Lip Stall Suppression in Powered Intakes

Carnevale, Mauro; Wang, Feng; Green, J. S.; Mare, Luca di

doi:10.2514/1.b35811

Cited by 30 publications

(15 citation statements)

References 33 publications

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“…Particle tracking is performed on a tetrahedral grid obtained by splitting the hexahedra of the CFD grid. The tracking implementation is fully parallel, as the CFD solver [21], and relies on message passing libraries (MPI).…”

Section: Methodsologymentioning

confidence: 99%

An Energy-Based Fouling Model for Gas Turbines: EBFOG

Casari

Pinelli

Suman

et al. 2016

Journal of Turbomachinery

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Fouling is a major problem in gas turbines for aeropropulsion because the formation of aggregates on the wet surfaces of the machine affects aerodynamic and heat loads. The representation of fouling in computational fluid dynamics (CFD) is based on the evaluation of the sticking probability, i.e., the probability a particle touching a solid surface has to stick to that surface. Two main models are currently available in literature for the evaluation of the sticking coefficient: one is based on a critical threshold for the viscosity, and the other is based on the normal velocity to the surface. However, both models are application specific and lack generality. This work presents an innovative model for the estimation of the sticking probability. This quantity is evaluated by comparing the kinetic energy of the particle with an activation energy which describes the state of the particle. The sticking criterion takes the form of an Arrhenius-type equation. A general formulation for the sticking coefficient is obtained. The method, named energy-based fouling (EBFOG), is the first “energy”-based model presented in the open literature able to account any common deposition effect in gas turbines. The EBFOG model is implemented into a Lagrangian tracking procedure, coupled to a fully three-dimensional CFD solver. Particles are tracked inside the domain, and equations for the momentum and temperature of each particle are solved. The local geometry of the blade is modified accordingly to the deposition rate. The mesh is modified, and the CFD solver updates the flow field. The application of this model to particle deposition in high-pressure turbine vanes is investigated, showing the flexibility of the proposed methodology. The model is particularly important in aircraft engines where the effect of fouling for the turbine, in particular the reduction of the high pressure (HP) nozzle throat area, influences heavily the performance by reducing the core capacity. The energy-based approach is used to quantify the throat area reduction rate and estimate the variation in the compressor operating condition. The compressor operating point as a function of the time spent operating in a harsh environment can be in this way predicted to estimate, for example, the time that an engine can fly in a cloud of volcanic ashes. The impact of fouling on the throat area of the nozzle is quantified for different conditions.

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Section: Methodsologymentioning

confidence: 99%

An Energy-Based Fouling Model for Gas Turbines: EBFOG

Casari

Pinelli

Suman

et al. 2016

Journal of Turbomachinery

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“…However, once the flow separates, evidence suggests that the blockage induced by the screen BC was capable of suppressing the flow distortion. Carnevale et al [11] carried out a computational study into flow separation in a subsonic civil aircraft intake and its interaction with downstream fan. Both steady and unsteady RANS models were respectively used to simulate the isolated intake and powered intake configurations.…”

Section: Numerical Investigations Using Cfd (Computational Fluidmentioning

confidence: 99%

Fan–Intake Interaction Under High Incidence

Cao

Vadlamani

Tucker

et al. 2016

Journal of Engineering for Gas Turbines and Power

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In this paper, we present an extensive numerical study on the interaction between the downstream fan and the flow separating over an intake under high incidence. The objectives of this investigation are twofold: (a) to gain qualitative insight into the mechanism of fan-intake interaction and (b) to quantitatively examine the effect of the proximity of the fan on the inlet distortion. The fan proximity is altered using the key design parameter, L/D, where D is the diameter of the intake and L is the distance of the fan from the intake lip.Both steady and unsteady Reynolds Averaged Numerical Simulations (RANS) were carried out. For the steady calculations, a low order fan model has been used while a full 3D geometry has been used for the unsteady RANS. The numerical methodology is also thoroughly validated against the measurements for the intake-only and fan-only configurations on a high bypass ratio turbofan intake and fan respectively. To systematically study the effect of fan on the intake separation and explore the design criteria, a simplified intake-fan configuration has been considered. In this fan-intake model, the proximity of the fan to the intake separation (L/D) can be conveniently altered without affecting other parameters.The key results indicate that, depending on L/D, the fan has either suppressed the level of the post-separation distortion or increased the separation-free operating range. At the lowest L/D (~ 0.17), around a 5° increase in the separation-free angle of incidence was achieved. This delay in the separation-free angle of incidence decreased with increasing L/D. At the largest L/D (~ 0.44), the fan was effective in suppressing the postseparation distortion rather than entirely eliminating the separation. Isentropic Mach number distribution over the intake lip for different L/D's revealed that the fan accelerates the flow near the casing upstream of the fan face, thereby decreasing the distortion level in the immediate vicinity. However, this acceleration effect decayed rapidly with increasing upstream distance from the fan-face. Previous work:An improved understanding of the intake aerodynamics and its interaction with the fan is hence crucial in developing the modern aircraft engines. Extensive studies were carried out in the literature by various researchers to address this issue. These

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“…Figure shows the analysis of an aspirated intake of an aero‐engine . The figure on the top‐left shows a section view of the mesh.…”

Section: Resultsmentioning

confidence: 99%

Hybrid meshing using constrained Delaunay triangulation for viscous flow simulations

Wang

Mare

2016

Numerical Meth Engineering

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SUMMARYIn this paper, we present a generalized prismatic hybrid meshing method for viscous flow simulations. One major difficulty in implementing a robust prismatic hybrid meshing tool is to handle boundary layer mesh collisions, and normally an extra data structure (e.g. quadtree in two-dimensional and octree in threedimensional) is required. The proposed method overcomes this difficulty via an heuristic approach, and it only relies on constrained delaunay triangulation/tetrahedralization (CDT). No extra data structures are required. Geometrical reasoning is used to approximate the maximum marching distance of each point by walking through the CDT. This is combined with post-processing of marching vectors and distance and prohibition of multilevel differences to form an automatic and robust mechanism to remove boundary layer mesh collisions. Benefiting from the matureness of CDT techniques, the proposed method is robust, efficient and simple to implement. Its capability is demonstrated by generating quality prismatic hybrid meshes for industrial models with complex geometries. The proposed method is believed to be able considerably reduce the effort to implement a robust hybrid prismatic mesh generator for viscous flow simulations.

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Lip Stall Suppression in Powered Intakes

Cited by 30 publications

References 33 publications

An Energy-Based Fouling Model for Gas Turbines: EBFOG

An Energy-Based Fouling Model for Gas Turbines: EBFOG

Fan–Intake Interaction Under High Incidence

Hybrid meshing using constrained Delaunay triangulation for viscous flow simulations

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