due to moisture in the steam flow.
In addition to the steady centrifugal loading, the blades are also subject to vibration.
The low pressure section rotating turbine blades are typically designed and optimized to cover a given operating speed as required by the different applications. Main operating parameters are annulus area, rotating speed, mass flow capability, and for the last stage blade, condensing pressure.
The difficulty associated with designing a steam turbine blade is exacerbated by the fact that the airfoil shape determines, in large part, both the forces imposed on the blade and its mechanical strength and resonant frequencies, as well as the thermodynamic performance of the blade. These considerations impose constraints on the choice of blade airfoil shape so that, of necessity, the optimum blade airfoil shape for a2012.

2016 Illinois House campaign 
In the 2018 midterm elections, Sommer faced an opponent in a general election for the first time since 2008.  Sommer won the election against Democrat Jill Blair with 59% of the votes.  He ran unopposed in the Republican primary.

Legislative career
On July 31, 2017 Sommer was appointed a member of the Trade Policy Task Force for a term ending December 31, 2018. The Trade Policy Task Force’s function is to analyze important issues relative to the growth of international trade and make recommendations to Congress, the United States Trade Representative, and the White House National Trade Council regarding trade policy. The Task Force also promotes Illinois as a market for exporting and importing.

Voting record 
 2003 - Voted for allowing the children of