In-house Computational Fluid Dynamics Research Articles

Numerical Simulation of Folding Tail Aeroelasticity Based on the CFD/CSD Coupling Method

This paper presents a CFD/CSD coupling method for aeroelastic simulation of folding tail morphing aircraft. The unsteady aerodynamic analysis is based on an in-house computational fluid dynamics (CFD) solver for the Euler equations, and emphasis is made on developing an efficient dynamic mesh method for the tail’s hybrid fold motion/elastic vibration deformation. The structural dynamic analysis is based on the computational structural dynamics (CSD) technique for solving the structural equation of motion in modal space. The aeroelastic coupling was achieved through successive iterations of CFD and CSD computations in the time domain. An adaptive multi-functional morphing aircraft allowing tail fold motion was selected to be studied. By using the developed method, aeroelastic simulation and mechanism analysis for fixed configurations at different folding angles and for variable configurations during the folding process were performed. The influence of folding rate on tail aeroelasticity and its influence mechanism were also analyzed.

Numerical Simulation of Folding Tail Aeroelasticity Based on the CFD/CSD Coupling Method

This paper presents a CFD/CSD coupling method for aeroelastic simulation of folding tail morphing aircraft. The unsteady aerodynamic analysis is based on an in-house computational fluid dynamics (CFD) solver for the Euler equations, and emphasis is made on developing an efficient dynamic mesh method for the tail’s hybrid fold motion/elastic vibration deformation. The structural dynamic analysis is based on the computational structural dynamics (CSD) technique for solving the structural equation of motion in modal space. The aeroelastic coupling was achieved through successive iterations of CFD and CSD computations in the time domain. An adaptive multi-functional morphing aircraft allowing tail fold motion was selected to be studied. By using the developed method, aeroelastic simulation and mechanism analysis for fixed configurations at different folding angles and for variable configurations during the folding process were performed. The influence of folding rate on tail aeroelasticity and its influence mechanism were also analyzed.

Numerical Investigation of Odor-Guided Navigation in Flying Insects: Impact of Turbulence, Wingbeat-Induced Flow, and Schmidt Number on Odor Plume Structures.

Odor-guided navigation is fundamental to the survival and reproductive success of many flying insects. Despite its biological importance, the mechanics of how insects sense and interpret odor plumes in the presence of complex flow fields remain poorly understood. This study employs numerical simulations to investigate the influence of turbulence, wingbeat-induced flow, and Schmidt number on the structure and perception of odor plumes by flying insects. Using an in-house computational fluid dynamics solver based on the immersed-boundary method, we solve the three-dimensional Navier-Stokes equations to model the flow field. The solver is coupled with the equations of motion for passive flapping wings to emulate wingbeat-induced flow. The odor landscape is then determined by solving the odor advection-diffusion equation. By employing a synthetic isotropic turbulence generator, we introduce turbulence into the flow field to examine its impact on odor plume structures. Our findings reveal that both turbulence and wingbeat-induced flow substantially affect odor plume characteristics. Turbulence introduces fluctuations and perturbations in the plume, while wingbeat-induced flow draws the odorant closer to the insect's antennae. Moreover, we demonstrate that the Schmidt number, which affects odorant diffusivity, plays a significant role in odor detectability. Specifically, at high Schmidt numbers, larger fluctuations in odor sensitivity are observed, which may be exploited by insects to differentiate between various odorant volatiles emanating from the same source. This study provides new insights into the complex interplay between fluid dynamics and sensory biology and behavior, enhancing our understanding of how flying insects successfully navigate using olfactory cues in turbulent environments.

The nonlinearity of scattering waves due to interaction between focusing waves and floating production storage and offloading

The study of the full-scale wave–structure interaction is essential to our understanding of the nonlinear characteristics of offshore structures in real-sea states. This paper deals with full-scale numerical studies of the interactions between focusing waves and a fixed floating production storage and offloading (FPSO) in an efficient potential-viscous coupled method. The potential-viscous method combines in-house computational fluid dynamics code developed at Shanghai Jiao Tong University (SJTU) for naval architecture and ocean engineering (naoe) based on an open field operation and manipulation (FOAM), i.e., naoe-FOAM-SJTU solver, with high-order spectral method. The approach is verified on a model-scaled case and shows reasonably good agreement with experimental data. A phase-separation method and a dynamic mode decomposition method are utilized to extract linear and higher-order harmonic components from the scattering waves. The scattering waves around the FPSO are found to affect the higher-order harmonic components. Two kinds of scale ratios are considered to magnify the focusing wave and FPSO by 10 and 100 times to discuss the scale effect, both non-breaking and green water conditions are included to investigate the flow phenomenon. The harmonic components of scattering waves are not proportional to the scale ratio, and the scale effects influence more on higher-order harmonic components. The third- and fourth-order harmonic components of scattering waves around the FPSO in large-scale cases are obvious.

Wake interaction between two spar-type floating offshore wind turbines under different layouts

Limited by layout space and manufacturing costs, wake interaction in offshore wind farms is inevitable and can have adverse effects on the performance of downstream wind turbines. To gain a better understanding of the wake interaction between Floating Offshore Wind Turbines (FOWTs), this paper conducts coupled aero-hydrodynamic simulations for two spar-type FOWTs under different layouts. The Unsteady Actuator Line Model (UALM) is used to analyze the unsteady aerodynamic loads of the wind turbine, while the hydrodynamic responses of the floating support platform are obtained using the Computational Fluid Dynamics (CFD) method. To predict the aero-hydrodynamic performance of the FOWT under combined wind and waves, an in-house CFD code developed at Shanghai Jiao Tong University (SJTU), called FOWT-UALM-SJTU solver, is utilized. First, grid convergence test and time step sensitivity study are performed to determine appropriate simulation parameters. Subsequently, numerical simulations of two FOWTs under tandem and offset layouts are conducted to investigate the influence of wake interaction on the performance of downstream FOWT. The dynamic responses of the FWOT, including aerodynamic loads, platform motions, and wake characteristics, are analyzed in detail. From the simulation results and discussions, several conclusions are drawn. Both platform motions and wake interaction contribute to an increased variation range of inflow wind speed experienced by the downstream FOWT, thereby exacerbating the instability of its aerodynamic loads. Under the tandem layout, the platform motions of the upstream FOWT and the downstream FOWT exhibit opposite effects on the aerodynamic loads of the downstream FOWT. Moreover, platform motions increase turbulence intensity in the wake region, accelerating wake velocity recovery and widening the wake width.

A computational method for complex-shaped hydraulic turbomachinery flow based on the immersed boundary method

Traditional numerical simulation techniques, such as sliding mesh, dynamic mesh, and others, have many limitations in dealing with flow simulation with the large-scale movement of solid boundaries, which is the case for simulating the flow of complex-shaped hydraulic turbomachinery such as propellers, pumps, and turbines. The immersed boundary (IB) method provides a new approach to solve the above-mentioned limitations. Therefore, this study proposes a sharp-interface IB method based on the level-set function that is suitable for simulating the flow through turbomachinery with complex geometries. This method is applied to actual three-dimensional numerical simulations of high-Reynolds number propellers using an in-house computational fluid dynamics solver. The results show that the proposed method can provide comparatively accurate predictions of unsteady load coefficients within the propeller flow passage and capture the correct propeller wake characteristics as well as the interaction between the propeller wake and free surface. This study is aimed at providing a theoretical basis and engineering reference for the application of the IB method in engineering numerical simulations.

Electric fields in a counterflow nonpremixed flame: measurement and simulation

In electric field modified flames, the electric body force on fluid elements can play a role in modifying the flow field, affecting flame characteristics by this modified flow motion. Numerical studies have developed ion kinetic mechanisms and appropriate transport models for charged species, validating them with a voltage-current trend in 1D premixed flames. Recent experimental approaches have measured the electric field by adopting the Electric Field Induced Second Harmonic generation (EFISH) technique. However, the quantification has turned out very challenging due to the inherent distortion in the EFISH signal, as well as inhomogeneous temperature and concentration fields in the combustion field. Here, we propose measurement and calibration schemes to quantify the EFISH signal in a laminar counterflow nonpremixed flame and present comparison with numerical results using an in-house multi-physics CFD (Computational Fluid Dynamics) code. Overall, the quantified electric fields agreed well with those from numerical simulation, specifically capturing null electric fields near the flame in the sub-saturated regime due to the electric field screening effect. In the saturated regime, notable discrepancy was found in a fuel stream when electrons moved through it: experiment indicated a significant number of negative ions in the fuel stream, whereas numerical results predicted negligible negative ions, due to the implemented ion-mechanism. This suggested that the experimentally obtained electric fields may serve as validation data for modeling studies to improve transport models and ion-mechanism. In-situ measurement of charged species in the presence of external electric fields should be a future work.

Investigation on Applicability of Subchannel Analysis Code ASFRE to Thermal Hydraulics Analysis in Fuel Assembly With Inner Duct Structure of Sodium Cooled Fast Reactor

Abstract In the design study of an advanced sodium-cooled fast reactor (advanced-SFR) in Japan Atomic Energy Agency (JAEA), the use of a specific fuel assembly (FA) with an inner duct structure called fuel assembly with an inner duct structure (FAIDUS) has been investigated to enhance safety of Advanced-SFR. Due to the asymmetric layout of fuel rods by the inner duct, it is necessary to estimate the coolant temperature distribution to confirm feasibility of FAIDUS. In JAEA, an in-house subchannel analysis code named thermal-hydraulic analysis of asymmetrical flow in reactor elements (ASFRE) has been developed as a FA design tool. For the typical FAs, the numerical results of ASFRE had been validated by comparisons with experimental data, in the previous study. As for the FAIDUS, confirmation of validity of the numerical results by ASFRE was not enough because the reference data on the thermal hydraulics in FAIDUS have not been obtained by the mockup experiment, yet. In this paper, therefore, the code-to-code comparisons with numerical results of ASFRE and those of an in-house computational fluid dynamics (CFD) code named single-phase thermal-hydraulic analysis in an irregular rod array layout (SPIRAL) were applied to make further discussion on applicability of ASFRE to the thermal hydraulics analysis in FAIDUS. Thermal hydraulic analyses of a typical FA and FAIDUS at high and low flowrate conditions were conducted. The applicability of ASFRE was indicated through the confirmation of the consistency of mechanism on appearance of the specific temperature distributions between the numerical results by ASFRE and those by SPIRAL. In addition, the necessity of modification on the empirical constants in numerical model of ASFRE to improve the predictive accuracy was indicated.

Simulations for Planning of Liquid Hydrogen Spill Test

In order to better understand the complex pooling and vaporization of a liquid hydrogen spill, Sandia National Laboratories is conducting a highly instrumented, controlled experiment inside their Shock Tube Facility. Simulations were run before the experiment to help with the planning of experimental conditions, including sensor placement and cross wind velocity. This paper describes the modeling used in this planning process and its main conclusions. Sierra Suite’s Fuego, an in-house computational fluid dynamics code, was used to simulate a RANS model of a liquid hydrogen spill with five crosswind velocities: 0.45, 0.89, 1.34, 1.79, and 2.24 m/s. Two pool sizes were considered: a diameter of 0.85 m and a diameter of 1.7. A grid resolution study was completed on the smaller pool size with a 1.34 m/s crosswind. A comparison of the length and height of the plume of flammable hydrogen vaporizing from the pool shows that the plume becomes longer and remains closer to the ground with increasing wind speed. The plume reaches the top of the facility only in the 0.45 m/s case. From these results, we concluded that it will be best for the spacing and location of the concentration sensors to be reconfigured for each wind speed during the experiment.

Conceptual design of narrow rectangular channel test section for research reactor application

Conceptual design was carried out on test section for studying heat transfer characteristics of narrow rectangular channel for research reactor application. Thermal hydraulic design requirements were specified through literature study on mid- to high-powered research reactors currently under operation or design. Engineering design was then carried out in streamlined fashion with help of in-house design code and computational fluid dynamics analysis. Considering various constraints and uncertainties in terms of engineering hot channel factors, sensitivity studies were performed and realistic test section design was obtained. For final design, stochastic operable heater power map is generated by merging individual operable ranges from each constraint, with random sampling of hot channel factors.

Effects of Asymmetric Vane Pitch on Reducing Low-Engine-Order Forced Response of a Turbine Stage

Asymmetric vane pitch is a key technique to suppress the forced response of downstream rotor blades. To address the problem of low-engine-order (LEO) excitation with high amplitude under an asymmetric configuration (half-and-half layout) widely recognized in the previous literature, we first apply the in-house computational fluid dynamics code Hybrid Grid Aeroelasticity Environment to perform full-annulus unsteady aeroelasticity simulations of the turbine stage, comparing the resonance response of rotor blades on different asymmetric configurations and analyzing the flow field at the vane exit, as well as the excitation force, modal force, and maximum vibrational amplitude on the rotor blades. Second, we reveal that the potential field of the vane row is the main source of the LEO excitation caused by asymmetric configuration on rotor blades, the vane wake and potential field jointly determine the LEO excitation strength of rotor blades, and the vane pitch difference ΔS can be used to regulate the strength of the LEO excitation. Finally, based on an in-depth understanding of flow physics under an asymmetric configuration, a more preferable and effective asymmetric configuration (non-half two-segment layout) is proposed. Our findings demonstrate that, with the proposed asymmetric configuration, the amplitude of the vane passing frequency was reduced by 48.32% compared to the uniform configuration; furthermore, the maximum vibrational amplitude of the three-nodal-diameter response of the rotor blade at the three-engine-order crossing decreased by 45.49% compared to the half-and-half layout. The non-half two-segment layout also significantly improves upon the half-and-half layout in terms of aerodynamic performance. The results presented in this paper provide a good theoretical basis for reducing blade vibration by applying asymmetric vane pitch in engineering practice.

Investigation on the potential of using carbon-free ammonia in large two-stroke marine engines by dual-fuel combustion strategy

Ammonia (NH3) as a carbon-free fuel is gaining much attention in the shipping industry for its enormous potential of global decarbonization, which is expected to achieve large-scale applications in marine engines by dual-fuel (DF) combustion technology. As such, this study was conducted to explore the emission reduction potential of NH3/diesel DF combustion strategy via low-pressure gas injection in large low-speed two-stroke marine engines using computational fluid dynamics (CFD) modeling coupled with chemical kinetics. An established in-house CFD platform, KIVA-CHEMKIN-CDAC, was employed to perform engine simulations, while an DF combustion mechanism was constructed in this work to mimic the oxidation behaviors of NH3 and diesel as well as the emissions formation. It was found that NH3 admission exhibits a significant inhibiting effect on the autoignition of pilot fuel. Increasing ammonia substitution ratio (ASR) will prolong the ignition delay, resulting in high intensity of premixed combustion. Generally, NH3/diesel DF combustion mode shows two-stage heat release shape. The first stage is characterized by the premixed combustion of diesel–NH3–air mixtures, whereas the dominant combustion regime of the second stage highly depends on the NH3 concentration in the premixed charge. In the very lean NH3-air mixtures, the second stage corresponds to the mixing-controlled diffusion combustion phase; but for the richer NH3-air mixtures, it could be controlled by the turbulent flame propagation. NOx emission decreases when the ASR does not exceed 40%, otherwise increases significantly. The former is probably due to the Thermal DeNOx process dominated by NH2 + NO = N2 + H2O, while the latter is due to the fuel-bound nitrogen. As expected, CO2 emission is reduced monotonically for the same total fuel energy with the increase of ASR, confirming that the utilization of zero-carbon fuel is the most direct means to reduce CO2 emissions. Moreover, there is a trade-off relationship between NOx and N2O emissions. This is because N2O formation usually occurs at lower temperatures (i.e., T < 1400 K). Furthermore, advancing the pilot-fuel injection timing could reduce the unburned NH3 and N2O emissions. Therefore, optimization of injection timing can achieve lower emissions while maintain higher efficiency.

Numerical Investigation on Aerodynamic Characteristics of an Active Jets-Matrix Serving as Pitch Control Surface

To facilitate future Hypersonic Flight Vehicle (HFV) implementation with high maneuverability throughout its reentry trajectory, an Active Jets-Matrix (AJM) is designed to serve as the flapless pitch control surface. The AJM consists of four control groups composed in total of 48 supersonic nozzles. The AJM aims to utilize the jet flow-interaction-induced additional control moment to improve the control efficiency during atmospheric entry. A comparative research method is employed to study the eight simulation cases for three different HFV configurations (baseline, mechanical control surface with 30° deflection, and the AJM configuration) and two AJM control moment adjustment strategies (nozzle chamber pressure regulation and discretized nozzle group on–off control). A conventional in-house computational fluid dynamics (CFD) solver with the two-equation SST turbulence model is employed to undertake the simulation tasks. Simulation results indicate that: (a) only the AJM configuration is capable of trimming the HFV in pitch channel; (b) nonlinearity exists between the augmentation moment and the specific control variable from respective adjustment strategies; (c) the chamber pressure regulation strategy bears higher overall efficiency, while the discretized control strategy induces more intense local jet-flow interaction. With a maximum control moment augmentation of 1.58, the AJM presents itself as a competitive candidate for future HFV flapless control methods.

Numerical Aeroelastic Analysis of a High-Aspect-Ratio Wing Considering Skin Flexibility

Aeroelastic deformation of the high-aspect-ratio wing from a solar-powered UAV will definitely lead to the difference of its performance between design and actual flight. In the present study, the numerical fluid–structural coupling analysis of a wing with skin flexibility is performed by a loosely coupled partitioned approach. The bidirectional coupling framework is established by combining an in-house developed computational fluid dynamics (CFD) code with a computational structural dynamics (CSD) analysis solver and a time-adaptive coupling strategy is integrated in it to improve the computational stability and efficiency of the process. With the proposed method, the fluid–structure interactions between the wing and fluid are simulated, and the results are compared between the deformed wing and its rigid counterpart regarding the aerodynamic coefficients, transition location, and flow structures at large angles of attack. It can be observed that after deformation, the laminar transition on the upper surface is triggered earlier at small angles of attack and the stall characteristic becomes worse. The calculated difference in aerodynamic performance between the deformed and the designed rigid wing can help designers better understand the wing’s real performance in the preliminary stage of design.

Numerical Analysis of the Condensing Steam Flow by Means of ANSYS Fluent and in-House Academic Codes With Respect to the Capacity for Thermodynamic Assessment

In this paper numerical analysis of the condensing steam flow in a converging-diverging nozzle is investigated. The ANSYS Fluent results are compared with the results of the in-house academic Computational fluid dynamics code with respect to the capacity for thermodynamic assessment. The “local” real gas equation of state is used as a mathematical complement of flow governing equations in the in-house code. In the Fluent code, the thermodynamic functions as well as the steam and water physical properties are calculated based on the IAPWS formulation with the use of the UDF. The condensation model with the Fuchs and Sutigin correction of the droplet growth equation and nucleation rate with the Kantrowitz correction is implemented in both CFD codes. The CFD results are compared with the obtained experimental data. The experiment was carried out using an in-house steam facility with a transonic steam tunnel. The investigated geometry is a converging-diverging nozzle as adopted under the International Wet Steam Experimental Project with the diverging section expansion rate of 3,000 s−1 and the total throat height of 40 mm.

Effects of Coanda jet direction on the aerodynamics and flow physics of the swept circulation control wing

Over the last decade, many flight tests of the conventional/canard/flying-wing layout UAVs (unmanned aerial vehicle) have proven that the trailing-edge circulation control (CC) is an effective method to generate a significant rolling moment for the rolling control. However, the Coanda jet’s three-dimensional effects, especially the Coanda jet direction, on the design of UCAVs (unmanned combat air vehicle) have not been revealed and discussed clearly yet. In order to solve this problem, the effects of the Coanda jet direction on the swept wing’s aerodynamics and flow physics are investigated in detail in this paper. An in-house CFD(computational fluid dynamics) solver HyperFLOW with the Spalart–Allmaras for Rotation and Curvature turbulence model and the velocity inlet boundary has been validated by 2-D and 3-D CC cases and is used in this work. The research reveals that compared with the Coanda jet in the freestream direction (FJ jet), the Coanda jet perpendicular to the trailing edge (PJ jet) has a more significant impact on the aerodynamic loads and flow structures for swept wings, including increasing lift, drag, and nose-down moment, enhancing the wingtip vortex and weakening the thickness vortex. In contrast, the FJ jet performs better in improving the lift-to-drag ratio of swept wings. On a typical UCAV, the generalizability of the conclusion about the Coanda jet direction effects on the aerodynamic characteristics is verified. The current research gets an insight into the three-dimensional effects of the trailing-edge CC and provides solid support for implementing the CC technology into practical aircraft concepts.

CFD Simulation and Experimental Study on Coupled Motion Response of Ship with Tank in Beam Waves

Tank sloshing is widely present in many engineering fields, especially in the field of marine. Due to the trend of large-scale liquid cargo ships, it is of great significance to study the coupled motion response of ships with tanks in beam waves. In this study, the CFD (Computational Fluid Dynamics) method and experiments are used to study the response of a ship with/without a tank in beam waves. All the computations are performed by an in-house CFD solver, which is used to solve RANS (Reynold Average Navier-Stokes) equations coupled with six degrees-of-freedom solid-body motion equations. The Level Set Method is used to solve the free surface. Verification work on the grid number and time step size has been conducted. The simulation results agree with the experimental results well, which shows that the numerical method is accurate enough. In this paper, several different working conditions are set up, and the effects of the liquid height in the tank, the size of the tank and the wavelength ratio of the incident wave on the ship’s motion are studied. The results show the effect of tank sloshing on the ship’s motion in different working conditions.

Predicting the airborne microbial transmission via human breath particles using a gated recurrent units neural network

PurposeThe purpose of this paper is to devise a tool based on computational fluid dynamics (CFD) and machine learning (ML), for the assessment of potential airborne microbial transmission in enclosed spaces. A gated recurrent units neural network (GRU-NN) is presented to learn and predict the behaviour of droplets expelled through breaths via particle tracking data sets.Design/methodology/approachA computational methodology is used for investigating how infectious particles that originated in one location are transported by air and spread throughout a room. High-fidelity prediction of indoor airflow is obtained by means of an in-house parallel CFD solver, which uses a one equation Spalart–Allmaras turbulence model. Several flow scenarios are considered by varying different ventilation conditions and source locations. The CFD model is used for computing the trajectories of the particles emitted by human breath. The numerical results are used for the ML training.FindingsIn this work, it is shown that the developed ML model, based on the GRU-NN, can accurately predict the airborne particle movement across an indoor environment for different vent operation conditions and source locations. The numerical results in this paper prove that the presented methodology is able to provide accurate predictions of the time evolution of particle distribution at different locations of the enclosed space.Originality/valueThis study paves the way for the development of efficient and reliable tools for predicting virus airborne movement under different ventilation conditions and different human positions within an indoor environment, potentially leading to the new design. A parametric study is carried out to evaluate the impact of system settings on time variation particles emitted by human breath within the space considered.

An active-controlled heaving plate breakwater trained by an intelligent framework based on deep reinforcement learning

This paper discusses the application of Deep Reinforcement Learning (DRL) to the control of a heaving plate breakwater. It is the first time that the DRL framework is utilized to find the optimal strategy for wave dissipation. The dynamic model of the wave-plate interaction, based on an in-house Computational Fluid Dynamics (CFD) solver, is presented. After training, exciting results show that the wave dissipation performance of the active-controlled heaving plate is more outstanding than that of the passive heaving plate, especially under comparatively long period waves. Meanwhile, the availability of the control strategy to different wave conditions is proved. The Fast Fourier Transform (FFT) analyses indicate that the heaving motion of the active-controlled plate can reduce the amplitude of the fundamental component of the transmitted wave, compared to the fixed plate. Finally, the influence of the hyper-parameters on the DRL convergence rate is discussed. This study proves the potential of DRL+CFD in actively dissipating ocean waves.

Numerical Analysis of Nozzle Erosion in Hybrid Rockets and Comparison with Experiments

Nozzle throat erosion in hybrid rocket engines is generally more emphasized than in solid rockets due to a greater concentration of oxidizing species in the combustion products. Therefore, its accurate understanding and modeling is of fundamental importance in order to correctly predict motor performance and possibly to help reducing the associated losses. Moreover, throttling and/or mixture ratio shift can significantly alter the conditions under which the thermal protection material is operating, further complicating the problem. The aim of this work is to numerically investigate the graphite nozzle erosion in hybrid rockets burning high-density polyethylene and oxygen. Nozzle throat erosion rate and wall temperature are evaluated as a function of the operating conditions by performing numerical simulations with a proven in-house computational fluid dynamics solver. The results obtained from a detailed parametric analysis are discussed and then used to derive a general closed-form regression law for rapid estimation of nozzle throat erosion rate for the analyzed propellant combination that is dependent on the operating conditions, chamber pressure and mixture ratio, and on the nozzle geometry. The possible role of combustion efficiency is also discussed. The regression law is then validated through comparison with the experimental results obtained from several lab-scale 2-kN-thrust-class firing tests, underlining a good ability to correctly capture the average nozzle erosion mass flux behavior with the operating conditions and highlighting the different role of the driving parameters.