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The Moderate or Intense Low-oxygen Dilution (MILD) combustion is a promising technique to reduce pollutant emissions of combustion processes, especially nitrogen oxides. This combustion mode involves Turbulence-Chemistry Interaction (TCI), which constitutes a challenge in terms of numerical simulation since it must be properly captured. Up to now, the TCI has been modelled and the corresponding models generally involve coefficients, leading to epistemic uncertainties and, therefore, to different numerical results depending on the used model. The study presented in this paper aims to assess the relevance of performing Large Eddy Simulation of a typical Jet-in-Hot-Coflow flame, simulating diluted combustion, assuming that the TCI is directly resolved, given the grid and the chemical kinetics resolutions. Avoiding TCI modelling allows for lower numerical uncertainties. However, simulations without TCI modelling will normally fail for other types of flames and for higher Reynolds-numbers, so that such simulations can normally only be conducted using TCI modelling. Here, the simulations are performed using Finite Rate Chemistry without TCI model on the Adelaide Jet-in-Hot-Coflow flame. First, the proposed methodology was experimentally validated, highlighting that the obtained reacting results are consistent in terms of temperature and mass fractions with the measurements. Additionally, the results obtained with the “TCI-resolved” assumption are compared to the results obtained using a classical TCI model, the Partially Stirred Reactor model. Moreover, the validity of the approach, consisting in directly resolving the TCI, is assessed based on an analysis of the local Damkohler number A large part of the mesh cells presents a very low Damkohler number, confirming that TCI modelling is not required for the burner under consideration.

The growing share of renewable energies in our electricity production, together with the still lacking storage capacity, strongly reinforces the need for more flexible electricity production units. In this context, combined cycle gas turbines (CCGTs) have a role to play, both in the current and future electricity production system due to their high efficiency, high load flexibility, and low CO2 emissions compared to other conventional thermal power plants. Nevertheless, bearing in mind our current challenges concerning climate change, the CO2 emissions of these CCGTs need to be reduced drastically. The amine-based absorption carbon capture (CC) process is currently the most mature and applicable CC technology. This process is known to require a considerable amount of thermal energy, degrading plant performance. However, to back-up renewable production, CCGTs will operate most of the time under part-load conditions. The impact of these part-load operations on the CC is still relatively unknown. Within this framework, this study aims to assess the performance of the CC process applied to a typical CCGT under part-load operation using specific simulation models. The CC plant model has been successfully validated against experimental data from a pilot-scale capture facility. Then, the CC plant has been scaled-up to the CCGT scale and the process has been optimized for each operating condition. The simulation results show that the specific reboiler duty increases for part-load operation, while the specific cooling requirements decrease. Moreover, the analysis of the yearly CCGT operation highlights a relative increase in CC energy penalty of 21% for an annual CCGT load factor of 0.5, impacting significantly plant performance. The next step will involve reducing this energy penalty.

Ammonia and hydrogen are promoted as potential energy carriers for centralized energy restitution. This article investigates ammonia/hydrogen/air premixed turbulent combustion, using Large-Eddy Simulations, in an academic atmospheric gas turbine swirled burner. A one-dimensional flame analysis demonstrates the existence of a trade-off in NOX and NH3 emissions for ammonia/hydrogen blends, and the possibility to obtain 1D flame propagation characteristics close to that of a lean methane flame by adjusting the amount of H2. Large-Eddy Simulations of the PRECCINSTA burner exhibit stable combustion, while the optimized trade-off equivalence ratio is pinpointed at φ=1.46 for XH2Fuel=0.46. Corresponding emissions are XNOX≈XNH3≈300 ppmv. Large amounts of hydrogen are found in the exhaust gases, inducing a low combustion efficiency. The flame structure, combustion dynamics, influence of kinetics modelling and mesh resolution are discussed. This work paves the way for future studies, in the perspective of applications to industrial systems., SCOPUS: ar.j, info:eu-repo/semantics/published

The aim of this chapter is twofold. On the one hand, it describes a complete simulation method to evaluate the performance of a Doppler LIDAR for aircraft wake vortices detection near the ground. The principal interest of the simulation presented here is to combine a LASER beam propagation methodwith fluid dynamics simulations. On the other hand, it proposes effective wind velocity map reconstruction algorithms.

Considering the growing interest in Power-to-Fuel, i.e., production of H2 using electrolysis to store excess renewable electricity, combustion-based technologies still have a role to play in the future of power generation. Especially in a decentralized production with small-scale cogeneration, micro-Gas Turbines (mGTs) offer great advantages related to their high adaptability and flexibility, in terms of operation and fuel. Hydrogen (or hydrogen enriched methane) combustion is well-known to lead to flame and combustion instabilities. The high temperatures and reaction rates reached in the combustor can potentially lead to flashback. In the past, combustion air humidification (i.e., water addition) has proven effective to reduce temperatures and reaction rates, leading to significant NOx emission reductions. Therefore, combustion air humidification can open a path to stabilize hydrogen combustion in a classical mGT combustor. However accurate data assessing the impact of humidification on the combustion is still missing for real mGT combustor geometries and operating conditions. In this framework, this paper presents a comparison between pure methane and hydrogen enriched methane/air combustions, with and without combustion air humidification, in a typical mGT combustion chamber (Turbec T100) using Large Eddy Simulations (LES) analysis. In a first step, the necessary minimal water dilution, to reach stable and low emissions combustion with hydrogen, was assessed using a one-dimensional (1D) approach. The one-dimensional unstretched laminar flame is computed for both pure methane (reference case) and hydrogen enriched methane/air combustion cases. The results of this comparison show that, for the hydrogen enriched combustion, the same level of flame speed as in the reference case can be reached by adding 10% (in mass fraction) of water. In a second step, the feasibility and flexibility of humidified hydrogen enriched methane/air combustion in an industrial mGT combustor have been demonstrated by performing high fidelity LES on a 3D geometry. Results show that steam dilution helped to lower the reactivity of hydrogen, and thus prevents flashback, enabling the use of hydrogen blends in the mGT at similar CO levels, compared to the reference case. These results will help to design future combustor toward more stability.

The development of turbulent vortical wakes released downstream of wind turbines is a key physical phenomenon as it presents many technological implications for windfarm design and exploitation. The numerical prediction of these wakes constitutes a challenging problem as they involve the shedding of fine vortical structures, their instabilities, and interactions with an ambient turbulent flow. The capture of these complex, three dimensional, unsteady flow phenomena calls for a Large Eddy Simulation (LES) approach. Yet, the computational cost of a scale resolved LES can be huge and the mesh generation process is not obvious when the zones of interest are not known a-priori. Adaptive mesh refinement (AMR) allows generating Eulerian elements only in the regions of interest of the flow, where an action takes place. The AMR strategy proposed here uses the MMG3D library coupled with the YALES2 unstructured finite volume solver. The method is successfully demonstrated on two test cases, the NTNU blind test case for which experimental data exist and the reference NREL 5MW under dynamic yaw conditions.

International audience; The constant growth of computational resources allows performing Large-Eddy Simulation (LES) on realistic flow configurations. In this context, it is important to properly model boundary conditions and particularly inflow turbulence. This study addresses wind tunnel applications where the object under investigation is downstream of a turbulence grid. This grid aims at generating a highly turbulent sheared flow for further use in wind turbines applications. In this work, an original strategy based on the actuator line method (ALM) is proposed to emulate the grid and generate realistic flow structures downstream at a moderate computational cost. As a first validation test of the proposed method, the LES of a single square rod is performed and the results are compared to a scale resolving simulation. In a second phase, the method is applied to a passive grid with non-homogeneous spacing, which generates fully-developed turbulence. Results are compared to experimental data and other state-of-the-art turbulence injection strategies such as homogeneous isotropic turbulence injection and also scale resolving simulations.

This study focuses on bridging the gap between the turbulence modelling methodologies of meterological and engineering codes by proposing a novel methodology to define the closure coefficients of Reynolds-Averaged Navier-Stokes turbulence models consistently with the physics of the atmospheric boundary layer. In this framework, different turbulence closures have been developed and tested on different full-scale test cases corresponding to different atmospheric stability conditions by performing microscale simulations with the inflow conditions provided by a numerical weather prediction (NWP) code. Developed turbulence models have been implemented into the open source computational fluid dynamics (CFD) toolbox, OpenFOAM and the inflow conditions have been acquired with another open source code, the Weather Research and Forecasting (WRF) model.

The phenomenon of meandering of the wind-turbine wake comprises the motion of the wake as a whole in both horizontal and vertical directions as it is advected downstream. The oscillatory motion of the wake is a crucial factor in wind farms, because it increases the fatigue loads, and, in particular, the yaw loads on downstream turbines. To address this phenomenon, experimental investigations are carried out in a wind-tunnel flow simulating an atmospheric boundary layer with the Coriolis effect neglected. A $$3 \times 3$$ scaled wind farm composed of three-bladed rotating wind-turbine models is subject to a neutral boundary layer over a slightly-rough surface, i.e. corresponding to offshore conditions. Particle-image-velocimetry measurements are performed in a horizontal plane at hub height in the wakes of the three wind turbines occupying the wind-farm centreline. These measurements allow determination of the wake centrelines, with spectral analysis indicating the characteristic wavelength of the wake-meandering phenomenon. In addition, measurements with hot-wire anemometry are performed along a vertical line in the wakes of the same wind turbines, with both techniques revealing the presence of wake meandering behind all three turbines. The spectral analysis performed with the spatial and temporal signals obtained from these two measurement techniques indicates a Strouhal number of $$\approx 0.20 - 0.22$$ based on the characteristic wake-meandering frequency, the rotor diameter and the flow speed at hub height.

The large employment of renewable energies requires flexible, efficient and low-carbon production from fossil fuels. From all non-renewable power production routes, the electricity produced with micro Gas Turbines (mGTs) running on natural gas has a very high load flexibility and the lowest CO2 emissions. However, if we want to move towards full carbon clean power production, then CO2 in the exhaust must be captured. In this scenario, mGTs coupled with a Carbon Capture (CC) plant could be a suitable option, but only a few numerical and experimental analyses are available which assess their real potential. The low concentration of CO2 in the mGT exhaust gas is disadvantageous from a CC point of view, however the concentration can be increased by performing Exhaust Gas Recirculation (EGR). Furthermore, the efficiency loss introduced by the CC plant can also be reduced by using the concept of micro Humid Air Turbine (mHAT). In this study, both the dry and the wet operations of the Turbec T100 coupled with a chemical-absorption plant are simulated and compared using the software Aspen Plus®. The goal of these simulations was to investigate state-of-the-art measures which could be applied to small-scale generation to assess what the energy impact of a carbon clean production would be. Simulation results show that applying EGR to a mGT or mHAT can reduce the exhaust gas mass flow rate by 50% and it can increase the concentration of CO2 by three times the traditional cycle. The humidification of the mGT can entirely compensate for the efficiency losses of the EGR application. Both cycle performances are strongly affected by the thermal input from the stripping process, decreasing the global electric efficiency by around 7.9 absolute percentage points in the mGT case and by 8.3 absolute percentage points in the mHAT case in full load conditions. The results of this paper can be used as a starting point for new cycle concepts between the mGT and CC plant.

From all fossil fuel power production routes, the electricity produced with Gas Turbines (GTs) running on natural gas has the lowest CO2 emissions. However, if we want to move towards full carbon clean power production, the CO2 in the exhaust must be captured. The energy impact of a Carbon Capture plant (CC) applied to the micro Gas Turbine (mGT) still remains unclear because few quantitative analyses are available. The low concentration of CO2 in the GT exhaust gas is disadvantageous from a CC point of view. Exhaust Gas Recirculation (EGR) is one of the technologies used to increase the CO2 concentration in the GT flue gas. It is potentially an effective method to reduce the high energy-penalty caused by the carbon capture. A typical capture method is an absorber–stripper system where the absorbent is commonly a 30wt% aqueous monoethanolamine (MEA) solution. In this work, a Turbec T100 mGT coupled with a chemical-absorption plant is considered. The entire plant has been simulated using Aspen Plus®. Simulation results show that the specific reboiler duty is rather constant (around 4.3 MJ/kgCO2) when varying the electrical power output of the mGT. The cycle performance is strongly affected by the thermal energy requirement for the stripping process, decreasing the global electric efficiency around 6.2 absolute percentage points. These results could be a starting point for future energy integrations between the mGT and the CC plant.

To fully embrace its opportunities in future decentralized power production, the current mGT has to become more flexible in terms of operation, i.e. decoupling heat and power production. Cycle humidification during periods with low heat demand is a possible route to handle this issue. Indeed, cycle humidification has already been proven to increase the mGT electrical efficiency. Nevertheless, even when applying the most advanced humidified cycle concept, i.e. the REgenerative EVAPoration cycle, the electrical performance increase remains rather limited. In this perspective, the more recent Maisotsenko (or M-power) cycle concept offers a larger potential for humidification, even though its potential was only proven on large-scale gas turbine cycles and never applied to the smaller mGT scale. In this paper, the concept of this M-power cycle is applied to a 100 kWe mGT (Turbec T100) to assess its performance, using Aspen Plus® simulations. Moreover, the impact of various inputs, component performance and control parameters is studied using a sensitivity analysis. The numerical results highlight that the M-power cycle has the highest waste heat recovery and thus the highest electric efficiency (up to 147 kWe electric power output with an electric efficiency of 42.1% at constant rotational speed and 41.1%, corresponding to an 8.3%point absolute increase, at constant power output). Moreover, this cycle concept allows to approach the thermodynamic limit for cycle humidification. Indeed, a large exergy destruction is avoided by not going for direct water injection, but rather using a gradual injection and evaporation. Additionally, from a technological point of view, the M-power cycle is also preferable for the small-scale mGT. Indeed, in the M-power cycle, saturation tower, aftercooler, recuperator and economizer are combined in one single component, significantly reducing the complexity of the cycle. The main limitation is the saturator, that requires a wet bulb effectiveness of up to 98% to achieve the simulated performance, which can be technological very challenging.

The aerodynamics of yawed wind turbine wakes remains a major investigation topic, especially for the use of yaw angle in control strategies. Large-Eddy Simulations are employed here to study the influence of yaw and inflow conditions on the prediction of the wind turbine wake structure. A single wind turbine setup with different yaw angles and three different inflow conditions is investigated and discussed with respect to experimental data. The wind turbine blades are modeled using the actuator line method (ALM) while tower and nacelle are represented with a body-fitted unstructured mesh. The high levels of upstream turbulence, experimentally generated by turbulence grids, are emulated here with oscillating ALM. Such approach demonstrates to be highly predictive on the turbulent flow characteristics compared to the emptied wind tunnel experimental data. Results with turbine show good agreement to the experiment data with only a slight overestimation on the magnitude of the wake deflection due to yaw. When compared to a deflection model, the confinement of the wind tunnel is highlighted. The radial and azimuthal time-averaged angle of attack exhibits a high probability of dynamic stall near the hub for a yawed turbine. These results show large discrepancies on the blade loading, highlighting the need for improved and specific models.

International audience; Accurate simulation of wind turbine wakes is critical for the optimization of turbine efficiency and prediction of fatigue loads. These wakes are three-dimensional, complex, unsteady and can evolve in geometrically complex environments. Modeling these flows calls thus for high-quality numerical methods that are able to capture and transport thin vortical structures on an unstructured grid. It is proposed here to assess the performances of a fourth-order finite-volume LES solver to perform massively parallel scale-resolving simulations of wind turbines wakes. In this framework, the actuator line method that takes the effect of the wind turbine blades on the flow into account is implemented. It is demonstrated that both near and far parts of the turbine wakes are accurately modeled as well as geometrical details. The methodology is assessed on two different test cases and validated with experimental results. It is demonstrated that the flow predictions are of equivalent quality on both structured and unstructured grids. The influence of the geometrical details (e.g. nacelle and tower) on the wake development as well as the influence of the discretization scheme are also investigated.

With the current shift towards more decentralized power production, micro Gas Turbines (mGTs) appear as a promising technology for small-scale Combined Heat and Power (CHP) production. Nevertheless, if we want to move towards a carbon-clean power production, the CO2 in the exhaust gas must be captured. In this context, mGTs coupled with a Carbon Capture (CC) plant might be a good candidate, however there is still an energy penalty. Especially when there is no demand for heat and the mGT is only producing electrical power, this penalty becomes a major drawback. In this case, a possible solution is waste heat recovery in the system to increase the efficiency or to reduce the energy penalty, but few analyses are available to assess the optimal solution. In this paper, we aim at identifying the optimal strategy for carbon clean mGT operation in CHP applications for different operation scenarios: full CHP mode and operation with no thermal load. The effect of different technological measures such as humidification and internal heat recoveries has been investigated. The goal of these simulations was to evaluate the most efficient strategy for each thermal scenario of the mGT by testing different combinations of the previous measures. Results show that full CHP operation of the mGT with carbon capture has still the highest performance. Nonetheless, if the thermal demand is zero, conversion into mHAT and heat recovery for the stripping process result in a sensible reduction of the CC plant energy penalty, moving closer to the efficiency of traditional mGTs. Future work would include a more detailed analysis concerning mixed operation (part-load heat demand) of the mGT and an exergy analysis to identify where more waste heat can be recovered., SCOPUS: cp.p, info:eu-repo/semantics/published

Most promising Generation IV nuclear reactor concepts are based on a liquid metal coolant. However, at low Prandtl (Pr ) numbers such as those of liquid metal, classical approaches derived for unity, or close to unity, Pr fail to accurately predict the heat transfer. This paper assesses the RANS modeling of forced turbulent convection at low Pr and in channel flow. Reference results at high Reynolds (Re ) number are required to ensure that the Peclet number is sufficiently high. Therefore, new reference results were obtained by performing a wall-resolved Large-Eddy Simulation of turbulent channel flows at a friction Reynolds number Reτ=2000Reτ=2000 and at Pr=0.01Pr=0.01 and 0.0250.025 (this also corresponds to the highest Re Direct Numerical Simulation (DNS) available in the literature for the flow, but without heat transfer). The LES velocity statistics are in very good agreement with those of the DNS and, as validated by the authors in previous publications, the LES approach used here accurately predicts the temperature statistics at low Pr . The LES results are used to assess RANS heat transfer modeling based on the effective turbulent Prandtl number (PrtPrt) concept. Among existing PrtPrt correlations, the correlation by Kays (1994) [10] is shown to yield the best results. Since it is also shown that the near-wall temperature profile does not follow a log-law, a new “law of the wall for temperature” is here proposed, which does not use any blending function. Its use as a wall-function is also validated in actual RANS simulations.

The aim of this paper is to verify that a modeling approach affordable at wind farm scale, in this case a fourth-order finite differences code combined with a rotating actuator disk, provides equivalent results in terms of wake meandering compared to a method with a higher fidelity level, i.e. a Vortex Particle-Mesh Method combined with immersed lifting lines. The analysis is performed on the wake centerlines obtained from Large Eddy Simulations of an isolated NREL 5-MW wind turbine subject to several synthetic turbulent inflows: 6%, 10%, and 15% turbulence intensity. A direct comparison of the wake centerlines reveals a good match between the two approaches up to five rotor diameters. Concerning the amplitude and wavelength of the wake meandering, the lower fidelity code leads to larger amplitudes and shorter wavelengths. Assuming that Taylor’s frozen turbulence hypothesis is applicable, the Strouhal number St is computed as the ratio between the rotor diameter and the wavelength. Obtained values are such that 0.22 ⩽ St ⩽ 0.4.

This study investigates the influence, on aircraft wake vortex behavior, of atmospheres that are stably stratified (neutral to very strong) and weakly turbulent, by means of large-eddy simulations at very high Reynolds number and on relatively fine grids. The atmospheric fields are first generated using large-eddy simulations of forced and stratified turbulence reaching a statistically stationary state. The obtained fields are shown to be realistic and consistent with the literature. A pair of counter-rotating vortices, with relatively tight cores, is then put in the obtained fields and evolved. The evolution of the wake vortex topology, transport, and decay is analyzed in depth by measuring the wake vortex characteristics in all cross planes. The vortex transport and deformation are related to the stratification and turbulence levels. Stratification combined with weak turbulence is seen to strongly affect the Crow instability development. Different decay mechanisms are identified, related to the interactions with the turbulence, the turbulent baroclinic vorticity, and/or between the vortices themselves. Finally, improved simplified models of vortex altitude evolution and of vortex decay (with two phases) are proposed and calibrated on the present results. They yield good agreement with the large-eddy simulation results and are usefully integrated in our operational models. Read More: http://arc.aiaa.org/doi/abs/10.2514/1.J051742

During two field measurement campaigns aircraft wake vortex trajectory and wind measurement data have been collected at Frankfurt airport. Three different approaches have been used to analyse the data in order to estimate crosswind threshold values supporting vortex-free corridors for departing aircraft. Although several competing effects such as wake vortex transport in and out of ground effect, temporal and spatial wind variability, and the spreading of aircraft trajectories after take-off, complicate the analyses, all three approaches lead to similar crosswind thresholds. Employing standard instrumentation at 10 m, a minimum crosswind threshold of 3.5–4.6 m s−1 has been identified to clear a safety corridor of 150 m width from wake vortices with a 95% probability within 60 s. Alternative estimations of crosswind thresholds employing different instrumentation and different height ranges are reported. Crosswind thresholds can be reduced if the wind is measured close to the air mass in which the vortices evolve. A definite crosswind threshold for operational use cannot be deduced solely from this study since critical factors such as risk and safety assessment have not yet been taken into account.

We investigate several algorithms to detect the centerline of a wind turbine wake. First, we apply these methods during Large Eddy Simulations of an isolated wind turbine subject to a uniform ( TI = 0%) and a synthetic turbulent inflow ( TI = 10%). The simulations are performed using a vortex-particle mesh method with the blades modeled using immersed lifting lines. The most robust algorithm is then applied to investigate the wakes positions inside a wind farm. At wind farm scale, the simulations are performed with a fourth-order finite difference code inside which the wind turbines are accounted for through advanced actuator disks.

The study of wind turbines requires a multidisciplinary approach that covers the electrical, mechanical and aerodynamic aspects. Most wind turbine studies focus their modelization effort on a single aspect and rely on simplified models for the other ones. The present paper aims at a complete modelization and investigation of the energy conversion chain of small wind turbines (up to 100kW), going from the turbulent wind resource to the electrical power injected into the grid. For that purpose, the following computational chain is set up: a synthetic turbulence is used as inflow to a Vortex Particle-Mesh method which computes the wind turbine coarse scale aerodynamics taking into account the rotor dynamics; the aero-mechanical results are used to feed an electrical simulation and the consistency of both simulations is ensured by using a common Maximum Power Point Tracking algorithm. We apply this methodology to compare the behavior of horizontal- and vertical-axis machines in a turbulent wind with two different turbulent intensities (low T I = 8.3% and high T I = 16%).

Background: It is a known fact that blood flow pattern and more specifically the pulsatile time variation of shear stress on the vascular wall play a key role in atherogenesis. The paper presents the conception, the building and the control of a new in vitro test bench that mimics the pulsatile flows behavior based on in vivo measurements. Methods: An in vitro cardiovascular simulator is alimented with in vivo constraints upstream and provided with further post-processing analysis downstream in order to mimic the pulsatile in vivo blood flow quantities. This real-time controlled system is designed to perform real pulsatile in vivo blood flow signals to study endothelial cells' behavior under near physiological environment. The system is based on an internal model controller and a proportional-integral controller that controls a linear motor with customized piston pump, two proportional-integral controllers that control the mean flow rate and temperature of the medium. This configuration enables to mimic any resulting blood flow rate patterns between 40 and 700 ml/min. In order to feed the system with reliable periodic flow quantities in vivo measurements were performed. Data from five patients (1 female, 4 males; ages 44-63) were filtered and post-processed using the Newtonian Womersley's solution. These resulting flow signals were compared with 2D axisymmetric, numerical simulation using a Carreau non-Newtonian model to validate the approximation of a Newtonian behavior. Results: This in vitro test bench reproduces the measured flow rate time evolution and the complexity of in vivo hemodynamic signals within the accuracy of the relative error below 5%. Conclusions: This post-processing method is compatible with any real complex in vivo signal and demonstrates the heterogeneity of pulsatile patterns in coronary arteries among of different patients. The comparison between analytical and numerical solution demonstrate the fair quality of the Newtonian Womersley's approximation. Therefore, Womersley's solution was used to calculate input flow rate for the in vitro test bench., SCOPUS: ar.j, info:eu-repo/semantics/published

The aerodynamics of Vertical Axis Wind Turbines (VAWTs) is inherently unsteady, which leads to vorticity shedding mechanisms due to both the lift distribution along the blade and its time evolution. In this paper, we perform large-scale, fine-resolution Large Eddy Simulations of the flow past Vertical Axis Wind Turbines by means of a state-of-the-art Vortex Particle-Mesh (VPM) method combined with immersed lifting lines. Inflow turbulence with a prescribed turbulence intensity (TI) is injected at the inlet of the simulation either from a precomputed synthetic turbulence field obtained using the Mann algorithm [1] or generated on the-fly using time-correlated synthetic velocity planes. The wake of a standard, medium-solidity, H-shaped machine is simulated for several TI levels. The complex wake development is captured in details and over long distances: from the blades to the near wake coherent vortices, then through the transitional ones to the fully developed turbulent far wake. Mean flow and turbulence statistics are computed over more than 10 diameters downstream of the machine. The sensitivity of the wake topology and decay to the TI and to the operating conditions is then assessed.

A new spectral model of the return signal from a LIDAR Doppler wake vortex detector is proposed. It has been experimentally discovered during ground-based and flight test campaigns but suffered a lack of theoretical evidence. Using high resolution fluid simulations of wake vortices, we highlight the physical meaning of this model. Comparisons with the traditional single Gaussian model show the superiority of this new approach is consistent with previous experimental results.