Turbulence Chamber Research Articles

Detailed characterization of extreme clustering at near-contact scales in isotropic turbulence

Recent measurements of inertial particles in isotropic turbulence (Hammond & Meng, J. Fluid Mech., vol. 921, 2021, A16) revealed surprising extreme clustering of particles at near-contact separations $(r)$ , whereby the radial distribution function, $g(r)$ , grows from $O(10)$ to $O(10^3)$ with a $(r/a)^{-6}$ scaling (where $a$ is the particle radius), and a surprising upturn of the mean inward particle-pair relative velocity (MIRV). Hydrodynamic interactions (HIs) were proposed to explain the extreme clustering, but despite predicting the correct scaling $(r/a)^{-6}$ , the HI theory underpredicted $g(r)$ by at least two orders of magnitude (Bragg et al., J. Fluid Mech., vol. 933, 2022, A31). To further understand the extreme clustering phenomenon and the relevance of HI, we characterize $g(r)$ and particle-pair kinematics for Stokes numbers $0.07 \leq St \leq 3.68$ in a homogeneous isotropic turbulence chamber using three-dimensional (3-D) particle tracking resolved to near–contact. A drift–diffusion equation governing $g(r)$ is presented to investigate the kinematic mechanisms of particle pairs. Measurements in all 24 conditions show that when $r/a\lessapprox 20$ , extreme clustering consistently occurs, scaling as $g(r) \sim (r/a)^{-k}$ with $4.5 \leq k \leq 7.6$ , which increases with $St$ . Here $g(r)$ varies with $St$ , particle size, density and polydispersity in ways that HI cannot explain. The extreme clustering region features an inward drift contributed by particle-pair turbophoresis and an inward radial relative acceleration. The latter indicates an interparticle attractive force at these separations that HI also cannot explain. The MIRV turns upward when approaching the extreme clustering region, opposite to direct numerical simulation predictions. These observations further support our previous assessment that extreme clustering arises from particle–particle interactions, but HI is not the main mechanism.

Study on the effect of turbulent jet combustion chamber on combustion characteristics at different ammonia energy ratio and optimization of an ammonia-diesel dual-fuel engine

In order to investigate the impact of turbulent jet combustion chamber (TJCC) on the combustion and emission characteristics of an ammonia-diesel dual-fuel (ADDF) engine and optimize the injection strategy of TJCC to achieve efficient and clean combustion at high ammonia energy ratio (AER), this paper established a three-dimensional simulation model. The findings demonstrated that raising the AER from 50% to 90% under heavy load conditions resulted in an increase in ITEg from 47.3% to 50.6% due to more uniform fuel distribution in the cylinder. Additionally, there was a significant reduction of over 70% in greenhouse gas (GHG) emissions, along with a decrease in the amount of diesel. The turbulent jet from TJCC caused the turbulence kinetic energy to rise in both intensity and range, which improved the mixing rate of diesel-ammonia-air and the flame propagation. The ITEg increased by 3.3%, 2%, and 0.7%, respectively, under the impact of the turbulent jet when AER was 50%, 70%, and 90%, respectively, compared to not injecting diesel in the TJCC. Finally, the ITEg reached 51.9% and unburned NH3, NO, and NO2 emissions were significantly reduced when AER was 90% and 10 mg of diesel was injected at 4°CA ATDC in the TJCC.

Renewable fuel and blend properties for the reduction of GHG emissions under different spark-ignited engine architectures

Despite the increasing efforts to electrify the transport sector, discussions remain on the interest of renewable and low-carbon fuels as an alternative solution to mitigate the impact on GHG. This work assesses the influence of liquid fuels’ properties on engine-out GHG emissions through the optimisation of both thermal efficiency and fuel’s carbon index, combined with highly efficient turbulent combustion chamber architecture, in an aim to maximise gains. The study helps underline the limitations and advantages associated to high efficiency fuels for spark-ignited combustion systems when applied to advance architectures. Limitations to the combination of such strategies have been observed, not commonly presented in previous studies. Indeed, the beneficial impact of optimised fuel properties on peak efficiency could be compromised when applied to high efficiency turbulent engines as their combination can aggravate heat transfer losses. Moreover, the fuel’s capacity to increase the maximal dilution rate could depend on the engine’s architecture. Despite these results, low-carbon fuels remain relevant to accelerate the decarbonisation of the transport sector due to benefits at higher load and a fuel’s lower carbon emissions. However, the importance of the synergetic optimisation of low carbon fuel formulation’s and combustion system’s design is underlined for more advanced technologies.

Self-similar propagation and flame acceleration of hydrogen-rich syngas turbulent expanding flames

In order to investigate the flame self-similar propagation and flame acceleration characteristics of hydrogen-rich syngas turbulent expanding flames, the turbulent combustion experimental studies of H2/CO/air mixtures with XH2 = 55%-95%, φ = 0.6–1.0, P = 1 bar-3 bar, u’=0.809–2.533 were conducted in a fan-stirred turbulent combustion chamber with an inner diameter of 380 mm. Results show that the normalized flame propagation speed ST/SL and turbulent flame Reynolds number ReT,flame could be represented by power-law correlations. With the increase of hydrogen fraction from 55% to 95%, the power exponent decreases from 0.413 to 0.301. The increase of hydrogen fraction makes the flame acceleration weaker because that the enhancing of laminar flame speed is more obvious than the differential-diffusion effect by decreasing Le. With the decrease of equivalence ratio from 1.0 to 0.6, the power exponent increases from 0.304 to 0.411 in this study. The relative high power exponent under low equivalence ratio is due to the coupling between differential-diffusion and the flame stretch on the local wrinkled flame structures. In addition, the influence of turbulence and flame intrinsic instabilities on flame acceleration propagation process of hydrogen-enriched syngas were studied. The acceleration exponent was extracted to quantitatively investigate the flame self-acceleration propagation in the transition stage, and the relationships between acceleration exponent and turbulence intensity (u’), Kovasznay number (Kz), turbulence integral length scale (LT), flame thickness (δ), thermal expansion ratio (ρu/ρb), effective Lewis number (Leeff) were analyzed

Reactive mass transfer of single bubbles in a turbulent flow chamber: The effect of temperature

Mass transfer at elevated temperatures is common in industrial equipments. In this work, the mass transfer coefficient between a single bubble and the surrounding liquid in a flow chamber at elevated temperatures was measured experimentally and analyzed from the following two aspects: liquid physical properties and molecular diffusion, where the latter is considered as the main factor. Based on Bao et al.’s work, a modified correlation was proposed to describe the effect of gas phase partial pressure resulted from the change of liquid temperature, from 25 °C to 85 °C, on the mass transfer coefficient. The volumetric mass transfer coefficient of single bubbles in the chamber can be compared to that in a stirred tank, even at elevated temperatures, especially at low stirring speeds.

Digital adaptive optics with interferometric homodyne encoding for mitigating atmospheric turbulence

Digital adaptive optics (DAO) created using homodyne encoding can mitigate atmospheric turbulence in passive imaging systems. This work demonstrates a self-referencing homodyne interferometry technique that combines the passive imaging utility of multiframe algorithmic procedures with the single-frame correction capability of the Shack–Hartmann adaptive optics technique. This paper presents image reconstruction improvements through the addition of (1) phase diversity modulation techniques within the interferometry reconstruction algorithm and (2) temporal image processing techniques applied after the interferometry reconstruction algorithm. By imaging quick response codes through a turbulent air chamber in the laboratory, it was possible to quantify the machine-readable performance gain provided by DAO when compared with a standard imaging camera. Results from this research verify that DAO from homodyne encoding provides turbulence mitigation for single frames of data, paving the way for environmentally robust, high-speed, self-contained imaging systems.

Experimental and numerical investigations of motion and mass transfer of single bubbles in a turbulent flow chamber

Background Gas-liquid mass transfer is a common transport phenomenon in the chemical industry. It is important to relate the mass transfer of single bubbles to the flow of the surrounding liquids. Many research on single bubbles mass transfer is on the experiment where the bubble is free rising in stagnant liquids, resulting a relative low liquid Reynolds number and short residence time. Therefore, the chamber flow is utilized to create a controllable flow field which can keep single bubbles in the chamber for a long period, which enables the accurate determination of the mass transfer coefficient.Methods First, the accuracy of three turbulence models describing the liquid flow in industrial stirred tanks were evaluated, by validating the liquid velocity and turbulent kinetic energy distribution in the chamber with experiments. Then, by coupling the turbulence model, volume of fluid method and several mass transfer models, the bubble motion and mass transfer were simulated. In this coupling approach, five classic models were respectively used to evaluate kL in the turbulent chamber flow.Significant findings This paper provides a reference for the selection of mass transfer model in the liquid flow chamber. The large eddy simulation is typically suitable for calculating turbulent liquid flow in the chamber. By coupling large eddy simulation and volume of fluid method, the mass transfer process of single bubbles in this cavity flow can be predicted. Considering the present partially contaminated and reactive system, Brauer mass transfer model can predict the mass transfer coefficient more accurately than other models.

Study and application of wall-roughness models in LES flows

This paper develops a new treatment of rough walls in turbulent high-enthalpy combustion chamber environments where the effect of the roughness on the (averaged) temperature profile can no longer be neglected. As the velocity and temperature profiles are affected by the roughness, a new framework is presented to take into account the effect of normalized sand grain roughnesses on the so called downward shift of the profiles in the logarithmic region. The application of the two presented methods exploits the roughness functions which can be found in the literature. The modeling presented in this paper is among the first attempts to combine a roughness model with a chemically reacting flow. Specifically, LES simulations are performed to verify the implementation of the models proposed for two setups, a periodic channel running on air and a rocket combustion chamber running on methane and oxygen. A Flamelet combustion model is used to model the chemical reactions. At the chamber walls, a roughness model is implemented in order to observe the effects on the temperature fields. The results are compared with the available experimental data.

Investigations on spark pre-chamber ignition and subsequent turbulent jet main chamber ignition in a novel optically accessible test rig

Turbulent jet ignition (TJI) is a promising strategy to ignite diluted air-fuel mixtures; this is usually generated by igniting a fraction of the mixture inside a small pre-chamber. Nevertheless, the processes that take place inside the pre-chamber, as well as the injection of the turbulent jet into the main chamber and its subsequent re-ignition are not fully understood. The current work presents an experimental investigation that studies the effects of the nozzle size, turbulence level, and air-fuel mixture on the pre-chamber ignition and main chamber re-ignition and combustion. To accomplish this, a series of experiments have been carried out under different boundary conditions. To understand the phenomena taking place in the pre- and main chamber, two different approaches were taken: On one hand, (1) pressure-based diagnostics were applied by fitting a pressure sensor in each of the chambers. This was done to trace the pressure evolution during the whole combustion event and to calculate the heat-release. On the other hand, (2) optical diagnostics were setup on both combustion chambers, using dual schlieren setups synchronized at the same frame rate. The optically accessible test rig and the combination of schlieren in the pre-chamber (PC) & main-chamber (MC) allows to visualize the ignition, flame propagation, quenching mechanisms and re-ignition under a wide range of boundary conditions. This combined with the pressure traces and heat-release give a full understanding of the ignition and combustion processes. Higher turbulence levels and equivalence ratios increase the propagation of the flame front and the peak pressure in the pre-chamber. The resulting higher nozzle-exit velocities lead, on one hand, to faster mixing and therefore to a larger portion of main chamber fuel within the jet, which decrease the main chamber combustion duration. On the other hand, to high quenching and longer re-ignition times, which show the adverse effect.

Experimental study of particle deposition on patterned microstructured surfaces in a chamber environment

Indoor respirable suspended particles may accumulate on textured surfaces such as sofa surfaces and office partitions via particle deposition. Previous studies mainly focus on particle deposition on non-patterned rough surfaces or patterned surfaces with texture scale larger than millimeters, and it is generally concluded that deposition rate increases due to the roughness. However, many indoor surfaces are patterned textures with scale in the order of 100 μm and there is a lack of study of particle deposition behavior in this regime. This study investigates the effect of patterned microstructured surfaces on particle deposition in a turbulent chamber. Different shapes (triangular, rectangular, semi-circular convex and semi-circular concave ribbed structures) and pitch-to-height ratios (i.e. ratio of spacing to height) of patterned structures were studied. Particle sizes ranging from 0.3 μm to 5 μm in diameter were tested. It is found that for submicron particles, deposition velocity was increased by the patterned microstructures, and triangular-ribbed surfaces achieved the highest deposition velocity, which was 10 times higher than that on a non-patterned surface. For micron particles, it is found that deposition velocity was lower than that of a non-patterned surface. Our results show that particle deposition is not always enhanced by roughness and it is possible to be reduced by a suitable length scale of patterned structures.

Reactive mass transfer of single bubbles in a turbulent flow chamber: Discussion on the effects of slippage and turbulence

The widely occurrence of gas–liquid mass transfer in the circulating flow is often involved but seldom discussed. Here, the mass transfer of single bubbles in a turbulent flow chamber was investigated. Force balance was performed to calculate the bubble slip velocity. In previous literatures, the effect of turbulence and slippage on the mass transfer was always discussed separately. In this work, we proposed that both slippage and turbulence contributed to gas–liquid mass transfer, and the mass transfer, in which turbulence had a more pronounced effect than slippage, increased with the increase of apparent liquid velocity in the chamber. A model, including two weighting coefficients and the models from Higbie, Frossling, and Lamont and Scott, was used for the comparison. The model can be used to describe kL in both quiescent and turbulent liquids as well as to express the mass transfer by considering both the effect of slippage and turbulence.

Mechanistic Influence of Chemical Agglomeration Agents on Removal of Inhalable Particles from Coal Combustion.

Particle pollution has been a research topic attracting the attention of the researchers around the world because inhalable particles are hazardous to humans and the environment. The major resource of particle pollution is the combustion of coal and biomass. Dust collectors, electrostatic precipitators, and bag filters are required to remove particles from flue. Because of the large specific surface areas of inhalable particles, they easily agglomerate to form larger aggregates; therefore, improving the capture efficiency of dust collectors is of importance. Herein, chemical agglomeration agents were sprayed into a turbulent agglomeration chamber to improve the removal efficiency of inhalable particles. The results showed that the total removal efficiency of inhalable particles was 59.2% for the three-composition agglomeration agents of kappa carrageenans/Tween-80/NH4Cl (KC/TW/NH4Cl). The mean particle diameter increased from 2.8 μm before agglomeration to above 10.0 μm after agglomeration. In the agglomeration process, nonionic TW accelerates the wetting properties, in which the polymer, KC, or anion polyacrylamide, promotes prolongation of the contact time between droplets and particles. Two different removal mechanisms are proposed to explain the effect of chemical agglomeration agents. Immersion agglomeration described the agglomeration process of only fine particles, and distribution agglomeration supported the capture of large particles for fine ones in polydispersed aerosols.

Technical note: Equilibrium droplet size distributions in a turbulent cloud chamber with uniform supersaturation

Abstract. In a laboratory cloud chamber that is undergoing Rayleigh–Bénard convection, supersaturation is produced by isobaric mixing. When aerosols (cloud condensation nuclei) are injected into the chamber at a constant rate, and the rate of droplet activation is balanced by the rate of droplet loss, an equilibrium droplet size distribution (DSD) can be achieved. We derived analytic equilibrium DSDs and probability density functions (PDFs) of droplet radius and squared radius for conditions that could occur in such a turbulent cloud chamber when there is uniform supersaturation. We neglected the effects of droplet curvature and solute on the droplet growth rate. The loss rate due to fallout that we used assumes that (1) the droplets are well-mixed by turbulence, (2) when a droplet becomes sufficiently close to the lower boundary, the droplet's terminal velocity determines its probability of fallout per unit time, and (3) a droplet's terminal velocity follows Stokes' law (so it is proportional to its radius squared). Given the chamber height, the analytic PDF is determined by the mean supersaturation alone. From the expression for the PDF of the radius, we obtained analytic expressions for the first five moments of the radius, including moments for truncated DSDs. We used statistics from a set of measured DSDs to check for consistency with the analytic PDF. We found consistency between the theoretical and measured moments, but only when the truncation radius of the measured DSDs was taken into account. This consistency allows us to infer the mean supersaturations that would produce the measured PDFs in the absence of supersaturation fluctuations. We found that accounting for the truncation radius of the measured DSDs is particularly important when comparing the theoretical and measured relative dispersions of the droplet radius. We also included some additional quantities derived from the analytic DSD: droplet sedimentation flux, precipitation flux, and condensation rate.

The role of turbulent fluctuations in aerosol activation and cloud formation

Aerosol indirect effects are one of the leading contributors to cloud radiative properties relevant to climate. Aerosol particles become cloud droplets when the ambient relative humidity (saturation ratio) exceeds a critical value, which depends on the particle size and chemical composition. In the traditional formulation of this problem, only average, uniform saturation ratios are considered. Using experiments and theory, we examine the effects of fluctuations, produced by turbulence. Our measurements, from a multiphase, turbulent cloud chamber, show a clear transition from a regime in which the mean saturation ratio dominates to one in which the fluctuations determine cloud properties. The laboratory measurements demonstrate cloud formation in mean-subsaturated conditions (i.e., relative humidity <100%) in the fluctuation-dominant activation regime. The theoretical framework developed to interpret these measurements predicts a transition from a mean- to a fluctuation-dominated regime, based on the relative values of the mean and standard deviation of the environmental saturation ratio and the critical saturation ratio at which aerosol particles activate or become droplets. The theory is similar to the concept of stochastic condensation and can be used in the context of the atmosphere to explore the conditions under which droplet activation is driven by fluctuations as opposed to mean supersaturation. It provides a basis for future development of cloud droplet activation parameterizations that go beyond the internally homogeneous parcel calculations that have been used in the past.

Ultra-low emission combustion of diesel-coconut biodiesel fuels by a mixture temperature-controlled combustion mode

Liquid fuels are likely to remain the main energy source in long-range transportation and aviation for several decades. To reduce our dependence on fossil fuels, liquid biofuels can be blended to fossil fuels – or used purely. In this paper, coconut methyl ester, standard diesel fuel (EN590:2017), and their blends were investigated in 25 V/V% steps. A novel turbulent combustion chamber was developed to facilitate combustion in a large volume that leads to ultra-low emissions. The combustion power of the swirl burner was 13.3 kW, and the air-to-fuel equivalence ratio was 1.25. Two parameters, combustion air preheating temperature and atomizing air pressure were adjusted in the range of 150–350 °C and 0.3–0.9 bar, respectively. Both straight and lifted flames were observed. The closed, atmospheric combustion chamber resulted in CO emission below 10 ppm in the majority of the cases. NO emission varied between 60 and 183 ppm at straight flame cases and decreased below 20 ppm when the flame was lifted since the combustion occurred in a large volume. This operation mode fulfills the 2015/2193/EU directive for gas combustion by 25%, which is twice as strict as liquid fuel combustion regulations. The 90% NO emission reduction was also concluded when compared to a lean premixed prevaporized burner under similar conditions. This favorable operation mode was named as Mixture Temperature-Controlled (MTC) Combustion. The chemiluminescent emission of lifted flames was also low, however, the OH* emission of straight flames was clearly observable and followed the trends of NO emission. The MTC mode may lead to significantly decreased pollutant emission of steady-operating devices like boilers, furnaces, and both aviation and industrial gas turbines, meaning an outstanding contribution to more environmentally friendly technologies.

Self-similar propagation and turbulent burning velocity of CH4/H2/air expanding flames: Effect of Lewis number

In this study we clarify the role of differential diffusion characterized by effective Lewis number, Leeff, on the self-similar accelerative propagation and the associated turbulent burning velocity of turbulent expanding flames. The turbulent flame trajectories of the CH4/H2/air mixtures were measured using a newly developed large-scale, fan-stirred turbulent combustion chamber generating near-isotropic turbulence. It is found that the normalized turbulent propagation speed scales as the turbulent flame Reynolds number, ReT,f=(urms/SL)(〈r〉/lf), roughly to the one-half power for the stoichiometric CH4/H2 = 80/20 flames with unity Leeff (=1), where the average flame radius, 〈r〉, is the length scale and the thermal diffusivity, α=SLlf, is the transport property, SL and lf are the laminar burning velocity and flame thickness, and urms is the root-mean-square (rms) turbulent fluctuation velocity. The propagation of the fuel lean CH4/H2 = 20/80 flames with sub-unity Leeff (<1) is still self-similar, however, the normalized turbulent propagation speed is much higher and the power exponent is greater than 1/2 even though these two flames have almost the same laminar burning velocity, flame thickness with SL, lf and experience the similar turbulence perturbations. The stronger self-similar propagation of the Leeff < 1 flames is the consequences of the couple effects of the differential diffusion and the flame stretch on the local wrinkled flamelets within the turbulent flame brush. Based on the present experimental data, a modified possible general correlation for turbulent burning velocity is obtained in terms of the Leeff and ReT,f with differential diffusion consideration. This correlation is able to predict not only the present experimental data but also the previous turbulent burning velocities measured using both turbulent Bunsen flames and expanding flames at high pressures.

Investigation on Hollow Beam Propagation through Turbulence Conditions in Free Space Optical Communication

In Free Space Optical Communication (FSO), the optical signal from the laser source severely affects while travelling through free space atmospheric channel due to scattering, absorption and other effects of atmospheric turbulence conditions. This degrades the performance of FSO communication. In this article, we have generated the hollow beam from the laser output by the inverse axicon lens called inverted axicon beam. An artificial controlled turbulence chamber is created and the test signal has been transmitted through the turbulence conditions by employing various modulation schemes such as PAM, PWM, PPM, ASK, BPSK and QPSK separately. In all cases, we measured parameters phase jitter and Time jitter experimentally and the results are compared. Two types of wavelength laser sources such as red and green lasers are used for the analysis. In which, ASK provides a better withstand ability to jitter than other modulation techniques with atmospheric turbulence.

Reactive mass transfer of single O2 bubbles in a turbulent flow chamber

A non-intrusive measurement method was used to quantify the mass transfer between an oxygen bubble (with a spherical equivalent diameter in the range 2–4 mm) and the turbulent sodium sulfite solution in which the bubble was driven to circulate. The variations of the position, size, and velocity of the single bubble with time were derived from the images recorded by a high-speed camera, and the average reactive mass transfer coefficients were calculated from the reduction of the volume of the bubble. The enhancement factors under various flow conditions caused by the catalyzed chemical reaction were provided. The flow field in the chamber was measured by 2D particle image velocimetry (PIV). The single-phase instantaneous flow field was compared with the multi-phase flow field in terms of the effect of the single bubble. A correlation of the bubble Sherwood number with the bubble Reynolds number was obtained under different liquid Reynolds numbers. We found that the slip velocity has a high capacity to keep the bubble surface mobile. Both the bubble Reynolds number based on the bubble slip velocity and liquid Reynolds number contributed to the mass transfer in the turbulent chamber.

Holographic deflection imaging measurement of electric charge on aerosol particles

We propose a simple noninvasive technique called holographic deflection imaging (HDI) to measure electric charge on individual aerosol particles. Particles in many flows such as atmospheric turbulence can carry electric charges, which add forces that compete with turbulence and affect particle dynamics. To measure particle charges, we devised a novel technique for polydispersed particles with bipolar charge distributions. The technique uses common optical hardware and a novel particle sizing algorithm for polydispersed size distributions. A charged particle sample is introduced into a vertical channel air flow and a horizontal electric field. For each particle, In-line digital holography is used to simultaneously track particle positions over successive holograms and decode size information from hologram interference fringes. This enables measurement of the electric-force-induced horizontal component of terminal velocity and the particle size. From velocity and size, particle charge is calculated using a force balance, assuming Stokes drag on spherical particles. Two experiments were conducted, one to validate HDI measurements of a bipolarly charged particle sample against an electrometer, and the other to demonstrate particle size effect on triboelectric charging of aerosols in a fan-driven isotropic turbulence chamber. The HDI setup was configured for each experiment, and measurement uncertainty was estimated. Experiment 1 found good agreement (< 5%) in mean charge between measurements by HDI and the electrometer. Experiment 2 found nearly symmetric bipolar charge distributions, which broadened with increasing particle surface area, as expected for triboelectric charging by the symmetrically installed fans.

Mitigation of atmospheric turbulence with random light carrying OAM

The results of the laboratory experiments are presented for synthesis of the Im-Bessel correlated beams by a Spatial Light Modulator (SLM) and a Digital Micromirror Device (DMD) as well as for their interactions with atmospheric turbulence simulated by either an SLM or a mixed-air turbulent chamber. The synthesis procedure of these beams relies on the incoherent superposition of their coherent modes being Laguerre-Gaussian (LG) functions having a variable radial mode and a fixed azimuthal mode carrying the Orbital Angular Momentum (OAM). As a result of such construction the correlation functions of these random beams have separable phase carrying the OAM with the index inherited from the coherent modes. The coherence states of these beams are controlled by the distribution of weights of the coherent modes in superposition, varying from perfectly coherent to nearly incoherent. We explore the effects of the cycling rates of the SLM and the DMD used for source synthesis on the average intensity and the scintillation index of the generated beams having different OAM indices and coherence states after propagation in atmospheric turbulence. Our analysis indicates that for fairly incoherent beams with sufficiently large OAM index and high cycling rates the atmospheric turbulence can be efficiently mitigated.