Jens Lahr

Name: Jens Lahr

Research Title: Investigation of Parameters Controlling the Fill Level in Cooling Galleries of Modern Diesel Engine Pistons

Name of Director of Studies: Dr. D. Ashman, Dr. M. S. Srai

Key Contact Details - Email: jens.lahr@bcu.ac.uk

About the Project: The drive and requirements for improved fuel economy of vehicles requires looking at all aspects of such vehicles. While much work has been undertaken in the past concerning the vehicle weight and aerodynamic, powertrain engineers have aimed to optimise the engine performance, leading to high cylinder pressure, especially in diesel engines.

Although further increase in pressure would reduce fuel consumption further, the internal engine temperatures encountered pose a limit. Therefore precise cooling is required, especially for components exposed to the burning fuel, such as the engine piston.

This project aims to investigate the coolant flow through the engine piston, to analyse the behaviour of coolant inside and to investigate the suitability and accuracy of current modelling software. Data obtained from physical testing and computer simulation will be analysed and compared.

Research Activities:
The research project includes the following subjects:

• physical testing on dedicated test bed
• instrumentation and control
• data logging
• high speed image capturing
• computational fluid dynamics

Findings: High speed imaging shows highly turbulent flow inside the gallery and the amount of oil in the gallery is strongly dependent on the operating conditions, in particular on the engine speed and the flow rate. The oil nozzle has also a strong effect, as higher oil jet speeds (free stream) cause high shear stress at the oil-air interface and cause strong turbulence. This in turn increases the amount of air drawn into the oil jet and therefore changing the properties of the bulk flow.