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Aero-propulsive performance assessment approach to boundary layer ingestion aircraft
No full textA promising solution towards more sustainable and efficient aircraft propulsion
relies upon the ingestion of the boundary layer flow that develops around the
airframe. Amongst the plethora of concepts, the propulsive fuselage concept
appears to be the most pragmatic configuration, as a direct adoption of
conventional tube-and-wing aircraft, which has an additional propulsor integrated
around its tail. Nonetheless, there is a lack of consensus in the quantification and
interpretation of the performance of such vehicles. Long-established
momentum-based bookkeeping schemes break down as their underlying
assumptions do not hold true in highly-integrated airframe-propulsion systems.
Alternative approaches have been brought forth by considering holistically the
aircraft to evaluate its performance and decompose its aerodynamic forces.
Notably, energy- and exergy-based approaches improve one’s understanding on the
cause and effect of boundary layer ingestion mechanisms but require high
computational demands with dense grids. In sought of a universal approach,
energy- and momentum-based methods are used together in this work to quantify
the coupled aerodynamic performance of boundary layer ingestion aircraft. The
strengths of near-field momentum integrations are coupled with more informative
energy-based flow assessments. The design space of a propulsive fuselage aircraft is
explored via CFD after a reduction of its modelling to an axi-symmetric partial
assembly of the fuselage and propulsor. With variations in the thruster position
along the tail, its flow passage through the fan and pressure rise, and exhaust
design, best performance is achieved with a concept where the propulsor lies at
90% of the fuselage chord, for a fan hub radius of 30% of the fuselage radius, that
ingests around 43% of the boundary layer mass-flow, and applies a pressure rise of
1.29, to generate around a third of the total propulsive force requirement whilst
savings 11% of fuel relative to a short-to-medium range aircraft propelled by
state-of-the-art turbofans. The reasons for such savings are detailed with a
first-of-its-kind fully energetic flow decomposition which aims at attributing
boundary layer ingestion benefits to changes in propulsor design.PhD in Aerospac
Flow field explorations and design improvements of a hybrid rocket motor LOx feed line
Get PDFThe oxidizer system in a hybrid rocket motor needs to deliver the flow from a pressurized storage tank to multiple combustor ports. Pressure losses in the oxidizer system directly impacts combustor pressure and consequently the vehicle performance. However, oxidizer feed line designs till date have been done using simple 1D tools. Higher fidelity flow analysis methods have not been reported in the literature to identify loss generating features. Therefore, a design improvement study was carried out to identify and alleviate the impact of undesirable flow features in a typical oxidizer system design. An experimentally calibrated 3D RANS approach is applied to a typical LOx feed system which includes steps, splitters, ports, and pipes with multiple bends. These design features result in varying degrees of flow separation, secondary flows and vortical flow features and result in total pressure losses of up to 7 %. This loss means that the storage tank needs to be pressurized further to accommodate such losses and ensure combustor performance. A targeted design improvement approach that features simple, alternative, implementable solutions in the loss-generating regions is discussed. The best of these design improvements can reduce the total pressure loss to 4 %, indicating a 43 % reduction in the losses and reduced impact on storage tank design and combustor performance. Therefore, this paper demonstrates that a higher fidelity design enhancement process of the oxidizer feed system, which is often neglected in such detailed studies, can result in overall vehicle level design improvements to ensure mission targets are met effectively.The work was funded by UK Space Agency by grant P20491 of the LaunchUK Technology Investment program.Acta Astronautic
Waves and structural strain induced by a uniform current flow underneath a semi-infinite floating solar coverage
Get PDFFloating solar panels installed on water reservoirs will be an increasingly popular renewable energy scenario. However, a significant current flow will occur when the reservoir gate is open to release water. Such a current flow can cause complex fluid-structure interaction at the edge of the solar panels, reversely analogized to a ship advancing through calm water, signifying the generation of a stern wave. This wave can damage the solar panels, which needs to be investigated to ensure operational safety. In this context, the present paper analyzes a mixed boundary problem of a uniform flow passing through a two-dimensional semi-infinite elastic plate using an analytical approach—the Wiener-Hopf technique. The mathematical model is based on the linearized velocity potential for fluid flow and the Kirchhoff-Love plate theory for an elastic plate. Three different edge conditions are considered here, namely, clamped, simply supported, and free. Extensive results and discussions are provided for the amplitudes of the propagation wave, and principal strain in the elastic thin plate. In particular, significant “resonance” fluid-structure interactions are found when the current speed is at certain special magnitudes. To support straightforward industrial applications, these special flow rates are given as a water depth Froude number. Overall, this study can provide valuable insights for floating solar projects on water reservoirs to control the water-release rate, thus minimizing the potential structural problems.L.H. acknowledges grants received from Innovate UK (No. 10048187, 10079774, 10081314), the Royal Society (IEC\ NSFC\ 223253, RG\R2\232462), and UK Department for Transport (TRIG2023 – No. 30066).Physical Review Fluid
Comparison of advanced oxidation processes for metaldehyde removal and downstream disinfection by-product formation
Get PDFMetaldehyde is the pesticide that has been found to exceed the maximum
regulatory concentration of 0.1 µg/L in drinking water the most in the UK in recent
years. As a result of the pesticide not being removed by conventional water
treatment processes, there has been an interest in alternative treatments
including advanced oxidation processes (AOPs). The latter have been reported
as promising technologies for the removal of recalcitrant micropollutants. A large
scale pilot study was carried out to compare the performance of two different
AOPs for removing metaldehyde from sources used to produce drinking water:
the UV/H₂O₂ AOP and O₃/H₂O₂ followed by UV/H₂O₂ AOP. Since AOPs can
increase the formation of disinfection by-products (DBP) under certain oxidation
conditions, it is important to assess their impact on DBP precursors. For this
purpose, the trihalomethane formation potential (THM FP) and the haloacetic
acid formation potential (HAA FP) were measured upon chlorination of samples
collected at different stages of the treatment. Both AOPs were shown to remove
metaldehyde efficiently achieving removals of up to 98%. They were able to
reduce metaldehyde concentration below the regulatory level with UV doses
lower than 1 kWh/m³ for initial metaldehyde concentrations of up to 2.10 µg/L.
Concentrations as high as this value can be found in sources used to produce
drinking water. The O₃/H₂O₂ - UV/H₂O₂ AOP was up to 33% more efficient than
the UV/H₂O₂ AOP when applied at UV doses lower than 0.60 kWh/m3. In this
work, the electrical energy applied to the system was expressed in kWh/m³ to
enable the comparison of both AOPs at similar operating conditions. Both AOPs
either increased or decreased the THM FP and the HAA FP between -85% and
+155% with respect to the inlet. However, the quality of the inlet water better
explained these changes rather than the UV and oxidant doses applied.MSc by Research in Wate
A cyclic self-enhancement technique for complex defect profile reconstruction based on thermographic evaluation
Get PDFAlthough machine Learning has demonstrated exceptional applicability in thermographic inspection, precise defect reconstruction is still challenging, especially for complex defect profiles with limited defect sample diversity. Thus, this paper proposes a self-enhancement defect reconstruction technique based on cycle-consistent generative adversarial network (Cycle-GAN) that accurately characterises complex defect profiles and generates reliable artificial thermal images for dataset augmentation, enhancing defect characterisation. By using a synthetic dataset from simulation and experiments, the network overcomes the limited samples problem by learning the diversity of complex defects from finite element modelling and obtaining the thermography uncertainty patterns from practical experiments. Then, an iterative strategy with a self-enhancement capability optimises the characterisation accuracy and data generation performance. The designed loss function structure with cycle consistency and identity loss constrains the GAN’s transfer variation to guarantee augmented data quality and defect reconstruction accuracy simultaneously, while the self-enhancement results significantly improve accuracy in thermal images and defect profile reconstruction. The experimental results demonstrate the feasibility of the proposed method by attaining high accuracy with optimal loss norm for defect profile reconstruction with a Recall score over 0.92. The scalability investigation of different materials and defect types is also discussed, highlighting its capability for diverse thermography quantification and automated inspection scenarios.This work was supported by the UK EPSRC Platform Grant: Through-life performance: From science to instrumentation (Grant number EP/P027121/1).Acta Mechanica Sinic
Investigation of the Effect of Sand on Annular Flow Behaviour in Horizontal Pipes
No full textAnnular flow is encountered in petroleum production systems, where reservoir
fluids are conveyed to surface via wells and transport lines and also nuclear
power plants, chemical and refining processes (e.g. reactors, heat exchangers).
In this type of flow regime, the gas, together with the entrained liquid droplets,
flows within the core of the pipe at high velocities, while the liquid flows as a film
along the pipe walls.
Experimental investigations on annular flow behaviour, sand transport and its
effect on annular flow in horizontal pipe are presented, with the aim of progressing
the understanding of such flow and facilitate the optimum design of hydrocarbon
production systems.
The experiments were conducted using a closed-loop horizontal pipe with an
internal diameter of 2-inch (0.0504m). The experiments could be categorized into:
water/air flow, water/sand flow, water/air/sand annular flow and sand sampling.
The water/air flow experiments could be subdivided into water/air flow (Plug,
Slug, Stratified-smooth and stratified-wavy flows) and water/air annular flow. The
results of water/air flow were plotted on flow regime map to aid the recognition of
the different flow regimes. For the water/air annular flow experiments, key flow
features are presented, with discussion on liquid hold up, film thickness, wave
frequency and pressure gradient.
The water/sand flow experiments investigated sand saltation, sand streaks,
moving dunes and sand beds. Also, sand particles of 212microns and
500microns for water/air/sand annular flow were investigated. Similarly, sand
sampling experiments were also carried out.
The OLGA dynamic multiphase flow simulator was run against the experimental
results. The OLGA simulations of the water/air annular flow shows a better liquid
hold-up match at lower superficial liquid velocities. For sand transport, OLGA also
identified sand flow in annular flow as no bed.
The main contributions of this study are: presenting the minimum transport
velocities for water/sand flow in horizontal pipe. For water/air annular flow, the
contributions are: detailed annular flow behaviours in horizontal pipes with
annular-wavy slug flow at low superficial liquid and gas velocities, and full
symmetrical annular flow from superficial gas velocity of 12m/s at low Vsl. The
study proves that superficial liquid velocity has impact and significance on wave
frequency: This has refuted Setyawan et al., (2014), whose report presented
superficial liquid velocity to be insignificant in wave frequency. The study also
identified that the higher the Vsl, the higher the interfacial shear stress but the
lower the wave velocity. Also, the higher the Vsl, the higher interfacial friction
factor/shear stress, but the lower the wave frequency.
For water/air/sand annular flow, this study identifies saltation and suspension as
the two main sand distribution in annular flow, with small-size particles being
transported at the gas core and the bigger particles at the bottom (i.e. in the liquid
film) along in the horizontal pipes. Finally, sand particles’ size does not appear to
have an impact on wave velocity and wall shear stress, while sand concentration
affects wall shear stress, but not wave velocity. Lastly, presence of sand particles
in the liquid film is associated with increase in wave amplitude in annular flow, as
more energy is being dissipated from the gas phase to keep the waves in motion.PhD in Energy and Powe
Unsteady aerodynamics of a coupled compact intake-fan in crosswind
Get PDFThe design of aero-engine intakes for compact nacelles can be an important contributor in achieving cruise fuel burn reductions. A key aspect for the design of viable compact intakes is considerations of the off-design crosswind and high incidence conditions. The aerodynamics of compact intakes is also notably dependent on the flow interaction with the fan. This work analyses the unsteady intake-fan interactions under crosswind conditions. The effect of crosswind velocity is evaluated together with the intake ground plane interaction and the unsteady aerodynamic coupling between the intake and fan. The overall aim of the research is to identify the flow structures and the unsteady mechanisms involved in the separation of the intake flow. The work uses an unsteady fully coupled time resolved Reynolds averaged Navier-Stokes computational method to identify the unsteady features of intake-fan flow separation in crosswind operations. The unsteady intake flow distortion is assessed as well as the spectral signatures and engine-order perturbations due to the unsteady flow distortion. Local separated regions were identified in the diffuser. These are associated with the characteristics of the boundary layer and are phase-locked with the local pressure pulses from the fan. This aspect should be considered in the design of compact intakes with relatively high diffusion. Additional assessments of the previously reported unsteady lip separation is provided with the identification of the frequencies of the flow features in post-separation conditions and the axial and azimuthal movement of the separation due to the interaction with the ground vortex.Engineering and Physical Sciences Research Council (EPSRC)Innovate UKL. Lobuono was supported by the Engineering and Physical Sciences Research Council [grant number EP/W524529/1], Rolls Royce plc., and Cranfield University. R. Christie and D. MacManus were partially funded by Innovate UK FANFARE project (113286).34th Congress of the International Council of the Aeronautical Sciences 202
Point-enhanced convolutional neural network: a novel deep learning method for transonic wall-bounded flows
Get PDFLow order models can be used to accelerate engineering design processes. Ideally, these surrogates should meet the conflicting requirements of large design space coverage, high accuracy and fast evaluation. Within the context of aerospace applications at transonic conditions, this can be challenging due to the associated non-linearity of the flow regime. Different methods have been investigated in the past to predict the flow-field around shapes such as airfoils or cylinders. However, they usually have reduced spatial resolution, limiting the prediction capabilities within the boundary layer which is of interest for transonic wall-bounded flows. This work proposes a novel Point-Enhanced Convolutional Neural Network (PCNN) method that combines the advantages of the well-established PointNet and convolutional neural network approaches. The PCNN model has relatively low memory requirements in the training process, preserves the spatial correlation in the domain and has the same resolution as a traditional computational method. The architecture is used for the flow-field prediction of civil aero-engine nacelles in which it is demonstrated that the flow features of peak isentropic Mach number (Mis), pre-shock isentropic Mach number and shock location (X/Lnac) are captured within ^Mis = 0.02, ^Mis=0.04, ^X/Lnac=0.007, respectively. The PCNN model successfully predicts the integral parameters of the boundary layer, in which the incompressible displacement thickness, momentum thickness and shape factor are typically within 5% of the CFD. Overall, the PCNN method is demonstrated for transonic wall-bounded flows for a range of flow physics that include shock waves and shock-induced separation.This project has received funding from the Clean Sky 2 Joint Undertaking (JU) under grant agreement number 101007598. The JU receives support from the European Union's Horizon 2020 research and innovation programme and the Clean Sky 2 JU members other than the Union.Aerospace Science and Technolog
Dataset "BIFURCATE FLOWER TRUSS: a novel locus controlling inflorescence branching in tomato contains a defective MAP kinase gene"
No full textData underlying manuscript entitled: "Identification and characterisation of bifuricate, a novel locus on chromosome 12 controlling truss branching and flower number in tomato"CNPq, 246783/2012-5; BBSRC, BB/L011611/
Pyrolysis or hydrothermal carbonisation for anaerobic-digested sewage sludge? A comparison of pyrochar and hydrochar structure and stability: data
No full textThermochemical conversion of sewage sludge was proven as a useful method for waste management. HTC showed the greatest potential to produce a material with higher adsorption capacity (100 cm3 /g for H180-4) but all chars should be subjected to an activation process to be able to compete with other kinds of feedstocks. The reduction of the H:C and O:C from the original SS after the treatments indicated a greater carbonisation degree, but a general reduction of the high heating value (HHV) from 17.94 MJ kgˆ’1 in SS to (14.93 MJ kgˆ’1 ). The torrefied char and hydrochars could be an attractive option to reduce energy of the process and drying stage in the case of HTC.John O'Reilly PhD studentship administered through Cranfield University to support the European Partnership Programme