scholarly journals Assessment of Steady and Unsteady Full Annulus Simulations Predictivity for a Low-Speed Axial Fan at Load-Controlled Windmill

2018 ◽  
Vol 2018 ◽  
pp. 1-12
Author(s):  
Aurélie Ortolan ◽  
Suk-Kee Courty-Audren ◽  
Nicolas Binder ◽  
Xavier Carbonneau ◽  
Yannick Bousquet ◽  
...  
Keyword(s):  
Numerical Analysis ◽  
Velocity Field ◽  
Detailed Analysis ◽  
Added Value ◽  
Classical Approach ◽  
Axial Fan ◽  
Low Speed ◽  
Unsteady Simulation ◽  
Temporal Periodicity

A steady mixing plane approach is compared with the time-averaged solution of an unsteady full annulus calculation for a conventional fan operating at load-controlled windmill. The objective is to assess the added value of a complete unsteady calculation compared with a more classical approach, especially concerning the effect of the spatial and temporal periodicity release in such an unusual operation as windmill. Experiment with global steady measurements and rotor radial characterizations was conducted. Numerical analysis demonstrates that windmilling global performances obtained with the time-averaged solution of the unsteady simulation are not far different from the steady case, especially in the rotor. Some differences arise in the stator, particularly regarding the velocity field. Temporal periodicity release in this row has clearly a significant effect on the flow unsteady response. A detailed analysis highlights that generic patterns of windmilling flows recorded on a steady approach are also reported on the unsteady case.

Selection of Airfoils for Vertical Axis Wind Turbines for Low Speed, Low Altitude Regions of Central India

2017 ◽  
Vol 7 (11) ◽  
pp. 113
Author(s):  
Abhineet Singh ◽  
Sonali Mitra ◽  
S.V.H. Nagendra ◽  
Pragyan Jain
Keyword(s):  
Numerical Analysis ◽  
Central India ◽  
Vertical Axis ◽  
College Campus ◽  
Low Speed ◽  
Vertical Axis Wind Turbines ◽  
Low Altitude ◽  
Naca 0015 ◽  
Naca 0012 ◽  
Selection Of

The present paper deals with the selection of airfoil profile for VAWTs which is to be installed in the college campus, located in Central India region. Both experimental and numerical analysis he been carried out for the three selected airfoils, NACA 0012, NACA 0015 & S2027. The results show a good correlation with the existing literature. Airfoil profile S2027 has been chosen which best suits our condition. 

scholarly journals Cancellation exponents and multifractal scaling laws in the solar wind magnetohydrodynamic turbulence

1996 ◽  
Vol 14 (8) ◽  
pp. 777-785 ◽  
Author(s):  
V. Carbone ◽  
R. Bruno
Keyword(s):  
Solar Wind ◽  
Velocity Field ◽  
Scaling Laws ◽  
Interplanetary Medium ◽  
Low Frequency ◽  
Scaling Exponent ◽  
Magnetohydrodynamic Turbulence ◽  
Low Speed ◽  
Multifractal Scaling

Abstract. Some signed measures in turbulence are found to be sign-singular, that is their sign reverses continuously on arbitrary finer scales with a reduction of the cancellation between positive and negative contributions. The strength of the singularity is characterized by a scaling exponent κ, the cancellation exponent. In the present study by using some turbulent samples of the velocity field obtained from spacecraft measurements in the interplanetary medium, we show that sign-singularity is present everywhere in low-frequency turbulent samples. The cancellation exponent can be related to the characteristic scaling laws of turbulence. Differences in the values of κ, calculated in both high- and low-speed streams, allow us to outline some physical differences in the samples with different velocities.

Numerical Analysis of Non-Radial Blading in a Low Speed and Low Pressure Turbine for Electric Turbocompounding Applications

2021 ◽  
Author(s):  
Eva Alvarez-Regueiro ◽  
Esperanza Barrera-Medrano ◽  
Ricardo Martinez-Botas ◽  
Srithar Rajoo
Keyword(s):  
Numerical Analysis ◽  
Numerical Simulations ◽  
Thermal Stresses ◽  
Waste Heat ◽  
Pressure Ratio ◽  
Low Pressure ◽  
Turbine Rotor ◽  
Operating Conditions ◽  
Blade Angle ◽  
Low Speed

Abstract This paper presents a CFD-based numerical analysis on the potential benefits of non-radial blading turbine for low speed-low pressure applications. Electric turbocompounding is a waste heat recovery technology consisting of a turbine coupled to a generator that transforms the energy left over in the engine exhaust gases, which is typically found at low pressure, into electricity. Turbines designed to operate at low specific speed are ideal for these applications since the peak efficiency occurs at lower pressure ratios than conventional high speed turbines. The baseline design consisted of a vaneless radial fibre turbine, operating at 1.2 pressure ratio and 28,000rpm. Experimental low temperature tests were carried out with the baseline radial blading turbine at nominal, lower and higher pressure ratio operating conditions to validate numerical simulations. The baseline turbine incidence angle effect was studied and positive inlet blade angle impact was assessed in the current paper. Four different turbine rotor designs of 20, 30, 40 and 50° of positive inlet blade angle are presented, with the aim to reduce the losses associated to positive incidence, specially at midspan. The volute domain was included in all CFD calculations to take into account the volute-rotor interactions. The results obtained from numerical simulations of the modified designs were compared with those from the baseline turbine rotor at design and off-design conditions. Total-to-static efficiency improved in all the non-radial blading designs at all operating points considered, by maximum of 1.5% at design conditions and 5% at off-design conditions, particularly at low pressure ratio. As non-radial fibre blading may be susceptible to high centrifugal and thermal stresses, a structural analysis was performed to assess the feasibility of each design. Most of non-radial blading designs showed acceptable levels of stress and deformation.

A Three-Dimensional Inverse Method for Turbomachinery: Part I—Theory

1990 ◽  
Vol 112 (3) ◽  
pp. 346-354 ◽  
Author(s):  
J. E. Borges
Keyword(s):  
Velocity Field ◽  
Inverse Method ◽  
Three Dimensional ◽  
Tangential Velocity ◽  
Inverse Methods ◽  
Meridional Section ◽  
Low Speed ◽  
Present Procedure ◽  
Blade Row ◽  
The Mean

There are surprisingly few inverse methods described in the literature that are truly three dimensional. Here, one such method is presented. This technique uses as input a prescribed distribution of the mean swirl, i.e., radius times mean tangential velocity, given throughout the meridional section of the machine. In the present implementation the flow is considered inviscid and incompressible and is assumed irrotational at the inlet to the blade row. In order to evaluate the velocity field inside the turbomachine, the blades (supposed infinitely thin) are replaced by sheets of vorticity, whose strength is related to the specified mean swirl. Some advice on the choice of a suitable mean swirl distribution is given. In order to assess the usefulness of the present procedure, it was decided to apply it to the design of an impeller for a low-speed radial-inflow turbine. The results of the tests are described in the second part of this paper.

scholarly journals Numerical analysis of axial fan characteristics

Mechanik ◽  
2018 ◽  
Vol 91 (7) ◽  
pp. 606-608
Author(s):  
Stanisław Wrzesień ◽  
Michał Frant ◽  
Maciej Majcher
Keyword(s):  
Numerical Analysis ◽  
Numerical Methods ◽  
Flow Rate ◽  
Total Pressure ◽  
Volumetric Flow Rate ◽  
Total Efficiency ◽  
Axial Fan ◽  
Axial Fans ◽  
Basic Characteristics

The paper presents an analysis and comparison of basic characteristics of axial fans, both analytically and numerically. Such characteristics are: the characteristics of the total pressure, power and total efficiency as a function of the volumetric flow rate. The presented results showed significant quantitative and qualitative differences in the characteristics obtained by two methods. The usefulness of numerical methods in relation to the results of the initial analytical project was confirmed.

Influence of Circumferential Inflow Distortion on the Performance of a Low Speed, High Aspect Ratio Contra Rotating Axial Fan

2014 ◽  
Vol 136 (7) ◽  
Author(s):  
Chetan Mistry ◽  
A. M. Pradeep
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Rotational Speed ◽  
Total Pressure ◽  
Flow Behavior ◽  
Axial Fan ◽  
Low Speed ◽  
Overall Performance ◽  
Design Speed ◽  
Inflow Conditions

The influence of circumferential inflow distorted on the performance and flow behavior of a high aspect ratio, low speed contra rotating fan is reported in this paper. The total pressure at the inlet is artificially distorted by means of 90 deg mesh sector with a porosity of 0.70. The performance of the contra rotating fan was studied under different speed combinations of the two rotors under clean and distorted inflow conditions. Detailed flow analyses were conducted under design and off-design conditions. In order to understand the effect of distortion and its extent, the distortion sector was rotated circumferentially at intervals of 15 deg to cover the entire annulus. Detailed measurements of the total pressure, velocity components, and flow angles were carried out at the inlet of the first rotor, between the two rotors, and at the exit of the second rotor. The study reveals a few interesting aspects on the effect of inflow distortion on the performance of a contra-rotating stage. For the design speed combination and lower rotational speed of rotor-2, a reduction in the overall operating range with a shift of the peak pressure point towards higher mass flow rate, was observed. It is observed that the effect of inflow distortion at the inlet of rotor-1 gets transferred in the direction of rotor-1 rotation and spreads across the entire annulus. The opposite sense of rotation of rotor-2 causes the distortion effect to get transferred in the direction of rotation of rotor-2 with an associated reduction in the total pressure near the hub. It is observed that a higher rotational speed of the second rotor has a beneficial effect on the overall performance due to the strong suction by generated higher rotational speed of rotor-2.

Performance of a Low Speed Axial Fan Under Distortion: An Experimental Investigation

2021 ◽  
Author(s):  
Sumit Tambe ◽  
Ugaitz Bartolom\xe9 Oseguera ◽  
Arvind Gangoli Rao
Keyword(s):  
Experimental Investigation ◽  
Axial Fan ◽  
Low Speed

Performance of a Low Speed Axial Fan Under Distortion: An Experimental Investigation

2020 ◽  
Author(s):  
Sumit Tambe ◽  
Ugaitz Bartolomé Oseguera ◽  
Arvind Gangoli Rao
Keyword(s):  
Flow Field ◽  
Symmetry Plane ◽  
Vortex Pair ◽  
Axial Fan ◽  
Low Speed ◽  
Fan Performance ◽  
Fuel Burn ◽  
Flow Phenomena ◽  
Order Of Magnitude ◽  
Distortion Index

Abstract In the pursuit of reducing the fuel burn, future aircraft configurations will feature several types of improved propulsion systems, e.g. embedded engines with boundary layer ingestion, high-bypass ratio engines with short intakes, etc. Depending on the design and phase of flight, the engine fan will encounter inflow distortion of varying strength, and fan performance will be adversely affected. Therefore, investigation of the flow phenomena causing performance losses in fan and distortion interaction is important. This experimental study shows the effect of varying distortion index on four aspects of fan performance: distortion topology, upstream redistribution, performance curve, and flow unsteadiness. A low speed fan is tested under 60° circumferential distortion of varying strength, generated using distortion screens. The flow field in the upstream redistribution region is measured using PIV (planar and stereo). The fan performance is obtained using total pressure measurements. The noise spectra measured by a microphone are used to quantify the unsteadiness in the flow field. The distortion index (DC60) varies linearly with the grid porosity at constant wall thickness and aspect ratio of the grid cells. However, the distortion topology is significantly different as a stream-wise vortex pair appears in distorted flow at higher DC60. The vortices are stronger at higher DC60, but their order of magnitude is much lower than the circulation corresponding to fan itself. The spinner, distortion index and topology significantly affect the upstream redistribution mechanism. The vortex pair redistributes the flow which results in lower asymmetry in the symmetry plane. With increasing distortion, the performance is reduced and the unsteadiness is increased.

Numerical Analysis of the Acoustic Field of a Ducted Axial Fan at Varying Tip Clearances

2019 ◽  
Vol 105 (1) ◽  
pp. 43-55 ◽  
Author(s):  
S. M. Alavi Moghadam ◽  
M. Meinke ◽  
W. Schröder
Keyword(s):  
Numerical Analysis ◽  
Acoustic Field ◽  
Axial Fan
Sign in / Sign up

Export Citation Format

Share Document