Browsing by Author "Mutangara, Ngonidzashe E."

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    Fundamental considerations in the design and performance assessment of propulsive fuselage aircraft concepts
    (Cambridge University Press (CUP), 2024) Moirou, Nicolas G. M.; Mutangara, Ngonidzashe E.; Sanders, Drewan S.
    Propulsive fuselage aircraft complement the two under-wing turbofans of current aircraft with an embedded propulsion system within the airframe to ingest the energy-rich fuselage boundary layer. The key design features of this embedding are examined and related to an aero-propulsive performance assessment undertaken in the absolute reference frame which is believed to best evaluate these effects with intuitive physics-based interpretations. First, this study completes previous investigations on the potential for energy recovery for different fuselage slenderness ratios to characterise the aerodynamics sensitivity to morphed fuselage-tail design changes and potential performance before integrating fully circumferential propulsors. Its installation design space is then explored with macro design parameters (position, size and operating conditions) where an optimum suggests up to 11% fuel savings during cruise and up to 16% when introducing compact nacelles and re-scaling of the under-wing turbofans. Overall, this work provides valuable insights for designers and aerodynamicists on the potential performance of their concepts to meet the environmental targets of future aircraft.
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    Potential for energy recovery from boundary-layer ingesting actuator disk propulsion
    (AIAA, 2024-01-26) Mutangara, Ngonidzashe E.; Smith, Lelanie; Craig, Kenneth J.; Sanders, Drewan S.
    The theoretical benefits of highly integrated propulsion systems are highlighted herein by assessing the potential for energy recovery utilization using actuator disk propulsion. Decomposing aerodynamic forces into thrust and drag for closely integrated bodies, particularly those employing boundary-layer ingestion, becomes challenging. In this work, a mechanical energy-based approach was taken using the power balance method. This allowed the performance to be analyzed through the mechanical flow power in the fluid domain, disregarding the need for any explicit definition of thrust and drag. Through this, the benefit of boundary-layer ingestion was observed from a wake energy perspective as a decrease in the downstream mechanical energy deposition and associated viscous dissipation. From a propulsion perspective, the reduction in power demand necessary to produce propulsive force indicated the possibility of power savings by utilizing the energy contained within the ingested boundary-layer flow.
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    Potential for energy recovery of unpowered configurations using power balance method computations
    (AIAA, 2021-07-30) Mutangara, Ngonidzashe E.; Smith, Lelanie; Craig, Kenneth J.; Sanders, Drewan S.
    New aircraft developments are made to improve aircraft performance and efficiency. One such method is integrating propulsion into the airframe. This allows for boundary-layer ingestion, which shows promise of significant power benefits. However, these benefits are difficult to quantify as the propulsion system and aircraft body become meticulously integrated. The thrust and drag are coupled and cannot be defined separately, making conventional performance analysis methods inapplicable. The power balance method (PBM) addresses this by quantifying aircraft performance in terms of mechanical flow power and change in kinetic-energy rate. The primary focus of this work was to perform computational studies implementing the PBM on unpowered aerodynamic bodies to evaluate their respective drag contributions. A secondary study was also conducted to quantify the energy recovery potential of various bodies using a potential for energy recovery factor. The computational fluid dynamics case studies showed that drag obtained using the PBM agreed to within 2% of conventional momentum-based approaches. Maximal energy recovery potential was consistently observed at the trailing ends of the geometries, with values ranging between 9 and 12%.
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    Thrust/drag decomposition using partial pressure fields
    (Association Aeronautique et Astronautique de France (3AF), 2023-03-31) Hart, Pierce L.; Mutangara, Ngonidzashe E.; Sanders, Drewan S.; Schmitz, Sven
    The accurate prediction of aircraft performance requires a robust definition of thrust/drag accounting. Traditional nacelle-pylon configurations have been treated as separate entities which are combined linearly; however, this is not feasible for embedded propulsion systems which have a higher degree of interaction than traditional designs. With the apparent shift to embedded propulsion systems in the N+3 generation of aircraft, of which boundary layer ingestion technology is a driving factor, improving our understanding of propulsion system interactions with an air-frame has never been more important. Since many of these interactions occur close to the body, a near-field decomposition method, partial pressure fields, is employed in CFD to provide insight as to the interactive aerodynamics of an embedded propulsion system.
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    A unified partial pressure field and velocity decomposition approach toward improved energetic aerodynamic force decompositions
    (Association Aeronautique et Astronautique de France (3AF), 2023-03-31) Mutangara, Ngonidzashe E.; Sanders, Drewan S.; Laskaridis, Panagiotis; Hart, Pierce L.; Schmitz, Sven
    Drag decomposition through energy and exergy-based methods has been shown to have a variety of advantages. One of these is identifying and quantifying the recoverable energy within a flow field. This describes the available energy that can be used to produce thrust through systems such as boundary layer ingestion. Another advantage highlighted from prior work is that the velocity decomposition approach can split the flow field into its isentropic and non-isentropic contributions. This provides region-specific formulations for drag assessment, wherein the isentropic field is associated with contributions originating from the bulk flow and the non-isentropic field with the shear layer. This paper aims to assess the performance of a modified form of the velocity decomposition approach for transonic flows. This modification involves unification with partial pressure field analysis, which provides better flow field separability due to the added decomposition of the pressure field.