Experimental and Numerical Investigation of the Flow Inside the Return Channel of a Centrifugal Process Compressor

2015 ◽  
Author(s):  
C. Rube ◽  
T. Rossbach ◽  
M. Wedeking ◽  
D. R. Grates ◽  
P. Jeschke
Keyword(s):  
Numerical Simulations ◽  
Numerical Investigation ◽  
High Flow ◽  
Performance Data ◽  
Pressure Measurements ◽  
Vaneless Diffuser ◽  
Numerical Predictions ◽  
Flow Phenomena ◽  
Centrifugal Process ◽  
Return Channel

This paper presents the first detailed experimental performance data for a new centrifugal process compressor test rig. Additional numerical simulations supported by extensive pressure measurements at various positions allow an analysis of the operational and loss behavior of the entire stage and its components. The stage investigated is a high flow rate stage of a single-shaft, multistage compressor for industrial applications and consists of a shrouded impeller, a vaneless diffuser, a U-bend and an adjoining vaned return channel. Large channel heights due to high flow rates induce the formation of highly three-dimensional flow phenomena and thus enlarge the losses due to secondary flows. An accurate prediction of this loss behavior by means of numerical investigations is challenging. The published experimental data offer the opportunity to validate the used numerical methods at discrete measurement planes, which strengthens confidence in the numerical predictions. CFD simulations of the stage are initially validated with global performance data and extensive static pressure measurements in the vaneless diffuser. The comparison of the pressure rise and an estimation of the loss behavior inside the vaneless diffuser provide the basis for a numerical investigation of the flow phenomena in the U-bend and the vaned return channel. The flow acceleration in the U-bend is further assessed via the measured two-dimensional pressure field on the hub wall. The upstream potential field of the return channel vanes allows an evaluation of the resulting flow angle. Measurements within the return channel provide information about the deceleration and turning of the flow. In combination with the numerical simulations, loss mechanisms can be identified and are presented in detail in this paper.

Experimental and Numerical Investigation of the Flow Inside the Return Channel of a Centrifugal Process Compressor

2016 ◽  
Vol 138 (10) ◽  
Author(s):  
C. Rube ◽  
T. Rossbach ◽  
M. Wedeking ◽  
D. R. Grates ◽  
P. Jeschke
Keyword(s):  
Numerical Simulations ◽  
Numerical Investigation ◽  
High Flow ◽  
Performance Data ◽  
Pressure Measurements ◽  
Vaneless Diffuser ◽  
Numerical Predictions ◽  
Flow Phenomena ◽  
Centrifugal Process ◽  
Return Channel

This paper presents the first detailed experimental performance data for a new centrifugal process compressor test rig. Additional numerical simulations supported by extensive pressure measurements at various positions allow an analysis of the operational and loss behavior of the entire stage and its components. The stage investigated is a high flow rate stage of a single-shaft, multistage compressor for industrial applications and consists of a shrouded impeller, a vaneless diffuser, a U-bend, and an adjoining vaned return channel. Large channel heights due to high flow rates induce the formation of highly three-dimensional flow phenomena and thus enlarge the losses due to secondary flows. An accurate prediction of this loss behavior by means of numerical investigations is challenging. The published experimental data offer the opportunity to validate the used numerical methods at discrete measurement planes, which strengthens confidence in the numerical predictions. CFD simulations of the stage are initially validated with global performance data and extensive static pressure measurements in the vaneless diffuser. The comparison of the pressure rise and an estimation of the loss behavior inside the vaneless diffuser provide the basis for a numerical investigation of the flow phenomena in the U-bend and the vaned return channel. The flow acceleration in the U-bend is further assessed via the measured two-dimensional pressure field on the hub wall. The upstream potential field of the return channel vanes allows an evaluation of the resulting flow angle. Measurements within the return channel provide information about the deceleration and turning of the flow. In combination with the numerical simulations, loss mechanisms can be identified and are presented in detail in this paper.

Experimental and Numerical Investigation of the Flow in a Vaneless Diffuser of a Centrifugal Compressor Stage. Part 2: Numerical Investigation

2005 ◽  
Vol 219 (10) ◽  
pp. 1061-1068 ◽  
Author(s):  
T Sato ◽  
J M Oh ◽  
A Engeda
Keyword(s):  
Numerical Investigation ◽  
Centrifugal Compressor ◽  
High Flow ◽  
Flow Coefficient ◽  
Compressor Stage ◽  
Vaneless Diffuser ◽  
Flow Measurements ◽  
Centrifugal Compressor Stage ◽  
Improved Performance ◽  
Very High

As user demands grew for improved performance and more reliable equipment and as compressor vendors sought improved analytical and design methodologies, the application of computational fluid dynamics (CFD) in the industrial world became a necessity. Fortunately, large increases in available, economic computing power together with development of improved computational methods now provide the industrial designer with much improved analytic capability. As CFD algorithms and software have continued to be developed and refined, it remains essential that validation studies be conducted in order to ensure that the results are both sufficiently accurate and can be obtained in a robust and predictable manner. Part I of this paper presented detailed flow measurements in a vaneless diffuser of a centrifugal compressor stage with a very high flow coefficient radial impeller, where measurements were carried out in the vaneless diffuser at seven radial positions downstream of the radial impeller designed for a very high flow coefficient of ϕ = 0.2. This paper, Part II, attempts to verify and validate the results numerically.

Experimental and Numerical Investigation of the Unsteady Endwall Flow in a Highly Loaded Axial Compressor Stator

2014 ◽  
Author(s):  
Christian Beselt ◽  
Dieter Peitsch ◽  
Ruben van Rennings ◽  
Frank Thiele ◽  
Klaus Ehrenfried
Keyword(s):  
Numerical Simulations ◽  
Pressure Distribution ◽  
Numerical Investigation ◽  
Pressure Fluctuations ◽  
Axial Compressor ◽  
Pressure Measurements ◽  
Rotating Instability ◽  
Operating Points ◽  
Measured Pressure ◽  
Highly Loaded

The unsteady endwall pressure distribution is investigated by means of highly resolved pressure measurements and numerical simulations in an axial compressor stator exhibiting the phenomenon of rotating instability. The endwall flow has been observed to play an important role in the inception of rotating instability. The statistical properties of the measured pressure fluctuations at the hub endwall of the axial compressor stator are compared for a series of blade loadings. The results allow conclusions about the location of regions being closely connected to the unsteady dynamics related to the rotating instability phenomenon. Furthermore the operating points with detected rotating instability are compared with unsteady numerical results.

Aerodynamic Tests on Centrifugal Process Compressors—the Influence of the Vaneless Diffusor Shape

1983 ◽  
Vol 105 (4) ◽  
pp. 902-909 ◽  
Author(s):  
K. Ludtke
Keyword(s):  
Mach Number ◽  
High Flow ◽  
Performance Tests ◽  
Multistage Process ◽  
Vaneless Diffuser ◽  
Number Range ◽  
Constant Area ◽  
Conical Diffuser ◽  
Centrifugal Process ◽  
The Given

Shop performance tests were conducted on a four-stage industrial centrifugal compressor. The first stage consisted of a radial plenum inlet, an open inducer type impeller with high hub/tip ratio and radial exit blades, a short vaneless diffuser, and a scroll including a conical diffuser. These stages with high flow coefficients and high tip speed Mach numbers are sometimes used as a first stage with multistage process compressors to increase the volumetric capacity of the given casing and reduce the number of stages. We have four versions of the vaneless diffuser with a radius ratio of 1.46: wide parallel walled, narrow parallel walled, constant area tapered, and reduced area tapered. The influence of these modifications was tested within a tip speed Mach number range of 0.94 to 1.07. Improvement of turn-down was obtained by narrowing and tapering. But the two extremely narrow diffusers reduced the rated point efficiencies beyond acceptable limits. The wide parallel walled diffuser has the highest efficiency and the most unfavorable surge, whereas the constant area diffuser achieved 10 percent better surge without practically any detrimental effects on efficiency.

Numerical Investigation of the Return Channel of a High-Flow Centrifugal Compressor Stage

2015 ◽  
Author(s):  
Holger Franz ◽  
Christoph Rube ◽  
Matthias Wedeking ◽  
Peter Jeschke
Keyword(s):  
Detailed Analysis ◽  
Centrifugal Compressor ◽  
High Flow ◽  
Compressor Stage ◽  
Test Rig ◽  
Cfd Simulations ◽  
Flow Phenomena ◽  
Compressor Performance ◽  
Return Channel ◽  
Insight Into

Steady-state simulations of a high-flow centrifugal compressor stage with return channel for industrial applications are carried out to determine the flow conditions in a new compressor test rig at the RWTH Aachen University. Overall performance predictions, conducted by means of CFD simulations, will be shown and discussed in this paper. Furthermore, a detailed analysis of the stage components is presented, providing an insight into the flow phenomena responsible for the compressor performance. Thereby, the analysis focuses on the return channel. The compressor has a shrouded impeller with 3D-twisted blades, operating at a high flow coefficient and moderate pressure ratios, as usual for multistage single-shaft compressors. The complete computational domain consists of an inlet duct, the impeller, a vaneless diffuser and return channel with bends to guide the flow. All CFD simulations have been carried out in advance of the test rig construction. The results of the simulations have been used to define the measurement locations within the test rig. Within this paper, the predicted flow phenomena in the return channel, which are strongly three-dimensional, are detailed and analyzed against the backdrop of their origin and their contribution to the overall losses. Furthermore, the available measurement results of the overall compressor performance are compared to the numerical simulations to validate the numerical setup. The objective of this paper is to give a detailed analysis of the flow in the return channel of a new compressor test rig built up at the Institute of Jet Propulsion and Turbomachinery of the RWTH Aachen University. The investigation is conducted to get an insight into the formation processes of the dominant flow phenomena affecting the overall stage performance. These investigations can form the basis for developing new strategies for return channel improvements.

Experimental and Numerical Investigation on the Influence of Process Speed on the Blanking Process

2002 ◽  
Vol 124 (2) ◽  
pp. 416-419 ◽  
Author(s):  
A. M. Goijaerts ◽  
L. E. Govaert ◽  
F. P. T. Baaijens
Keyword(s):  
Stainless Steel ◽  
Constitutive Model ◽  
Numerical Simulations ◽  
Ferritic Stainless Steel ◽  
Fracture Criterion ◽  
Fracture Initiation ◽  
Rate Dependence ◽  
Numerical Predictions ◽  
Punch Velocity ◽  
Blanking Process

In a previous work a numerical tool was presented which accurately predicted both process force and fracture initiation for blanking of a ferritic stainless steel in various blanking geometries. This approach was based on the finite element method, employing a rate-independent elasto-plastic constitutive model combined with a fracture criterion which accounts for the complete loading history. In the present investigation this work is extended with respect to rate-dependence by employing an elasto-viscoplastic constitutive model in combination with the previously postulated fracture criterion for ferritic stainless steel. Numerical predictions are compared to experimental data over a large range of process speeds. The rate-dependence of the process force is significant and accurately captured by the numerical simulations at speeds ranging from 0.001 to 10 mm/s. Both experiments and numerical simulations show no influence of punch velocity on fracture initiation.

Numerical investigation of 3-D flow phenomena in interblade channel with tie-boss

2021 ◽  
Author(s):  
Tomáš Radnic ◽  
Jindřich Hála ◽  
Martin Luxa ◽  
Šimurda David
Keyword(s):  
Numerical Investigation ◽  
Flow Phenomena

Experimental Characterization of Vaneless Diffuser Rotating Stall: Part VI — Reduction of Three Impeller Results

2006 ◽  
Author(s):  
E. A. Carnevale ◽  
G. Ferrara ◽  
L. Ferrari ◽  
L. Baldassarre
Keyword(s):  
Rotating Stall ◽  
Radius Ratio ◽  
Vaneless Diffuser ◽  
Cross Sectional ◽  
Stall Inception ◽  
Return Channel ◽  
Geometrical Scale ◽  
And Diffusion ◽  
Basic Configuration

Vaneless diffuser rotating stall is a major problem for centrifugal compressors since it is a limit to their working range. In the literature some good correlations for predicting stall inception can be found but they do not adequately cover the case of the last stage configuration, especially for very low blade-outlet-width-to-impeller-radius-ratio impellers typically used in high-pressure applications. Extensive research has been performed to define diffuser stall limits for this family of stages: three impellers characterized by different blade-outlet-width-to-impeller-radius-ratios have been tested with different diffuser configurations (different pinch shapes, diffuser widths and diffusion ratios). The basic configuration comprises a 1:1 geometrical scale stage with a return channel upstream, a 2D impeller with a vaneless diffuser and a volute with a constant cross sectional area downstream. Several diffuser types with different widths and diffusion ratios were tested. Detailed experimental results have been reported in previous works [1, 2, 3 and 4]. In this paper experimental data are reviewed in order to analyze impeller influence on diffuser stability and to develop some summarizing consideration on stall behavior of vaneless diffuser for impeller with low blade-outlet-width-to-impeller-radius-ratio.

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