Aerodynamic Design Optimization of the MTT Radial Micro Turbine

Aerodynamic Design Optimization of the MTT Radial Micro Turbine

Govindarajan, S.

Colonna, P. (mentor)
Pini, M. (mentor)
Visser, W.P.J. (mentor)

Aerospace Engineering

Flight Performance and Propulsion

2015-09-29

Micro turbines are touted to become the prime system for the combined heat and power(CHP) applications in light of their significant advantages in terms of performance, size, costs and reduced CO2 emissions [1]. Micro Turbine Technology B.V. (MTT) is currently developing a 3KW recuperated micro turbine for such applications. Commercially available off the shelf turbocharger components are used since they provide high performance with relatively low costs since they are mass produced.The drawback in using these components is that they are manufactured for the automotive sector and inherently operate at different conditions than the MTT operating point. Here in lies an interesting scope for performance improvement by optimizing the turbine and within the current work the focus is on aerodynamic optimization of the radial inflow turbine used in the MTT system. This study is a follow-up from the recommendations provided in [2] and [3]. A goal driven optimization is performed on the rotor geometry using ANSYS DesignXplorer and a total of four design solutions were obtained. The most important findings from the response surfaces, sensitivity analysis from the optimization were: • From the parametric sensitivity it was clear that all of the six design variables have a significant impact on efficiency. The exducer angles have the most predominant effect on efficiency with that of shroud larger than hub. • All of the optimal candidates exhibited an increase in the total-to-total efficiency ranging from a minimum of 6.38 percentage points to a maximum of 7.90 percentage points as compared to the baseline geometry. This efficiency improvement was accompanied by an increase in mass flow rate with a minimum value of 69.15 g/s and a maximum of 73.51 g/s. These design solutions are then coupled with the diffuser domain to study the performance characteristics and the interaction between the components. The most important outcomes from these simulations were: The efficiency of the rotor drops by 3 percentage points on an average due to the additional pressure losses introduced when coupled with the diffuser. • The diffuser performance has improved and the Cp experiences a maximum increase of 17.63 percentage points (Candidate D) and a minimum of 12.70 percentage points (Candidate B). The swirl coefficient for optimum diffuser performance is found at values close to 0.22. If the swirl coefficient is increased or decreased from this optimum, diffuser performance drops. The best design solution in terms of rotor efficiency and overall total-to-static efficiency is Candidate C. However it exhibits a poorer diffuser performance than the other optimal candidates. From this study, it is apparent that there is compromise between rotor and diffuser performance. • The improvement in rotor efficiency(

microturbine
optimization
CFD analysis

http://resolver.tudelft.nl/uuid:0dd55171-6768-4e46-b6cd-970eb912e2ac

2016-09-29

Student theses

master thesis

(c) 2015 Govindarajan, S.