On Cross-Flow Fan Theoretical Performance and Efficiency Curves: An Energy Loss Analysis on Experimental Data

2004 ◽  
Vol 126 (5) ◽  
pp. 743-751 ◽  
Author(s):  
Andrea Toffolo
Keyword(s):  
Experimental Data ◽  
Flow Field ◽  
Cross Flow ◽  
Experimental Measurements ◽  
Loss Analysis ◽  
Numerical Reconstruction ◽  
Global And Local ◽  
Cross Flow Fan ◽  
Systematic Database ◽  
Theoretical Performance

Contrary to conventional turbomachinery, cross-flow fan flow field is non-axisymmetrical and its complex configuration strongly affects performance and efficiency characteristic curves. The formulation of a theory on cross-flow fan operation is made even tougher since the strength and the eccentricity of the vortex that forms within the impeller are deeply influenced by the geometry of the impeller and of the casing as well. In this paper, a numerical reconstruction of the flow field, validated against an extensive systematic database of global and local experimental measurements, is analyzed. The aim is to achieve a general interpretation of performance and efficiency curves, and to lead them back to one theoretical archetype, whatever the fan configuration being considered.

Momentum Exchanges and Energy Transfers in Cross Flow Fans

1987 ◽  
Author(s):  
Joseph Mazur ◽  
Trilochan Singh
Keyword(s):  
Experimental Investigation ◽  
Flow Field ◽  
Cross Flow ◽  
Operating Conditions ◽  
Energy Transfers ◽  
Cross Flow Fan

An experimental investigation of the flow in a cross flow fan at three operating conditions is reported. Velocity and pressure maps for the flow field are presented along with a determination of the momentum exchanges and energy transfers between the blading and the flow field regions.

URANS Simulation of an Appended Hull During Steady Turn With Propeller Represented by an Actuator Disk Model

2011 ◽  
Author(s):  
Charles M. Dai ◽  
Ronald W. Miller
Keyword(s):  
Flow Field ◽  
Cross Flow ◽  
Field Measurements ◽  
Navier Stokes ◽  
Experimental Measurements ◽  
Complex Flow ◽  
Ship Maneuvering ◽  
Disk Model ◽  
Actuator Disk ◽  
Propeller Wake

This paper reports on the comparison between computational simulations and experimental measurements of a surface vessel in steady turning conditions. The primary purpose of these efforts is to support the development of physics-based high fidelity maneuvering simulation tools by providing accurate and reliable hydrodynamic data with relevance to maneuvering performances. Reynolds Averaged Unsteady Navier Stokes Solver (URANS): CFDSHIPIOWA was used to perform simulations for validation purposes and for better understanding of the fundamental flow physics of a hull under maneuvering conditions. The Propeller effects were simulated using the actuator disk model included in CFDShip-Iowa. The actuator disk model prescribes a circumferential averaged body force with axial and tangential components. No propeller generated side forces are accounted for in the model. This paper examines the effects of actuator disk model on the overall fidelity of a RANS based ship maneuvering simulations. Both experiments and simulations provide physical insights into the complex flow interactions between the hull and various appendages, the rudders and the propellers. The experimental effort consists of flow field measurements using Stereo Particle-Image Velocimetry (SPIV) in the stern region of the model and force and moment measurements on the whole ship and on ship components such as the bilge keels, the rudders, and the propellers. Comparisons between simulations and experimental measurements were made for velocity distributions at different transverse planes along the ship axis and different forces components for hull, appendages and rudders. The actuator disk model does not predict any propeller generated side forces in the code and they need to be taken into account when comparing hull and appendages generated side forces in the simulations. The simulations were compared with experimental results and they both demonstrate the cross flow effect on the transverse forces and the propeller slip streams generated by the propellers during steady turning conditions. The hull forces (include hull, bilge keels, skeg, shafting and strut) predictions were better for large turning circle case as compared with smaller turning circle. Despite flow field simulations appear to capture gross flow features qualitatively; detailed examinations of flow distributions reveal discrepancies in predictions of propeller wake locations and secondary flow structures. The qualitative comparisons for the rudders forces also reveal large discrepancies and it was shown that the primary cause of discrepancies is due to poor predictions of velocity inflow at the rudder plane.

A Semipotential Flow Theory for the Dynamics of Cylinder Arrays in Cross Flow

1985 ◽  
Vol 107 (4) ◽  
pp. 500-506 ◽  
Author(s):  
M. P. Paidoussis ◽  
S. J. Price ◽  
D. Mavriplis
Keyword(s):  
Experimental Data ◽  
Flow Field ◽  
Fluid Dynamic ◽  
Dynamic Stiffness ◽  
Cross Flow ◽  
Flow Region ◽  
High Mass ◽  
Duct Flow ◽  
Cylinder Arrays ◽  
Fluidelastic Instability

This paper presents a semianalytical model, involving the superposition of the empirically determined cross flow about a cylinder in an array and the analytically determined vibration-induced flow field in still fluid, for the purpose of analyzing the stability of cylinder arrays in cross flow and predicting the threshold of fluidelastic instability. The flow field is divided into two regions: a viscous bubble of separated flow, and an inviscid, sinuous duct-flow region elsewhere. The only empirical input required by the model in its simplest form is the pressure distribution about a cylinder in the array. The results obtained are in reasonably good accord with experimental data, only for low values of the mass-damping parameter (e.g., for liquid flows), where fluidelastic instability is predominantly caused by negative fluid-dynamic damping terms. For high mass-damping parameters (e.g., for gaseous flows), where fluidelastic instability is evidently controlled by fluid-dynamic stiffness terms, the model greatly overestimates the threshold of fluidelastic instability. However, once measured fluid-dynamic stiffness terms are included in the model, agreement with experimental data is much improved, yielding the threshold flow velocities for fluidelastic instability to within a factor of 2 or better.

Numerical Simulation and Experimental Verification of a Vertical Jet in Swirling Cross-Flow

2012 ◽  
Vol 235 ◽  
pp. 90-95
Author(s):  
Shun Li Kou ◽  
Guo Neng Li
Keyword(s):  
Experimental Data ◽  
Flow Field ◽  
Flow Velocity ◽  
Velocity Ratio ◽  
Cross Flow ◽  
Tunable Laser ◽  
Simulation Method ◽  
Numerical Results ◽  
Cross Flow Velocity ◽  
Vertical Jet

In order to investigate the bending and mixing characteristics in a vertical jet issuing into a swirling cross-flow, large eddy simulation method was employed to simulate the flow field of a jet in swirling cross-flow. Several jet to cross-flow velocity ratios (r=15, 30, 60) were investigated. The numerical results were compared to the experimental data measured from a phase tunable laser and CCD system. The Reynolds number Re based on the characteristic length of the cross-flow tunnel and the jet velocity lies between 22,537 and 90,146. Numerical results showed that the penetration depth of the vertical jet maintains nearly unchanged when the jet to cross-flow velocity ratio is large enough (r>30), which agreed well with the experimental data and was different from the flow field of jet in straight cross-flow. On the other hand, the case of r=60 obtained largest spread width, and the spread width maintains relatively large in a large penetration zone, which is consist with the experimental finding.

Numerical Simulation of the 3D Turbulent Flow Field in a Cross-Flow Fan Used in the Air Conditioner

2012 ◽  
Vol 538-541 ◽  
pp. 462-465 ◽  
Author(s):  
Yong Chao Zhang ◽  
Qing Guang Chen ◽  
Wei Bin Wang ◽  
Bin Xie
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Turbulent Flow ◽  
3D Model ◽  
Cross Flow ◽  
Internal Flow ◽  
Air Conditioner ◽  
Full Field ◽  
Overall Performance ◽  
Cross Flow Fan

Aiming at a cross-flow fan used in some kind of air conditioner, the full field 3D model was built, and the numerical simulation of the inner turbulent flow under design condition is resented. The results display the characteristics of flow field in the cross-flow fan, especially the velocity field, pressure field and the velocity distributing before the evaporator. The results can provide basis for optimizing the fan design and the internal flow, and have important value of engineering applications in the increase of the overall performance in operation.

Aerodynamic and Aeroacoustic Performance of Cross Flow Fan With Inlet Guide Vane

2012 ◽  
Author(s):  
Jie Tian ◽  
Hua Ouyang ◽  
Kangjie Sun ◽  
Xiaocheng Zhu ◽  
Zhiming Zheng ◽  
...  
Keyword(s):  
Flow Field ◽  
Power Consumption ◽  
Flow Rate ◽  
Cross Flow ◽  
Internal Flow ◽  
Inlet Guide Vane ◽  
Inlet Flow ◽  
Blade Passing Frequency ◽  
Different Types ◽  
Cross Flow Fan

Effect of internal flow field and aeroacoustics of cross flow fan (CFF) with different types of inlet guide vanes (IGVs) is analyzed by experimental and numerical methods. With the base type of IGV (BA), pressure rise of CFF is increased at the same flow rate as the one without IGV (Prototype-No IGV). However, power consumption of CFF with IGV is also increased at the same flow rate. Moreover, total sound pressure level of CFF with IGV is highly increased by 9dBA and more than 15 dBA increase of SPL is also found at the first three harmonics of blade passing frequency of CFF. Internal flow field of CFF with different types of IGVs is analyzed by numerical method. Design method of IGV used in CFF is discussed based on simulated results and improved IGV (OP) is manufactured and measured. Compared with BA, OP has lower flow rate and highly decreased noise not only in total SPL but also in the first three harmonics of blade passing frequency. Compared with the prototype, OP has a little larger noise but lower power consumption benefit at the same flow rate. According to the analysis, it can be concluded that inlet flow condition of CFF is improved with suitable IGV and inlet flow separation is reduced. Benefit of large decrease of power consumption with a little increase of noise penalty of CFF can be achieved with careful design of IGV. Moreover, alteration of airfoil in CFF from single arc to more complex airfoils is convenient to design with the help of IGV.

scholarly journals Cross-Flow Tidal Turbines with Highly Flexible Blades—Experimental Flow Field Investigations at Strong Fluid–Structure Interactions

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 797
Author(s):  
Stefan Hoerner ◽  
Iring Kösters ◽  
Laure Vignal ◽  
Olivier Cleynen ◽  
Shokoofeh Abbaszadeh ◽  
...  
Keyword(s):  
Flow Field ◽  
High Speed ◽  
Cross Flow ◽  
Speed Ratio ◽  
Fluid Structure Interactions ◽  
Dimensional Parameter ◽  
Fluid Structure ◽  
Passive Flow Control ◽  
Tidal Turbines ◽  
Tidal Turbine

Oscillating hydrofoils were installed in a water tunnel as a surrogate model for a hydrokinetic cross-flow tidal turbine, enabling the study of the effect of flexible blades on the performance of those devices with high ecological potential. The study focuses on a single tip-speed ratio (equal to 2), the key non-dimensional parameter describing the operating point, and solidity (equal to 1.5), quantifying the robustness of the turbine shape. Both parameters are standard values for cross-flow tidal turbines. Those lead to highly dynamic characteristics in the flow field dominated by dynamic stall. The flow field is investigated at the blade level using high-speed particle image velocimetry measurements. Strong fluid–structure interactions lead to significant structural deformations and highly modified flow fields. The flexibility of the blades is shown to significantly reduce the duration of the periodic stall regime; this observation is achieved through systematic comparison of the flow field, with a quantitative evaluation of the degree of chaotic changes in the wake. In this manner, the study provides insights into the mechanisms of the passive flow control achieved through blade flexibility in cross-flow turbines.

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