Pressure flow field and inlet flow distortion metrics reconstruction from velocity data

This paper reports a study of the combined effects of swirl and circumferential inlet flow distortion on the flow field of an axial flow fan stage. The study involves steady state measurements of the flow field at the rotor inlet, exit and the stator exit of the single stage axial flow fan subjected to circumferential inlet flow distortion and swirl. Flow field survey was done at two flow coefficients, namely, ϕ = 0.45 and ϕ = 0.285. The flow at the inlet to the rotor was measured using a three hole pressure probe and five hole pressure probes were used at the rotor and stator exits. The study indicated that at the design flow coefficient swirl had caused deterioration of the performance in addition to that caused by distortion. In addition, the attenuation of distortion was high in the presence of swirl.

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Using Computational Fluid Dynamics to Simulate Multiple Axial Flow Fans in Air-Cooled Steam Condensers

ASME 2011 Power Conference, Volume 1 ◽

10.1115/power2011-55057 ◽

2011 ◽

Author(s):

S. J. van der Spuy ◽

T. W. von Backstro¨m ◽

D. G. Kro¨ger

Keyword(s):

Fluid Dynamics ◽

Computational Fluid Dynamics ◽

Flow Field ◽

Axial Flow ◽

Test Facility ◽

Pressure Jump ◽

Flow Distortion ◽

Inlet Flow ◽

Actuator Disc ◽

Inlet Flow Distortion

The large number of axial flow fans used in modern dry-cooled power plant air-cooled steam condensers necessitates the use of simplified numerical models when simulating the perfromance of such a condenser. Three simplified fan models are presented and implemented using computational fluid dynamics (CFD). These are referred to as the pressure jump, actuator disc and extended actuator disc models. The paper compares the CFD results obtained using these three models to experimental results obtained on a multiple axial flow fan test facility. The test facility was configured in such a way that it could accommodate different fan platform heights to vary the level of inlet flow distortion for the facility. The simulations show that the general flow field adjacent to the facility is independent of the simplified fan model that is used in the CFD analysis. However, the predicted flow field directly upstream of the edge fan varies according to the method used to represent the fan. It is also found that the more sophisticated fan models give a more accurate estimate of fan operation at higher levels of inlet flow distortion than the less sophisticated fan models.

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Inlet flow distortion in turbomachinery - Comparison of theory and experiment in a transonic fan stage

AIAA Journal ◽

10.2514/3.8327 ◽

1983 ◽

Vol 21 (12) ◽

pp. 1769-1770 ◽

Cited By ~ 1

Author(s):

B. S. Seidel ◽

M. D. Matwey

Keyword(s):

Flow Distortion ◽

Inlet Flow ◽

Inlet Flow Distortion ◽

Transonic Fan ◽

Theory And Experiment

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Investigation of Flows in Rectangular Diffusers With Inlet Flow Distortion

Volume 1: Turbomachinery ◽

10.1115/82-gt-67 ◽

1982 ◽

Cited By ~ 1

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.

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

ASME 2007 Power Conference ◽

10.1115/power2007-22048 ◽

2007 ◽

Cited By ~ 1

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.

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

Volume 1A: Aircraft Engine; Fans and Blowers ◽

10.1115/gt2014-26249 ◽

2014 ◽

Cited By ~ 2

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.

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Inlet Flow Distortion

Propulsion and Power ◽

10.1007/978-3-319-75979-1_6 ◽

2018 ◽

pp. 249-267 ◽

Cited By ~ 1

Author(s):

Joachim Kurzke ◽

Ian Halliwell

Keyword(s):

Flow Distortion ◽

Inlet Flow ◽

Inlet Flow Distortion

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Nacelle Aerodynamic Optimization and Inlet Compatibility

Volume 1: Aircraft Engine; Fans and Blowers; Marine ◽

10.1115/gt2015-42346 ◽

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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