
Author(s) Guo, D
Year 2019
Abstract The ability to perform underwater and coastal area monitoring missions without surfacing would increase submarine's safety and its combat ability. An innovative bi-modal unmanned/underwater air system (BUUAS) and its concept of operations (CONOPS) are proposed to reduce the risk of submarine's exposure. The BUUAS is firstly released from a submerged submarine and travels underwater to keep a distance from the submarine. Then it will exit the water using an innovative propulsion system that would allow a transition from water to air with the purpose of carrying out a planned air mission. When the airborne mission is finished, the BUUAS will dive back into the water and cruise to the submarine to be collected.

This study aims to design and develop this system that can achieve the proposed CONOPS. The project addresses three critical aspects, namely, i) the study of an optimised configuration considering both aerodynamic and hydrodynamic performance aspects, ii) the exploration for an effective transition between water/air media and iii) the design of the water/air hybrid propulsion system. A variable-sweep wing configuration with a novel wing-deployment mechanism is considered for an efficient operation in water and air. Numerical simulation, water and wind tunnel experimental tests were conducted to assess the performance characteristics of the propulsion unit in water and the aerodynamic characteristics in air. The assessment data supports the feasibility of the bi-modal vehicle configuration and the stability analysis demonstrates the vehicle has static and dynamic stable behaviour during its flight. The water jet transition propulsion system is powered by pressurized CO2 and was developed to enable a fast take-off transition from water to air. The preliminary design covers the system sizing using an analytical model calibrated by the high-fidelity numerical simulation approach and the design of a specialized gas release mechanism adopted in the propulsion unit. The thrust and launch experiments were performed to verify the transition propulsion system design results and applicability. The air and water experimental results of the customized compact hybrid propulsion system confirm its provision of sufficient power for flight and underwater cruise.
Degree Masters by Research
Institution RMIT University
School, Department or Centre Engineering
Subjects Flight Dynamics
Aerodynamics (excl. Hypersonic Aerodynamics)
Aerospace Structures
Aircraft Performance and Flight Control Systems
Keyword(s) BUUAS
Transition propulsion system
Hybrid propulsion system
Variable sweep wing configuration
Wind tunnel test
Numerical simulation
Composite materials
Stability analysis
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Created: Wed, 16 Oct 2019, 10:08:34 EST by Adam Rivett
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