Creating Lighter and More Effi­cient Radial Turbines

In our research project GAMMA we closely work together with MTU Friedrichshafen to optimize com­po­nents of large tur­bocharg­ers. Nicolas Lachen­maier, one of the leading aero­dy­nam­ics engi­neers at MTU, uses CAESES® for the design of the turbine com­po­nents. He provides a few insights into the com­plex­ity of turbine wheel design.

Inter­view with Nicolas Lachen­maier, MTU

Hi Nicolas! What is your academic/​career back­ground, how did you find your way to MTU Friedrichshafen?

Nicolas: I’ve earned a Bachelor’s degree in Math­e­mat­ics and received a Master’s degree in Com­pu­ta­tional Engi­neer­ing in 2014. As my hometown lies close to Friedrichshafen, applying to MTU was a natural choice. Fur­ther­more, I started working on tur­bo­ma­chin­ery within my Master thesis at BMW. So MTU’s offer to work as CFD engineer in the field of radial turbines matched my pro­fes­sional expe­ri­ences and plans quite well. 

What are your respon­si­bil­i­ties at MTU Friedrichshafen ?

Nicolas: MTU is devel­op­ing tur­bocharged diesel and gas engines for off-highway appli­ca­tions. I am taking care of the aero­dy­namic design of the radial turbines within the engines’ tur­bocharg­ers, i.e. I’m design­ing new, more effi­cient turbines with the help of CFD methods and eval­u­at­ing exper­i­men­tal results from the test stand.

What projects are you cur­rently working on? 

Nicolas: My main focus cur­rently lies on the gov­ern­ment-funded research project GAMMA. It is my task to create an auto­mated opti­miza­tion and design chain that helps creating lighter and more effi­cient radial turbines with high durability.

What are the engi­neer­ing chal­lenges when you develop a new tur­bocharger turbine?

Nicolas: From the engines per­spec­tive the turbine effi­ciency is probably the most impor­tant design cri­te­rion. Modern CFD codes are doing a good job helping the designer to decide whether an improve­ment is to be expected. However, main­tain­ing the struc­tural integrity of the turbine wheel while con­tin­u­ously raising its effi­ciency is a tough chal­lenge: Assuring that the stresses remain low and the eigen­fre­quen­cies high while max­i­miz­ing the effi­ciency without increas­ing the inertia of the wheel can be, well, tedious.

How does CAESES® support you in this task?

Nicolas: In close col­lab­o­ra­tion with FRIEND­SHIP SYSTEMS AG we have built up a CAESES® model of a radial turbine that enables us to judge a new turbine design from several per­spec­tives very early in the design phase: The geometry model allows us to perform CFD based aero­dy­namic cal­cu­la­tions as well as all the sim­u­la­tions revolv­ing around the mechan­ics of the geometry. We run an eigen­fre­quency analysis, have a closer look at the tem­per­a­ture and cen­trifu­gal force induced stresses and finally cal­cu­late the center of mass and inertia of the wheel.

What do you like about CAESES®? 

Nicolas: I enjoy how the software is specif­i­cally designed to enable and accel­er­ate an auto­mated geometry gen­er­a­tion for opti­miza­tion purposes.

Any future ideas for the use of CAESES® in your department?

Nicolas: Well, I do hope that we’ll use the tool for the design of new water pumps in the future.

The New Design Process at MTU

Through the use of para­met­ric CAESES® models at MTU, a much larger set of physical quan­ti­ties can now be computed auto­mat­i­cally in a single loop. Most of the time-con­sum­ing manual iter­a­tions between the strength and aero­dy­nam­ics depart­ments in the early stage of a design are now elim­i­nated. The fol­low­ing table gives you a com­par­i­son of which quan­ti­ties were avail­able in the former turbine design process and after CAESES® was fully inte­grated into the workflow:

Download Tech Brief

A short summary of this case study can be found in this tech brief (PDF).

More Infor­ma­tion

Thanks a lot to Nicolas and MTU Friedrichshafen for sharing these insights. More infor­ma­tion about turbine wheel design includ­ing some ani­ma­tions can also be found in the case study Turbine Blade Opti­miza­tion includ­ing Scallops. General infor­ma­tion about tur­bo­ma­chin­ery design with CAESES® can be found in the tur­bo­ma­chin­ery section.

With kind per­mis­sion of MTU Friedrichshafen