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Computer Aided Engineering has an important role in developing today’s advanced designs. Our experienced engineers use the latest tools and techniques and can work to the most demanding of constraints and performance requirements. Computer-aided engineering is CPU intensive, so we have in place a Linux cluster of workstations, capable of handling the high CPU requirements.
We have a wealth of expertise in using finite element analysis to characterise the structural design, and in fluid dynamics.
Solid Modelling and System Design
FEA and Structural Computations
With
increasingly complex exhaust and emissions control systems, the space and
packaging constraints are more demanding than ever. The packaging of system
components and the exhaust gas flow are critical to system performance, accessibility
is required for system maintenance and the space envelope is no bigger whereas
the exhaust systems have grown in size, and these are just a few of the design
constraints.
Using the latest software packages such as Catia v5 and v4, ProEngineer and Solid Works we are able to design the exhaust system to fit the available space envelope while meeting the necessary design constraints and optimising its performance, and can exchange 3-D models with customers to ensure accuracy and speed the design process. We can model design performance using FEA (Finite Element Analysis) and computation fluid dynamics and then carry the design through to verification and testing if required.
Campbell plot for silencer on test vehicle
The acoustic performance, often referred to as NVH (Noise, Vibration and Harshness) is a major parameter of any exhaust system design. The system needs to accommodate the characteristics of the particular engine and vehicle, and must meet the legislated standards or often the OEM’s higher standards.
We can manage the whole design process from start-to-finish, modelling the key parameters such as engine noise, flow induced noise and radiated noise, then verifying actual system performance on our test rigs.
Fluid structure interaction analysis is used to understand and predict the
radiated noise from the exhaust system. We are currently undertaking a research
project together with Chalmers University and partly financed by the Swedish
Government to further develop this advanced analysis capability that integrates
the complete chain of CAE tools.
Radiated noise is caused by vibrations in the structure which originate from the pressure pulsations of the engine. Custom developed software can couple the CFD analysis with the structural analysis and the acoustic noise radiation analysis. This enables us to simulate the complete acoustic characteristics of an exhaust system design just knowing the pressure pulsations from the engine.
Predicting the behaviour and characteristics of different designs early-on
in the design process is of fundamental importance to good design. We use
a variety of tools such as ABAQUS for FEA (Finite Element Analysis) calculations
and PAM-STAMP 2G for forming simulations, using ICEM software to prepare the
CAD models (meshing) before analysis.
Typical FEA calculations we undertake
include:
In designing any exhaust system, but particularly those with after-treatment
such as CRT® or SCRT®, computational fluid dynamics
(CFD) is a powerful tool used to optimise the performance of the whole system.
Not only for predicting fluid flow behaviour, but also the transfer of heat
or phase change and chemical reaction – all important elements in exhaust
system design. We use CFD to optimise parameters such as acoustic performance,
backpressure, the utilisation of catalysts (UI index measurement) and in SCR-based
systems, the dispersion of urea in the gas stream. This enables us to meet
the most challenging customer performance requirements and the legislated
emissions regulations. We use the market leading Fluent software and typical
CFD calculations include:
