Numerical Simulation of the Axial Fan Performance Degradation Due to Sand Ingestion

2002 ◽  
Author(s):  
A. Ghenaiet ◽  
S. C. Tan ◽  
R. L. Elder
Keyword(s):  
Lift Coefficient ◽  
Pressure Rise ◽  
Aerodynamic Performance ◽  
Performance Degradation ◽  
Tip Clearance ◽  
Sand Particle ◽  
Axial Fan ◽  
Stall Margin ◽  
Static Pressure Distribution ◽  
Aerodynamic Lift

This paper presents a method based on Lieblein and Koch correlations for assessing the performance degradation of an axial fan due to sand ingestion. The method is based on mean line analysis, and predicted aerodynamic performance includes the adiabatic efficiency, pressure rise coefficient and stall margin. Changes to the blade geometry which affect the fan aerodynamic performance are mainly due to erosion which reduces the blade chord and increases the tip clearance and surface roughness. Erosion damage has a significant effect on the aerodynamic lift coefficient, which is related to the static pressure distribution. An in-house developed trajectory code, combined with restitution factors and an erosion model (applicable for cast aluminium alloy and stainless steel), was used to predict particle trajectories and the amount of material removed. The method was applied successfully to a contra-whirl axial fan where reasonably good agreement was found between predicted and experimental results. Tests were conducted with MIL-E 5007E sand particle sizes of between 0.0 and 1000.0 microns. A method for predicting life expectancy of the fan is also presented. The methodology shows that critical blade parameters necessary for performance degradation simulation can be successfully obtained in this way.

Effect of Axial Sweep and Tip Extension on Performance of an Axial Fan

2016 ◽  
Author(s):  
Ankit Bhai Patel ◽  
K. Viswanath ◽  
Dhyanjyoti Deb Nath
Keyword(s):  
Performance Improvement ◽  
Flow Direction ◽  
Pressure Rise ◽  
Aerodynamic Performance ◽  
Secondary Flows ◽  
Tip Vortex ◽  
Low Flow ◽  
Pressure Probe ◽  
Axial Fan ◽  
Stall Margin

Performance enhancement in terms of stall margin increment, increased pressure rise coefficient and increased efficiency is of great need for low speed axial fans. Stacking line modifications in terms of sweep, skew, dihedral or combination of these, as well as blade tip geometry modifications are assumed to be one of the ways to achieve finite performance improvement. Non radial stacking of blade profiles modifies secondary flows, tip vortex effects, hub passage vortex and thus affects aerodynamic performance parameters such as stall margin, efficiency, pressure rise, blade loading. In literature many studies have confined to comparison of few cases which led to conflicting results as modification of stacking line may have different effects in different cases. In the present work, comparison of performance of axial fan rotor with three different blade configurations BSL (baseline), SWP (swept blade) and EXTN (swept blade with extended tip) are considered. The BSL configuration is designed on basis of non-free vortex design. The SWP configuration is obtained by shifting radial stacking line of the BSL in axial flow direction by 10° (Forward sweep). The EXTN configuration is obtained by extending tip profile on pressure surface as well as suction surface by 3% locally. Experiments have been conducted on these three configurations to study effects of these modifications on aerodynamic performance. The flow field has been surveyed using Kiel probe, Three hole pressure probe at many flow rates starting from fully open to fully closed. Unsteady flow analysis at exit of rotors of all configurations is carried out using fast response pressure probe. Experimental results show slight performance improvement in terms of increased stall margin, efficiency, as well as total pressure rise for SWP rotor as well as EXTN rotor compared to BSL rotor at low flow coefficients.

Aerodynamics of Contra-Rotating Fans With Swept Blades

2015 ◽  
Author(s):  
K. Vijayraj ◽  
M. Govardhan
Keyword(s):  
Rotational Speed ◽  
Axial Flow ◽  
Pressure Rise ◽  
Aerodynamic Performance ◽  
The Other ◽  
Flow Structures ◽  
Current Investigation ◽  
Rotating System ◽  
Stall Margin ◽  
Static Head

A Counter-Rotating System (CRS) is composed of a front rotor and a rear rotor which rotates in the opposite direction. Compared with traditional rotor-stator system, the rear rotor is used not only to recover the static head but also to supply energy to the fluid. Therefore, to achieve the same performance, the use of a CRS may lead to a reduction of the rotational speed and may generate better homogeneous flow downstream of the stage. On the other hand, the mixing area in between the two rotors induces complicated interacting flow structures. Blade sweep has attracted the turbomachinery blade designers owing to a variety of performance benefits it offers. However, the effect of blade sweep on the performance, stall margin improvements whether it is advantageous/disadvantageous to sweep one or both rotors has not been studied till now. In the current investigation blade sweep on the performance characteristics of contra rotating axial flow fans are studied. Two sweep schemes (axial sweeping and tip chord line sweeping) are studied for two sweep angles (20° and 30°). Effect of blade sweep on front rotor and rear rotor are dealt separately by sweeping one at a time. Both rotors are swept together and effect of such sweep scheme on the aerodynamic performance of the stage is also reported here. The performance of contra rotating fan is significantly affected by all these parameters. Blade sweep improved the pressure rise and stall margin of front rotors. Axially swept rotors are found to have higher pressure rise with reduced incidence losses near the tip for front rotors. Sweeping the rear rotor is not effective since the pressure rise is less than that of unswept rotor and also has less stall margin.

Design and Test of a Novel Highly-Loaded Compressor

2019 ◽  
Author(s):  
Chengwu Yang ◽  
Ge Han ◽  
Shengfeng Zhao ◽  
Xingen Lu ◽  
Yanfeng Zhang ◽  
...  
Keyword(s):  
Pressure Ratio ◽  
Axial Compressor ◽  
Pressure Rise ◽  
Tip Clearance ◽  
Leakage Flow ◽  
Flow Angle ◽  
Stall Margin ◽  
High Pressure Ratio ◽  
Numerical Predictions ◽  
Highly Loaded

Abstract The blades of rear stages in small size core compressors are reduced to shorter than 20 mm or even less due to overall high pressure ratio. The growing of tip clearance-to-blade height ratio of the rear stages enhance the leakage flow and increase the possibility of a strong clearance sensitivity, thus limiting the compressor efficiency and stability. A new concept of compressor, namely diffuser passage compressor (DP), for small size core compressors was introduced. The design aims at making the compressors robust to tip clearance leakage flow by reducing pressure difference between pressure and suction surfaces. To validate the concept, the second stage of a two-stage highly loaded axial compressor was designed with DP rotor according to a diffuser map. The diffuser passage stage has the same inlet condition and loading as the conventional compressor (CNV) stage, of which the work coefficient is around 0.37. The predicted performance and flow field of the DP were compared with the conventional axial compressor in detail. The rig testing was supplemented with the numerical predictions. Results reveal that the throttle characteristic of DP indicates higher pressure rise and the loss reduction in tip clearance is mainly responsible for the performance improvement. For the compressor with DP, the pressure and flow angle are more uniform on exit plane. What’s more, the rotor with diffused passage reveals more robust than the conventional rotor at double clearance gap. Furthermore, the experimental data indicate that DP presents higher pressure rise at design and part speeds. At design speed, the stall margin was extended by 7.25%. Moreover, peak adiabatic efficiency of DP is also higher than that of CNV by about 0.7%.

Prediction of an axial turbomachine performance degradation due to sand ingestion

2005 ◽  
Vol 219 (4) ◽  
pp. 273-287 ◽  
Author(s):  
A Ghenaiet ◽  
S C Tan ◽  
R L Elder
Keyword(s):  
Gas Turbines ◽  
Numerical Study ◽  
Axial Compressor ◽  
Performance Degradation ◽  
Tip Clearance ◽  
Cumulative Impacts ◽  
Axial Fan ◽  
Compressor Blades ◽  
Subsequent Performance ◽  
Blade Geometry

Erosion of compressor blades due to operation in particulate environments is a serious problem for the manufacturers and users of industrial and aeronautical gas turbines, because of drastic degradations in performance, mostly through blunting of blade leading edges, reduction of chord and increase of tip clearance and surface roughness. This paper presents a numerical study to assess the effects of erosion by sand ingestion on blade geometry deterioration and the subsequent performance degradation. These computations were carried out for an axial turbomachine in steps; first, calculations of particle trajectories and erosion resulting from cumulative impacts by sand particles (MIL-E 5007E, 0–1000 μm) were carried out, then, the required data were used in the estimation of performance degradation based on a mean-line method that included Lieblein and Koch-Smith loss correlations, in addition to an erosion fault model derived from blade geometry deterioration. This global procedure was successfully validated upon an axial fan stage, and can be generalized easily to other axial compressor designs.

Accounting for Eccentricity in Compressor Performance Predictions

2017 ◽  
Vol 139 (9) ◽  
Author(s):  
Anna M. Young ◽  
Teng Cao ◽  
Ivor J. Day ◽  
John P. Longley
Keyword(s):  
Axial Velocity ◽  
Pressure Rise ◽  
Two Dimensions ◽  
Tip Clearance ◽  
Flow Coefficient ◽  
Three Dimensional Model ◽  
Stall Margin ◽  
Rule Of Thumb ◽  
Compressor Performance ◽  
Flow Gradients

In this paper, experiments and numerical modeling are used to quantify the effects of clearance and eccentricity on compressor performance and to examine the influence of each on flow distribution and stall margin. A change in the size of the tip-clearance gap influences the pressure rise and the stall margin of a compressor. Eccentricity of the tip-clearance gap then further exacerbates the negative effects of increasing tip-clearance. There are few studies in the literature dealing with the combined effect of clearance and eccentricity. There is also little guidance for engine designers, who have traditionally used rules of thumb to quantify these effects. One such rule states that the stall margin of an eccentric machine will be equal to that of a concentric machine with uniform clearance equal to the maximum eccentric clearance. In this paper, this rule of thumb is checked using experimental data and found to be overly pessimistic. In addition, eccentric clearance causes a variation in axial velocity around the circumference of the compressor. The current study uses a three-dimensional model which demonstrates the importance of radial flow gradients in capturing this redistribution. Flow redistribution has been treated analytically in the past, and for this reason, previous modeling has been restricted to two dimensions. The circumferential variation in axial velocity is also examined in terms of the local stability of the flow by considering the stalling flow coefficient of an equivalent axisymmetric compressor with the same local tip-clearance. The large clearance sector of the annulus is found to operate beyond its equivalent axisymmetric stall limit, which means that the small clearance sector of the annulus must be stabilizing the large clearance sector. An improved rule of thumb dealing with the effects of eccentricity is presented.

An Experimental Investigation on the Erosion of a Helico-Axial Pump With Gas Presence

2020 ◽  
Author(s):  
Yi Chen ◽  
Abhay Patil ◽  
Yiming Chen ◽  
Gerald Morrison ◽  
Marisela Rojas
Keyword(s):  
Volume Fraction ◽  
Pressure Rise ◽  
Leading Edge ◽  
Oil And Gas Industry ◽  
Performance Degradation ◽  
Oil Field ◽  
Tip Clearance ◽  
Centrifugal Pumps ◽  
Impeller Blade ◽  
Axial Pump

Abstract Electrical submersible pump (ESP) technology has been widely applied in the oil and gas industry due to its high productivity. However, erosion always causes the reduction of productivity and sometimes even the failure of an ESP system. This study explores the effect of gas presence on erosion mechanism on an ESP which is composed of 4 stages of Helico-Axial Pump (HAP). A 200-hour erosion test has been performed on this ESP. During the test, the ESP was running at 3600 RPM with a liquid flow rate of 880 GPM, 20% inlet Gas Volume Fraction (GVF), and 0.24% sand concentration by weight. Performance tests were conducted every 50 hours to acquire the performance maps and monitor the performance degradation. Analysis of volume/weight loss and performance degradation is conducted to investigate pump wear. Two types of erosion are found at the impeller: the volume loss found notably at the leading edge is mainly caused by two-body impact erosion, while the tip clearance increment between the impeller housing and impeller blade tip is mainly caused by the three-body abrasive erosion. Unlike most conventional centrifugal pumps, there is no observable wear found at the trailing edge of the impeller. The presence of the gas shows a negative effect on both types of erosion. The consequence of the erosion is the performance degradation, especially at the condition with higher pressure rise. It is suggested to apply this HAP in the oil field with more gas and higher bottom hole pressure.

Effect of the tip clearance variation on the performance of a centrifugal compressor with considering impeller deformation

2011 ◽  
Vol 225 (8) ◽  
pp. 1143-1155 ◽  
Author(s):  
H-L Wang ◽  
G Xi ◽  
J-Y Li ◽  
M-J Yuan
Keyword(s):  
Centrifugal Compressor ◽  
Great Influence ◽  
Pressure Rise ◽  
Aerodynamic Performance ◽  
Structure Design ◽  
Tip Clearance ◽  
Working Environment ◽  
Field Analysis ◽  
The Real ◽  
Aerodynamic Pressure

The effects of impeller tip clearance variation on centrifugal compressor performance have been investigated experimentally and numerically in a centrifugal compressor. In order to accurately calculate the real tip clearance, the influence of impeller geometry deformation caused by the thermal load (temperature variation) and mechanical loads (aerodynamic pressure and centrifugal force) under working condition on the compressor aerodynamic performance is taken into account by fluid/solid interaction method during the computational fluid dynamics flow field analysis process. In this article, tip clearance flow under the real working environment is investigated with three different tip clearance cases. The impeller deformation combined with the adjustment of tip clearance causes some influence on the aerodynamic performance and on the structure reliability of the compressor system. For the aerodynamic design, an increase in the impeller tip clearance decreases the overall pressure rise and isentropic efficiency of the compressor, mainly due to the tip clearance loss in the impeller. Regarding structure design, the uniform relative tip clearance from the inlet to the outlet CR = 7.3 per cent is changed to non-uniform distribution from 6.4 per cent to 4.15 per cent. The largest deformation location occurs at the blade inducer and trailing-edge tip. The relative clearance near the outlet of the blade is reduced about 3.15 per cent which will cause great influence on the impeller working reliability.

Understanding the Flow Behavior in a Low Hub-Tip Ratio, High Aspect Ratio Contra-Rotating Axial Fan Stage

2012 ◽  
Author(s):  
Chetan S. Mistry ◽  
A. M. Pradeep
Keyword(s):  
Aspect Ratio ◽  
Total Pressure ◽  
Numerical Study ◽  
Flow Behavior ◽  
Experimental Studies ◽  
Pressure Rise ◽  
Operating Conditions ◽  
Speed Ratio ◽  
Axial Fan ◽  
Stall Margin

This paper discusses the results of a parametric study of a pair of contra-rotating axial fan rotors. The rotors were designed to deliver a mass flow of 6 kg/s at 2400 rpm. The blades were designed with a low hub-tip ratio of 0.35 and an aspect ratio of 3.0. Numerical and experimental studies were carried out on these contra-rotating rotors operating at a Reynolds number of 1.25 × 105 (based on blade chord). The axial spacing between the rotors was varied between 50 to 120 % of the chord of rotor 1. The performance of the rotors was evaluated at each of these spacing at design and off-design speeds. The results from the numerical study (using ANSYS CFX) were validated using experimental data. In spite of certain limitations of CFD under certain operating conditions, it was observed that the results agreed well with those from the experiments. The performance of the fan was evaluated based on the variations of total pressure, velocity components and flow angles at design and off-design operating conditions. The measurement of total pressure, flow angles etc. are taken upstream of the first rotor, between the two rotors and downstream of the second rotor. It was observed that the aerodynamics of the flow through a contra rotating stage is significantly influenced by the axial spacing between the rotors and the speed ratio of the rotors. With increasing speed ratios, the strong suction generated by the second rotor, improves the stage pressure rise and the stall margin. Lower axial spacing on the other hand, changes the flow incidence to the second rotor and thereby improves the overall performance of the stage. The performance is investigated at different speed ratios of the rotors at varying axial spacing.

Numerical study on the effect of the tip clearance of a 100 HP axial fan on the aerodynamic performance and unsteady stall characteristics

2020 ◽  
Vol 34 (12) ◽  
pp. 5117-5137
Author(s):  
Seul-Gi Lee ◽  
Yong-In Kim ◽  
Hyeon-Mo Yang ◽  
Sung Kim ◽  
Sang-Yeol Lee ◽  
...  
Keyword(s):  
Numerical Study ◽  
Aerodynamic Performance ◽  
Tip Clearance ◽  
Axial Fan

Effect of hub clearance of cantilever stator on aerodynamic performance and flow field of a transonic axial-flow compressor

2021 ◽  
pp. 095441002199370
Author(s):  
Botao Zhang ◽  
Bo Liu ◽  
Xiaochen Mao ◽  
Hejian Wang
Keyword(s):  
Flow Field ◽  
Pressure Ratio ◽  
Axial Flow ◽  
Aerodynamic Performance ◽  
Tip Clearance ◽  
Leakage Flow ◽  
Stall Margin ◽  
Axial Flow Compressor ◽  
Stator Blade ◽  
Flow Compressor

To investigate the effect of hub clearance of cantilever stator on the aerodynamic performance and the flow field of the transonic axial-flow compressor, the performance of single-stage compressors with the shrouded stator and cantilever stator was studied numerically. It is found that the hub corner separation on the stator blade suction surface (SS) was modified by introducing the hub leakage flow. The separation vortex on the SS of the stator blade root at about 10% axial chord length caused by the interaction of the shock wave and boundary layer was also controlled. Compared with the tip clearance size of the rotor blade, the stator hub clearance size (HCS) has a much less effect on the overall aerodynamic performance of the compressor, and there is no obvious effect on the flow field in the upstream blade row. With the increase of HCS, the leakage loss and the blockage degree in the flow field near the stator hub are increased and further make the adiabatic efficiency and the total pressure ratio of the compressor gradually decrease. Meanwhile, the stall margin of the compressor was changed slightly, but the response of the stall margin to the change of the HCS is nonlinear and insensitive. The stator hub leakage flow (HLF) can not only change the flow field near the hub but also redistribute the flow law within the range of the entire blade span. It will contribute to further understand the mechanism of the HLF and provide supports for the design of the cantilever stator of transonic compressors.

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