Engineering topics

Kielb, Robert E.

Publications and source records attributed to Kielb, Robert E..

6 records

NASA NTRS2005

NESTEM Probabilistic Analysis Used to Study Mistuned Bladed Disks and Blisks With Aerodynamic and Structural Coupling

This document summarizes the initial results from a research effort at the NASA Glenn Research Center on blisk and bladed disk mistuning, including both structural and aerodynamic coupling. The structural coupling model is based on the Fundamental Mistuning Model (FMM, developed by Feiner and Griffin). This effort extends the FMM technique to accept aerodynamic coupling coefficients from computational fluid dynamic codes. The model was applied to a representative modern front compressor stage. Flutter stability and forced response were determined with structural coupling only, with aerodynamic coupling only, and with both structural and aerodynamic coupling. Tuned, randomly mistuned, and near alternately mistuned rotors were considered.

Kielb, Robert E.↗

NASA NTRS1989

Computing Flutter Boundaries

MISER2 computer program calculates flutter boundaries and aeroelastic response of cascade of arbitrarily mistuned airfoils. Based on typical section formulation incorporating incompressible, subsonic and supersonic cascade, unsteady aerodynamic theories. Each blade modeled as two-degree-of-freedom oscillator that has inertial coupling between bending and torsional motions. Written in FORTRAN 4.

Kielb, Robert E.↗

NASA NTRS1988

Flutter of a fan blade in supersonic axial flow

An application of a simple aeroelastic model to an advanced supersonic axial flow fan is presented. Lane's cascade theory is used to determine the unsteady aerodynamic loads. Parametric studies are performed to determine the effects of mode coupling, Mach number, damping, pitching axis location, solidity, stagger angle, and mistuning. The results show that supersonic axial flow fan and compressor blades are susceptible to a strong torsional mode flutter having critical reduced velocities which can be less than one.

Kielb, Robert E.↗

NASA NTRS1988

Test facilities of the structural dynamics branch of NASA Lewis Research Center

The NASA Lewis Research Center Structural Dynamics Branch conducts experimental and analytical research related to the structural dynamics of aerospace propulsion and power systems. The experimental testing facilities of the branch are examined. Presently there are 10 research rigs and 4 laboratories within the branch. These facilities are described along with current and past research work.

Montague, Gerald T.↗

NASA NTRS1988

Evaluation of a turbine blade damper using an integral approach

An integrated experimental/analytical approach to friction damper design optimization in cases where gas turbine blade-response data are unavailable under actual engine operating conditions is presently applied to the case of a damper designed to relieve a blade-cracking problem on a liquid fuel rocket engine's turbopump. Attention is given to the experimental methods and analytical models used, as well as to the predicted damper performance. The inclusion of macroslip, microslip, and variable normal load effects was found to be necessary.

Kielb, Robert E.↗

NASA NTRS1987

SSME blade damper technology

Before 1975 turbine blade damper designs were based on experience and very simple mathematical models. Failure of the dampers to perform as expected showed the need to gain a better understanding of the physical mechanism of friction dampers. Over the last 10 years research on friction dampers for aeronautical propulsion systems has resulted in methods to optimize damper designs. The first-stage turbine blades on the Space Shuttle Main Engine (SSME) high-pressure oxygen pump have experienced cracking problems due to excessive vibration. A solution is to incorporate a well-designed friction dampers to attenuate blade vibration. The subject study, a cooperative effort between NASA Lewis and Carnegie-Mellon University, represents an application of recently developed friction damper technology to the SSME high-pressure oxygen turbopump. The major emphasis was the contractor's design known as the two-piece damper. Damping occurs at the frictional interface between the top half of the damper and the underside of the platforms of the adjacent blades. The lower half of the damper is an air seal to retard airflow in the volume between blade necks.

Kielb, Robert E.↗