The Stress Problem of Vibrating Compressor Blades

1955 ◽  
Vol 22 (1) ◽  
pp. 57-64
Author(s):  
Jan R. Schnittger
Keyword(s):  
Turbine Blades ◽  
General Nature ◽  
Compressor Blades ◽  
Stress Problem ◽  
Simplified Analysis ◽  
Compressor And Turbine Blades

Abstract In order to demonstrate the general nature of the actual vibrations of compressor and turbine blades, the author undertakes a simplified analysis in which a single stiff blade, with one translational and one pitching mode, is studied. It is shown that all problems of stress in vibrating compressor blades whether they arise from forced or self-sustained vibrations may be related to the magnitude of finite mechanical or aerodynamic disturbances.

Effects of Warping and Pretwist on Torsional Vibration of Rotating Beams

1984 ◽  
Vol 51 (4) ◽  
pp. 913-920 ◽  
Author(s):  
K. R. V. Kaza ◽  
R. E. Kielb
Keyword(s):  
Aspect Ratio ◽  
Torsional Vibration ◽  
Equations Of Motion ◽  
Turbine Blades ◽  
Mode Shapes ◽  
Compressor Blades ◽  
Rotating Beams ◽  
Special Cases ◽  
Torsional Frequency ◽  
Compressor And Turbine Blades

The effect of pretwist and warping on the torsional vibration of short-aspect-ratio rotating beams is examined for application to the modeling of turbofan, turboprop, and compressor blades. The equations of motion and the associated boundary conditions by using both Wagner’s hypothesis and Washizu’s theory are derived and a few minor limitations of the Wagner’s hypothesis, as applied to thick blades, are pointed out and discussed. The equations for several special cases are solved in a closed form. Results are presented indicating the effect of warping, pretwist, and rotation on torsional vibration of beams as aspect ratio is varied. The results show that the structural warping and pretwist terms have a significant effect on torsional frequency and mode shapes of short-aspect-ratio blades whereas the inertial warping terms have negligible effect. Since the torsional frequencies and mode shapes are very important in aeroelastic analyses by using modal methods, the structural warping terms should be included in modeling turbofan, turboprop, compressor, and turbine blades.

scholarly journals Use of an Inverse Method for the Design of High Efficiency Compressor and Turbine Blades With Large Change in Radius

1984 ◽  
Author(s):  
G. Meauzé ◽  
A. Lesain
Keyword(s):  
Inverse Method ◽  
High Efficiency ◽  
Radial Flow ◽  
Turbine Blades ◽  
Large Change ◽  
Airfoil Optimization ◽  
Time Marching ◽  
Flow Compressor ◽  
Compressor And Turbine Blades ◽  
Made In

Extension of the time-marching computations of flows in 2-D blade cascades to the case of cascades with variable radius and stream tube thickness. One of the specific cases analyzed is that of purely radial cascades. Direct and inverse calculations are made, in non-viscous subsonic or supersonic flows, with or without shock waves. Examples of the design of high efficiency airfoil optimization for radial flow compressor rotors or Stators or inward flow turbine inlet guide vanes are presented.

scholarly journals GEOMETRY MODELING OF 3D TURBINE STAGES - HOW TO OBTAIN HIGH QUALITY GRID AND OVERCOME DISCRETIZATION PROBLEMS

2016 ◽  
Vol 4 (2) ◽  
pp. 197-205
Author(s):  
Galina Ilieva
Keyword(s):  
Finite Elements ◽  
Complex Geometry ◽  
Turbine Blades ◽  
Grid Generation ◽  
Current Paper ◽  
High Quality ◽  
Compressor Blades ◽  
Geometry Modeling ◽  
Wide Range ◽  
Flow Domain

The process of geometry modeling of 3D turbine blades is basically related to the necessity of finite elements with high quality to be obtained, in the process of flow domain approximation. Various approaches for geometry modeling and grid generation, ways to attain elements of high quality and having positive volumes, have been under research and are presented in current paper. Developed methodology and established techniques to high quality grid, are implemented into practice, for geometry modeling of a wide range of turbine and compressor blades of complex geometry.

Mean Velocity Scaling and Friction Coefficient Estimation for Rough Surface Turbulent Boundary Layers in Turbomachines

2014 ◽  
Author(s):  
Ju Hyun Shin ◽  
Seung Jin Song
Keyword(s):  
Flat Plate ◽  
Rough Surface ◽  
Boundary Layers ◽  
Turbine Blades ◽  
Axial Compressor ◽  
Turbulent Boundary Layers ◽  
Flat Plates ◽  
Mean Velocity ◽  
Coefficient Estimation ◽  
Compressor And Turbine Blades

Based on flat plate results, mean velocity and friction coefficient estimation methods are proposed for rough surface turbulent boundary layers on axial compressor and turbine blades. The ratio of the displacement thickness to boundary layer thickness (δ*/δ) was first suggested by Zagarola and Smits (1998) for smooth pipe flows. The same parameter is proposed in this paper to scale the normalized mean velocity defect of smooth and rough surface flat plate turbulent boundary layers with zero, favorable, and adverse pressure gradients. The available mean velocity defect profiles of smooth and rough surface boundary layers from axial compressor and turbine blades are also scaled and compared to the flat plate results. Irrespective of the Reynolds number (Reθ), pressure gradient (K), and roughness (k), δ*/δ provides appropriate scaling for collapsing the flat plate and turbomachinery data. From the results, a new one-variable power law based on δ*/δ is proposed to estimate the mean velocity profile. The proposed power law can accurately estimate boundary layers on flat plates, compressor blades, and turbine blades. Finally, a new empirical Cf correlation is proposed for rough surface turbulent boundary layers under pressure gradients. The proposed Cf correlation is based on that of Bergstrom et al. (2005) and newly incorporates the acceleration parameter K. It can accurately estimate Cf in turbulent boundary layers of rough surface flat plates as well as those of smooth turbine blades.

scholarly journals Leading Edge Separation Bubbles on Turbomachine Blades

1993 ◽  
Author(s):  
R. E. Walraevens ◽  
N. A. Cumpsty
Keyword(s):  
Boundary Layer ◽  
Reynolds Number ◽  
Turbine Blades ◽  
Leading Edge ◽  
Freestream Turbulence ◽  
Compressor Blades ◽  
Pressure Distributions ◽  
Quantitative Measurements ◽  
Small Influence ◽  
Separation Bubbles

Results are presented for separation bubbles of the type which can form near the leading edges of thin compressor or turbine blades. These often occur when the incidence is such that the stagnation point is not on the nose of the aerofoil. Tests were carried out at low speed on a single aerofoil to simulate the range of conditions found on compressor blades. Both circular and elliptic shapes of leading edge were tested. Results are presented for a range of incidence, Reynolds number and turbulence intensity and scale. The principal quantitative measurements presented are the pressure distributions in the leading edge and bubble region, as well as the boundary layer properties at a fixed distance downstream where most of the flows had reattached. Reynolds number was found to have a comparatively small influence, but a raised level of freestream turbulence has a striking effect, shortening or eliminating the bubble and increasing the magnitude of the suction spike. Increased freestream turbulence also reduces the boundary layer thickness and shape parameter after the bubble. Some explanations of the processes are outlined.

Sign in / Sign up

Export Citation Format

Share Document