Latest News November 2021
Welcome to the Frewer Engineering November Newsletter. Enjoy catching up on the latest developments of our technology and capabilities.
We hope you enjoy the read!
Cutting-Edge CFD Methods
We are continuing to push the limits of our software capabilities, researching advanced applications of CFD by predicting complex phenomena such as cavitation on marine propellers. Whilst our expertise carried over from the aerospace sector gives us an assured knowledge of advanced blading, understanding the factors specifically influencing marine props is essential for accurate modelling of their efficiency through the water. Pictured above is a CFD model built with rotating discontinuous polyhedral meshes used to predict characteristic drag and torque curves for real B-Series propeller geometries. Predicting values representing drag, tip vortices and anticipated void fractions of cavitation allows us to predict propeller performance and highlights design flaws earlier in the design process, saving our customers precious time and money.
Filament Winding Pressure Vessels
A growing trend seen by Frewer’s Advanced Composites Division throughout 2021 is the rise in demand for structural analysis of filament-wound pressure vessels. One such project reaching its conclusion in November has required us to convert the customer’s manufacturing tape-laying output data into the equivalent laminate input data required for our Siemens NASTRAN FEA toolsets. With burst strength coupled with a challenging maximum allowable wall thickness being the critical drivers for the project, a number of iteration variants had to be run, balancing manufacturability with performance to optimise the structure for operational service. As with all such pressure vessel designs, an effective integration of metallic end fittings was crucial to the integrity of the part. Achieving this, coupled with early confirmation of critical composite material properties data, a pre-requisite for all FEA work, allowed us to find a solution that precisely matched the customer’s performance specifications.
Make from Model: The Future of Design?
Model based definition design methods have the potential to supercharge the prototyping stages of the design process. Creating parameterised authoritative digital product models with fully defined geometric dimensioning and tolerancing facilitates agile model modification throughout product development and allows prototypes to be made at any design maturity. Paired with rapid prototyping, scale or full-size models of a product can be produced at the click of a button. Our low force stereolithographic 3D printing capability creates models which provide a unique insight for locating, diagnosing, and solving technical challenges, resolving potential manufacturing and assembly issues before they arise. Additionally, this provides our customers with a physical model of their product, enabling them to directly feedback to us and reduce the inherent risks of product development. The same CAD/CAM model can then be refined and used downstream by end-manufacturers without design drawings changing hands!
Gas Path Optimisation
We can optimise gas paths to avoid unwanted flow features and improve flow efficiency though complex geometry and tight bends in large pipework systems. Using advanced CFD software, sources of turbulence, pressure losses, choke points and more unwanted flow features can be located. (See pictured ‘Oil flow’ plot, a useful visual tool for initially identifying areas of disturbed flow.) Our suite of analysis tools enables us to assess the influence and magnitude of flow non-uniformity, scrutinising identified problem areas in detail to create a comprehensive review of fluid flow. Our multi-skilled design & analysis engineers are then equipped to rapidly tool up and make appropriate design changes, providing an agile solution for demanding customer requirements, whether they be transport, flow rate or pressure related.
Gas Turbine Development Throttling Up
Over the last few years, the aerospace sector has rapidly evolved into a greening industry after being held accountable as a heavy producer of carbon dioxide in transportation sectors worldwide. An aggressive approach to improving efficiency and reducing emissions is needed to meet stringent new emissions regulations. These are designed to progress aerospace towards net-zero, despite a continued increase in demand for air travel. Frewer Engineering is committed to applying our advanced design capabilities and extensive gas turbine development expertise to realising these efficiency improvements for modern jet engines. We have recently passed technical design reviews for large civil aerospace gas turbine projects, notably supporting the development of a world-class geared turbo fan, promising to substantially reduce the noise and CO2 emissions of fight, and almost completely eliminate emissions of NOx.
Hydrogen in a Post-COP26 World
In the post-COP26 world, focus is naturally turning to clean energy alternatives and of these, hydrogen power offers huge advantages. Unfortunately, there are also huge challenges to make stored hydrogen practical and safe for everyday life. Filament-wound composite tanks are of course nothing new for this application and in themselves are practical solutions for storing highly pressurized hydrogen. However, this is only part of the solution if hydrogen tanks are to become commonplace as power storage devices. Before the aerospace or automotive industries can realistically consider using them, solutions need to be found for safely diffusing these ‘potential bombs’ in the event of impact or fire damage. Fitting PRVs alone is not sufficient as even controlled leaks are no safer for a car kept in a garage or for passengers in an aircraft. Frewer Engineering is working with customers at the forefront of these technical challenges in our own efforts to create a net-zero world.
In order to understand the dynamic behaviour of rotor systems, including modal effects, the influence of whirl and forced system responses, advanced rotordynamic methods are employed. Our rotordynamics team has been busy this month, conducting analysis on rotating aero engine rig hardware. This involved using advanced rotordynamics software and techniques to produce Campbell diagrams and force and deflection predictions, which take account of out-of-balance shafts and shaft whirling effects. This analysis allows the team to predict the operational limits of rotating features such as bearings with stability analysis, and tune the stiffness with variable bearing stiffness and damping modelling. Critical vibrational frequencies can then be predicted in a final system configuration to inform the user on which operational speeds and subsequent vibrational frequencies must be avoided to prevent resonance.