Aerodynamic Design of Exo-Skeletal Engine Fan Blades

2005 ◽  
Author(s):  
Galib H. Abumeri ◽  
James F. Schmidt ◽  
Christos C. Chamis
Keyword(s):  
Rotor Blade ◽  
Subsonic Flow ◽  
Computational Simulation ◽  
Leading Edge ◽  
Boundary Layer Separation ◽  
Rotor Blades ◽  
Aerodynamic Design ◽  
Design Code ◽  
Performance Map ◽  
Fan Blade

The aerodynamic feasibility of fan rotor blades for the revolutionary Exo-Skeletal Engine (ESE) is assessed for a subsonic mission using the NASA Engine Structures Technology Benefit Estimator (EST/BEST) computational simulation system. The ESE calls for the elimination of the shafts and disks completely from the engine center, and places the attachment of the rotor blades in spanwise compression to a rotating casing. The preliminary aerodynamic design of the fan rotor blade estimated an overall adiabatic efficiency of 91.8%. The flow is supersonic near the blade leading edge but quickly transitions into a subsonic flow without any turbulent boundary layer separation on the blade. The performance map for the fan rotor blade is calculated using a 2D off-design code. The results show that the ESE fan blade has reasonable stall and choke margins. It will be demonstrated in this paper that a computational simulation capability is readily available to evaluate new and revolutionary technology such as the ESE.

scholarly journals Aerodynamic Design and Testing of an Improved 1st Stage Compressor Rotor for a Heavy Duty Gas Turbine

1981 ◽  
Author(s):  
I. Ispas ◽  
H. J. Zollinger
Keyword(s):  
Gas Turbine ◽  
Rotor Blade ◽  
Aerodynamic Design ◽  
Heavy Duty ◽  
High Loss ◽  
Compressor Rotor ◽  
Performance Map ◽  
Computer Codes ◽  
Heavy Duty Gas Turbine ◽  
Design And Testing

To evaluate the potential of the compressor of Sulzer’s Typ 3 gas turbine, a series of engine tests was analyzed with two computer codes. The comparison between measured and calculated performance map are given in the paper. The design goal was to find modifications, which can be applied easily to already operating engines. The simplest option-increase of shaft speed with the existing blades-would have caused high loss due to increased tip Mach number. The calculation revealed, that a newly designed first rotor blade is an appropriate modification to increase massflow and efficiency. No further change is required, because the calculations indicate, that all subsequent stages operate at near optimum incidence. The calculations were confirmed experimentally. The paper presents the new rotor blade and its influence on the compressor calculated and measured performance.

scholarly journals A Study on Axial Skewing Effect of a Turbine Stator by 3-D Navier-Stokes Analysis

1996 ◽  
Author(s):  
Naixing Chen ◽  
Qian Zhou ◽  
Weiguang Huang
Keyword(s):  
Leading Edge ◽  
Boundary Layer Separation ◽  
Engineering Thermophysics ◽  
Aerodynamic Characteristics ◽  
Radial Force ◽  
Rotor Blades ◽  
Navier Stokes ◽  
Flow Angle ◽  
Turbine Stator ◽  
Stator Vane

The objective of the present paper is to investigate the axial skewing effect of a turbine stator blading on its aerodynamic characteristics systematically, to find the possibility for reducing the secondary losses by using axially skewed bladings and to understand better its flow physics in turbomachinery. In the present paper a typical turbine stator blading is applied as an example to generate a set of axially skewed bladings for systematical study and illustration of their differences of aerodynamics characteristics. The paper gives the procedure for generating different forward-skewed and backward-skewed blades with the same profile sections at the same radius and the numerical method used is also described briefly. The method is based on the 3-D time-marching finite volume Navier-Stokes solution and was developed by the Institute of Engineering Thermophysics, Chinese Academy of Sciences. The turbulence model proposed by Baldwin and Lomax is used here for predicting the effective viscosity. The calculated results and their comparisons are also given in the present paper. On the basis of the analysis it is shown that the appropriate use of skewed blades gives designers another possibility to control the flow in the blade channel. By adopting forward-skewed blades to replace the straight blades can be reduced the blade loading near the leading edge and in the central part of the span. It is also found that the pressure gradient at the endwall of forward-skewed blading yields the radial force that enables to avoid the boundary layer separation from the endwall. The axial skew of blade enables to restrain the strength of the secondary flow. Therefore, the total pressure loss can be reduced. An attention should be paid: if the skewed blade for stator is chosen to be used, the radial distribution of the outlet flow angle from stator vane is required to meet the optimal incidence satisfaction to the rotor blades. Otherwise, it results in the reduction of efficiency.

The Supersonic Turbine: A Design and Cascade Study

1971 ◽  
Author(s):  
Irving Fruchtman
Keyword(s):  
Rotor Blade ◽  
Leading Edge ◽  
Rotor Blades ◽  
Minimum Length ◽  
Two Dimensional ◽  
Turbine Stage ◽  
Low Loss ◽  
Free Vortex ◽  
Cooling Flows ◽  
Mach Numbers

Fundamental concepts are given for the design of a turbine stage with supersonic gas velocities relative to the blading. Minimum-length nozzles (stators) and free-vortex-type rotor blades are specified and a correlation of their published performance is given. A blade selection chart is given to provide a method for obtaining appropriate low-loss rotor blade configurations. A series of two-dimensional cascade experiments are described in which the performance of film-cooled, blunted leading-edge rotor blades were measured. Blade performance is given over a range of inlet Mach numbers and cooling flows.

scholarly journals Active Thermography for the Detection of Sub-Surface Defects on a Curved and Coated GFRP-Structure

2021 ◽  
Vol 11 (20) ◽  
pp. 9545
Author(s):  
Friederike Jensen ◽  
Marina Terlau ◽  
Michael Sorg ◽  
Andreas Fischer
Keyword(s):  
Rotor Blade ◽  
Test Specimen ◽  
Surface Defects ◽  
Leading Edge ◽  
Turbine Rotor ◽  
Rotor Blades ◽  
Contactless Measurement ◽  
Viewing Angle ◽  
Pulse Thermography ◽  
Long Pulse

Initial defects, for example, those occurring during the production of a rotor blade, encourage early damages such as rain erosion at the leading edge of wind turbine rotor blades. To investigate the potential that initial defects have for early damage, long-pulse thermography as a non-destructive and contactless measurement technique is applied to a strongly curved and coated test specimen for the first time. This specimen is similar in structural size and design to a rotor blade leading edge and introduced with sub-surface defects whose diameters range between 2mm and 3.5mm at depths between 1.5mm and 2.5mm below the surface. On the curved and coated test specimen, sub-surface defects with a depth-to-diameter ratio of up to 1.04 are successfully detected. In particular, defects are also detectable when being observed from a non-perpendicular viewing angle, where the intensity of the defects decreases with increasing viewing angle due to the strong surface curvature. In conclusion, long-pulse thermography is suitable for the detection of sub-surface defects on coated and curved components and is therefore a promising technique for the on-site application during inspection of rotor blade leading edges.

scholarly journals An Experimental Investigation of the Convective Heat Transfer on a Small Helicopter Rotor with Anti-Icing and De-Icing Test Setups

Aerospace ◽  
2021 ◽  
Vol 8 (4) ◽  
pp. 96
Author(s):  
Abdallah Samad ◽  
Eric Villeneuve ◽  
Caroline Blackburn ◽  
François Morency ◽  
Christophe Volat
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Leading Edge ◽  
Liquid Water Content ◽  
Rotor Blades ◽  
Direct Result ◽  
Average Error ◽  
Good Prediction ◽  
Series Of Experiments

Successful icing/de-icing simulations for rotorcraft require a good prediction of the convective heat transfer on the blade’s surface. Rotorcraft icing is an unwanted phenomenon that is known to cause flight cancelations, loss of rotor performance and severe vibrations that may have disastrous and deadly consequences. Following a series of experiments carried out at the Anti-icing Materials International Laboratory (AMIL), this paper provides heat transfer measurements on heated rotor blades, under both the anti-icing and de-icing modes in terms of the Nusselt Number (Nu). The objective is to develop correlations for the Nu in the presence of (1) an ice layer on the blades (NuIce) and (2) liquid water content (LWC) in the freestream with no ice (NuWet). For the sake of comparison, the NuWet and the NuIce are compared to heat transfer values in dry runs (NuDry). Measurements are reported on the nose of the blade-leading edge, for three rotor speeds (Ω) = 500, 900 and 1000 RPM; a pitch angle (θ) = 6°; and three different radial positions (r/R), r/R = 0.6, 0.75 and 0.95. The de-icing tests are performed twice, once for a glaze ice accretion and another time for rime ice. Results indicate that the NuDry and the NuWet directly increased with V∝, r/R or Ω, mainly due to an increase in the Reynolds number (Re). Measurements indicate that the NuWet to NuDry ratio was always larger than 1 as a direct result of the water spray addition. NuIce behavior was different and was largely affected by the ice thickness (tice) on the blade. However, the ice acted as insulation on the blade surface and the NuIce to NuDry ratio was always less than 1, thus minimizing the effect of convection. Four correlations are then proposed for the NuDry, the NuWet and the NuIce, with an average error between 3.61% and 12.41%. The NuDry correlation satisfies what is expected from heat transfer near the leading edge of an airfoil, where the NuDry correlates well with Re0.52.

scholarly journals Leading Edge Blowing to Mimic and Enhance the Serration Effects for Aerofoil

2021 ◽  
Vol 11 (6) ◽  
pp. 2593
Author(s):  
Yasir Al-Okbi ◽  
Tze Pei Chong ◽  
Oksana Stalnov
Keyword(s):  
Boundary Layer ◽  
Angle Of Attack ◽  
Leading Edge ◽  
Boundary Layer Separation ◽  
Shear Instability ◽  
Vortical Flow ◽  
High Angle ◽  
High Angle Of Attack ◽  
Layer Separation ◽  
Aerodynamic Performances

Leading edge serration is now a well-established and effective passive control device for the reduction of turbulence–leading edge interaction noise, and for the suppression of boundary layer separation at high angle of attack. It is envisaged that leading edge blowing could produce the same mechanisms as those produced by a serrated leading edge to enhance the aeroacoustics and aerodynamic performances of aerofoil. Aeroacoustically, injection of mass airflow from the leading edge (against the incoming turbulent flow) can be an effective mechanism to decrease the turbulence intensity, and/or alter the stagnation point. According to classical theory on the aerofoil leading edge noise, there is a potential for the leading edge blowing to reduce the level of turbulence–leading edge interaction noise radiation. Aerodynamically, after the mixing between the injected air and the incoming flow, a shear instability is likely to be triggered owing to the different flow directions. The resulting vortical flow will then propagate along the main flow direction across the aerofoil surface. These vortical flows generated indirectly owing to the leading edge blowing could also be effective to mitigate boundary layer separation at high angle of attack. The objectives of this paper are to validate these hypotheses, and combine the serration and blowing together on the leading edge to harvest further improvement on the aeroacoustics and aerodynamic performances. Results presented in this paper strongly indicate that leading edge blowing, which is an active flow control method, can indeed mimic and even enhance the bio-inspired leading edge serration effectively.

Influence of Leading Edge Fillet and Nonaxisymmetric Contoured Endwall on Turbine NGV Exit Flow Structure and Interactions With the Rim Seal Flow

2013 ◽  
Author(s):  
Özhan H. Turgut ◽  
Cengiz Camcı
Keyword(s):  
Flow Structure ◽  
Total Pressure ◽  
Guide Vane ◽  
Axial Flow ◽  
Leading Edge ◽  
Turbine Rotor ◽  
Rotor Blades ◽  
Constant Thickness ◽  
Computational Evaluation ◽  
Nozzle Guide

Three different ways are employed in the present paper to reduce the secondary flow related total pressure loss. These are nonaxisymmetric endwall contouring, leading edge (LE) fillet, and the combination of these two approaches. Experimental investigation and computational simulations are applied for the performance assessments. The experiments are carried out in the Axial Flow Turbine Research Facility (AFTRF) having a diameter of 91.66cm. The NGV exit flow structure was examined under the influence of a 29 bladed high pressure turbine rotor assembly operating at 1300 rpm. For the experimental measurement comparison, a reference Flat Insert endwall is installed in the nozzle guide vane (NGV) passage. It has a constant thickness with a cylindrical surface and is manufactured by a stereolithography (SLA) method. Four different LE fillets are designed, and they are attached to both cylindrical Flat Insert and the contoured endwall. Total pressure measurements are taken at rotor inlet plane with Kiel probe. The probe traversing is completed with one vane pitch and from 8% to 38% span. For one of the designs, area averaged loss is reduced by 15.06%. The simulation estimated this reduction as 7.11%. Computational evaluation is performed with the rotating domain and the rim seal flow between the NGV and the rotor blades. The most effective design reduced the mass averaged loss by 1.28% over the whole passage at the NGV exit.

Analysis of the Stress Intensity of Rotor Blade in Hydraulic Retarder

2011 ◽  
Vol 179-180 ◽  
pp. 1453-1458
Author(s):  
Jun Yan
Keyword(s):  
Stress Intensity ◽  
Coordinate Transformation ◽  
Rotor Blade ◽  
Distribution Functions ◽  
Rotor Blades ◽  
Fea Model ◽  
Numeric Simulation ◽  
Braking Torque ◽  
Flow Pressure ◽  
Hydraulic Retarder

Based on CFD numeric simulation for hydraulic retarder under full-filled condition, the pressure distribution functions of the rotor blades surfaces are approached by coordinate transformation and surface fitting. Through the APDL program, loads which involved not only centrifugal force but also flow pressure are loaded on the FEA model according to the approximating pressure functions. The FEA model is solved and the blades strength is analyzed more accurately. Noted moment and speed, that is respectively 4000 N • m and 1343rpm, is determined under the promise of blade strength, and controlling strategy is made that constant braking torque shoud be carried out when speed is higher than noted value .

Study of Gas Flow in Micronozzles Using an Unstructured DSMC Method

2009 ◽  
Author(s):  
Ehsan Roohi ◽  
Masoud Darbandi ◽  
Vahid Mirjalili
Keyword(s):  
Boundary Layer ◽  
Knudsen Number ◽  
Gas Flow ◽  
Subsonic Flow ◽  
Flow Behavior ◽  
Boundary Layer Separation ◽  
Back Pressure ◽  
Viscous Force ◽  
Dsmc Method ◽  
Wide Range

The current research uses an unstructured direct simulation Monte Carlo (DSMC) method to numerically investigate supersonic and subsonic flow behavior in micro convergent–divergent nozzle over a wide range of rarefied regimes. The current unstructured DSMC solver has been suitably modified via using uniform distribution of particles, employing proper subcell geometry, and benefiting from an advanced molecular tracking algorithm. Using this solver, we study the effects of back pressure, gas/surface interactions (diffuse/specular reflections), and Knudsen number, on the flow field in micronozzles. We show that high viscous force manifesting in boundary layers prevents supersonic flow formation in the divergent section of nozzles as soon as the Knudsen number increases above a moderate magnitude. In order to accurately simulate subsonic flow at the nozzle outlet, it is necessary to add a buffer zone to the end of nozzle. If we apply the back pressure at the outlet, boundary layer separation is observed and a region of backward flow appears inside the boundary layer while the core region of inviscid flow experiences multiple shock-expansion waves. We also show that the wall boundary layer prevents forming shocks in the divergent part. Alternatively, Mach cores appear at the nozzle center followed by bow shocks and an expansion region.

Generation Mechanism of Broadband Whoosh Noise in an Automotive Turbocharger Centrifugal Compressor

2021 ◽  
pp. 1-35
Author(s):  
Rick Dehner ◽  
Pranav Sriganesh ◽  
Ahmet Selamet ◽  
Keith Miazgowicz
Keyword(s):  
Centrifugal Compressor ◽  
Combustion Engine ◽  
Three Dimensional ◽  
Leading Edge ◽  
Broadband Noise ◽  
Rotor Blades ◽  
Generation Mechanism ◽  
Primary Concern ◽  
Frequency Range ◽  
Modal Decomposition

Abstract The present study focuses on the acoustics of a turbocharger centrifugal compressor from a spark-ignition internal combustion engine. Whoosh noise is typically the primary concern for this type of compressor, which is loosely characterized by broadband sound elevation in the 4 to 13 kHz range. To identify the generation mechanism of broadband whoosh noise, the present study combines three approaches: three-dimensional (3D) computational fluid dynamics (CFD) predictions, experiments, and modal decomposition of 3D CFD results. After establishing the accuracy of predictions, flow structures and time-resolved pressures are closely examined in the vicinity of the main blade leading edge. This reveals the presence of rotating instabilities that may interact with the rotor blades to generate noise. An azimuthal modal decomposition is performed on the predicted pressure field to determine the number of cells and the frequency content of these rotating instabilities. The strength of the rotating instabilities and the frequency range in which noise is generated as a consequence of the rotor-rotating instability interaction, is found to correspond well with the qualitative trend of the whoosh noise that is measured several duct diameters upstream of the rotor blades. The variation of whoosh frequency range between low and high rotational speeds is interpreted through this analysis. It is also found that the whoosh noise primarily propagates along the duct as acoustic azimuthal modes. Hence, the inlet duct diameter, which governs the cut-off frequency for multi-dimensional acoustic modes, determines the lower frequency bound of the broadband noise.

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