We are witnessing a period of great change in the automotive industry. Road transport in the EU accounts for around 20% of all emissions of CO2, the main greenhouse gas. The shift to hybrid/electric powertrains in passenger car and light-duty vehicles with ultra-low or zero CO2 tailpipe emissions continues, but a complete transition will take decades. This is especially so for heavy-duty applications, which are not well-suited to current electrical energy storage technology. In fact, between 1990 and 2010 CO2 emissions from heavy-duty vehicles actually grew by ~36% [1], due to expanding demand for road freight and stagnant fuel economy. Irrespective of the future powertrain technology mix across sectors, the internal combustion (IC) engine will remain the most numerous prime mover, and the consensus [2] is that we must continue to strive to raise the efficiency of thermal propulsion systems in order to reduce CO2 emissions across all modes of transport.


A key enabling technology for high thermal efficiency is the multi-stage turbocharged engine air system (e.g., Fig. 1), which can attain higher boost pressures, provide greater air flow, and faster transient response, enabling thermal efficiency strategies and reduced emissions from IC engines. These are complex systems, designed using 1D engine simulation tools, followed by physical testing on engine. However, due to modelling inaccuracies, multiple design and test iterations are required. Improving the physical accuracy of these models will require representative validation test data. This motivated the design and commissioning of a new experimental facility: TASR, the Transient Air System Rig.


  • To measure performance of multi-stage engine air systems under engine-realistic conditions, but without an engine

  • To reproduce the unsteady gas dynamics in an IC engine exhaust manifold undergoing a specified transient event

To meet these objectives, TASR will need to be able to generate two timescales of unsteadiness:

  1. Transient – timescale of engine acceleration, in the order of 100 Hz

  2. Pulsating – timescale of exhaust pulses due to opening and closing of valves, order of 101–102 Hz