Numerical Analysis of Deposits and Corrosion Influence on a Centrifugal Compressor Performance

Author(s):  
Mohammad R. Aligoodarz ◽  
Mohammad Reza Soleimani Tehrani ◽  
Hadi Karrabi ◽  
Mohammad R. Roshani

Turbo machineries including compressors performance degrades over the period of operation and deviates from design levels due to causes including dust entrance into the compressor, blades mechanical damage, erosion and corrosion. These lead to reduction in compressor performance, efficiency and pressure ratio. Subsequently gas turbine performance is affected since their operation sate is correlated. In this study the numerical investigation of common causes that determine geometric characteristics of a 2-stage centrifugal compressor running in a gas station, including blades fouling and corrosion is performed. 3D Numerical modeling is implemented along with utilization of Shear Stress Transport (SST) turbulence model and independency from the grids is verified.

Author(s):  
Ce Yang ◽  
Ben Zhao ◽  
C. C. Ma ◽  
Dazhong Lao ◽  
Mi Zhou

Two different inlet configurations, including a straight pipe and a bent pipe, were experimentally tested and numerically simulated using a high-speed, low-mass flow centrifugal compressor. The pressure ratios of the compressor with the two inlet configurations were tested and then compared to illustrate the effect of the bent inlet pipe on the compressor. Furthermore, different circumferential positions of the bent inlet pipe relative to the volute are discussed for two purposes. One purpose is to describe the changes in the compressor performance that result from altering the circumferential position of the bent inlet pipe relative to the volute. This change in performance may be the so-called clocking effect, and its mechanism is different from the one in multistage turbomachinery. The other purpose is to investigate the unsteady flow for different matching states of the bent inlet pipe and volute. Thus, the frequency spectrum of unsteady pressure fluctuation was applied to analyze the aerodynamic response. Compared with the straight inlet pipe, the experimental results show that the pressure ratio is modulated and that the choke point is shifted in the bent inlet pipe. Similarly, the pressure ratio can be influenced by altering the circumferential position of the bent inlet pipe relative to the volute, which may have an effect on the unsteady pressure in the rotor section. Therefore, the magnitude of interest spectral frequency is significantly changed by clocking the bent inlet pipe.


Author(s):  
M. Morini ◽  
M. Pinelli ◽  
P. R. Spina ◽  
M. Venturini

Gas turbine operating state determination consists of the assessment of the modification, due to deterioration and fault, of performance and geometric data characterizing machine components. One of the main effects of deterioration and fault is the modification of compressor and turbine performance maps. Since detailed information about actual modification of component maps is usually unavailable, many authors simulate the effects of deterioration and fault by a simple scaling of the map itself. In this paper, stage-by-stage models of the compressor and the turbine are used in order to assess the actual modification of compressor and turbine performance maps due to blade deterioration. The compressor is modeled by using generalized performance curves of each stage matched by means of a stage-stacking procedure. Each turbine stage is instead modeled as a couple of nozzles, a fixed one (stator) and a moving one (rotor). The results obtained by simulating some of the most common causes of blade deterioration (i.e., compressor fouling, compressor mechanical damage, turbine fouling and turbine erosion, occurring in one or more stages simultaneously) are reported in this paper. Moreover, compressor and turbine maps obtained through a stage-by-stage procedure are compared to the ones obtained by means of map scaling.


Author(s):  
Pau Cutrina Vilalta ◽  
Hui Wan ◽  
Soumya S. Patnaik

Abstract In this paper, we use various regression models and Artificial Neural Network (ANN) to predict the centrifugal compressor performance map. Particularly, we study the accuracy and efficiency of Gaussian Process Regression (GPR) and Artificial Neural Networks in modelling the pressure ratio, given the mass flow rate and rotational speed of a centrifugal compressor. Preliminary results show that both GPR and ANN can predict the compressor performance map well, for both interpolation and extrapolation. We also study the data augmentation and data minimzation effects using the GPR. Due to the inherent pressure ratio data distribution in mass-flow-rate and rotational-speed space, data augmentation in the rotational speed is more effective to improve the ANN performance than the mass flow rate data augmentation.


Author(s):  
Ziliang Li ◽  
Xingen Lu ◽  
Ge Han ◽  
Yanfeng Zhang ◽  
Shengfeng Zhao ◽  
...  

Centrifugal compressors often suffer relatively low efficiency and a terrible operating range particularly due to the complex flow structure and intense impeller/diffuser interaction. Numerous studies have focused on improving the centrifugal compressor performance using many innovative ideas, such as the tandem impeller, which has become increasingly attractive due to its ability to achieve the flow control with no additional air supply configurations and control costs in compressor. However, few studies that attempted to the investigation of tandem impeller have been published until now and the results are always contradictory. To explore the potential of the tandem impeller to enhance the compressor performance and the underlying mechanism of the flow phenomena in the tandem impellers, this paper numerically investigated a high-pressure-ratio centrifugal compressor with several tandem impellers at off-design operating speeds. The results encouragingly demonstrate that the tandem impeller can achieve a performance enhancement over a wide range of operating conditions. Approximately 1.8% maximum enhancement in isentropic efficiency and 5.0% maximum enhancement in operating range are achieved with the inducer/exducer circumferential displacement of [Formula: see text] = 25% and 50%, respectively. The observed stage performance gain of the tandem impellers decreases when the operating speed increases due to the increased inducer shock, increased wake losses, and deteriorated tandem impeller discharge flow uniformity. In addition, the tandem impeller can extend the impeller operating range particularly at low rotation speeds, which is found to be a result from the suppression of the low-momentum fluid radial movement. The results also indicate that the maximum flux capacity of the tandem impeller decreases due to the restriction of the inducer airfoil Kutta–Joukowsky condition.


2014 ◽  
Vol 137 (3) ◽  
Author(s):  
Stefan Ubben ◽  
Reinhard Niehuis

Adjustable diffuser vanes offer an attractive design option for centrifugal compressors applied in industrial applications. However, the knowledge about the impact on compressor performance of a diffuser vane clearance between vane and diffuser wall is still not satisfying. This two-part paper summarizes results of experimental investigations performed with an industrial-like centrifugal compressor. Particular attention was directed toward the influence of the diffuser clearance on the operating behavior of the entire stage, the pressure recovery in the diffuser, and on the diffuser flow by a systematic variation of the parameters diffuser clearance height, diffuser vane angle, radial gap between impeller exit and diffuser inlet, and rotor speed. Compressor map measurements provide a summary of the operating behavior related to diffuser geometry and impeller speed, whereas detailed flow measurements with temperature and pressure probes allow a breakdown of the losses between impeller and diffuser and contribute to a better understanding of relevant flow phenomena. The results presented in Part I show that an one-sided diffuser clearance does not necessarily has a negative impact on the operation and loss behavior of the centrifugal compressor, but instead may contribute to an increased pressure ratio and improved efficiency as long as the diffuser passage is broad enough with respect to the clearance height. The flow phenomena responsible for this detected performance behavior are exposed in Part II, where the results of detailed measurements with pressure probes at diffuser exit and particle image velocimetry (PIV) measurements conducted inside the diffuser channel are discussed. The experimental results are published as an open computational fluid dynamics (CFD) testcase “Radiver 2.”


2012 ◽  
Vol 2012 ◽  
pp. 1-11 ◽  
Author(s):  
C. Xu ◽  
R. S. Amano

Centrifugal compressor developments are interested in using optimization procedures that enable compressor high efficiency and wide operating ranges. Recently, high pressure ratio and efficiency of the centrifugal compressors require impeller design to pay attention to both the blade angle distribution and the meridional profile. The geometry of the blades and the meridional profile are very important contributions of compressor performance and structure reliability. This paper presents some recent studies of meridional impacts of the compressor. Studies indicated that the meridional profiles of the impeller impact the overall compressor efficiency and pressure ratio at the same rotational speed. Proper meridional profiles can improve the compressor efficiency and increase the overall pressure ratio at the same blade back curvature.


Author(s):  
Levi André B. Vigdal ◽  
Lars E. Bakken

The introduction of variable inlet guide vanes (VIGVs) upfront of a compressor stage affects performance and permits tuning for off-design conditions. This is of great interest for emerging technology related to subsea compression. Unprocessed gas from the wellhead will contain liquid condensate, which affects the operational condition of the compressor. To investigate the effect of guide vanes on volume flow and pressure ratio in a wet gas compressor, VIGVs are implemented upfront of a centrifugal compressor stage to control the inlet flow direction. The guide vane geometry and test rig setup have previous been presented. This paper documents how changing the VIGV setting affects compressor performance under dry and wet operating conditions. The reduced performance effect and operating range at increased liquid content are of specific interest. Also documented is the change in the VIGV effect relative to the setting angle.


Author(s):  
C. Rodgers

Centrifugal impeller blade trimming has long been used in the turbocharger industry to adapt a single impeller casting to a series of flow capacities, but surprisingly little published literature exists on the effects of trimming to compressor performance. This paper is presented as partial remedy, and describes the performance characteristics of a single stage centrifugal compressor designed and tested to cover a range of flow requirements by impeller blade and diffuser vane trimming. Stage and component test performance characteristics are presented for five trimmed flowpath contours covering a flow capacity range of approximately five to one at a DeLaval number of 0.75. The impeller tip diameter was 356mm, and the highest overall stage efficiency measured was 84.8% at an (air) pressure ratio of 1.5.


Author(s):  
Chaitanya V. Halbe ◽  
Walter F. O’Brien ◽  
William T. Cousins ◽  
Vishnu Sishtla

The performance of a compressor is known to be affected by the ingestion of liquid droplets. Heat, mass and momentum transfer as well as the droplet dynamics are some of the important mechanisms that govern the two-phase flow. This paper presents numerical investigations of three-dimensional two-phase flow in a two-stage centrifugal compressor, incorporating the effects of the above mentioned mechanisms. The results of the two-phase flow simulations are compared with the simulation involving only the gaseous phase. The implications for the compressor performance, viz. the pressure ratio, the power input and the efficiency are discussed. The role played by the droplet-wall interactions on the rate of vaporization, and on the compressor performance is also highlighted.


1990 ◽  
Vol 112 (1) ◽  
pp. 25-29 ◽  
Author(s):  
H. Hayami ◽  
Y. Senoo ◽  
K. Utsunomiya

Low-solidity circular cascades, conformally transformed from high-stagger linear cascades of double-circular-arc vanes with solidity 0.69, were used as a part of the diffuser system of a transonic centrifugal compressor. Performance test results were compared with data of the same compressor with a vaneless diffuser. Good compressor performance and a wider flow range as well as a higher pressure ratio and a higher efficiency, superior to those with a vaneless diffuser, where the flow range was limited by choke of the impeller, were demonstrated. The test circular cascade diffusers demonstrated a good pressure recovery over a wide range of flow angles, even when the inflow Mach number to the cascade was over unity.


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