# Design of an Axial Turbine for Highly Downsized Internal Combustion Engines
## 5 Conclusions  
Initially, 3D optical scans were performed, which allowed the proper measurement of the properties of the OEM turbocharger, such as the rotational moment of inertia of the turbine, compressor and shaft, and to use much of this data as references for the mechanical design of the axial turbine. A dyno-calibrated 1D Ricardo-Wave engine model (Ford EcoBoost 1.0 L) was used to calculate the aerothermal boundary conditions for the design of the turbine at every interval of 1000 rpm from 1000 to 6000 rpm to have all the required boundary conditions data to design/test the turbine at different engine operating points.  
The initial idea of low-aspect-ratio prismatic blades having similar efficiency to 3D twisted blades was tested via thermodynamic calculations and streamline optimization and then verified. Many turbines of several size ranges and different blade types (prismatic vs. 3D twisted) were predesigned at 2000 and 4000 engine rpm (full load) operating points, mapped and compared to check the suitability for the engine and compressor requirements. After choosing the final design, it has been simulated by means of increasing-precision CFD RANS analysis, including 2D cascades for airfoil profile optimization, axisymmetric simulations and full 3D simulations. FEA analysis concluded the turbine design phase, as this validated the preliminary structural calculations performed in the preliminary design phase.  
The pool-up performance of the proposed axial turbine was found to be up to 2.67 times higher than the OEM radial one. The power output of the axial turbine was comparable to that of the original radial one for lower engine rpm values (\(<\)2000 rpm) and was significantly greater for higher engine revs, therefore potentially allowing for the implementation of an electric MGU to further increase the power unit efficiency, and potential removal of the crankshaft-connected alternator.  
The proposed solution showed a cost increase by 17% for the turbine part only (radial rotor vs. axial stator + rotor). This cost rise could be reduced with intelligent manufacturing methods, and in any case, does not represent an overall increase in the turbocharger cost by the same amount, as that cost of all the other parts would negate such an increase. Further, it was demonstrated that the proposed design can be fitted on the engine of choice without any interface change, which helps to mitigate the increase in the cost of the vehicle, particularly when considering the resultant performance increase as well.  
[PERSON] and [PERSON] were the research students who conducted the project at Brunel University London. [PERSON] is the turbomachinery group leader in the Centre of Advanced Powertrains and Fuels (CAPF) at Brunel University London, who conceived of the project, the layout of the investigations and checked the  
Figure 52: Electrical resistance welding (ERW) concept for production cost savings for the stators (red/blue—electrodes): to be simulated.  
computational outcome of the resultant modelling effort and subsequent discussion while [PERSON] provided control and draft checking and editing as well. All authors have read and agreed to the published version of the manuscript.  
This research has received funding from the Engineering and Physical Sciences Research Council Impact Acceleration Account for the project titled \"Axial Turbine Design for Advanced Turbocharger Application\" with Brunel University internal CHIME code (11573109).