UWE Bristol Engineering showcase 2015

Sven Cumner
MEng – Motorsport Engineering
Project Supervisor
Dr Changho Yang
Optimisation of Turbocharger Wastegate Design
Modern Turbocharging Applications
In the modern automotive world, turbocharging is becoming more and
more common place. Advancements in the technology have allowed
automotive manufacturers to develop small capacity engines with the
power of large engines, that still maintain the frugal economy and low
emissions of a smaller engine. Modern motorsport series, such as Formula
One, are now also adapting to the need for smaller, turbocharged engines,
creating more fuel efficient vehicles and boosting development of
turbocharger technologies. Understanding how this technology works and
how it can be applied more effectively to an internal combustion engine is
vital in today’s motorsport industry.
Why does the common wastegate valve need to be redeveloped?
The standard wastegate system consists of a flat faced, sharp edged valve
seat and valve. This typical valve and valve seat geometry is not
aerodynamically efficient and is likely to flow badly at small-angle valve
openings. Rather than focussing on outright flow capability, the aim of this
study was to improve the quality of the flow through the valve, and in to
the rest of the exhaust system. Increasing the quality of the flow focusses
on increasing the predictability and efficiency of the flow, to allow more
precise control of the wastegate in advanced, modern powertrains.
Wastegate control may become a more useable, important control system
in future engines, if the wastegate flow characteristics can be predicted
more accurately
Concept Valve Designs
After the factory wastegate valve was modelled, several alternative
concepts were developed, from rudimentary sketches in to Solidworks
models integrated in to the entire turbocharger assembly. A valuable
feature of modelling the valve assembly like the real system is that the
geometry of the valve concepts could be tested to see if they would
physically work within the factory turbine housing. The aim was to make
sure the original turbine housing could be used without modification, hence
the concept valves needing to work with the original housing geometry.
Above top left: Factory wastegate valve, open 10 degrees.
Above top right: Hemisphere valve with circled areas indicating
improved symmetrical flow area across the valve.
Above bottom left: Concave Cone valve
Above bottom middle/right: Wedge valve
Below top/middle: ANSYS CFD flow simulations for turbine/wastegate.
Below bottom: Temperature and pressure plots on flow domain
Project summary
This project developed the theory and understanding
of wastegate valve design, along with showcasing
some of the problems faced by engineers attempting
to optimise this system.
Project Objectives
To create an optimised pairing of concept valve and
valve seat designs, giving rise to a more predictable,
controllable wastegate flow stream. This was done
through the use of Solidworks CAD modelling and
ANSYS CFD analysis.
Project Conclusion
• No ‘perfect’ valve/valve seat duo was created,
however improvements were seen with some of
the concept designs.
• A ‘Concave Cone’ valve brought about the most
stable, laminar flow from the turbine of the
turbocharger.
• An ‘Up/Down Wedge’ valve brought about the
best wastegate flow, directing exhaust gases in two
broad streams along the upper and lower faces of
the exhaust down-pipe.