SBIR-STTR Award

Design Concepts for Low Aspect Ratio High Pressure Turbines for High Bypass Ratio Turbofans
Award last edited on: 2/8/2017

Sponsored Program
SBIR
Awarding Agency
NASA : GRC
Total Award Amount
$865,381
Award Phase
2
Solicitation Topic Code
A1.07
Principal Investigator
Robert Boyle

Company Information

N&R Engineering Management & Services Corporation (AKA: N&R Engineering Mnagement Support Services)

6659 Pearl Road Suite 201
Parma Heights, OH 44130
   (440) 845-7020
   vnagpal@nrengineering.com
   www.nrengineering.com
Location: Single
Congr. District: 07
County: Cuyahoga

Phase I

Contract Number: ----------
Start Date: ----    Completed: ----
Phase I year
2016
Phase I Amount
$123,837
The proposal is to identify cycle improvements and verify structural feasibility of shrouding a low aspect ratio High Pressure Turbine(HPT) rotor designed to use ceramic blades. When the clearance-to-span ratio between the rotating blades and the stationary casing is the same as the clearance-to-span ratio between the rotating shroud and the stationary casing, stage efficiency improves. However, shrouding rotor blades increases centrifugal stresses, and metallic HPT rotor blades are typically unshrouded in order to maximize stage output. Ceramic Matrix Composite(CMC) blades weigh much less than metallic blades. Shrouded CMC blades have lower centrifugal stresses than unshrouded metallic blades. The fuel burn reduction from an increase in stage efficiency due to shrouded HPT blades will be determined. The fuel burn reduction due to the higher temperature capability of CMC blades will also be determined. Cycle efficiency improvements from shrouding HPT rotor blades will increase for future engines. The HPT blade aspect ratio will decrease as engine Overall Pressure Ratio(OPR) increases. Future HPT blade aspect ratios may be less than half of current aspect ratios. While the absolute clearance may decrease in future engines, the relative clearance is likely to increase. Aerothermal analyses will determine the improvement in fuel burn from shrouding cooled HPT rotor blades. Structural analyses will determine stresses for unshrouded metallic and CMC rotor blades, and for shrouded CMC blades.

Phase II

Contract Number: ----------
Start Date: ----    Completed: ----
Phase II year
2017
Phase II Amount
$741,544
The performance gains and weight reductions from using Ceramic Matrix Composite(CMC) turbine blades in both the High Pressure Turbine(HPT) and Low Pressure Turbine(LPT) will be determined. Shrouding HPT rotor blades becomes feasible when low density CMC materials replace current metallic HPT rotor blades. The proposal has two components. The first is to identify stage efficiency improvements and verify structural feasibility of shrouding a low aspect ratio HPT rotor blade designed to use CMC blades. The second is to perform similar analyses for metallic and CMC LPT blades . HPT stage efficiency gains will be determined using CFD analyses for shrouded and unshrouded HPT turbines as a function of clearance and stage reaction. The increase in blade component stresses due to the presence of a shroud, and the stresses in the shroud itself will be determined from structural analyses. Comparing analytic results with available structural data for shrouded metallic LPT blades will increase confidence in the structural predictions of shrouded HPT blades.The reduction in engine weight from using CMC blades in the LPT will be determined. Current metallic LPT blades are shrouded, so that no significant stage aerodynamic efficiency gain is anticipated from replacing metallic LPT blades with CMC blades. In a geared turbine fewer LPT stages, or greater work per stage, may be achieved from using CMC rotor blades.