A Review on Centrifugal Compressor Design Methods

2019

Centrifugal Compressors play an essential role in oil, gas and petrochemical industries. Their extensive usage is due to their smooth operation and high reliability compared to other other compressor types. One of the main characteristics of these turbomachines is their performance curve, which is an important criterion for selecting the appropriate compressor for a desired working condition. In the presented article, the effect of impeller’s geometry on performance curve and other compressors characteristics is numerically investigated. The 3D CFD code is used to achieve the performance curves that are dedicated to each geometrical configuration. The results indicate that some of the selected geometrical parameters have a significant effect on performance curve margins. Increasing the shroud angle moves the surge point to the higher flow coefficients, while the pressure ratio remains constant and increasing the blade’s trailing edge angle, leads to increase in pressure ratio.

The design and off-design performance characteristics of single stage centrifugal compressor consisting of 12 vanes impeller interfacing with 11 vanes diffuser have been studied experimentally and numerically. The impeller has been designed and developed with radial exit, 30o inlet blade angle (with tangent), 77 mm diameter and the discharge volute considering constant mean flow velocity. The performance of the compressor at varying capacity (60 to 120 % of design) by controlling the discharge valve and with the variation of rotating speed (15000 to 35000 rpm) by regulating speed of the coupled gas turbine has been conducted at the recently developed test rig. The numerical simulation has been done by adopting viscous Reynolds Average Navier-Stokes (RANS) equations with and without Coriolis Force & Centrifugal Force in rotating reference frame (impeller) and stationary reference frame (casing) respectively utilizing CFD software Fluent 14. The flow around a single vane of impeller interfacing with single vane of diffuser, the rotational periodicity and sliding mesh at the interfacing zone between rotating impeller and stationery diffuser are considered. Non dimensional performance curves derived from experimental and numerical results are presented and compared. The numerical results are found to match very closely with the experimented data near the design point and deviation is observed at the both side of the designed operating point. Non-uniform pressure profiles towards the impeller exit and strong cross flow from blade to blade are detected at low flow operating conditions. Total pressure, static pressure and velocity distributions at design and off design operation obtained from the CFD results are analysed and presented here.

INCAS BULLETIN, 2018

The active control for centrifugal compressor systems consists in using, monitoring and managing the sensors to detect fluid disturbances, the actuators to introduce desired perturbations and a suitable controller to determine the optimal actuator actions using the sensor information. The object of an interesting centrifugal compressor design is to obtain the most air through a given diameter compressor, with a minimum number of stages while maintaining high efficiencies and aerodynamic stability over the operating range. The high efficiency of the axial compressor system decreases dramatically when used in small high-pressure applications, especially due to the large relative tip clearance. In addition, the high centrifugal force, dominating the pressure rise, results in a superior operability and the short axial length of the centrifugal compressor offers rotor-dynamic multiple advantages. These qualities allow the centrifugal compressor system to be used as the last stage of a high-pressure compressor of an aero engine as well as turbo pump assemblies used in liquid-propelled rocket engines.

Journal of Thermal Science, 2008

In this research, the centrifugal compressor of a turbocharger is investigated experimentally and numerically.

Academia Letters, 2021

It has always been important to study the development and improvement of turbomachines' design, owing to their numerous uses and high energy consumption. Accordingly, optimizing turbomachine performance is crucial for sustainable development. The design of impellers significantly affects the performance of centrifugal compressors .

Applied Sciences, 2019

Centrifugal compressor performance is affected by many parameters, optimization of which can lead to superior designs. Recognizing the most important parameters affecting performance helps to reduce the optimization process cost. Of the compressor components, the impeller plays the most important role in compressor performance, hence the design parameters affecting this component were considered. A turbocharger centrifugal compressor with vaneless diffuser was studied and the parameters investigated included meridional geometry, rotor blade angle distribution and start location of the main blades and splitters. The diffuser shape was captured as part of the meridional geometry. Applying a novel approach to the problem, full factorial analysis was used to investigate the most effective parameters. The Response Surface Method was then implemented to construct the surrogate models and to recognize the best points over a design space created as based on the Box-Behnken methodology. The ...

International Journal of Heat and Fluid Flow, 1985

Maximizing efficiency is the main goal in centrifugal compressor design. Thus a computer code has been developed to optimize geometric and fluid dynamic variables with respect to several design constraints. Computations are performed with an adiabatic one-dimensional approach using state-of-the-art loss and slip correlations. The optimization takes into account mechanical stress limits. Results with different loss and slip correlations are compared with the available experimental data. Changes in optimum efficiency and specific speed due to variations of mass flow rate and pressure ratio are also presented and discussed together with the trends of the optimum geometric features.

Energies, 2019

The performance of an automotive turbocharger centrifugal compressor has been studied by developing a comprehensive one-dimensional (1D) code as verified through experimental results and a three-dimensional (3D) model. For 1D analysis, the fluid stream in compressor is modeled using governing gas dynamics equations and the loss mechanisms have been investigated and added to the numerical model. The objective is to develop and offer a 1D model, which considers all loss mechanisms, slip, blockage and also predicts the surge margin and choke conditions. The model captures all features from inlet duct through to volute discharge. Performance characteristics are obtained using preliminary geometry and the blade characteristics. A 3D numerical model was also created and a viscous solver used for investigating the compressor characteristics. The numerical model results show good agreement with experimental data through compressor pressure ratio and efficiency. The effect of the main compre...

SAE Technical Paper Series, 2014

Turbochargers are commonly used in automotive engines to increase the internal combustion engine performance during off design operation conditions. When used, a most wide operation range for the turbocharger is desired, which is limited on the compressor side by the choke condition and the surge phenomenon. The ported shroud technology is used to extend the operable working range of the compressor, which permits flow disturbances that block the blade passage to escape and stream back through the shroud cavity to the compressor inlet. The impact of this technology on a speed-line at near optimal operation condition and near surge operation condition is investigated. A numerical study investigating the flow-field in a centrifugal compressor of an automotive turbocharger has been performed using Large Eddy Simulation. The wheel rotation is handled by the numerically expensive sliding mesh technique. In this analysis, the full compressor geometry (360 deg) is considered. Numerical solutions with and without ported shroud for a near optimal operation condition and near-surge operation condition. The flow-field of the different cases is analyzed to elucidate the functionality of the ported shroud. In agreement with previous observations, it was found that the ported shroud reduces the flow disturbances in the blade passage for all operating conditions. However, the compressor efficiency for the off-design operation condition was found to be higher without the ported shroud, supporting the findings reported recently by an experimental investigation. The computational results are validated with experimental measurements in terms of the performance parameters and available Particle Image Velocimetry data.

In this paper, the tip clearance effects on flow field of a low speed centrifugal compressor without and with partial shroud (PS) fitted on to the rotor blade tip at three values of tip clearance, viz. = 2.2%, 5.1% and 7.9% of rotor blade height at the exit at three flow coefficients, namely, = 0.18, 0.28, and 0.34, was studied. Based on the theory of computational fluid dynamics (CFD), performance curves and parameter distributions of the compressor were obtained from the 3-D numerical simulation by using ANSYS CFX 15.0. The centrifugal compressor in aerodynamic requirement is that edge velocities along the impeller channel passage surfaces like hub, shroud, pressure and suction surfaces vary smoothly without sudden decelerations, which cause flow separation leading to losses. Using the periodic boundaries and defined flow conditions at inflow / exit flow and blade rotations, the turbulent viscous flow between blade channels are computed. The efficiency related parameters using average quantities, besides flow pattern in terms of velocities, streamlines and pressure distribution on blade surfaces are graphically interpreted. An attempt is also made to study the influence of pressure loads on structural deformations in the chosen blade profile. This paper highlights aero-mechanical features of centrifugal impeller obtained from several numerical simulations, which are expected to provide a sound basis for further investigations.

Revista de Engenharia Térmica

This work presents the design of a centrifugal compressor for natural gas in three steps. The first step is the 1-D preliminary design heavily based on empirical data, only the design point was considered here. The second step is the flow analysis in the meridional plane. The last step is the CFD analysis to verify if the 1-D design methodology is adequate. The CFD simulations showed good agreement with the results obtained in the preliminary design, proving the importance of empirical data in the design of centrifugal compressors.

Journal of Engineering Science and Military Technologies, 2017

In this study an effort was made to develop a flow simulation modeling and performance prediction for a centrifugal compressor stage of a heavy-duty D. I. diesel engine. The model is implemented in simulation software in MATLAB language. Additionally, a contribution of this paper to demonstrate that off-design performance of a centrifugal compressor stage in a turbocharger system can be accurately simulated using commercial CFD software, with design software, FLOEFD to generate high quality meshes and model solving. The vector plots, contour plots and stream line plots are generated for better understanding of fluid flow through centrifugal compressor stage. Correlation coefficients have been introduced in the calculation program, in order to be closer to the CFD simulation results. The results obtained from mathematical computation model were validated with the CFD analysis and experimental results performed using a test bench for the variation of the performance parameters such as isentropic efficiency, power input, and total pressure ratio with mass flow rate, the results are also presented in graphical form. The results reveal that reasonable agreement between mathematical models, the numerical results obtained from the CFD simulations and the real measurements; the maximum difference never exceeds 5%. The results indicate that the developed mathematical computation model can yield better predictions of performance for a centrifugal compressor stage in a turbocharger system.

An attempt is made in the present study to investigate the superior turbulence model for simulating three dimensional flows in centrifugal compressor. The strong channelled curvature and intensive rotations prevalent in centrifugal compressor resulting high swirling and secondary flow nictitates choosing appropriate turbulence model for accurate performance predictions. The various turbulence models offered in FLUENT viz Spalart Allmaras (curvature correction), Transition SST (curvature correction), Scaled Adaptive Simulations (Curvature correction with compressibility effect), Reynolds stress model (compressibility effect) were investigated presently for Eckardt Impeller. Reynolds stress model though involves higher computational time was found to be the superior model. It is essential to investigate the onset of surge and choke for completely understanding the performance of a centrifugal compressor. Choking phenomena was observed when the speed reached 16000 rpm with relative Mach number reaching unity in the impeller region. The maximum flow rate at 16000 rpm was 0.4 kg/s per blade and remained constant then 16500 rpm. Surging was founded to initiate when the back pressure has to reach 1.8 bar resulting in zero discharge.

Abstract: A simple one dimensional approach to determine the size of the centrifugal impeller for maximum through flow has been indicated. This design procedure does not mean that the centrifugal impeller could be finally decided on the results obtained from this article. It must be borne in mind that this only deals with some aspects of the design and in itself is not a complete one by which the impeller could have its final shape and size. The major idea of introducing this paper is to highlight the importance of some of the parameters that go towards influencing the design of the centrifugal impeller.

Journal of Turbomachinery, 2020

Turbochargers are a vital component for aiding engine manufacturers in meeting the latest emissions standards. However, their range of operation is limited for low mass flows by compressor surge. Operation in surge results in pressure and mass flow oscillations that are often damaging to the compressor and its installation. Since surge is a highly complex flow regime, full unsteady three-dimensional models are generally too computationally expensive to run. The majority of current low-dimensional surge models use a cubic compressor characteristic that needs to be fitted to experimental data. Therefore, each time a compressor is studied using these models, costly experimental testing is required. In this paper, a new technique for obtaining an axisymmetric centrifugal compressor characteristic is presented. This characteristic is built using the equations of mass, momentum, and energy from first principles in order to provide a more complete model than those currently obtained via ex...