CERES :: Browsing by Author "Prince, Simon A."

Browsing by Author "Prince, Simon A."

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Open Access
The Aerodynamics of High Speed Aerial Weapons
(Cranfield University, 1999-09) Prince, Simon A.; Qin, N.; Birch, T.
The focus of this work is the investigation of the complex compressible flow phenomena associated with high speed aerial weapons. A three dimen- sional multiblock finite volume flow solver was developed with the aim of studying the aerodynamics of missile configurations and their component structures. The first component of the study involved the aerodynamic investigation of the isolated components used in the design of conventional missile config- urations. The computational study of nine ogive-cylinder body experimental test cases is presented together with a new interpretation of the complex vortical flow including the windward appearance of a "vortex shock wave". In addition, a simple modification to improve the accuracy of the Baldwin- Lomax/Degani-Schi fl`' turbulence model is put forward, and the phenomenon of "phantom vorticity" in Euler solutions and its alleviation are described. Inclined Delta Wings in supersonic flow were computed in order to study the aerodynamics of wings alone, and in particular the vortex-shock interactions which occur on their leeward surfaces. The second component of the study was the computational and experimen- tal investigation of a generic cruciform missile configuration. The compli- cated interactions between shock waves and boundary/shear layers that are seen to occur around and in the wake of the cruciform wing arrangement were studied and described. The third component of the research involved an assessment of the pre- diction technologies used in the design of modern weapons. In particular the role of Computational Fluid Dynamics in the process of design.
Open Access
Analysis of triangular cross-section slender bodies in supersonic regime using RANS simulations
(AIAA, 2023-06-08) Bourny, Quentin; Proenca, Anderson; Di Pasquale, Davide; Prince, Simon A.
This paper presents an investigation on the ability of RANS simulations to capture the aerodynamic forces and the flow topology of triangular cross-section slender bodies. At Cranfield University’s Transonic and Supersonic Wind Tunnel, force measurements and Schlieren images were obtained at zero incidence, Mach number equals to 2.5, and Reynolds number of 2.38 · 10^5 (based on section width). Tests were performed for three bodies of different nose geometries, but constant nose fineness ratio of 1.732. Tests were compared with RANS simulations for three turbulence models: Spalart-Allmaras, k− epsilon Realizable and k − omega SST using the ANSYS Computational Fluid Dynamics software Fluent. In addition, simulations for a configuration presented in the literature which investigated several angles of attack were also conducted. At Mach 2.5, the normal force was predicted accurately by all turbulence models. The axial force, however, was clearly predicted more accurately with the k − epsilon Realizable model. At the other hand, this turbulence model showed inferior ability to capture the flow features, particularly the leeside vortices. Spalart-Allmaras and k − omega SST gave similar results.
Open Access
Application of a semi-empirical method to model subsonic vortex lift over sharp leading-edge delta wings
(AIAA, 2023-01-19) Huynh, Daniel; Di Pasquale, Davide; Prince, Simon A.; Ahuja, Vivek
A semi-empirical method is applied as a complement to the FlightStream solver, to more accurately model subsonic vortex lift over a sharp leading-edge delta wing. The method, based on the prediction of flow patterns and the application of the Polhamus method, is particularly well-adapted to a preliminary aerodynamic design phase. Within a few minutes, it can accurately predict the aerodynamic forces generated by the flow over a delta wing, which are strongly affected by the presence of a leading-edge vortex. This study presents a detailed analysis where computed results are compared against experimental data. Those were obtained from a test case of a 65° subsonic delta wing experiment (case 1), along with a sensitivity analysis against sweep angle and aspect ratio where multiple subsonic delta wings were tested (case 2). A good agreement is observed between computed data and experimental results, within pre-stall, before the vortex bursts. Analysed results demonstrate the validity of the method, for multiple wing configurations associated with different flow conditions.
Open Access
The application of passive air jet vortex-generators to stall suppression on wind turbine blades
(Wiley, 2016-05-16) Prince, Simon A.; Badalamenti, Carmine; Regas, Constantinos
An experimental study was performed to assess the feasibility of passive air jet vortex-generators to the performance enhancement of a domestic scale wind turbine. It has been demonstrated that these simple devices, properly designed and implemented, can provide worthwhile performance benefits for domestic wind turbines of the type investigated in this study. In particular, this study shows that they can increase the maximum output power coefficient, reduce the cut-in wind speed and improve power output at lower wind speeds while reducing the sensitivity to wind speed unsteadiness. A theoretical performance analysis of a 500 kW stall-regulated wind turbine, based on blade element momentum theory, indicates that passive air jet vortex-generators would be capable of recovering some of the power loss because of blade stall, thereby allowing attainment of rated power output at slightly lower average wind speeds
Open Access
CFD analysis on novel vertical axis wind turbine (VAWT)
(MDPI, 2024-11-12) Bang, Chris Sungkyun; Rana, Zeeshan A.; Prince, Simon A.
The operation of vertical axis wind turbines (VAWTs) to generate low-carbon electricity is growing in popularity. Their advantages over the widely used horizontal axis wind turbine (HAWT) include their low tip speed, which reduces noise, and their cost-effective installation and maintenance. A Farrah turbine equipped with 12 blades was designed to enhance performance and was recently the subject of experimental investigation. However, little research has been focused on turbine configurations with more than three blades. The objective of this study is to employ numerical methods to analyse the performance of the Farrah wind turbine and to validate the findings in comparison with experimental results. The investigated blade pitch angles included both positive and negative angles of 7, 15, 20 and 40 degrees. The k-ω SST model with the sliding mesh technique was used to perform simulations of a 14.4 million element unstructured mesh. Comparable trends of power output results in the experimental investigation were obtained and the assumptions of mechanical losses discussed. Wake recovery was determined at an approximate distance of nine times the turbine diameter. Two large complex quasi-symmetric vortical structures were observed between positive and negative blade pitch angles, located in the near wake region of the turbine and remaining present throughout its rotation. It is demonstrated that a number of recognised vortical structures are transferred towards the wake region, further contributing to its formation. Additional notable vortical formations are examined, along with a recirculation zone located in the turbine’s core, which is described to exhibit quasi-symmetric behaviour between positive and negative rotations.
Open Access
Delay of dynamic stall using pulsed air-jet vortex generators
(AIAA, 2017-11-28) Green, R. B.; Prince, Simon A.; Wang, Y.; Khodagolian, V.; Coton, F. N.
Open Access
The development of a simple method for drag estimation for wedge-like fairings in hypersonic flow
(ICAS, 2016-09-30) Roussel, Alexandre; Prince, Simon A.; Viguer, Matthieu; Kshitij, Abhinav; Stollery, John; Garry, Kevin
The addition of wedge-like fairings onto the side of missiles and space launch vehicles, to shield devices such as cameras or reaction jet nozzles, creates additional drag, particularly when in supersonic/hypersonic flow. An experimental and computational study was performed to obtain data on wedge configurations and develop simple theories for the drag due to these types of fairings.
Open Access
Drag estimation on wedge-shaped protuberances in high-speed flows
(AIAA, 2020-01-05) Kshitij, Abhinav; Prince, Simon A.; Stollery, John L.
A semi-empirical method is developed to estimate drag on wedge-shaped projections in hypersonic flow. Force balance measurements from gun tunnel tests directly measure total drag on blunt wedges, where the boundary layer and the entropy layer are weakly coupled. Detailed flowfield analysis from numerical simulations provides estimated locations of peak pressure ratio and skin friction. Schlieren images are used for detecting incipient separation in incoming flows with laminar and turbulent boundary layers. Test results indicate the presence of local hotspots at reattachment points of strong detached shocks on the wedge compression ramp, and of primary and secondary vortical structures around lateral faces. Total drag is found to decrease with decreasing bluntness but increasing slenderness in wedges tend to increase skin friction drag.
Open Access
The effect of steady and pulsed air jet vortex generator blowing on an aerofoil section model undergoing sinusoidal pitching
(Vertical Flight Society, 2019-07-01) Prince, Simon A.; Green, Richard; Coton, Frank; Wang, Yaxing
Experimental results are reported on the assessment of steady and pulsed air jet vortex generators (AJVGs) for the suppression of dynamic stall on a sinusoidal pitching RAE9645 airfoil model. Tests at Rec of 1 million, at reduced pitching frequencies between 0.01 and 0.10 were performed with and without steady and pulsed AJVG blowing. The effect of jet momentum coefficient (0.0003< C μ < 0.0046), jet duty cycle (0.25< DC< 1) and jet pulsing frequency (0.29< F +< 2.93) were investigated. Pulsed air jet blowing with F + in the range 0.5–1.0 and with a duty cycle in the range 0.4–0.5, was found to be the most effective to achieve full suppression of dynamic stall vortex formation.
Open Access
Estimation of three-dimensional boundary layer velocity profiles on swept wings and blended wing bodies
(ICAS, 2021-09-10) Ma, Kexin; Prince, Simon A.
A rapid process of boundary layer (BL) velocity profile reconstruction is frequently required for wing surface drag estimation or for aircraft engine intake design. With the Viscous Full-Potential (VFP) method, accurate prediction of local boundary layer parameters can be provided with high speed. However, no information is given concerning velocity distribution within the boundary layer. Existing boundary layer reconstruction methods have been applied to five test cases of different freestream Mach number range, and comparisons have been carried out between their results and experimental velocity profiles. A new optimized method which can give reliable results for both the streamwise and the crossflow directions at different subsonic airspeed has then been developed. Comparisons have then been performed, for two of these test cases, between velocity profiles calculated using measured boundary layer parameters and VFP simulated ones. These results indicate that boundary layer velocity profiles calculated with the new method using boundary layer parameters computed by VFP simulations are reasonably accurate for a high aspect-ratio and medium (or small) sweep angle wing, at subsonic airspeed under suitable flow conditions. A VFP simulation followed by calculation using the new boundary layer reconstruction method can be a rapid process for the reconstruction of boundary layer profiles. This process has finally been demonstrated on a blended wing body for the reconstruction of velocity profiles on its upper surface, where the boundary layer could be ingested by an engine intake.
Open Access
Experimental and numerical studies of shock wave -- boundary-layer interactions over a cone-cylinder-flare in hypersonic flows
(AIAA, 2025-01-06) Arfi, Benjamin W.; Corcoral, Erwan A.; Prince, Simon A.; Rana, Zeeshan A.; Tsentis, Spyros
The present study provides experimental and numerical results for turbulent shockwave boundary layer interactions (SBLIs) over a blunt cone-cylinder-flare geometry, on which there is a lack of available data. Experiments were conducted in the Cranfield hypersonic gun tunnel, at Mach 8.2. Two configurations with varying nose length were studied using experimental testing and computational fluid dynamics (CFD). Three dimensionality has been generated by placing the model at incidence. The objective was to extend the range of data available for hypersonic flows and contribute to the design of re-entry vehicles. Experimental results cover forces and moments, that the numerical study aimed to replicate with Reynolds Averaged Navier-Stokes (RANS) modeling, and extended by analyzing the separated flow regions over the model. Additionally, the effect of the nose length on the aerodynamic forces and boundary layer transition were presented.
Open Access
Experimental evaluation of a passive flow-control device for a tiltrotor aircraft
(2022-11-28) Proenca, Anderson R.; Prince, Simon A.; Banks-Davies, Lynton; Garry, Kevin P.
This work presents a preliminary investigation into tiltrotor propeller/nacelle/wing flows, and the flow breakdowns that can lead to the phenomenon of whirl flutter. Static blade measurements were performed, results suggesting that tubercles have the potential to provide an increase in performance for the baseline blade design. A small-scale propeller rig (0.7 m swept diameter) has been designed, manufactured, and commissioned at Cranfield’s 8x6 Wind Tunnel. This new rig operates well under static and up to wind speeds of at least 30 m/s. The effect of blade pitch angle (0 to 10◦ ) and propeller rotational speed (0 to 3000 rpm) have been investigated successfully. Forces measured on the wing set at angles of attack within the range 0 to 22◦ indicate the well-established effects due to propeller slipstream. Overall, the propeller wake flow slightly decreases the lift generated by the wing model, whilst also delaying stall. Pressure taps and accelerometers mounted on the wing and propeller nacelle effectively captured the slipstream effects, blade passing frequency, and flow separation regions. Finally, blades containing tubercle-shaped vortex generators were mounted to the propeller rig. Preliminary test results for the tubercle blades are reported in the paper. Overall, effects due to the propeller slipstream are dominant on forces, pressure distribution and vibration of the wing model. At the current stage of this ongoing investigation, it is not possible to conclude whether the tubercles provide any benefit to either the propeller or wing aerodynamic efficiencies. The rig is being equipped to measure propeller thrust and torque. Flow field investigation will also be carried out in future campaigns.
Open Access
Experimental investigation of a variable geometry vertical axis wind turbine
(SAGE, 2020-07-14) Prince, Simon A.; Badalamenti, Carmine; Georgiev, Dimitar
An experimental study is presented on the performance of a vertical axis wind turbine with variable blade geometry of the design developed by Austin Farrah. This is experimentally compared with the performance of a correspondingly sized Bach-type Savonius turbine using the same electrical generator and measurement instrumentation in a wind tunnel. Experiments were performed for Reynolds numbers, based on blade chord, in the range 5 × 103 to 1 × 105, and for blade settings between −40° and +40o. The study shows that for the tip speed ratios that have been investigated, the Farrah vertical axis wind turbine design can only marginally outperform a corresponding two-bladed Bach-type Savonius turbine and then only when its blades are set to 40° pitch angle. The presence of a small inner cylinder, which rotates with the turbine, does not enhance its performance due to the fact that it is immersed in an extensive column of relatively static air.
Open Access
Feasibility of a spinning cylinder on the leading and trailing edges of a flap for high lift
(AIAA, 2023-01-19) Francannet, Antoine; Prince, Simon A.; Di Pasquale, Davide; Proenca, Anderson
This paper presents a numerical feasibility study of a spinning cylinder mounted on the leading edge and trailing edge of a flap to improve lift force generation. The baseline used in this study is a two-dimensional NLR 7301 airfoil with a single-slotted trailing-edge flap. For this configuration, experimental data is available in the literature. The Ansys computational fluid dynamics (CFD) simulation software has been used in this work to simulate the aerodynamic properties of several configurations. Firstly, a turbulence model dependency study over the existing geometry was conducted, providing lift, drag and pitching moment coefficients, as well as pressure distribution for three angles of attack. Data was then acquired using the Spalart-Allmaras turbulence model at Mach and (chord-based) Reynolds numbers 0.185 and 2.51×10^6, respectively. Three configurations with a leading-edge spinning cylinder and one with a trailing-edge spinning cylinder were investigated. Results suggest that the introduction of a cylinder in the baseline geometry decreased lift and drag performance by inducing flow separation. Nevertheless, for the leading edge configurations, the rotation of the cylinder allowed recovery of the original flapped airfoil performance by re-energizing the flow around the flap and reattaching the boundary layer. For the trailing edge configuration, the spinning cylinder generated additional lift due to Magnus and suction effects at high rotation speed of the cylinder, and by modifying the flow circulation around the flap’s trailing edge. Overall, no benefit over the lift-to-drag ratio could be derived from this preliminary study.
Open Access
Hypersonic boundary layer reduction with optimisation of the Hyshot II intake using numerical methods
(AIAA, 2024-01-04) Burrows, Sam; Rana, Zeeshan A.; Prince, Simon A.
The Hyshot project demonstrated that the quality of flow in a scramjets combustion chamber is essential to achieve critical mass flow condition in a small profiled supersonic combustion chamber. This investigation utilises a steady RANS and real gas thermal model to explore boundary layer growth over various comparable compression ramp profiles in a hypersonic freestream condition. The results in this investigation suggested that given a constant net flow deflection angle and ramp length, the displacement thickness developing on a hypersonic compression ramp is inversely proportional to the magnitude of static pressure the ramp produces at the wall, where the highest pressures theoretically achievable are that of an isentropic compression process. A quasi isentropic compression distribution was achieved when the rate of deflection along a ramp’s length is linear. The data collected also suggests that the difference in displacement thickness growth of the quasi isentropic ramp relative to the nominal flat plate increases as the flight Reynold’s number increases, where the displacement thicknesses has the potential to reduce by over 50% relative to an equivalent flat plate. Low Reynold’s numbers have found to yield the opposite effect, where isentropic turning of a hypersonic flow may increase the difference in these cases. Such reductions have been shown to theoretically allow for a critical mass flow rate in a two dimensional scramjet combustion chamber without requiring slot bleed systems, whilst achieving the required flow conditions for the auto-ignition of hydrogen. It is suggested that a scramjet design based upon these findings would still require some form of porous bleed system to compensate for the growth in the boundary layer as it expands about the compression ramp into the combustion chamber, which has potential to be incorporated onto an axisymetric design to optimise the effective mass flow rate per body diameter.
Open Access
The influence of high-speed SPIV data processing parameters on aircraft wing vortex wake assessment
(ICAS, 2018-12-31) Garry, Kevin; Di Pasquale, Davide; Prince, Simon A.; Lawson, Nicholas J.
SPIV is a powerful tool to assess aircraft wing vortex wakes. Current optical systems enable velocity vector measurements at sample rates of 10Hz. This facilitates detailed assessment of flows containing multiple, potentially unsteady, vortices. SPIV data from the wake of a high-lift wing is used to investigate data sampling strategies on the magnitude of vortex trajectory and strength.
Open Access
The influence of high-speed SPIV data processing parameters on aircraft wing vortex wake assessment
(ICAS, 2018-09-14) Garry, Kevin; Di Pasquale, Davide; Prince, Simon A.; Lawson, Nicholas J.
This paper uses Stereoscopic Particle Image Velocimetry (SPIV) data from the near wake of a detailed sub-scale ½ model of a representative transport aircraft wing with leading and trailing edge high lift systems and outboard aileron representation, to analyse the influence of data sampling period and frequency on the magnitude and position of the vortices resolved within the wake. The paper also evaluates the extent of vortex ‘wander’ at various stages of development within the near wake and offers guidance for optimum time-averaging strategy when investigating complex longitudinal vortex interaction studies in similar flow fields.
Open Access
Investigations of a combustible inertial launch design
(British Interplanetary Society, 2015-06-30) Yemets, V.; Prince, Simon A.; Wilkinson, Ray
The paper develops a subject of a combustible inertial (self-feeding) launch vehicle for nano and pico satellites. A part of the paper considers a flight of the rocket using ballistic, aerodynamic and thermal calculations. Another part describes experimental investigations of a laboratory-scale model of the rocket engine. Plans for future work and prospects of the self-feeding technology combined with pulse engine mode for microlaunchers and small satellite micro propulsion concludes the paper.
Open Access
On the assessment of CFD methods for vortical flows
(ICAS, 2021-09-10) Gonzales, Roberto; Prince, Simon A.
In this study, a general assessment was made on the capabilities of a wide range of turbulence models – both linear and non-linear eddy viscosity models, and simulation techniques to predict the process of vortex formation, growth and breakdown on a series of models at a range of Mach numbers (subsonic, transonic and supersonic) and angles of attack. The analysis was made on isolated components as a first approach to study the aerodynamics of a high-speed vehicle concept and used experimental data as the basis for a detailed validation exercise. These components included a family of slender axisymmetric bodies, a family of delta wings with different leading-edge radii and a double delta wing with different edge fillet configurations. Individual studies were made on each component, and different simulation approaches were used on each of them. It was found that the most accurate turbulence models were the k-e Realisable and k-w SST models, while the Scale Adaptive Simulation method was found to be the most accurate scale resolving turbulence approach.
Open Access
Progress towards a rapid method for conceptual aerodynamic design for transonic cruise
(AIAA, 2020-01-05) Prince, Simon A.; Di Pasquale, Davide; Garry, Kevin P.
Results are presented from a study aimed at demonstrating the accuracy and efficiency of a lower order aerodynamic prediction method for transonic cruise flows around aircraft configurations, including conventional swept wing-body and also blended wing-body designs. The Viscous Full Potential (VFP) method, coupling the solution of the full potential equations with the integral boundary layer equations can yield data of almost equivalent accuracy as Navier-Stokes based CFD methods but at 0.5% - 2% of the physical time. In addition it is shown, using both the VFP approach and Delayed Detached Eddy Simulation (DDES) that the flow physics of the stall mechanism associated with blended wing-body configurations is far more complex than that experienced on more conventional swept-tapered wings. The mechanism appears to involve an initial tip stall but also involves highly 3D vortical flows inboard on the upper surface of the wing which significantly distorts the transonic shock wave.