Some features of the unsteady pressure field in transonic airfoil buffeting

1979 ◽  
Author(s):  
F. ROOS
Keyword(s):  
Pressure Field ◽  
Unsteady Pressure ◽  
Transonic Airfoil

Unsteady Flow Structure on a Centrifugal Pump: Experimental and Numerical Approaches

2002 ◽  
Author(s):  
Jose´ Gonza´lez ◽  
Carlos Santolaria ◽  
Eduardo Blanco ◽  
Joaqui´n Ferna´ndez
Keyword(s):  
Numerical Model ◽  
Centrifugal Pump ◽  
Pressure Field ◽  
Pressure Fluctuations ◽  
Side Wall ◽  
Relative Effect ◽  
Pressure Transducers ◽  
Unsteady Pressure ◽  
Blade Passing Frequency ◽  
Wide Range

Both experimental and numerical studies of the unsteady pressure field inside a centrifugal pump have been carried out. The unsteady patterns found for the pressure fluctuations are compared and a further and more detailed flow study from the numerical model developed will be presented in this paper. Measurements were carried out with pressure transducers installed on the volute shroud. At the same time, the unsteady pressure field inside the volute of a centrifugal pump has been numerically modelled using a finite volume commercial code and the dynamic variables obtained have been compared with the experimental data available. In particular, the amplitude of the fluctuating pressure field in the shroud side wall of the volute at the blade passing frequency is successfully captured by the model for a wide range of operating flow rates. Once the developed numerical model has shown its capability in describing the unsteady patterns experimentally measured, an explanation for such patterns is searched. Moreover, the possibilities of the numerical model can be extended to other sections (besides the shroud wall of the volute), which can provide plausible explanations for the dynamic interaction effects between the flow at the impeller exit and the volute tongue at different axial positions. The results of the numerical simulation are focused in the blade passing frequency in order to study the relative effect of the two main phenomena occurring at that frequency for a given position: the blade passing in front of the tongue and the wakes of the blades.

Experimental Investigation of a Single Stage Axial Flow Compressor With Controlled Diffusion Airfoils

1996 ◽  
Author(s):  
S. Pieper ◽  
J. Schulte ◽  
A. Hoynacki ◽  
H. E. Gallus
Keyword(s):  
Pressure Field ◽  
Flow Behavior ◽  
Measurement Techniques ◽  
Three Dimensional ◽  
Tip Clearance ◽  
Time Dependent ◽  
Suction Surface ◽  
Average Technique ◽  
Unsteady Pressure ◽  
Controlled Diffusion

In order to verify an inverse design concept for modern compressor bladings, a subsonic compressor front stage with IGV was investigated. One objective of the design was to survey the flow field in detail, with emphasis on 3D viscous and unsteady aspects of the flow. Therefore, the compressor was equipped with various steady and unsteady measurement techniques. Additionally, a compressor design was chosen that allows an extension up to three stages with regard to the investigation of multistage axial compressor flow behavior. Test results of the steady measurements are discussed for IGV, rotor, and stator flow at design conditions as well as the overall stage performance. The measurements of the steady flow behavior confirm the expected design performance and show the high potential of the controlled diffusion airfoil concept. Only at the side walls near hub and casing there are some differences between design and measurement due to the complex three dimensional flow. For the study of unsteady effects, detailed measurements using hot-wire probes, glue-on hot-films, and semiconductor pressure transducers were performed. All measurements are evaluated using the ensemble-average technique. The results show how the boundary layers of the inlet guide vanes and stator blades develop in a flow that is periodically disturbed by the rotor. Time-dependent pressure distributions at midspan of both stators are described. In addition, the unsteady pressure field at the casing above the rotor was investigated. The minimum wall pressure is located away from the blade suction surface. The effects of tip clearance flow on the performance are presented. The radial extent covers 15% span from the tip. At rotor exit, the unsteady pressure field and the time-dependent three-dimensional velocity vectors illustrate the salient features of the viscous flow associated with the rotor.

Fast Response Wall Pressure Measurement as a Means of Gas Turbine Blade Fault Identification

1991 ◽  
Vol 113 (2) ◽  
pp. 269-275 ◽  
Author(s):  
K. Mathioudakis ◽  
A. Papathanasiou ◽  
E. Loukis ◽  
K. Papailiou
Keyword(s):  
Gas Turbine ◽  
Turbine Blade ◽  
Pressure Field ◽  
Fast Response ◽  
Gas Turbine Blade ◽  
Unsteady Pressure ◽  
Rotating Blade ◽  
Processing Techniques ◽  
Industrial Gas Turbine ◽  
Unsteady Pressure Measurements

The distortions of the pressure field around rotating blades of turbomachinery components due to alterations of their shape can be utilized for the identification of faults related to the blading. Measurement of the unsteady pressure field near the wall provides information on such flow and pressure distortions and can thus be used for diagnostic purposes. An experimental investigation of the compressor rotating blade pressure field of an industrial gas turbine has been undertaken, in order to demonstrate the feasibility of the abovementioned principle. Various realistic gas turbine blade faults have been examined. Application of the appropriate processing techniques demonstrates that unsteady pressure measurements can be used to identify the occurrence of minor blade faults (not traceable by standard techniques) as well as the kind of fault. The proposed methodology has the potential for being incorporated in a computerized engine health monitoring system.

Experimental and Numerical Investigation of the Unsteady Surface Pressure in a Three-Stage Model of an Axial High Pressure Turbine

2004 ◽  
Vol 128 (2) ◽  
pp. 261-272 ◽  
Author(s):  
Carmen E. Kachel ◽  
John D. Denton
Keyword(s):  
High Pressure ◽  
Velocity Field ◽  
Surface Pressure ◽  
Pressure Field ◽  
Pressure Fluctuations ◽  
Pressure Waves ◽  
Stage Model ◽  
Unsteady Pressure ◽  
Unsteady Surface Pressure ◽  
Blade Row

This paper presents the results of a numerical and experimental investigation of the unsteady pressure field in a three-stage model of a high pressure steam turbine. Unsteady surface pressure measurements were taken on a first and second stage stator blade, respectively. The measurements in the blade passage were supplemented by time resolved measurements between the blade rows. The explanation of the origin of the unsteady pressure fluctuations was supported by unsteady three-dimensional computational fluid dynamic calculations of which the most extensive calculation was performed over two stages. The mechanisms affecting the unsteady pressure field were: the potential field frozen to the upstream blade row, the pressure waves originating from changes in the potential pressure field, the convected unsteady velocity field, and the passage vortex of the upstream blade row. One-dimensional pressure waves and the unsteady variation of the pitchwise pressure gradient due to the changing velocity field were the dominant mechanisms influencing the magnitude of the surface pressure fluctuations. The magnitude of these effects had not been previously anticipated to be more important than other recognized effects.

Further Developments in the Aerodynamic Analysis of Unsteady Supersonic Cascades—Part 1: The Unsteady Pressure Field

1977 ◽  
Vol 99 (4) ◽  
pp. 509-516 ◽  
Author(s):  
J. M. Verdon
Keyword(s):  
Velocity Potential ◽  
Pressure Field ◽  
Supersonic Stream ◽  
Axial Velocity Component ◽  
Unsteady Pressure ◽  
Pressure Distributions ◽  
Successive Solution ◽  
Construction Procedure ◽  
Present Procedure ◽  
Dependent Variables

This paper presents, in two parts, a theoretical investigation of the aerodynamic response produced by an oscillating cascade placed in a supersonic stream with subsonic axial velocity component. Predictions are based on the successive solution of two linear boundary value problems which treat the velocity potential and the pressure, respectively, as basic dependent variables. A solution for the potential has been reported earlier and is used here to provide upper surface blade pressure distributions. This information serves as a boundary condition for the second problem. The solution for the unsteady pressure field, described in Part 1, is obtained by a construction procedure which parallels that used earlier to determine the potential. With the present procedure, blade pressure difference distributions and aerodynamic coefficients are accurately and efficiently determined for both subresonant and superresonant blade motions. Supersonic resonance phenomena and selected numerical results are discussed in Part 2 of the paper.

Unsteady pressure field around oscillating prism predicted by LES

1993 ◽  
Vol 46-47 ◽  
pp. 551-556 ◽  
Author(s):  
S Sakamoto ◽  
S Murakami ◽  
S Kato ◽  
A Mochida
Keyword(s):  
Pressure Field ◽  
Unsteady Pressure
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