The Analysis of Aerodynamic Load for High Speed Centrifugal Compressor Blade

2013 ◽  
Vol 675 ◽  
pp. 103-106
Author(s):  
Gui Hua Zhu ◽  
Tuan Hui Qiu ◽  
Min Xie
Keyword(s):  
Flow Rate ◽  
Centrifugal Compressor ◽  
High Speed ◽  
Fluid Model ◽  
Pressure Ratio ◽  
Design Flow ◽  
Aerodynamic Load ◽  
Impeller Blade ◽  
Rate Condition ◽  
Rotating Speed

With the ANSYS Workbench software,the 3D fluid model of the impeller for the centrifugal compressor is set up,whose design flow is 3.2kg/s,rotating speed is 32473r/min,pressure ratio is 3.8,and then with the method of CFD,the k-ε two equations model is selected as the turbulence model,in the condition of design speed,the fluid region of the impeller is simulated under eight different flow rate,the aerodynamic load of the impeller blade and its distribution is acquired under different flow rate,the results showed that the location of the largest aerodynamic load is in the blade that near the outlet of impeller,under the design flow rate condition,the largest aerodynamic load is 0.1969MPa,the aerodynamic load increases with the flow rate decreases.

Velocity characteristics in a multiphase pump under different tip clearances

2020 ◽  
pp. 095765092094653
Author(s):  
Guangtai Shi ◽  
Zongku Liu ◽  
Yexiang Xiao ◽  
Helin Li ◽  
Xiaobing Liu
Keyword(s):  
Velocity Distribution ◽  
Flow Rate ◽  
High Speed ◽  
Stokes Equations ◽  
Design Flow ◽  
Tip Clearance ◽  
High Speed Photography ◽  
Hydraulic Loss ◽  
Impeller Blade ◽  
Multiphase Pump

To investigate the effect of tip clearance on the velocity distribution in a multiphase pump, the internal flow and velocity distribution characteristics in pump under different tip clearances are studied using experimental and numerical methods. Simulations based on the Reynolds-Averaged Navier-Stokes equations (RANS) and the standard k-ε turbulence model are carried out using ANSYS CFX. Under conditions of inlet gas void fraction (IGVF) is 5% at the flow rate of 0.6Q, 0.7Q and 0.8Q (Q is the design flow rate), the accuracy of the numerical method is verified by comparing with the experimental data using high-speed photography. Results show that the leakage flow interacts with the main flow and evolves into the tip leakage vortex (TLV). Due to the TLV, the pressure, velocity, turbulent kinetic energy (TKE), vorticity and streamlines on the S2 stream surface in the impeller and diffuser are changed greatly under different tip clearances. The velocities at the impeller outlet and diffuser inlet along the radial direction are also changed. The axial velocity distribution is similar to the meridional velocity distribution at the impeller blade outlet. While the relative velocity and absolute velocity distribution show the opposite trends. In addition, the vorticity is larger near the tip separated vortex and the hydraulic loss in pump is also increased due to the TLV.

scholarly journals Aerodynamic Optimization Design of a 150 kW High Performance Supercritical Carbon Dioxide Centrifugal Compressor without a High Speed Requirement

2020 ◽  
Vol 10 (6) ◽  
pp. 2093 ◽  
Author(s):  
Dongbo Shi ◽  
Yonghui Xie
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Flow Rate ◽  
Centrifugal Compressor ◽  
High Speed ◽  
Design Method ◽  
Pressure Ratio ◽  
Aerodynamic Optimization ◽  
Design Software ◽  
Supercritical Carbon

Supercritical carbon dioxide (S-CO2) Brayton cycle technology has the advantages of excellent energy density and heat transfer. The compressor is the most critical and complex component of the cycle. Especially, in order to make the system more reliable and economical, the design method of a high efficiency compressor without a high speed requirement is particularly important. In this paper, thermodynamic design software of a S-CO2 centrifugal compressor is developed. It is used to design the 150 kW grade S-CO2 compressor at the speed of 40,000 rpm. The performance of the initial design is carried out by a 3-D aerodynamic analysis. The aerodynamic optimization includes three aspects: numerical calculation, design software and the flow part geometry parameters. The aerodynamic performance and the off-design performance of the optimal design are obtained. The results show that the total static efficiency of the compressor is 79.54%. The total pressure ratio is up to 1.9. The performance is excellent, and it can operate normally within the mass flow rate range of 5.97 kg/s to 11.05 kg/s. This research provides an intelligent and efficient design method for S-CO2 centrifugal compressors with a low flow rate and low speed, but high pressure ratio.

The Experimental Study of Matching Between Centrifugal Compressor Impeller and Diffuser

1999 ◽  
Vol 121 (1) ◽  
pp. 113-118 ◽  
Author(s):  
H. Tamaki ◽  
H. Nakao ◽  
M. Saito
Keyword(s):  
Flow Rate ◽  
Centrifugal Compressor ◽  
Static Pressure ◽  
Pressure Ratio ◽  
Design Flow ◽  
Negative Slope ◽  
Compressor Stage ◽  
Rate Analysis ◽  
System Pressure ◽  
Compressor Impeller

The centrifugal compressor for a marine use turbocharger with its design pressure ratio of 3.2 was tested with a vaneless diffuser and various vaned diffusers. Vaned diffusers were chosen to cover impeller operating range as broad as possible. The analysis of the static pressure ratio in the impeller and the diffusing system, consisting of the diffuser and scroll, showed that there were four possible combinations of characteristics of impeller pressure ratio and diffusing system pressure ratio, The flow rate, QP, where the impeller achieved maximum static pressure ratio, was surge flow rate of the centrifugal compressor determined by the critical flow rate. In order to operate the compressor at a rate lower than QP, the diffusing system, whose pressure recovery factor was steep negative slope near QP, was needed. When the diffuser throat area was less than a certain value, the compressor efficiency deteriorated; however, the compressor stage pressure ratio was almost constant. In this study, by reducing the diffuser throat area, the compressor could be operated at a flow rate less than 40 percent of its design flow rate. Analysis of the pressure ratio in the impeller and diffusing systems at design and off-design speeds showed that the irregularities in surge line occurred when the component that controlled the negative slope on the compressor stage pressure ratio changed.

High Dimensional Matching Optimization of Impeller–Vaned Diffuser Interaction for a Centrifugal Compressor Stage

2020 ◽  
Vol 142 (12) ◽  
Author(s):  
Ruihong Qin ◽  
Yaping Ju ◽  
Lee Galloway ◽  
Stephen Spence ◽  
Chuhua Zhang
Keyword(s):  
Centrifugal Compressor ◽  
High Speed ◽  
Pressure Ratio ◽  
Sequential Optimization ◽  
High Dimensional ◽  
Compressor Stage ◽  
Optimization Strategy ◽  
Impeller Blade ◽  
Vaned Diffuser ◽  
Flow Angle

Abstract The matching and interaction between the impeller and vaned diffuser is the most important aerodynamic-coupling between the components of a high-speed centrifugal compressor. Many research studies have been carried out during the last decade, both experimentally and numerically, on the flow mechanisms underlying impeller–vaned diffuser matching and interaction, with the aim of achieving a high-performance stage. However, the published work lacks any study that optimizes the matching of the impeller–vaned diffuser components in the environment of a full compressor stage due to two unresolved issues, i.e., identifying an effective matching optimization strategy and the high dimensional nature of the problem. To tackle these difficulties, four different optimization strategies (i.e., (1) integrated, (2) single component, (3) parallel, and (4) sequential optimization strategies) have been proposed and validated through a high dimensional matching optimization of the Radiver compressor test case published by the Institute of Jet Propulsion and Turbomachinery at Rheinisch-Westfälische Technische Hochschule (RWTH) Aachen University. Particular attention has been paid to the slope of the diffuser total pressure ratio characteristic near the surge point to further extend the stage surge margin. The results showed that the integrated optimization strategy was the most effective one for achieving good matching of the impeller–vaned diffuser interaction due to its inherently strong coupling optimization. Compared with the baseline compressor, the optimized stage achieved a gain of 1.2% in total-to-total isentropic efficiency at the peak efficiency point as well as a predicted 26.17% increase in stable operating range. For the stage examined in this study, a fore-loaded design of impeller blade as well as an increased vane angle for the diffuser vane was beneficial to the impeller–vaned diffuser matching. The more uniform spanwise distributions of the impeller discharge flow angle and the diffuser vane incidence presented the opportunity for a more optimized matching of the flow field between the 3D impeller and the 2D vaned diffuser. The outcomes of this work are particularly relevant for the advanced design of high-speed centrifugal compressors.

Active Stabilization of Centrifugal Compressor Using Adjustable Geometry Impeller

2001 ◽  
Author(s):  
K. M. Saad Eldin
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
High Speed ◽  
Characteristic Curve ◽  
Pressure Ratio ◽  
Rotating Stall ◽  
Maximum Efficiency ◽  
Impeller Blade ◽  
Stable Regime

Abstract Recent work has shown that variable impeller geometry of the centrifugal compression system can be actively stabilized against the instability known as surge, thereby realizing a significant gain in system mass flow rate. In this context, the paper presents an experimental study about the influence of the impeller blade configuration on the extension of the stabilized characteristic margin beyond the natural surge line and enlarge the usable compressor operating region. This method is estimated from the two major control methods which: surge avoidance control and surge suppression control. The impeller of tandem type with zero overlap is found to be a good sample to satisfy the above concept. The impeller is working as full bladed at stable regime, but it could be transferred into tandem bladed when the mass flow rate decreases below a certain minimum value, just before rotating stall occurs. The operating point moves downwards to another characteristic curve belonging to the new configuration, which has a surge margin less than the original one by 56 percent, at high speed. Herein the effect of tandem shift angle on extending the stabilized range is studied experimentally and a control criterion is suggested. The pressure ratio at the new characteristic curve is decreased by about 3 percent and maximum efficiency is decreased also by about 28 percent.

Unsteady Flow Phenomena in a Centrifugal Compressor Channel Diffuser

2000 ◽  
Author(s):  
Jeong-Seek Kang ◽  
Sung-Kook Cho ◽  
Shin-Hyoung Kang
Keyword(s):  
Wavelet Transform ◽  
Flow Rate ◽  
Centrifugal Compressor ◽  
High Speed ◽  
Incidence Angle ◽  
Pressure Ratio ◽  
Flow Area ◽  
Operating Condition ◽  
Unsteady Pressure ◽  
Multi Scale

The aim of this paper is to understand the time averaged pressure field and unsteady pressure patterns in a high speed centrifugal compressor channel diffuser. Pressure distributions from the impeller exit to the channel diffuser exit are measured and discussed for various flow conditions. Unsteady pressure signals from six fast-response sensors in the channel diffuser are analyzed by decomposition method and wavelet transform. Measured results are shown for various operating condition from choke to surge that the effect of operating condition is well discussed. The strong non-uniformity in the pressure distribution is obtained over the diffuser shroud wall caused by the impeller-diffuser interaction. As the flow rate increases, flow separation near the throat, due to large incidence angle, increases aerodynamic blockage and reduces the aerodynamic flow area downstream. Thus the minimum pressure location occurs downstream of the geometric throat, and it is named as the aerodynamic throat. And at choke condition, normal shock occurs downstream of this aerodynamic throat. The variation in the location of the aerodynamic throat is discussed. The pressure ratio waveforms by blade passing show regular oscillation not only for the normal but also for the surge conditions and the high frequency fluctuations are superposed on the oscillating pressure waveform as the flow rate increases. Periodic unsteadiness by blade passing does not decay in the diffuser channel. It depends on the operating point and is generally larger in the channel than in the vaneless space. Aperiodic unsteadiness rapidly decrease downstream of diffuser channel. At surge, the spectrum becomes broad banded with peaks at the surge frequency as well as blade passage frequency and the impeller rotating frequency. The surge signal was analyzed using wavelet transform and it is found that surge signal is composed of not only surge scale and blade scale but also multi-scale aperiodic waves. The broadband spectrum in surge condition is due to this multi-scale aperiodic waves.

Stall Margin Improvement in a Centrifugal Compressor Through Endwall Reshaping

2012 ◽  
Author(s):  
Suhas R. Sope ◽  
Quamber H. Nagpurwala
Keyword(s):  
Flow Rate ◽  
Centrifugal Compressor ◽  
Separation Bubble ◽  
Pressure Ratio ◽  
Tip Clearance ◽  
Ansys Fluent ◽  
Impeller Blade ◽  
Stall Margin ◽  
Blade Height ◽  
Positive Tendency

This paper presents the results of numerical studies on the effect of endwall reshaping on the performance and stall margin of a centrifugal compressor. The endwall (shroud) of a baseline compressor was reshaped by introducing a convex hump at a location downstream of the inducer where the flow turns from axial to radial direction. The depth of the hump was varied as 3%, 6%, and 9% of the local impeller blade height. The impeller was also locally reshaped to match the shroud, maintaining the baseline tip clearance. Other geometric parameters of the reshaped impeller were kept same as those of the baseline impeller. An implicit, coupled, density based solver (ANSYS FLUENT) was used with first order upwind discretization scheme. The local reshaping of the endwall and impeller blades showed a positive tendency of increase in compressor stall margin without any appreciable reduction in efficiency. Endwall reshaping of 9% of the local blade height resulted in reducing the stall mass flow rate by 6.4 % of the baseline stall flow rate. Further, the peak total pressure ratio showed a marginal increase of 0.8%. Reshaping of the endwall was observed to cause local acceleration of the flow, thus weakening separation bubble and delaying inception of stall.

scholarly journals The Experimental Study of Matching Between Centrifugal Compressor Impeller and Diffuser

1997 ◽  
Author(s):  
Hideaki Tamaki ◽  
Hidefumi Nakao ◽  
Masayasu Saito
Keyword(s):  
Flow Rate ◽  
Centrifugal Compressor ◽  
Static Pressure ◽  
Pressure Ratio ◽  
Design Flow ◽  
Negative Slope ◽  
Compressor Stage ◽  
Rate Analysis ◽  
System Pressure ◽  
Compressor Impeller

The centrifugal compressor for a marine use turbocharger with its design pressure ratio of 3.2 was tested with a vaneless diffuser and various vaned diffusers. Vaned diffusers were chosen to cover impeller operating range as broad as possible. The analysis of the static pressure ratio in the impeller and the diffusing system — consists of the diffuser and scroll — showed that there were four possible combinations of characteristics of impeller pressure ratio and that of diffusing system pressure ratio. The flow rate, QP, where the impeller achieved maximum static pressure ratio was the critical flow rate determined surge flow rate of the centrifugal compressor. In order to operate the compressor less than QP, the diffusing system whose pressure recovery factor was steep negative slope near QP was needed. Using the diffuser throat area less than a certain value, the compressor efficiency deteriorated, however the compressor stage pressure ratio was almost constant. In this study, the compressor by reducing the diffuser throat area could be operated at the flow rate less than 40% of its design flow rate. Analysis of the pressure ratio in the impeller and diffusing systems at design and off design speeds showed that the irregularities in surge line occurred when the component which controlled the negative slope on the compressor stage pressure ratio changed.

Numerical Efforts of Aerodynamic Re-Design in a Transonic Centrifugal Compressor: Part 1 — Basic Approach

2017 ◽  
Author(s):  
Justin (Jongsik) Oh
Keyword(s):  
Centrifugal Compressor ◽  
Pressure Ratio ◽  
Design Flow ◽  
Angle Distribution ◽  
Aerodynamic Design ◽  
Blade Angle ◽  
Original Design ◽  
Trailing Edge ◽  
Impeller Blade ◽  
Transonic Centrifugal Compressor

Growing demands for higher specific output power in turbomachinery applications have drawn attention to aerodynamic design philosophy for a single-stage transonic centrifugal compressor with higher pressure ratios. As Part 1 of numerical efforts, some fundamental approaches in aerodynamic design were carried out in a classical 6:1 pressure-ratio compressor design of 1970’s which was selected as a baseline. The effects of the impeller blade angle distribution, the addition of the splitter blade, the changes of the tangential divergence angle of the channel-wedge diffuser and some tweaks in diffuser vane shapes near the trailing-edge were investigated in steady-state RANS CFD solutions with the conventional mixing plane interface. New blade angle distributions together with the introduction of splitter blades in the impeller brought significant improvements in the compressor pressure ratio, efficiency and operability, thanks to reduced shock strengths and enhanced blade loadings in the spanwise direction. Helicity contours on the cross sectional planes in the impeller support the benefits observing a power balance among the shroud passage vortex, the blade vortices and the tip leakage vortex. With a reduced tangential divergence in the channel-wedge diffuser passage from the original design, an impressively extended surge margin was obtained. It was confirmed from the helicity contours that a streamwise vortex structure at the entrance region of the diffuser vane plays a key role in the range of operation. A diffuser vane shape with the curved pressure surface near the trailing-edge provided a slightly higher pressure ratio and efficiency around design flow than that with the original cut-off trailing-edge. An elliptical trailing-edge diffuser vane showed rather performance drops because of the counter-clockwise hub vortex breakdown near the suction surface, resulting in less flow diffusion. Through investigations of a set of design cases, two final compressor designs, differing in the diffuser vane shape near the trailing-edge, were obtained within the work scope of the present study. However, selecting one of the two will depend on design duties for the following component because of the level of exit swirls and their rate of changes over the flow rates.

Effect of Recirculation Device With Counter Swirl Vane on Performance of High Pressure Ratio Centrifugal Compressor

2011 ◽  
Author(s):  
Hideaki Tamaki
Keyword(s):  
High Pressure ◽  
Mach Number ◽  
Flow Rate ◽  
Centrifugal Compressor ◽  
Pressure Ratio ◽  
Negative Slope ◽  
Tip Leakage Flow ◽  
Recirculation Flow ◽  
Operating Range ◽  
High Pressure Ratio

Centrifugal compressors used for turbochargers need to achieve a wide operating range. The author has developed a high pressure ratio centrifugal compressor with pressure ratio 5.7 for a marine use turbocharger. In order to enhance operating range, two different types of recirculation devices were applied. One is a conventional recirculation device. The other is a new one. The conventional recirculation device consists of an upstream slot, bleed slot and the annular cavity which connects both slots. The new recirculation device has vanes installed in the cavity. These vanes were designed to provide recirculation flow with negative preswirl at the impeller inlet, a swirl counterwise to the impeller rotational direction. The benefits of the application of both of the recirculation devices were ensured. The new device in particular, shifted surge line to a lower flow rate compared to the conventional device. This paper discusses how the new recirculation device affects the flow field in the above transonic centrifugal compressor by using steady 3-D calculations. Since the conventional recirculation device injects the flow with positive preswirl at the impeller inlet, the major difference between the conventional and new recirculation device is the direction of preswirl that the recirculation flow brings to the impeller inlet. This study focuses on two effects which preswirl of the recirculation flow will generate. (1) Additional work transfer from impeller to fluid. (2) Increase or decrease of relative Mach number. Negative preswirl increases work transfer from the impeller to fluid as the flow rate reduces. It increases negative slope on pressure ratio characteristics. Hence the recirculation flow with negative preswirl will contribute to stability of the compressor. Negative preswirl also increases the relative Mach number at the impeller inlet. It moves shock downstream compared to the conventional recirculation device. It leads to the suppression of the extension of blockage due to the interaction of shock with tip leakage flow.

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