The Influence of Inlet Flow Distortion on the Performance of a Centrifugal Compressor and the Development of Improved Inlet Using Numerical Simulations—Part I: Experimental Test Comparison for Compressor Stage Performance

2000 ◽  
Author(s):  
Yunbae Kim ◽  
Abraham Engeda ◽  
Ron Aungier ◽  
Greg Direnzi
Keyword(s):  
Flow Structure ◽  
Centrifugal Compressor ◽  
Experimental Test ◽  
Stagnation Temperature ◽  
Compressor Stage ◽  
Flow Distortion ◽  
Inlet Flow ◽  
Curved Pipe ◽  
Inlet Flow Distortion ◽  
Stage Efficiency

Abstract The performance of centrifugal compressors can be seriously affected by inlet flow distortion that is by non-uniform inlet flow. The distortion can be in static pressure or stagnation temperature, but the most common distortion is stagnation pressure. Such distortions often occur because of the unsatisfactory nature of the inlet configuration and the resulting inlet flow structure. In this current work, Part I of two parts, experimental test has been carried out for the comparison of a centrifugal compressor stage efficiency with two different inlet configurations, one of which is straight with constant area and the other is a 90-degree curved pipe with nozzle shape as inlet models. The comparative result from the test showed significant stage efficiency difference between the two different inlet configurations. The result is analyzed and attempt is made to understand the flow structure caused by each type of configuration and the resulting effect on the performance of the stage.

The Investigation of Distorted and Enhanced Inlet Flow Influence on the Performance of a Centrifugal Compressor Stage

2001 ◽  
Author(s):  
Yunbae Kim ◽  
Abraham Engeda ◽  
Ron Aungier ◽  
Greg Direnzi
Keyword(s):  
Centrifugal Compressor ◽  
Design Method ◽  
Compressor Stage ◽  
Flow Properties ◽  
Flow Distortion ◽  
Inlet System ◽  
Inlet Flow ◽  
Centrifugal Compressor Stage ◽  
Stage Performance ◽  
Inlet Flow Distortion

Abstract The performance of a centrifugal compressor can be seriously affected by inlet flow distortions due to the unsatisfactory nature of the inlet configuration and the resulting inlet flow structure. In the previous work, experimental tests were carried out for the comparison of a centrifugal compressor stage performance with two different inlet configurations: one of which was a straight pipe with constant cross-sectional area as an ideal model and the other is a 90-degree curved pipe with nozzle shape as an actual model. The comparative test results indicated significant compressor stage performance difference between the two different inlet configurations. In addition, the numerical simulation part of the previous work clearly showed that the inlet flow distortion is caused by the pressure driven secondary flow developed in the curved section in the case of the bend inlet, resulting in locally concentrated incidence at the impeller inlet and thus the compressor stage performance degradation. An improved inlet model with the design method has been proposed based on the comparisons of the designated flow properties. In the present work, further numerical simulations on the compressor stage including the impeller and the diffuser with three different inlets are carried out to investigate the performance behavior of the compressor exposed to different inlet configurations. The three different inlet systems include the original bend inlet as well as the proposed inlet model based on the developed design method. Since the flow from the bend inlet is not axisymmetric due to the circumferential and radial distortion on the cross-section, the impeller and the diffuser are modeled with fully 360-degree passages, which accommodates the inlet flow distortion and the impeller-diffuser interaction influence on the entire flow passage of the compressor. The stage performance with the different inlet systems are evaluated and compared with the previous experimental result. The diffuser performance and the flow properties in the vaneless region are compared among those inlet models. The proposed inlet system indicated the benefit of performance improvement over the original inlet system.

The Inlet Flow Structure of a Centrifugal Compressor Stage and Its Influence on the Compressor Performance

2003 ◽  
Vol 125 (5) ◽  
pp. 779-785 ◽  
Author(s):  
Abraham Engeda ◽  
Yunbae Kim ◽  
Ronald Aungier ◽  
Gregory Direnzi
Keyword(s):  
Centrifugal Compressor ◽  
Experimental Tests ◽  
Compressor Stage ◽  
Cross Sectional ◽  
Inlet Flow ◽  
Curved Pipe ◽  
Centrifugal Compressor Stage ◽  
Nozzle Shape ◽  
Compressor Performance ◽  
Stage Performance

The performance of centrifugal compressors can be seriously degraded by inlet flow distortions that result from an unsatisfactory inlet configuration. In this present work, the flow is numerically simulated and the flow details are analyzed and discussed in order to understand the performance behavior of the compressor exposed to different inlet configurations. In a previous work, complementary to this present work, experimental tests were carried out for the comparison of a centrifugal compressor stage performance with two different inlet configurations: one of which was a straight pipe with constant cross-sectional area and the other a 90-deg curved pipe with nozzle shape. The comparative test results indicated significant compressor stage performance difference between the two different inlet configurations. Steady-state compressor stage simulation including the impeller and diffuser with three different inlets has been carried out to investigate the influence of each inlet type on the compressor performance. The three different inlet systems included a proposed and improved inlet model. The flow from the bend inlet is not axisymmetric in the circumferential and radial distortion, thus the diffuser and the impeller are modeled with fully 360-deg passages.

scholarly journals Investigation of Flows in Rectangular Diffusers With Inlet Flow Distortion

1982 ◽  
Author(s):  
M. M. Al-Mudhafar ◽  
M. Ilyas ◽  
F. S. Bhinder
Keyword(s):  
Experimental Study ◽  
Velocity Profiles ◽  
Pressure Recovery ◽  
Two Dimensional ◽  
Flow Distortion ◽  
Inlet Flow ◽  
Inlet Velocity ◽  
Inlet Distortion ◽  
Mach Numbers ◽  
Inlet Flow Distortion

The results of an experimental study on the influence of severely distorted velocity profiles on the performance of a straight two-dimensional diffuser are reported. The data cover entry Mach numbers ranging from 0.1 to 0.6 and several inlet distortion levels. The pressure recovery progressively deteriorates as the inlet velocity is distorted.

The Effect of Non-Uniform Aerodynamic Loading on the Blade Responses

2007 ◽  
Author(s):  
Abdelgadir M. Mahmoud ◽  
Mohd S. Leong
Keyword(s):  
Turbine Blades ◽  
Forced Response ◽  
Flow Section ◽  
Flow Distortion ◽  
Inlet Flow ◽  
Bladed Disk ◽  
Aerodynamic Loading ◽  
Bladed Disk Assembly ◽  
Flow Generator ◽  
Inlet Flow Distortion

Turbine blades are always subjected to severe aerodynamic loading. The aerodynamic loading is uniform and Of harmonic nature. The harmonic nature depends on the rotor speed and number of nozzles (vanes counts). This harmonic loading is the main sources responsible for blade excitation. In some circumstances, the aerodynamic loading is not uniform and varies circumferentially. This paper discussed the effect of the non-uniform aerodynamic loading on the blade vibrational responses. The work involved the experimental study of forced response amplitude of model blades due to inlet flow distortion in the presence of airflow. This controlled inlet flow distortion therefore represents a nearly realistic environment involving rotating blades in the presence of airflow. A test rig was fabricated consisting of a rotating bladed disk assembly, an inlet flow section (where flow could be controlled or distorted in an incremental manner), flow conditioning module and an aerodynamic flow generator (air suction module with an intake fan) for investigations under laboratory conditions. Tests were undertaken for a combination of different air-flow velocities and blade rotational speeds. The experimental results showed that when the blades were subjected to unsteady aerodynamic loading, the responses of the blades increased and new frequencies were excited. The magnitude of the responses and the responses that corresponding to these new excited frequencies increased with the increase in the airflow velocity. Moreover, as the flow velocity increased the number of the newly excited frequency increased.

Numerical Investigation of the Effect of Diffuser and Volute Design Parameters on the Performance of a Centrifugal Compressor Stage

2016 ◽  
Author(s):  
Lei Yu ◽  
William T. Cousins ◽  
Feng Shen ◽  
Georgi Kalitzin ◽  
Vishnu Sishtla ◽  
...  
Keyword(s):  
Centrifugal Compressor ◽  
Gas Flow ◽  
Pressure Rise ◽  
Design Parameters ◽  
Compressor Stage ◽  
Flow Distortion ◽  
Cross Sectional ◽  
Centrifugal Stage ◽  
And Performance ◽  
The Impact

In this effort, 3D CFD simulations are carried out for real gas flow in a refrigeration centrifugal compressor. Both commercial and the in-house CFD codes are used for steady and unsteady simulations, respectively. The impact on the compressor performance with various volute designs and diffuser modifications are investigated with steady simulations and the analysis is focused on both the diffuser and the volute loss, in addition to the flow distortion at impeller exit. The influence of the tongue, scroll diffusion ratio, diffuser length, and cross sectional area distribution is examined to determine the impact on size and performance. The comparisons of total pressure loss, static pressure recovery, through flow velocity, and the secondary flow patterns for different volute designs show that the performance of the centrifugal compressor depends upon how well the scroll portion of the volute collects the flow from the impeller and achieves the required pressure rise with minimum flow losses in the overall diffusion process. Finally, the best design is selected based on compressor stage pressure rise and peak efficiency improvement. An unsteady simulation of the full wheel compressor stage was carried out to further examine the interaction of impeller, diffuser and the volute. The unsteady flow interactions are shown to have a major impact on the performance of the centrifugal stage.

Lip Separation and Inlet Flow Distortion Control in Ducted Fans Used in VTOL Systems

2014 ◽  
Author(s):  
Ali Akturk ◽  
Cengiz Camcı
Keyword(s):  
Angle Of Attack ◽  
Axial Flow ◽  
Vertical Force ◽  
High Angle ◽  
Flow Distortion ◽  
High Angle Of Attack ◽  
Inlet Flow ◽  
Flight Velocity ◽  
Ducted Fan ◽  
Inlet Flow Distortion

This paper describes a novel ducted fan inlet flow conditioning concept that will significantly improve the performance and controllability of ducted fan systems operating at high angle of attack. High angle of attack operation of ducted fans is very common in VTOL (vertical take off and landing) UAV systems. The new concept that will significantly reduce the inlet lip separation related performance penalties in the edgewise/forward flight zone is named DOUBLE DUCTED FAN (DDF). The current concept uses a secondary stationary duct system to control inlet lip separation related momentum deficit at the inlet of the fan rotor occurring at elevated edgewise flight velocities. The DDF is self-adjusting in a wide edgewise flight velocity range and its corrective aerodynamic effect becomes more pronounced with increasing flight velocity due to its inherent design properties. Most axial flow fans are designed for an axial inlet flow with zero or minimal inlet flow distortion. The DDF concept is proven to be an effective way of dealing with inlet flow distortions occurring near the lip section of any axial flow fan system, especially at high angle of attack. In this present paper, a conventional baseline duct without any lip separation control feature is compared to two different double ducted fans named DDF CASE-A and DDF CASE-B via 3D, viscous and turbulent flow computational analysis. Both hover and edgewise flight conditions are considered. Significant relative improvements from DDF CASE-A and DDF CASE-B are in the areas of vertical force (thrust) enhancement, nose-up pitching moment control and recovery of fan through-flow mass flow rate in a wide horizontal flight range.

Inlet Flow Distortion

2018 ◽  
pp. 249-267 ◽  
Author(s):  
Joachim Kurzke ◽  
Ian Halliwell
Keyword(s):  
Flow Distortion ◽  
Inlet Flow ◽  
Inlet Flow Distortion

Nacelle Aerodynamic Optimization and Inlet Compatibility

2015 ◽  
Author(s):  
Jingjing Chen ◽  
Yadong Wu ◽  
Zhonglin Wang ◽  
Anjenq Wang
Keyword(s):  
Pressure Loss ◽  
Operating Conditions ◽  
Maximum Pressure ◽  
Aerodynamic Optimization ◽  
Flow Distortion ◽  
Inlet Flow ◽  
Induction System ◽  
Air Intake ◽  
Inlet Flow Distortion ◽  
The Impact

The design of air induction system is targeting to balance the internal and external flow characteristics as well as the structure and aerodynamic integrity. An optimized air intake design that providing velocity and pressure distributions with least drag and maximum pressure recovery could end up at the expense of higher inlet flow distortion and lower stability margin. Indeed, design requirements and considerations at different operating conditions, such as takeoff, and high AOA maneuvers, could be significantly different from that of cruise and level flight. One of the most challenged operating conditions to be certified for FAR33 & FAR25 requirements is ground crosswind condition, when “Engine” is operating statically on the ground with high crosswind presented. It could accommodate inlet separation or distortion resulted from crosswind, and triggers fan or core stall, as well as induces high fan and/or engine vibrations. Studies of engine inlet compatibility become one of the major tasks required during the engine developing phase. This research is a parametric study of using CFD to evaluate operational characteristics of the air induction system. Comparisons of various inlet designs are made and characterized into four categories, i.e., i) Inlet pressure loss, ii) Nacelle drag, iii) Inlet flow distortion, and iv) Inlet Mach distribution. The objective is to assess the impact of air induction design of turbofan upon inlet compatibility. The research introduces the Kriging model and weighting coefficients to optimize internal total pressure loss and external drag using the isolated nacelle model. Bezier equation was used to fit the optimized curves obtained by changing several control points of the baseline configuration of nacelle. To study the impact of asymmetric lip on flow separation in ground crosswind condition, the paper built crosswind model which introduce a inlet boundary as fan face. Comparisons are then made between the original and optimal nacelle, to show correlation between inlet compatibility and air intake profile.

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