Identification of Acoustic Dipole Sources in a Propylene Centrifugal Compressor Stage

2010 ◽  
Author(s):  
Hongtao Tang ◽  
Datong Qi ◽  
Fuan Lu
Keyword(s):  
Centrifugal Compressor ◽  
Three Dimensional ◽  
Dipole Source ◽  
Compressor Stage ◽  
Impeller Blade ◽  
Centrifugal Compressor Stage ◽  
Rotor Stator Interaction ◽  
Last Stage ◽  
Harmonic Components ◽  
Dipole Sources

Three-dimensional unsteady turbulent flow in a propylene centrifugal compressor stage was numerically studied in order to identify primary acoustic dipole sources. The investigated model is the last stage of a propylene compressor used in the megaton ethylene production. The leakage clearance between the impeller and diffuser was simplified and modeled to capture the rotor-stator interaction accurately. A series of sixth-order polynomials, the use of which significantly sped up the computation compared with directly using Helmholtz real gas equation as the gas model, were fitted with a relative error less than 0.03% based on the thermodynamic data of propylene obtained by the Helmholtz equation. According to Lowson’s equation, the root mean square of the partial derivative of static pressure with respect to time during two revolutions of the impeller was taken as the parameter to measure dipole source intensity. The spatial distribution and frequency characteristics of the dipole sources were also investigated intensively. As a result of the present study, the primary dipole source is located at the junction of the impeller and diffuser, and its intensity is dominated by the components at the impeller blade passing frequency (BPF) and its higher harmonics, which are induced by the strong rotor-stator interaction. The spectrum analysis downstream of the impeller indicates that the higher harmonic components of dipole sources attenuate faster than the BPF component along the streamwise direction, and it is the BPF that dominates the noise characteristic in the volute casing of the studied model.

1D and 3D-Design Strategies for Pressure Slope Optimization of High-Flow Transonic Centrifugal Compressor Impellers

2018 ◽  
Author(s):  
A. Hildebrandt ◽  
T. Ceyrowsky
Keyword(s):  
Centrifugal Compressor ◽  
High Flow ◽  
Flow Coefficient ◽  
Design Parameters ◽  
Angle Distribution ◽  
Compressor Stage ◽  
Impeller Blade ◽  
Design Point ◽  
Centrifugal Compressor Stage ◽  
Transonic Centrifugal Compressor

The present paper deals with the numerical and theoretical investigations of the effect of geometrical dimensions and 1D-design parameters on the impeller pressure slope of a transonic centrifugal compressor stage for industrial process application. A database being generated during the multi-objective and multi-point design process of a high flow coefficient impeller, comprising 545 CFD (Computational Fluid Dynamics) designs is investigated in off-design and design conditions by means of RANS (Reynolds Averaged Navier Stokes) simulation of an impeller with vaneless diffuser. For high flow coefficients of 0.16 < phi < 0.18, the CFD-setup has been validated against measurement data regarding stage and impeller performance taken from MAN test rig experimental data for a centrifugal compressor stage of similar flow coefficient. The paper aims at answering the question how classical design parameter, such as the impeller blade angle distribution, impeller suction diameter and camber line length affect the local and total relative diffusion and pressure slope towards impeller stall operation. A second order analysis of the CFD database is performed by cross-correlating the CFD data with results from impeller two-zone 1D modelling and a rapid loading calculation process by Stanitz and Prian. The statistical covariance of first order 1D-analysis parameters such as the mixing loss of the impeller secondary flow, the slip factor, impeller flow incidence is analyzed, thereby showing strong correlation with the design and off-design point efficiency and pressure slope. Finally, guide lines are derived in order to achieve either optimized design point efficiency or maximum negative pressure slope characteristics towards impeller stall operation.

scholarly journals Effect of the Unsteadiness on the Diffuser Flow in a Transonic Centrifugal Compressor Stage

2009 ◽  
Vol 2009 ◽  
pp. 1-11 ◽  
Author(s):  
N. Bulot ◽  
I. Trébinjac
Keyword(s):  
Flow Field ◽  
Flow Structure ◽  
Centrifugal Compressor ◽  
Wake Flow ◽  
Pressure Waves ◽  
Pressure Side ◽  
Compressor Stage ◽  
Impeller Blade ◽  
Centrifugal Compressor Stage ◽  
Diffuser Flow

The study is focused on the analysis of the flow structure within the vaned diffuser of a transonic high-pressure centrifugal compressor stage. The analyzed time-dependent flow field comes from unsteady computations of the stage using a 3D Navier-Stokes code with a phase-lagged technique, at an operating point close to the design point. A good comparison with available experimental data allowed the use of CFD for investigating the details of the flow in order to assess the effect of the unsteadiness in the diffuser flow development. Applying various data processing techniques, it is shown that the unsteadiness is due to the jet and wake flow structure emerging from the radial impeller and to the pressure waves brought about by the interaction between the vane bow shock wave and the impeller blade. The interaction between the pressure waves and the vane pressure side boundary layer leads to a pulsating behavior of separated bubbles within the diffuser. The pressure waves are similar in shape and strength whatever the blade height. The observed change in the flow field from hub to tip is due to migration of the low momentum fluid contained in the wake toward the pressure side/hub corner.

Deterministic Blade Row Interactions in a Centrifugal Compressor Stage

1992 ◽  
Vol 114 (2) ◽  
pp. 304-311 ◽  
Author(s):  
K. R. Kirtley ◽  
T. A. Beach
Keyword(s):  
Centrifugal Compressor ◽  
Three Dimensional ◽  
Secondary Flows ◽  
Navier Stokes ◽  
Pressure Side ◽  
Compressor Stage ◽  
Trailing Edge ◽  
Tip Leakage ◽  
Centrifugal Compressor Stage ◽  
Blade Row

The three-dimensional viscous flow in a low-speed centrifugal compressor stage is simulated using an average passage Navier–Stokes analysis. The impeller discharge flow is of the jet/wake type with low-momentum fluid in the shroud-pressure side corner coincident with the tip leakage vortex. This nonuniformity introduces periodic unsteadiness in the vane frame of reference. The effect of such deterministic unsteadiness on the time mean is included in the analysis through the average passage stress, which allows the analysis of blade row interactions. The magnitude of the divergence of the deterministic unsteady stress is of the order of the divergence of the Reynolds stress over most of the span from the impeller trailing edge to the vane throat. Although the potential effects on the blade trailing edge from the diffuser vane are small, strong secondary flows generated by the impeller degrade the performance of the diffuser vanes.

Numerical study on the Effect of Interaction Vaned Diffuser with Impeller on the Performance of a Modified Centrifugal Compressor

2013 ◽  
Vol 30 (2) ◽  
pp. 113-121 ◽  
Author(s):  
L. H. Jawad ◽  
S. Abdullah ◽  
R. Zulkifli ◽  
W. M. F. W. Mahmood
Keyword(s):  
Centrifugal Compressor ◽  
Numerical Study ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Internal Flow ◽  
Compressor Stage ◽  
Vaned Diffuser ◽  
Centrifugal Compressor Stage ◽  
Compressor Impeller ◽  
Inlet Conditions

ABSTRACTThis paper is a numerical simulation that was made in the three-dimensional flow, carried out in a modified centrifugal compressor, having vaned diffuser stage, used as an auto-motive turbo charger. Moreover, the performance of the centrifugal compressor was dependent on the proper matching between compressor impeller and vaned diffuser, influencing significantly surge and the efficiency of centrifugal compressor stages. In addition, a modified compressor impeller, coupled with vane and vaneless diffuser, has been found to have similar internal flow patterns for both the vaneless and vaned diffuser design. The vaned diffuser effect has been paid particular attention in terms of better analysis where the diffuser was designed for high sub-sonic inlet conditions. Another aim of this research was to study and simulate the effect of vaned diffuser on the performance of a centrifugal compressor. The simulation was undertaken by using a commercial software, the so-called ANSYS CFX, to predict numerically the performance in terms of pressure ratio, poly tropic efficiency and mass flow rate for the centrifugal compressor stage. The results were generated from CFD and were analyzed for better understanding of the fluid flow through centrifugal compressor stage. Conclusively, it was observed that the effect of the vaned diffuser is to convert the kinetic energy into a high static pressure after analyzing the results of the simulation.

scholarly journals Centrifugal Compressor Impeller Aerodynamics: A Numerical Investigation

1990 ◽  
Author(s):  
Daniel J. Dorney ◽  
Roger L. Davis
Keyword(s):  
Centrifugal Compressor ◽  
Equations Of Motion ◽  
Three Dimensional ◽  
Elliptic Partial Differential Equation ◽  
Solution Procedure ◽  
Design Flow ◽  
Navier Stokes ◽  
Impeller Blade ◽  
Compressor Impeller ◽  
Rotor Stator Interaction

A three-dimensional, Navier-Stokes analysis is presented for the prediction of viscous flows through centrifugal impellers. Based on the Navier-Stokes rotor/stator interaction procedure developed by Rai, the present analysis uses a zonal grid methodology to discretize the impeller flow field and to facilitate the relative motion of the impeller. A blade surface oriented O-grid generated from an elliptic partial differential equation solution procedure is patched into an algebraically generated H-grid which is used to discretize the inlet, exit and blade-to-blade regions. The equations of motion are integrated using a spatially third-order accurate, implicit, iterative, upwind, finite difference, time-marching technique. Predicted results are presented for flow through a low speed centrifugal compressor impeller operating at design flow conditions. Comparison of these predicted results with experimental data demonstrates the capability of this procedure to predict impeller blade loading and provide insight into the secondary flow structure within the impeller blade passage.

scholarly journals Deterministic Blade Row Interactions in a Centrifugal Compressor Stage

1991 ◽  
Author(s):  
K. R. Kirtley ◽  
T. A. Beach
Keyword(s):  
Centrifugal Compressor ◽  
Three Dimensional ◽  
Secondary Flows ◽  
Navier Stokes ◽  
Pressure Side ◽  
Compressor Stage ◽  
Trailing Edge ◽  
Tip Leakage ◽  
Centrifugal Compressor Stage ◽  
Blade Row

The three-dimensional viscous flow in a low speed centrifugal compressor stage is simulated using an average passage Navier-Stokes analysis. The impeller discharge flow is of the jet/wake type with low momentum fluid in the shroud-pressure side corner coincident with the tip leakage vortex. This nonuniformity introduces periodic unsteadiness in the vane frame of reference. The effect of such deterministic unsteadiness on the time-mean is included in the analysis through the average passage stress, which allows the analysis of blade row interactions. The magnitude of the divergence of the deterministic unsteady stress is of the order of the divergence of the Reynolds stress over most of the span, from the impeller trailing edge to the vane throat. Although the potential effects on the blade trailing edge from the diffuser vane are small, strong secondary flows generated by the impeller degrade the performance of the diffuser vanes.

Unsteady Flow in a Centrifugal Compressor Stage Equipped With a Vaned Diffuser and Cavities

2017 ◽  
Author(s):  
Mohand Younsi ◽  
Christophe Corneloup ◽  
François Moyroud ◽  
Antoine Baldacci
Keyword(s):  
Centrifugal Compressor ◽  
Transient Flow ◽  
Flow Behavior ◽  
Numerical Procedure ◽  
Transformation Method ◽  
Operating Conditions ◽  
Compressor Stage ◽  
Absolute Level ◽  
Impeller Blade ◽  
Centrifugal Compressor Stage

The purpose of this work is to present the Computational Fluid Dynamics (CFD) transient flow simulations of a centrifugal compressor stage with cavities. The cavities are included in the CFD model for several reasons. First the leakage flows and the windage effects are important to predict the absolute level performance of the stage (efficiency). Secondly the cavities also play an important role in the generation of the aerodynamic forcing on the impeller as well as in the prediction of the aerodynamic damping. As the compressor stage contains unequal numbers of blades and vanes, the Time Transformation method, an extension of the time inclining method is used in this work. This method which requires only a few passages per row is employed to reduce computational load and accurately model the full wheel. The numerical procedure is applied at design point firstly and then extended to the off-design operating conditions, permitting to compare and understand the transient flow behavior. The ability of the method to predict the impeller/diffuser interactions and cavity unsteady pressure response is discussed. The respective contributions of the diffuser, impeller blade passages and side cavities in terms of impeller forcing amplitude and frequency content are studied. In addition to this, comparisons between the experiment, the reduced model and the equivalent part wheel periodic solution are made to demonstrate the accuracy and computational efficiency of the considered transformation method.

scholarly journals Flow Studies in a Centrifugal Compressor Stage

2014 ◽  
Author(s):  
R. Rajendran
Keyword(s):  
Centrifugal Compressor ◽  
Flow Behavior ◽  
Compressor Stage ◽  
Impeller Blade ◽  
Vaned Diffuser ◽  
Flow Angle ◽  
Centrifugal Compressor Stage ◽  
Operating Range ◽  
Impeller Outlet ◽  
Outlet Flow

The overall efficiency of a compressor is dependent on the design of both the impeller and the diffuser. The vaned diffuser reduces the operating range compared to the vaneless diffuser. However, by proper setting of the diffuser with reference to the impeller, it is possible to achieve a good stage performance. This paper describes the experimental investigation of the detailed flow behavior inside a centrifugal compressor stage for three different setting angles of the vaned diffuser with reference to the fixed impeller blade outlet angle. It is seen that diffuser setting angles lower than the impeller outlet flow angle gives wide operating range.

Unsteady Aerodynamics of a Centrifugal Compressor Stage: Validation of Two Different CFD Solvers

2012 ◽  
Author(s):  
Oliver Borm ◽  
Hans-Peter Kau
Keyword(s):  
Numerical Simulations ◽  
Centrifugal Compressor ◽  
Three Dimensional ◽  
Unsteady Aerodynamics ◽  
Compressor Stage ◽  
Vaned Diffuser ◽  
Centrifugal Compressor Stage ◽  
Sst Turbulence Model ◽  
Compressor Map ◽  
State Mixing

The unsteady flow field of a centrifugal compressor stage with vaned diffuser has been numerically investigated. Three dimensional steady as well as unsteady numerical simulations have been carried out with the CFD programs Numeca and OpenFOAM. The investigated numerical approaches range from a steady state mixing-plane simulation to an unsteady full annulus 360° computation. The numerical investigation was done at 80% design speed with the Spalart-Allmaras as well as the k-w SST turbulence model. All numerical simulations were compared to the experiments in the compressor map. The velocity field of one operating point near the surge line was analysed in more detail. Similarities and differences between numerical and experimental results are discussed and their causes and effects pointed out.

Sign in / Sign up

Export Citation Format

Share Document