Two-phase Conditions Research Articles

Gas–Liquid Two-Phase Flow Investigation of Side Channel Pump: An Application of MUSIG Model

This paper introduces a novel application of a multiphase flow model called the Multi-Size-Group model (MUSIG) to solve 3D complex flow equations in a side channel pump, in order to analyze the flow dynamics of the gas phase distribution and migration under different inlet gas volume fractions (IGVFs). Under different IGVF, the suction side is more likely to concentrate bubbles, especially near the inner radius of the impeller, while there is very little or no gas at the outer radius of the impeller. The diameter of bubbles in the impeller are similar and small for most regions even at IGVF = 6% due to the strong shear turbulence flow which eliminates large bubbles. Additionally, this method also can capture the coalescence and breakage evolution of bubbles. Once a mixture of fluid goes into the impeller from the inlet pipe, the large bubbles immediately break, which accounts for the reason why nearly all side channel pumps have the capacity to deliver gas–liquid two-phase flow. The results in this study provide a foundation and theoretical value for the optimal design of side channel pumps under gas–liquid two-phase conditions to increase their application.

Two-Phase Equilibrium Conditions in Nanopores.

It is known that thermodynamic properties of a system change upon confinement. To know how, is important for modelling of porous media. We propose to use Hill’s systematic thermodynamic analysis of confined systems to describe two-phase equilibrium in a nanopore. The integral pressure, as defined by the compression energy of a small volume, is then central. We show that the integral pressure is constant along a slit pore with a liquid and vapor in equilibrium, when Young and Young–Laplace’s laws apply. The integral pressure of a bulk fluid in a slit pore at mechanical equilibrium can be understood as the average tangential pressure inside the pore. The pressure at mechanical equilibrium, now named differential pressure, is the average of the trace of the mechanical pressure tensor divided by three as before. Using molecular dynamics simulations, we computed the integral and differential pressures, and p, respectively, analysing the data with a growing-core methodology. The value of the bulk pressure was confirmed by Gibbs ensemble Monte Carlo simulations. The pressure difference times the volume, V, is the subdivision potential of Hill, . The combined simulation results confirm that the integral pressure is constant along the pore, and that scales with the inverse pore width. This scaling law will be useful for prediction of thermodynamic properties of confined systems in more complicated geometries.

Discontinuous Space Vector PWM Strategy for Three-Phase Three-Level Electric Vehicle Traction Inverter Fed Two-Phase Load

Discontinuous pulse width modulation (DPWM) strategies are usually adopted to reduce the switching loss and output current ripple of three-phase three-level traction inverters under three-phase load conditions. However, if there is a short circuit in any arbitrary phase or the inverter is used to feed a two-phase load, the output performance of conventional DPWM strategies will be deteriorated. Here, four improved DPWM (IDPWM) strategies for three-phase three-level neutral-point-clamped (NPC) traction inverter fed two-phase load are proposed. Unlike three-phase load conditions, the phase angle and the amplitude of each basic voltage vector in the space vector diagram are modified under two-phase load conditions. Consequently, sectors are re-divided and duty cycles of basic vectors during synthesis are recalculated. Clamping intervals of each phase for the four type discontinuous PWM (DPWM) strategies are rearranged according to the modified space vector diagram; then, the proposed DPWM strategies can be obtained. Compared with the conventional DPWM strategies, the output current waveform quality of the proposed strategy is significantly improved. Meanwhile, the amplitude of the neutral-point voltage ripple is also reduced.

A benchmark data set for two-phase Coriolis metering

For more than a decade there has been growing interest in the use of Coriolis mass flow metering applied to two-phase (gas/liquid) and multiphase (oil/water/gas) conditions. It is well-established that the mass flow and density measurements generated from multiphase flows are subject to large errors, and a variety of physical models and correction techniques have been proposed to explain and/or to compensate for these errors. One difficulty is the absence of a common basis for comparing correction techniques, because different flowtube designs and configurations, as well as liquid and gas properties, may result in quite different error curves. Furthermore, some researchers with interests in the modelling aspects of the field may not have suitable multiphase laboratory facilities to generate their own data sets. This paper offers a small data set that may be used by researchers as a benchmark i.e. a common data set for comparing correction techniques. The data set was collected at the UK National Flow Laboratory TUV-NEL, using air and a viscous oil, and provides experimental points over a wide flow range (8:1 turndown) and with Gas Volume Fraction (GVF) values up to 60%. As a first investigation using the benchmark data set, we consider how data sparsity (i.e. the flow rate and GVF spacing in the experimental grid) affects the accuracy of a correction model. A range of neural network models are evaluated, based on different subsets of the benchmark data set. The data set and some exemplary code are provided with the paper. Additional data sets are available on a web site created to support this initiative.

Investigation of In-Plane Fluid Elastic Instability for a Triangular Tube Bundle Subjected to Two-Phase Flow

Abstract In recent years, in a newly installed replacement steam generator, in-plane (IP) fluid elastic instability (FEI) for the heat transfer tubes has occurred. The fluid elastic instability is one of the severe vibrations in the heat transfer tube bundle and should be avoided. There have been many studies on the out-of-plane (OOP) fluid elastic instability, and the design evaluation guideline based on Connors' equation and the results of flow tests has been established. On the other hand, no evaluation guideline has been established for in-plane fluid elastic instability, and no critical coefficient has been determined in high-temperature, high-pressure steam–water two-phase conditions. Therefore, in this paper, in order to develop the guideline for evaluating in-plane fluid elastic instability, the critical coefficients were obtained using two types of test equipment for rotate triangular array in two-phase flow (SF6 ethanol) simulating steam–water flow under high-temperature and high-pressure conditions.

Impacts of crosslinker concentration on nanogel properties and enhanced oil recovery capability

The use of nanogels, or crosslinked polymeric nanoparticles, has been proposed as a means of improving oil recovery in low permeability reservoirs. Nanogels can transport deep into reservoirs and improve homogeneity due to their small size and deformability. Typically, nanogels are polymerized using monomers and crosslinkers, which transform polymers from linear structures to 3D structures. Nanogel properties — including its swelling ratio and strength — can be fine-tuned by the crosslinker concentration. In this study, we investigated the impacts of crosslinker concentration on partially hydrolyzed polyacrylamide (HPAM)-based nanogels. The effect of the degree of crosslinking on the physicochemical properties of nanogel, the corresponding adsorbing behavior on rock surfaces, and consequently, the oil recovery improvement was studied.The results show the nanogels maintained a lower swelling ratio and less negative charge when synthesized at a higher crosslinker concentration. Higher crosslinker concentrations also resulted in lower dispersion viscosity because of the lower volumetric fraction and weaker interparticle attraction. The relationship between viscosity and dispersion concentration is in an agreement with the Krieger-Dougherty model.Core flooding experiments were conducted under a water-only condition and an oil–water two-phase condition. Nanogels with a lower crosslinker concentration were better able to reduce core permeability. It was discovered that nanogel injection pressure continuously increased in water-saturated porous media, whereas it reached a stable state in a two-phase condition. Core flooding tests in water-saturated cores also indicated that nanogels with a higher degree of crosslinking adsorbed more onto rock surfaces. The adsorption over time of each test fits well with the pseudo-second order equation. In addition, despite similar interfacial reduction capability, nanogels crosslinked to a lesser degree were able to improve oil recovery to a greater extent.

Experimental investigation on flow boiling characteristics of radial expanding minichannel heat sinks applied for two-phase flow inlet

Generally, two-phase (TP) flow inlet condition is not allowed for conventional microchannel heat exchangers, and a certain subcooled degree of liquid is strictly required to guarantee the efficient operation of system. To solve multi-heat sources cooling issue, a type of circular radial expanding minichannels heat sink (REMHS) utilizing flow boiling of deionized water is proposed in present work. Flow boiling heat transfer of REMHS is investigated with the inlet vapor mass qualities in the range of 0.01–0.53. Under TP flow inlet, slug-annular and annular flows are the main flow patterns observed in REMHS in this work, where the low-medium mass flux (22–132 kg/m2s) and medium-high heat flux (33.1–176.4 kW/m2) conditions are applied. The experimental results illustrate that the proposed REMHS under TP flow inlet maintains a stable and high flow boiling heat transfer performance without occurring heat deterioration. When xin increases from 0.04 to 0.53, the maximum local heat transfer coefficient increases by 22% from 42.5 to 51.9 kW/m2K. The flow distribution among the expanding channel array is relatively uniform and the heat transfer capability in the REMHS displays a good symmetry under TP flow inlet. The maximum discrepancy in heat transfer coefficient is below 19% within our experimental range. Six classic flow boiling heat transfer correlations are compared with the experimental results, and Li & Wu's correlation gives a good prediction on all the measured data with MAE of 21.1%. Besides, the thermal independence of REMHS connected in series is also examined, and the mutual interaction in heat transfer between the REMHS in series is trivial, the proposed REMHS is expected to be applied to multi-heat source cooling.

An equivalent single phase approach to production data analysis in gas condensate reservoirs

In gas condensate reservoirs (GCR) operating below dewpoint pressure, two-phase conditions introduce non-linearities into the diffusivity equation, rendering conventional single-phase production data analysis unreliable. Recent studies, presented in a companion paper published in 2018, demonstrated the application of an equivalent single phase approach to improve the quality of GCR production data analysis using “Blasingame” type curves. That study analysed production data from radial GCR simulation models with fluid maximum liquid dropout ranging from 1% to 42%. The pressure-saturation/kr data for the computation of equivalent-phase pseudovariables was determined using an approach based on two-phase steady-state (SS) theory. For saturated reservoirs, less consistent improvements in permeability, skin and drainage area estimates were obtained – an observation attributed to unrepresentative pressure-saturation/kr data.This current study builds on the earlier work, by examining alternative sources of pressure-saturation data for use in the analysis of saturated GCR cases. PVT liquid-saturation curves and sufficiently representative pressure-saturation responses from the near-wellbore region of numerical simulations are considered. The results suggest that pressure-saturation data representative of the response in the near-wellbore region during transient flow is adequate for the two-phase analysis of long term production data using type curves. The results further highlight reservoir and well operating conditions under which each source of pressure-saturation data is most suitable for use with the equivalent-phase approach. A new time-based adjustment is also introduced to improve the quality of the equivalent-phase type curve analysis for cases in which the entire reservoir becomes saturated prior to stable boundary dominated flow (BDF) conditions.Finally, results are presented which show that our equivalent-phase approach can be successfully combined with other conventional production data analysis tools, e.g. type curves for hydraulically fractured wells, and straight-line techniques used in the analysis of BDF data, all of which were originally developed for analysing single phase systems.

Exergy analysis of microchannel heat exchangers

This study investigates the exergetic efficiencies of four plain microchannel heat exchangers under single-phase and two-phase flow conditions using de-ionised water as the working fluid. The friction factor and heat transfer coefficient data of microchannels are obtained using experimental studies from the literature. The exergetic efficiencies of microchannels are compared to reveal the effect of different geometrical parameters. The results showed that the microchannel aspect ratio is an insignificant parameter on the exergetic efficiency for single-phase flow conditions. However, the exergetic efficiency increased around 90% with the decreasing of the microchannel aspect ratio in two-phase tests. On the other hand, the microchannel heat exchanger having shorter heated length exhibited about 10% and 90% improved exergetic efficiency both in single-phase and two-phase regimes respectively. Moreover, the thermo-economic analysis has been performed in two-phase conditions to propose design guidelines for microchannel heat exchangers from the exergy and thermo-economic performance perspectives.

Experimental study on the characteristics of formation and dissociation of CO2 hydrates in porous media

Geologic carbon sequestration (GCS) has been pursued as a feasible strategy to store the large amount of CO2 to curb its emission to the atmosphere in an effort to mitigate the greenhouse effects. CO2 hydrate, which can form when the pressure and temperature satisfy its stability condition, can provide a self-trapping mechanism for an offshore CO2 geologic storage. For example, direct sequestration of CO2 in the form of hydrate crystals can be achieved in the storage aquifer under the seafloor. Besides, the formation of CO2 hydrates in an upper layer of the CO2 storage zone can potentially provide a secondary caprock. These applications, however, require a thorough understanding of the formation and dissociation of CO2 hydrates in porous media, which are largely unknown yet. In this manuscript, a laboratory study on the formation and dissociation of CO2 hydrates in two different environments, a two- (CO2-water) or three-phase (CO2-water in glass beads) condition, is presented. Based on the experimental results, it can be anticipated that the pressure and temperature change will be negligible when the formation of CO2 hydrate is induced for GCS in the actual soil/rock layers. Besides, the formation of CO2 hydrate in porous media may be faster, compared to the two-phase bulk condition that has been typically used in many laboratory studies, as solid grains help accelerate the hydrate formation by providing nucleus sites of crystals. Further elaborations on the role of solid grains would bring a clear path for the feasible application in the subsea area.

Single- and Two-Phase Open-Circuit Fault Tolerant Control for Dual Three-Phase PM Motor Without Phase Shifting

A fault tolerant control strategy for dual three-phase permanent magnet synchronous motor (DTP-PMSM) with 0° phase shifting between two windings is proposed in this paper. When a DTP-PMSM suffers from single- or two-phase open-circuit fault, to maintain the torque performance, current in faulty phase must be compensated by other healthy phases, which causes asymmetric self- and mutual inductances. Therefore, the 2nd harmonic component can be observed in the dq -axis currents and torque ripple also increases. To analyse this harmonic component in two types of faults, post-fault model of no-phase-shifting DTP-PMSM based on vector space decomposition (VSD) method is built in this paper. Then, proportion-integral-resonant (PIR) controller which can be used to suppress the specific periodic disturbance is applied to compensate the 2nd harmonic components. As the resonant controller is rarely dependent on motor parameters, phase and amplitude of current harmonic, the PIR controller can be applied in no-phase-shifting DTP-PMSM to suppress the harmonic caused by single- and two-phase open-circuit faults. The experimental results validate the effectiveness of the proposed fault tolerant control under single- and two-phase open-circuit faulty conditions.

An experimental study of two-phase flow instability in a multi-loop natural circulation system

In this research, an experiment was carried out in a multi-loop natural circulation system to study its response behaviors under single-phase and two-phase flow instability conditions. The experimental facility consists of primary and secondary natural circulation loops, as well as an external forced circulation loop, which serves as a final heat sink to the system. The secondary loop is meant to simulate passive residual heat removal system found in the advanced reactors and some small modular reactors. The experiment was carried out under low-pressure conditions and constant heating powers. Within single-phase region, the thermal hydraulic parameters were found to vary linearly with the heating powers. By gradually increasing the power beyond the single-phase region, oscillation of the thermal hydraulic parameters was observed in both natural circulation loops. Critical conditions for the occurrence of instabilities in both natural circulation loops were determined. Flow-induced instabilities causing vibrations and acoustical noises were observed in the shell and tube heat exchanger connecting the two natural circulation loops. At higher power, fully mature oscillations were observed and characterized. In addition, effect of temperature rise in the system heat sink was also investigated. The oscillation period of the observed oscillations is about twice the boiling channel residence period. The oscillation amplitudes increase with increasing heater’s inlet temperature and heat sink temperature for the primary and secondary loops respectively. However, the influence of the heater’s inlet temperature on the flow instability is observed to be non-linear. This paper can contribute in the identification and determination of threshold values of thermal hydraulic parameters that are capable of triggering flow instabilities, which are important in the design and safe operations of natural circulation systems. It can also provide some useful information about how temperature rise in the system heat sink can influence the occurrence and amplification of flow instability in a natural circulation system.

Numerical study on pressure fluctuation in a multiphase rotodynamic pump with different inlet gas void fractions

Pressure fluctuation in the single-phase pump has been widely discussed, while less attention was paid for that in the multiphase pump. Therefore, this study investigated the pressure fluctuation in a multiphase rotodynamic pump. Unsteady simulations based on Euler two-fluid model were done with ANSYS-CFX software when the inlet gas void fractions (IGVFs) were 0.0%, 3.0%, 9.0%, and 15.0%. Under pure water (IGVF=0.0%) and gas-liquid two-phase (IGVFs=3.0%, 9.0%, 15.0%) conditions, the reliability of numerical method was verified by comparison with the experimental data. The numerical results showed that the dominant frequency in the impeller and guide vane corresponded to the blade numbers of guide vane and impeller, respectively. This illustrated that the rotor-stator interaction was the main cause for the generation of fluctuation in such pump. Meanwhile, the maximum fluctuation amplitude appeared near the impeller outlet at IGVF=0.0%, while it appeared near the guide vane inlet under two-phase conditions. Furthermore, the maximum fluctuation amplitudes at IGVF=3.0%, 9.0%, 15.0% are 1.9, 2.9, and 3.3 times as large as that at IGVF=0.0%.

Comparison of approximation-assisted heat exchanger models for steady-state simulation of vapor compression system

Finite-volume heat exchanger models are generally the most time-consuming component in a Component-based Vapor Compression Cycle simulation. While the approach of Performance Maps is commonly used, this method has its limitations. This study compares 3 approximation-assisted heat exchanger (HX) models for the steady-state simulation of vapor compression system: interpolation black-box model, Kriging black-box model, and Kriging-assisted three-zone model. We applied the 3 models to approximate the pressure drop (ΔP) and enthalpy change (Δh) of five different HXs at ten-thousand refrigerant inlet conditions randomly selected from the respective input domains of the HXs. Moreover, we applied the 3 models to simulate three different vapor compression systems at various test conditions. The approximation results were compared against the baseline finite-volume results. The results show that, for approximation of HX performance, Kriging metamodel gave the most accurate approximation with an overall ΔP and Δh mean absolute error (MAE) of 4.46% and 0.9%, respectively. For system simulations, Kriging metamodel gave the most accurate results. Its largest COP and capacity errors were 2.54% and 1.45%, respectively. The results also show that the three-zone model gave large error for Δh approximation at those operating conditions where the HX had an average two-phase outlet condition (xout,avg < 1.0) but with superheated vapor in part of the coil (vap% > 0). For computational efficiency, by using the approximation-assisted models, the system simulation time was sped up by a factor of 10 to 600, depending on the testing conditions.

Experimental Investigations on the Inner Flow Behavior of Centrifugal Pumps under Inlet Air-Water Two-Phase Conditions

Centrifugal pumps are widely used and are known to be sensitive to inlet air-water two-phase flow conditions. The pump performance degradation mainly depends on the changes in the two-phase flow behavior inside the pump. In the present paper, experimental overall pump performance tests were performed for two different rotational speeds and several inlet air void fractions (αi) up to pump shut-off condition. Visualizations were also performed on the flow patterns of a whole impeller passage and the volute tongue area to physically understand pump performance degradation. The results showed that liquid flow modification does not follow head modification as described by affinity laws, which are only valid for homogeneous bubbly flow regimes. Three-dimensional effects were more pronounced when inlet void fraction increased up to 3%. Bubbly flow with low mean velocities were observed close to the volute tongue for all αi, and returned back to the impeller blade passages. The starting point of pump break down was related to a strong inward reverse flow that occurred in the vicinity of the shroud gap between the impeller and volute tongue area.

Friction and local pressure loss characteristics of a 5 × 5 rod bundle with spacer grids

This paper presents the experimental results and analyses of the friction and local pressure loss coefficient of a 5 × 5 rod bundle with spacer grid. Based on the experimental data, friction and local pressure loss models were assessed and the role of spacer grid was discussed. The results showed that Cheng and Todreas model could predict bare rod friction loss well, and Chun model applied for high Re but would severely underestimate grid local loss for small Re. For two-phase condition, a universal correlation was proposed for bare rod two-phase friction multiplier, and it was found that all existing models cannot predict grid local loss multiplier very well. High prediction accuracy could be obtained by combining homogenous flow model, the liquid-mixture density ratio and a modification factor as a function of the grid parameter ε (axial projected area of grid strip to flow area) and void fraction.

Flow boiling heat transfer in silicon microgaps with multiple hotspots and variable pin fin clustering

Microfluidic interlayer cooling has been demonstrated as a practical solution for the vertical stacking of high power microelectronics. Although a considerable amount of studies has been presented for single phase cooling with this approach, the flow boiling features in more complex arrangements have not been as thoroughly studied. The embedded cooling of microelectronics is feasible with the use of dielectric refrigerants, which are ideally used in two-phase conditions in order to exploit the latent heat of vaporization. In the present investigation, the two-phase cooling in silicon microgaps is assessed under variable power and heat transfer surface area densities. The dielectric refrigerant HFE-7200 is used as the working fluid under flow boiling conditions, analyzing useful characteristics such as the two-phase flow regime, heat transfer, and pressure drop. The present investigation uses a numerical model that is capable of predicting the relevant features of flow boiling phenomena through a mechanistic phase-change model. The results from this study demonstrate that multiple hotspots with variable pin densities can be effectively controlled, with relatively uniform temperatures, under flow boiling conditions with dielectric fluids.

Experimental Study of the Static and Dynamic Characteristics of a Long (L/D = 0.75) Labyrinth Annular Seal Operating Under Two-Phase (Liquid/Gas) Conditions

AbstractA two-phase annular-seal stand at the Turbomachinery Laboratory of Texas A&amp;M University is utilized to experimentally investigate a labyrinth seal operating under two-phase flow conditions (a mixture of silicone oil and air). A long labyrinth seal (length-to-diameter ratio L/D = 0.75, diameter D = 114.729 mm, and radial clearance Cr = 0.213 mm) is tested at a supply pressure of 62 bars-g with inlet gas volume fraction GVFi ranging from 90 to 100%. Tests were conducted at three pressure ratios PR (0.3, 0.4, 0.5), three rotating speeds (5, 10, 15 krpm), six GVFi (90%, 92%, 94%, 96%, 98%, and 100%), and three inlet-preswirl inserts, namely, zero, medium, and high. Specifically, the ratio between the fluid's circumferential velocity and the shaft surface's velocity are in ranges of 0.0–0.2, 0.5–1.6, and 0.5–2.7 for the zero, medium, and high preswirls respectively. The direct dynamic stiffness KΩ is negative. As GVFi decreases (more liquid), KΩ becomes more negative for the zero preswirl. The effect of changing GVFi on KΩ for the medium and high preswirls is not as clear as for the zero preswirl. For the zero preswirl, as GVFi decreases, the cross-coupled dynamic stiffness kΩ and direct damping C damping increase. However, the effective damping Ceff values converge to almost the same positive value for higher frequencies. Hence, there is no significant effect of change in GVFi for the zero preswirl. For the high preswirl, as GVFi decreases, kΩ decreases and C increases. As GVFi decreases, Ceff becomes less negative and eventually becomes positive for frequencies higher than Ωc. This result indicates that at certain frequencies, the presence of liquid can make the labyrinth seals with high preswirl more stable. For the seal tested, a compressor running at 15 krpm and PR (ratio of seal exit pressure and seal inlet pressure) = 0.5 with the first critical speed of 7500 rpm (125 Hz) would experience an increase in stability with presence of liquid in the flow stream for the medium and high preswirls. However, for the range of GVFi considered here, if swirl brakes are used in a compressor application to reduce the preswirl, there would be no impact of liquid presence on the stability of the compressor. Concerning static measurements, leakage rate m˙ increases with decreases in GVFi but remains unchanged with increasing preswirl.

Modified Venturini Modulation Method for Matrix Converter Under Unbalanced Input Voltage Conditions

Based on Venturini method, it is in favor of the modulation technique for controlling the matrix converter due to only use of the comparison between the duty cycles in time domain and the triangular carrier wave for generating the gating signals and the achievable voltage ratio between fundamental output magnitude and fundamental input magnitude to 0.866. However, even with simple modulation method and achieving maximum fundamental output magnitude, the possible input voltage unbalance conditions accordingly influence on the output performances (more reduction and distortion). Thus, a control strategy based on Venturini method is presented in this paper, in order to solve the impacts of unbalanced input voltage conditions on the matrix converter performances. Conceptually, this strategy is done by modifying the mathematical model for controlling the modulating waves to satisfy the desirable feature, as generated in the event of normal situation. Up to this approach, it can support either single-phase condition or two-phase condition. Performance of the proposed control strategy was verified by the simplified simulation model in the MATLAB/Simulink software. It is clearly shown that the matrix converter can be controlled for regulating the balanced output voltages with showing good steady-state and dynamic operations without the energy storage devices.

Computational Investigation of Weakly Turbulent Flame Kernel Growths in Iso-Octane Droplet Clouds in CVC Conditions

Numerical simulations of turbulent flame kernel growths in monodisperse clouds of iso-octane liquid droplets are conducted in conditions relevant to constant volume combustors. The simulations make use of a low-Mach number Navier-Stokes solver and a thermodynamic pressure evolution model has been implemented to reproduce the pressure variation that may be issued from either experiments or from a standard (i.e., analytical) compression law. Chemistry is described with a representative skeletal mechanism featuring 29 species and 48 elementary reaction steps. The computational results clearly confirm the enhancement of flame propagation in constant volume combustion conditions. The impact of the droplet diameter on the turbulent flame development is scrutinized for two distinct values of the Stokes number St equal to 0.1 and 1.0. Significant influence on the flame dynamics is put into evidence. This is a direct outcome of the equivalence ratio and temperature heterogeneities, which are themselves very sensitive to the choice of the Stokes number value. Then, small-scale turbulence-scalar interactions (TSI) are studied by analyzing the fields of the scalar gradients and strain-rate. Their dynamics is investigated for both non-reactive and reactive two-phase flows conditions. The TSI analysis is performed on the basis of time evolution equations written for quantities that characterize the couplings between the velocity gradient tensor and scalar gradients vectors. Special emphasis is placed on the possible influence of mass exchange terms between the liquid and gaseous phases.