Wake Turbulence Structure Downstream of a Cambered Airfoil in Transonic Flow: Effects of Surface Roughness and Freestream Turbulence Intensity

Zhang, Qiang; Ligrani, Phillip M.

doi:10.1155/ijrm/2006/60234

Cited by 8 publications

(6 citation statements)

References 27 publications

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“…The data of Zhang and Ligrani [8] show that magnitudes of Integrated Aerodynamic Losses change by much larger amounts as either the freestream Mach number or turbulence intensity are altered, when the airfoil is roughened (compared to smooth airfoil results). Other recent investigations are described by Zhang et al [37,38] and by Zhang and Ligrani [39,40].…”

Section: International Journal Of Rotating Machinerymentioning

confidence: 78%

“…With this approach, the local stagnation pressure loss is normalized by a quantity which does not vary with cascade exit location. Zhang et al [5,37,38], Jackson et al [54], Chappell et al [55], and Zhang and Ligrani [8,27,39,40] employ integrated aerodynamic loss IAL to quantify aerodynamic losses in turbine components. Dimensional magnitudes of Integrated Aerodynamic Loss, IAL, are determined by integrating profiles of (P oi − P oe ) with respect to y in the transverse flow direction across the wake for one single vane spacing, from −p/2 to p/2 [54].…”

Section: Local Total Pressure Loss Coefficient and Integratedmentioning

confidence: 99%

“…section. Additional details on experimental apparatus and procedure details are provided by Zhang et al [37,38], and Zhang and Ligrani [27,39,40]. Wake profile data are presented for two different locations downstream the vane trailing edge, which illustrate the influences of varying freestream turbulence intensity level, surface roughness, and vane Mach number on local aerodynamic losses, Integrated…”

Section: Cambered Vanes With No-film Coolingmentioning

confidence: 99%

See 2 more Smart Citations

Aerodynamic Losses in Turbines with and without Film Cooling, as Influenced by Mainstream Turbulence, Surface Roughness, Airfoil Shape, and Mach Number

Ligrani

2012

International Journal of Rotating Machinery

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The influences of a variety of different physical phenomena are described as they affect the aerodynamic performance of turbine airfoils in compressible, high-speed flows with either subsonic or transonic Mach number distributions. The presented experimental and numerically predicted results are from a series of investigations which have taken place over the past 32 years. Considered are (i) symmetric airfoils with no film cooling, (ii) symmetric airfoils with film cooling, (iii) cambered vanes with no film cooling, and (iv) cambered vanes with film cooling. When no film cooling is employed on the symmetric airfoils and cambered vanes, experimentally measured and numerically predicted variations of freestream turbulence intensity, surface roughness, exit Mach number, and airfoil camber are considered as they influence local and integrated total pressure losses, deficits of local kinetic energy, Mach number deficits, area-averaged loss coefficients, mass-averaged total pressure loss coefficients, omega loss coefficients, second law loss parameters, and distributions of integrated aerodynamic loss. Similar quantities are measured, and similar parameters are considered when film-cooling is employed on airfoil suction surfaces, along with film cooling density ratio, blowing ratio, Mach number ratio, hole orientation, hole shape, and number of rows of holes.

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Section: International Journal Of Rotating Machinerymentioning

confidence: 78%

Section: Local Total Pressure Loss Coefficient and Integratedmentioning

confidence: 99%

Section: Cambered Vanes With No-film Coolingmentioning

confidence: 99%

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Aerodynamic Losses in Turbines with and without Film Cooling, as Influenced by Mainstream Turbulence, Surface Roughness, Airfoil Shape, and Mach Number

Ligrani

2012

International Journal of Rotating Machinery

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“…Nowadays, many researchers also pay attention to the quality of an airfoil surface. Since even a slight roughness of the streamlined body significantly changes the structure of the wake flow [10], it shifts the transition to turbulence and the separation points. The first fundamental result investigations of this phenomenon are presented in the works in [11,12].…”

Section: Introductionmentioning

confidence: 99%

Hot-Wire Investigation of Turbulence Topology behind Blades at Different Shape Qualities

et al. 2022

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The scope of this paper is to perform a detailed experimental investigation of the shape error effect on the turbulence evolution behind NACA 64-618 airfoil. This airfoil is 3D-printed with predefined typical shape inaccuracies. A high-precision optical 3D scanner was used to assess the shape and surface quality of the manufactured models. The turbulent flow was studied using hot-wire anemometry. The developed force balance device was provided to measure the aerodynamic characteristics of the airfoil. Experimental studies were carried out for three angles of attack, +10∘, 0∘, −10∘, and different chord-based Reynolds numbers from 5.3×104 to 2.1×105. The obtained results show that the blunt trailing edge and rough surface decline the aerodynamic performance of the blades. In addition, the experimental results revealed a strong sensitivity of the Taylor microscale Reynolds number to the type of shape inaccuracy, especially at Re≈1.7×105. We also discuss the evolution of the Reynolds stress components, the degree of flow anisotropy, and the power spectrum distributions depending on the airfoil inaccuracies.

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“…One of which is the impact of surface roughness. Even its slight deviation can lead to significant changes in turbulence [40]. According to [52], with increasing level of roughness, the vortex shedding frequency decreases.…”

Section: Introductionmentioning

confidence: 99%

Anisotropy of turbulent flow behind an asymmetric airfoil

et al. 2021

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Feature of turbulent flow anisotropy behavior behind an asymmetric NACA 64-618 airfoil investigated in this paper. Experimental studies were performed using a hot-wire anemometery with X-probe at the chord-based Reynolds number $$1.7 \times 10^5$$ 1.7 × 10 5 . The average ensemble velocity and Reynolds stress components are used to determine the wake topology and anisotropy of turbulence. The obtained data allowed to identify the outside wake region, which is characterized by low instability and a high degree of anisotropy of the turbulent flow. This tendency is observed at different angles incident. Further, to gain better insight into the physics of this phenomenon the structure of turbulence have been evaluated. Integral turbulence length and time scales were estimated by the area of the autocorrelation function of velocity fluctuations. Then, using the second-order structural function, we obtained the dissipation characteristics of the flow. In addition, the features of the energy spectrum in the region with high and low degrees of turbulence anisotropy were analyzed.

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Wake Turbulence Structure Downstream of a Cambered Airfoil in Transonic Flow: Effects of Surface Roughness and Freestream Turbulence Intensity

Cited by 8 publications

References 27 publications

Aerodynamic Losses in Turbines with and without Film Cooling, as Influenced by Mainstream Turbulence, Surface Roughness, Airfoil Shape, and Mach Number

Aerodynamic Losses in Turbines with and without Film Cooling, as Influenced by Mainstream Turbulence, Surface Roughness, Airfoil Shape, and Mach Number

Hot-Wire Investigation of Turbulence Topology behind Blades at Different Shape Qualities

Anisotropy of turbulent flow behind an asymmetric airfoil

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