Fernando Gisbert

ITP Aero · Simulation Technologies

The turbulent dispersion and deposition of airborne solid particles is studied by means of fully-resolved numerical simulations. The computational domain, consisting in a cubical cavity with differentially heated opposed walls filled with air, reproduces the experimental conditions of measurements previously reported in the literature. The computat...

This paper assesses the accuracy of QDNS simulations for predicting the flow about linear Low-Pressure Turbine cascades. Simulations are performed with a compact high-order numerical scheme based on the Flux Reconstruction method. Numerical results obtained using this technique are compared against a large set of experimental data including pressur...

A main route for SARS-CoV-2 (severe acute respiratory syndrome coronavirus) transmission involves airborne droplets and aerosols generated when a person talks, coughs, or sneezes. The residence time and spatial extent of these virus-laden aerosols are mainly controlled by their size and the ability of the background flow to disperse them. Therefore...

Airborne particles are a major route for transmission of COVID-19 and many other infectious diseases. When a person talks, sings, coughs, or sneezes, nasal and throat secretions are spewed into the air. After a short initial fragmentation stage, the expelled material is mostly composed of spherical particles of different sizes. While the dynamics o...

This paper compares experimental and numerical data for a low-speed high-lift Low Pressure Turbine (LPT) cascade under unsteady flow conditions. Three Reynolds numbers representative of LPTs have been tested, namely, 5×104, 105, 2×105; at two reduced frequencies, fr = 0.5 and 1, also representative of LPTs. The experimental data was obtained at the...

This paper compares experimental and numerical data for a low-speed high-lift Low Pressure Turbine (LPT) cascade under unsteady flow conditions. Three Reynolds numbers representative of LPTs have been tested, namely, 5 × 104, 105, 2 × 105; at two reduced frequencies, fr = 0.5 and 1, also representative of LPTs. The experimental data was obtained at...

A comprehensive comparison between Implicit Large Eddy Simulations and experimental results of a modern high-lift low-pressure turbine airfoil has been carried out for an array of Reynolds numbers (Re). Experimental data were obtained in a low-speed linear cascade at the Polithecnic University of Madrid using hot-wire anemometry and LDV. The numeri...

A comprehensive comparison between Implicit Large Eddy Simulations (ILES) and experimental results of a modern high-lift low-pressure turbine airfoil has been carried out for an array of Reynolds numbers (Re). Experimental data were obtained in a low-speed linear cascade at the Polithecnic University of Madrid using hot-wire anemometry and LDV. The...

The effect of the Coriolis forces on the transition mechanism of low-pressure turbines is numerically studied using a compact high-order Flux Reconstruction method using implicit LES. The method is validates using stationary experimental and fundamental DNS analyses. It is seen that Coriolis forces tend to destabilise the suction-side bubble shear...

This paper describes the strategies followed to implement a nodal-based Discontinuous Galerkin Flux Reconstruction solver (DGFR) for the compressible Navier-Stokes equations on hybrid unstructured grids, that is going to be executed on multiple Graphics Processing Units (GPUs). DGFR schemes exhibit some features, such as the strong data locality, t...

The implementation of an edge-based three-dimensional Reynolds Average Navier–Stokes solver for unstructured grids able to run on multiple graphics processing units (GPUs) is presented. Loops over edges, which are the most time-consuming part of the solver, have been written to exploit the massively parallel capabilities of GPUs. Non-blocking commu...

A new formulation of the mixing plane boundary condition to analyze the steady state interaction between adjacent rows of a turbomachine, used in conjunction with steady two-dimensional non-reflecting boundary conditions, is presented. Existing mixing plane formulations rely on the differences between some variables at the rows that conform the mix...

The effect of mixing plane boundary condition in conjugate heat transfer analysis is studied. The vehicle is a 1.5 stage warm turbine rig solved using a loosely coupled fluid/solid heat transfer method. To reduce the elapsed time, two and three dimensional CFD cavities are solved simultaneously in a Graphics Processing Units (GPU) cluster. The exper...

The implementation of an edge-based three-dimensional RANS equations solver for unstructured grids that runs on multiple graphics processing units (GPUs) is presented. The loops over edges, which are the most time consuming parts of the solver, have been written to exploit the massively parallel capabilities of the GPUs. We have used non-blocking c...

The implementation of an implicit edge-based three-dimensional RANS equations solver for unstructured grids that runs on both central processing units (CPUs) and graphics processing units (GPUs) is presented. A new subsonic non-reflecting boundary conditions treatment at inlets and outlets are described. A simplified two-dimensional stability analy...

The implementation of an edge-based three-dimensional RANS equations solver for unstructured grids that runs on both central processing units (CPUs) and graphics processing units (GPUs) is presented. This CPU/GPU duality is kept without double-writing the code, reducing programming and maintenance costs. The GPU implementation is based on the stand...

A correlation-based transition model has been introduced in a RANS solver to improve the prediction of the transition from laminar to turbulent flow regime in low-pressure turbine blades. The model has been validated by comparing the numerical results against experimental data. The transition model correctly predicts the transition process due to t...

A methodology to minimize blade secondary losses by modifying turbine end-walls is presented. The optimization is addressed using a gradient-based method, where the computation of the gradient is performed using an adjoint code and the secondary kinetic energy is used as a cost function. The adjoint code is implemented on the basis of the discrete...

The minimization of the secondary losses of a low-pressure turbine row by modifying its end walls, using a gradient-based optimization method is presented. The cavities of the turbine row are included in the simulation and the comparison with the case without cavities is discussed. It is concluded that the presence of the cavity alters significantl...

The adjoint Navier-Stokes equations are solved by means of a preconditioned multigrid method. The use of this solver is motivated by the design improvements that may be obtained with a gradient-based optimisation method. The resolution of the adjoint Navier-Stokes equations yields significant computational savings, proportional to the number of opt...

The development of a parallel unstructured multigrid solver for the solution of the compressible Favre-Averaged Navier-Stokes equations is described. The flow domain is discretized using unstructured hybrid grids made up of hexahedral, pentahedral, tetrahedral and triangular prismatic cells handled by a single unifying edge-based data-structure. Tu...

The effect of the finite extent of linear cascades on the unsteady pressure distribution of vibrating blades is assessed by means of a numerical study. The span of a reference cascade made up of flat plates has been changed to investigate its influence on the computed influence coefficients. It is concluded that the number of passages required to m...