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Caitlin Smythe - One of the best experts on this subject based on the ideXlab platform.

  • Detailed Performance Analysis of a Centrifugal Compressor Stage With Pipe Diffuser and Immerged Tandem Deswirler
    Volume 2C: Turbomachinery, 2015
    Co-Authors: Johannes Schmidt, Philipp Schwarz, Benjamin Wilkosz, Peter Jeschke, Caitlin Smythe
    Abstract:

    Commonly, the pipe diffuser and deswirler are aerodynamically decoupled from each other to ensure better mixing of the inhomogeneous pipe flow before entering the deswirler and to prevent upstream effects of the deswirler bend and blading on the pipe diffuser. Close-coupling of these two components, however, can lead to a significantly lower radial extent of the Stage, resulting in a decrease of Stage weight and engine frontal area. The geometry investigated includes a Centrifugal Compressor Stage with a compact diffusion system, including a pipe diffuser and tandem deswirler whose first blade row is immerged into the pipe diffuser. Stage and component performance of this compact configuration is compared to two different Stage configurations with decoupled deswirlers. Performance maps and 1-D pressure build-up data show that the compact Stage is able to reach efficiency and pressure build-up of the compared Stages which contain the same impeller and same diffuser inlet geometry. The performance of one of the compared Stages with significantly higher radial Stage extent is even exceeded. However, a loss in surge margin of about 2% has been detected which seems to be the major problem in reducing Stage size by close-coupling the deswirl system to the pipe diffuser, since this can have a major effect on the diffuser inlet pressure build-up.Copyright © 2015 by ASME

  • Experimental Investigation of a Truncated Pipe Diffuser With a Tandem Deswirler in a Centrifugal Compressor Stage
    Journal of Turbomachinery, 2013
    Co-Authors: Robert Kunte, Peter Jeschke, Caitlin Smythe
    Abstract:

    The subject of this paper is the experimental investigation of three different geometric configurations of the diffusing sys- tem in a high pressure Centrifugal Compressor Stage for a jet engine application. The objective of this study is twofold. On the one hand, it seeks to explain the impact of truncating a diffuser and a redesigned tandem deswirler on the global Stage perfor- mance; on the other hand, it aims to correlate the performance differences with local flow phenomena. For this purpose, a state- of-the-art Centrifugal Compressor test rig was used. Particle image velocimetry measurements visualize the separation behavior in the pipe diffuser passage. Thereby it is shown that the truncation of the diffuser changed the boundary conditions for the down- stream deswirler including a high incidence. Thus, a new tandem deswirler design was implemented and measured. Moreover, the relative position of the two tandem rows is investigated. An opti- mal relative circumferential position for the Stage efficiency and static pressure rise was found. This paper gives fundamental insight into the physical mechanisms of the influence of three geometric configurations in a Centrifugal Compressor Stage, es- pecially in the pipe diffuser and the deswirler. Hence, this study contributes in furthering knowledge of the fundamental princi- ples of flow phenomena in the diffusing system of a Centrifugal Compressor.

  • Experimental Investigation of a Truncated Pipe Diffuser With a Tandem Deswirler in a Centrifugal Compressor Stage
    Volume 8: Turbomachinery Parts A B and C, 2012
    Co-Authors: Robert Kunte, Peter Jeschke, Caitlin Smythe
    Abstract:

    The subject of this paper is the experimental investigation of three different geometric configurations of the diffusing system in a high pressure Centrifugal Compressor Stage for a jet engine application. The objective of this study is twofold. On the one hand, it seeks to explain the impact of truncating a diffuser and a redesigned tandem deswirler on the global Stage performance; on the other hand, it aims to correlate the performance differences with local flow phenomena. For this purpose, a state-of-the-art Centrifugal Compressor test rig was used. Particle image velocimetry measurements visualize the separation behavior in the pipe diffuser passage. Thereby it is shown that the truncation of the diffuser changed the boundary conditions for the downstream deswirler including a high incidence. Thus, a new tandem deswirler design was implemented and measured. Moreover, the relative position of the two tandem rows is investigated. An optimal relative circumferential position for the Stage efficiency and static pressure rise was found. This paper gives fundamental insight into the physical mechanisms of the influence of three geometric configurations in a Centrifugal Compressor Stage, especially in the pipe diffuser and the deswirler. Hence, this study contributes in furthering knowledge of the fundamental principles of flow phenomena in the diffusing system of a Centrifugal Compressor.Copyright © 2012 by ASME

  • Experimental and Numerical Investigation of Tip Clearance and Bleed Effects in a Centrifugal Compressor Stage With Pipe Diffuser
    Journal of Turbomachinery, 2012
    Co-Authors: Robert Kunte, Philipp Schwarz, Benjamin Wilkosz, Peter Jeschke, Caitlin Smythe
    Abstract:

    The subject of this paper is the experimental and numerical investigation\nof a state-of-the-art high pressure Centrifugal Compressor Stage\nwith pipe diffuser for a jet engine application. This study shows\nthe impact of impeller tip clearance- and bleed-variation on the\nCentrifugal Stage. The purpose of this paper is threefold. In the\nfirst place, it investigates the effects on the Stage performance.\nSecondly, it seeks to explain local flow-phenomena, especially in\nthe diffuser. Finally, it shows that steady CFD simulations are capable\nof predicting these phenomena. Experimental data were gathered using\nconventional pitot and three-hole-probes as well as particle-image-velocimetry.\nNumerical simulations with the CFD solver TRACE were conducted to\nget fundamental insight into the flow. Thus, this study contributes\ngreatly towards understanding the principle of the flow phenomena\nin the pipe diffuser of a Centrifugal Compressor.

  • Experimental and Numerical Investigation of Tip Clearance and Bleed Effects in a Centrifugal Compressor Stage With Pipe Diffuser
    Volume 7: Turbomachinery Parts A B and C, 2011
    Co-Authors: Robert Kunte, Philipp Schwarz, Benjamin Wilkosz, Peter Jeschke, Caitlin Smythe
    Abstract:

    The subject of this paper is the experimental and numerical investigation of a state-of-the-art high pressure Centrifugal Compressor Stage with pipe diffuser for a jet engine application. This study shows the impact of impeller tip clearance- and bleed-variation on the Centrifugal Stage. The purpose of this paper is threefold. In the first place, it investigates the effects on the Stage performance. Secondly, it seeks to explain local flow-phenomena, especially in the diffuser. Finally, it shows that steady CFD simulations are capable of predicting these phenomena. Experimental data were gathered using conventional pitot and three-hole-probes as well as Particle-Image-Velocimetry. Numerical simulations with the CFD solver TRACE were conducted to get fundamental insight into the flow. Thus, this study contributes greatly towards understanding the principle of the flow phenomena in the pipe diffuser of a Centrifugal Compressor.Copyright © 2011 by ASME

Peter Jeschke - One of the best experts on this subject based on the ideXlab platform.

  • Detailed Performance Analysis of a Centrifugal Compressor Stage With Pipe Diffuser and Immerged Tandem Deswirler
    Volume 2C: Turbomachinery, 2015
    Co-Authors: Johannes Schmidt, Philipp Schwarz, Benjamin Wilkosz, Peter Jeschke, Caitlin Smythe
    Abstract:

    Commonly, the pipe diffuser and deswirler are aerodynamically decoupled from each other to ensure better mixing of the inhomogeneous pipe flow before entering the deswirler and to prevent upstream effects of the deswirler bend and blading on the pipe diffuser. Close-coupling of these two components, however, can lead to a significantly lower radial extent of the Stage, resulting in a decrease of Stage weight and engine frontal area. The geometry investigated includes a Centrifugal Compressor Stage with a compact diffusion system, including a pipe diffuser and tandem deswirler whose first blade row is immerged into the pipe diffuser. Stage and component performance of this compact configuration is compared to two different Stage configurations with decoupled deswirlers. Performance maps and 1-D pressure build-up data show that the compact Stage is able to reach efficiency and pressure build-up of the compared Stages which contain the same impeller and same diffuser inlet geometry. The performance of one of the compared Stages with significantly higher radial Stage extent is even exceeded. However, a loss in surge margin of about 2% has been detected which seems to be the major problem in reducing Stage size by close-coupling the deswirl system to the pipe diffuser, since this can have a major effect on the diffuser inlet pressure build-up.Copyright © 2015 by ASME

  • Numerical Investigation of the Return Channel of a High-Flow Centrifugal Compressor Stage
    Volume 2C: Turbomachinery, 2015
    Co-Authors: Holger Franz, Christoph Rube, Matthias Wedeking, Peter Jeschke
    Abstract:

    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.Copyright © 2015 by ASME

  • Numerical Investigation of the Unsteady Flow Inside a Centrifugal Compressor Stage With Pipe Diffuser
    Journal of Turbomachinery, 2013
    Co-Authors: Daniel R Grates, Peter Jeschke, Reinhard Niehuis
    Abstract:

    The subject of this paper is the investigation of unsteady flow inside a transonic Centrifugal Compressor Stage with pipe-diffuser by utilizing unsteady 3D Navier-Stokes simulations (unsteady 3D URANS). The CFD results obtained are compared with detailed experimental data gathered using various steady and unsteady measurement techniques. The basic phenomena and mechanisms of the complex and highly unsteady flow inside the Compressor with pipe-diffuser are presented and analyzed in detail.Copyright © 2013 by ASME

  • Experimental Investigation of a Truncated Pipe Diffuser With a Tandem Deswirler in a Centrifugal Compressor Stage
    Journal of Turbomachinery, 2013
    Co-Authors: Robert Kunte, Peter Jeschke, Caitlin Smythe
    Abstract:

    The subject of this paper is the experimental investigation of three different geometric configurations of the diffusing sys- tem in a high pressure Centrifugal Compressor Stage for a jet engine application. The objective of this study is twofold. On the one hand, it seeks to explain the impact of truncating a diffuser and a redesigned tandem deswirler on the global Stage perfor- mance; on the other hand, it aims to correlate the performance differences with local flow phenomena. For this purpose, a state- of-the-art Centrifugal Compressor test rig was used. Particle image velocimetry measurements visualize the separation behavior in the pipe diffuser passage. Thereby it is shown that the truncation of the diffuser changed the boundary conditions for the down- stream deswirler including a high incidence. Thus, a new tandem deswirler design was implemented and measured. Moreover, the relative position of the two tandem rows is investigated. An opti- mal relative circumferential position for the Stage efficiency and static pressure rise was found. This paper gives fundamental insight into the physical mechanisms of the influence of three geometric configurations in a Centrifugal Compressor Stage, es- pecially in the pipe diffuser and the deswirler. Hence, this study contributes in furthering knowledge of the fundamental princi- ples of flow phenomena in the diffusing system of a Centrifugal Compressor.

  • NUMERICAL INVESTIGATION OF THE UNSTEADY FLOW INSIDE A Centrifugal Compressor Stage WITH PIPE DIFFUSER
    Proceedings of ASME Turbo Expo 2013: Turbine Technical Conference and Exposition, 2013
    Co-Authors: Daniel R Grates, Peter Jeschke, Reinhard Niehuis
    Abstract:

    The subject of this paper is the investigation of unsteady flow inside a transonic Centrifugal Compressor Stage with pipe- diffuser by utilizing unsteady 3D Navier-Stokes simulations (unsteady 3D URANS). The CFD results obtained are compared with detailed experimental data gathered using various steady and unsteady measurement techniques. The basic phenomena and mechanisms of the complex and highly unsteady flow inside the Compressor with pipe-diffuser are presented and analyzed in detail.

Robert Kunte - One of the best experts on this subject based on the ideXlab platform.

  • Experimental Investigation of a Truncated Pipe Diffuser With a Tandem Deswirler in a Centrifugal Compressor Stage
    Journal of Turbomachinery, 2013
    Co-Authors: Robert Kunte, Peter Jeschke, Caitlin Smythe
    Abstract:

    The subject of this paper is the experimental investigation of three different geometric configurations of the diffusing sys- tem in a high pressure Centrifugal Compressor Stage for a jet engine application. The objective of this study is twofold. On the one hand, it seeks to explain the impact of truncating a diffuser and a redesigned tandem deswirler on the global Stage perfor- mance; on the other hand, it aims to correlate the performance differences with local flow phenomena. For this purpose, a state- of-the-art Centrifugal Compressor test rig was used. Particle image velocimetry measurements visualize the separation behavior in the pipe diffuser passage. Thereby it is shown that the truncation of the diffuser changed the boundary conditions for the down- stream deswirler including a high incidence. Thus, a new tandem deswirler design was implemented and measured. Moreover, the relative position of the two tandem rows is investigated. An opti- mal relative circumferential position for the Stage efficiency and static pressure rise was found. This paper gives fundamental insight into the physical mechanisms of the influence of three geometric configurations in a Centrifugal Compressor Stage, es- pecially in the pipe diffuser and the deswirler. Hence, this study contributes in furthering knowledge of the fundamental princi- ples of flow phenomena in the diffusing system of a Centrifugal Compressor.

  • Experimental Investigation of a Truncated Pipe Diffuser With a Tandem Deswirler in a Centrifugal Compressor Stage
    Volume 8: Turbomachinery Parts A B and C, 2012
    Co-Authors: Robert Kunte, Peter Jeschke, Caitlin Smythe
    Abstract:

    The subject of this paper is the experimental investigation of three different geometric configurations of the diffusing system in a high pressure Centrifugal Compressor Stage for a jet engine application. The objective of this study is twofold. On the one hand, it seeks to explain the impact of truncating a diffuser and a redesigned tandem deswirler on the global Stage performance; on the other hand, it aims to correlate the performance differences with local flow phenomena. For this purpose, a state-of-the-art Centrifugal Compressor test rig was used. Particle image velocimetry measurements visualize the separation behavior in the pipe diffuser passage. Thereby it is shown that the truncation of the diffuser changed the boundary conditions for the downstream deswirler including a high incidence. Thus, a new tandem deswirler design was implemented and measured. Moreover, the relative position of the two tandem rows is investigated. An optimal relative circumferential position for the Stage efficiency and static pressure rise was found. This paper gives fundamental insight into the physical mechanisms of the influence of three geometric configurations in a Centrifugal Compressor Stage, especially in the pipe diffuser and the deswirler. Hence, this study contributes in furthering knowledge of the fundamental principles of flow phenomena in the diffusing system of a Centrifugal Compressor.Copyright © 2012 by ASME

  • Experimental and Numerical Investigation of Tip Clearance and Bleed Effects in a Centrifugal Compressor Stage With Pipe Diffuser
    Journal of Turbomachinery, 2012
    Co-Authors: Robert Kunte, Philipp Schwarz, Benjamin Wilkosz, Peter Jeschke, Caitlin Smythe
    Abstract:

    The subject of this paper is the experimental and numerical investigation\nof a state-of-the-art high pressure Centrifugal Compressor Stage\nwith pipe diffuser for a jet engine application. This study shows\nthe impact of impeller tip clearance- and bleed-variation on the\nCentrifugal Stage. The purpose of this paper is threefold. In the\nfirst place, it investigates the effects on the Stage performance.\nSecondly, it seeks to explain local flow-phenomena, especially in\nthe diffuser. Finally, it shows that steady CFD simulations are capable\nof predicting these phenomena. Experimental data were gathered using\nconventional pitot and three-hole-probes as well as particle-image-velocimetry.\nNumerical simulations with the CFD solver TRACE were conducted to\nget fundamental insight into the flow. Thus, this study contributes\ngreatly towards understanding the principle of the flow phenomena\nin the pipe diffuser of a Centrifugal Compressor.

  • Experimental and Numerical Investigation of Tip Clearance and Bleed Effects in a Centrifugal Compressor Stage With Pipe Diffuser
    Volume 7: Turbomachinery Parts A B and C, 2011
    Co-Authors: Robert Kunte, Philipp Schwarz, Benjamin Wilkosz, Peter Jeschke, Caitlin Smythe
    Abstract:

    The subject of this paper is the experimental and numerical investigation of a state-of-the-art high pressure Centrifugal Compressor Stage with pipe diffuser for a jet engine application. This study shows the impact of impeller tip clearance- and bleed-variation on the Centrifugal Stage. The purpose of this paper is threefold. In the first place, it investigates the effects on the Stage performance. Secondly, it seeks to explain local flow-phenomena, especially in the diffuser. Finally, it shows that steady CFD simulations are capable of predicting these phenomena. Experimental data were gathered using conventional pitot and three-hole-probes as well as Particle-Image-Velocimetry. Numerical simulations with the CFD solver TRACE were conducted to get fundamental insight into the flow. Thus, this study contributes greatly towards understanding the principle of the flow phenomena in the pipe diffuser of a Centrifugal Compressor.Copyright © 2011 by ASME

Isabelle Trébinjac - One of the best experts on this subject based on the ideXlab platform.

  • Description of the unsteady flow pattern from peak efficiency to near surge in subsonic Centrifugal Compressor Stage
    2013
    Co-Authors: X. Carbonneau Y. Bousquet, Isabelle Trébinjac, M. Roumeas
    Abstract:

    This paper aims to describe the flow structure modifications when the operating point moves from peak efficiency to near stall condition in a moderate pressure ratio Centrifugal Compressor Stage consisted of a splittered unshrouded impeller and a vaned diffuser. The investigations are based on three-dimensional U-RANS simulation results. The flow is described in the impeller and in the vaned diffuser through time-averaged flow quantities and unsteady fluctuations. Results show that at low mass flow rate, the effects of secondary flow in the impeller are more pronounced, inducing both, high time-averaged values and temporal fluctuations of the flow angle near the shroud at the diffuser inlet, leading to vane suction side boundary layer separation. Pressure waves due to impeller diffuser interaction spread through the vaned diffuser generating unsteadiness which intensifies at near surge condition.

  • Assessment of Steady and Unsteady Model Predictions for a Subsonic Centrifugal Compressor Stage
    Volume 8: Turbomachinery Parts A B and C, 2012
    Co-Authors: Yannick Bousquet, Xavier Carbonneau, Isabelle Trébinjac
    Abstract:

    The most common procedure to obtain the performance of a Centrifugal Compressor in an industrial development process is based on the use of a steady RANS model with the mixing-plane approach. However some phenomena such as the flow interaction between the impeller and the diffuser can be the source of unsteady effects which can affect the steady model prediction. This paper investigates the ability of a steady simulation to predict the overall performance and the flow structures in a subsonic Centrifugal Compressor Stage by comparison with time-dependent results. Simulations are performed considering three operating points : peak efficiency, close to the stability limit and close to the blockage. The results show that the steady model is accurate enough to predict the Stage static-to-total pressure ratio. However, in location where high level of fluctuation are expected, the steady model shows some weakness to predict the time average quantities of the flow structure.

  • Analysis of the flow in a transonic Centrifugal Compressor Stage from choke to surge
    Proceedings of the Institution of Mechanical Engineers Part A: Journal of Power and Energy, 2011
    Co-Authors: Isabelle Trébinjac, Nicolas Bulot, Nicolas Buffaz
    Abstract:

    Numerical and experimental investigations were conducted in a transonic Centrifugal Compressor Stage composed of a backswept splittered unshrouded impeller and a vaned diffuser. Unsteady three-dimensional simulations were performed with the code elsA that solves the turbulent-averaged Navier–Stokes equations, at three operating points: choked flow, peak efficiency, and near surge. Numerical results were validated with experimental data coming from laser Doppler anemometry and unsteady pressure measurements.This article focuses on the change in flow structures when the operating point moves from choke to surge. The main changes in the impeller consist in an enlargement of the wake (of the jet-wake flow structure) and an increase in the exit time-averaged flow angle. Consequently, in the diffuser passage, the main flow trajectory moves towards the vane pressure side, and the boundary layer separation transfers from pressure side to suction side.The interaction between the vane bow shock wave and the impelle...

  • Surge Inception in a Transonic Centrifugal Compressor Stage
    Volume 7: Turbomachinery Parts A B and C, 2011
    Co-Authors: Isabelle Trébinjac, Nicolas Bulot, Xavier Ottavy, Nicolas Buffaz
    Abstract:

    Numerical and experimental investigations were conducted in a transonic Centrifugal Compressor Stage composed of a backswept splittered unshrouded impeller and a vaned diffuser. Unsteady 3D simulations were performed with the code elsA that solves the turbulent averaged Navier-Stokes equations, at three operating points: choked flow, peak efficiency and near surge. Unsteady pressure measurements up to 150 kHz were carried out in the entry zone of the vaned diffuser (in the vaneless space and in the semi-vaneless space) when the Compressor came into surge. These static pressure sensors were mounted on the shroud enwall. The paper focuses on the vaneless and semi-vaneless space where the surge originates. A detailed analysis of the flow pattern coming from the unsteady computations from choked flow towards surge led to identify the physical mechanisms involved in the surge inception. It is shown that, when approaching surge, the flow is destabilized by a severe modification of the shock system in the vaned diffuser inlet. The first perturbation is acquired from the transducer located just upstream of the shock foot (i.e. on the vane suction side surface), indicating a movement of the shock towards the vaneless space. This perturbation travels upstream and leads to the strongest short-wavelength perturbation acquired from the transducer located just upstream of the vane leading edge. This strongest short-wavelength perturbation which level may reach almost four times the mean exit pressure value triggers the full scale instability.Copyright © 2011 by ASME

  • Effect of Unsteadiness on the Performance of a Transonic Centrifugal Compressor Stage
    Journal of Turbomachinery, 2009
    Co-Authors: Isabelle Trébinjac, Pascale Kulisa, Nicolas Bulot, Isabelle Trébinjac, Nicolas Rochuon
    Abstract:

    Numerical and experimental investigations were conducted in a transonic Centrifugal Compressor Stage composed of a backswept splittered unshrouded impeller and a vaned diffuser. The characteristic curves of the Compressor Stage resulting from the unsteady simulations and the experiments show a good agreement over the whole operating range. On the contrary, the total pressure ratio resulting from the steady simulations is clearly overestimated. A detailed analysis of the flow field at design operating point led to identify the physical mechanisms involved in the blade row interaction that underlie the observed shift in performance. Attention was focused on the deformation in shape of the vane bow shock wave due its interaction with the jet and wake flow structure emerging from the impeller. An analytical model is proposed to quantify the time-averaged effects of the associated entropy increase. The model is based on the calculation of the losses across a shock wave at various inlet Mach numbers corresponding to the moving of the jet and wake flow in front of the shock wave. The model was applied to the Compressor Stage performance calculated with the steady simulations. The resulting curve of the overall pressure ratio as a function of the mass flow is clearly shifted towards the unsteady results. The model in particular enhances the prediction of the choked mass flow.

Reinhard Niehuis - One of the best experts on this subject based on the ideXlab platform.

  • Numerical Investigation of the Unsteady Flow Inside a Centrifugal Compressor Stage With Pipe Diffuser
    Journal of Turbomachinery, 2013
    Co-Authors: Daniel R Grates, Peter Jeschke, Reinhard Niehuis
    Abstract:

    The subject of this paper is the investigation of unsteady flow inside a transonic Centrifugal Compressor Stage with pipe-diffuser by utilizing unsteady 3D Navier-Stokes simulations (unsteady 3D URANS). The CFD results obtained are compared with detailed experimental data gathered using various steady and unsteady measurement techniques. The basic phenomena and mechanisms of the complex and highly unsteady flow inside the Compressor with pipe-diffuser are presented and analyzed in detail.Copyright © 2013 by ASME

  • NUMERICAL INVESTIGATION OF THE UNSTEADY FLOW INSIDE A Centrifugal Compressor Stage WITH PIPE DIFFUSER
    Proceedings of ASME Turbo Expo 2013: Turbine Technical Conference and Exposition, 2013
    Co-Authors: Daniel R Grates, Peter Jeschke, Reinhard Niehuis
    Abstract:

    The subject of this paper is the investigation of unsteady flow inside a transonic Centrifugal Compressor Stage with pipe- diffuser by utilizing unsteady 3D Navier-Stokes simulations (unsteady 3D URANS). The CFD results obtained are compared with detailed experimental data gathered using various steady and unsteady measurement techniques. The basic phenomena and mechanisms of the complex and highly unsteady flow inside the Compressor with pipe-diffuser are presented and analyzed in detail.

  • Experimental Investigation of a Centrifugal Compressor Stage With Focus on the Flow in the Pipe Diffuser Supported by Particle Image Velocimetry (PIV) Measurements
    Volume 6: Turbomachinery Parts A B and C, 2008
    Co-Authors: Uwe Zachau, Reinhard Niehuis, Carsten Buescher, Herwart Hoenen, D. C. Wisler, Zaher M. Moussa
    Abstract:

    Centrifugal Compressor Stages with pipe diffusers are considered to perform with high efficiency. Yet very little information on these kinds of diffusers is available to this day. Therefore, experimental investigations have been performed on a Centrifugal Compressor Stage with a pipe diffuser. An extensive measurement series using various steady, unsteady and laser optical measurement techniques has been performed to detect the highly three dimensional diffuser flow and create a benchmark for further development steps. Whereas this paper presents the test rig and the results gathered under nominal conditions, in a follow-up paper the results of the parameter variation studies covering bleed variation, impeller tip clearance and impeller-diffuser misalignment are compared to the nominal baseline and evaluated with respect to the Compressor Stage performance. For the investigations performed under nominal conditions it was found that the diffuser flow separates on the pressure side in the first half of the pipe. In the last 30% of the pipe hardly any deceleration of the flow takes place. From this, special attention is drawn to the parameter variations regarding a first proposal for a diffuser design change, which consists in shortening the diffuser. Ongoing investigations cover this design proposal. Along with the results of the ongoing investigations, the numerical investigations accompanying the experimental work will also be presented in follow-up papers.Copyright © 2008 by ASME