Turbulent Regime Research Articles

Scaling regimes in rapidly rotating thermal convection at extreme Rayleigh numbers

The geostrophic turbulence in rapidly rotating thermal convection exhibits characteristics shared by many highly turbulent geophysical and astrophysical flows. In this regime, the convective length and velocity scales and heat flux are all diffusion-free, i.e. independent of the viscosity and thermal diffusivity. Our direct numerical simulations (DNS) of rotating Rayleigh–Bénard convection in domains with no-slip top and bottom and periodic lateral boundary conditions for a fluid with the Prandtl number $Pr=1$ and extreme buoyancy and rotation parameters (the Rayleigh number up to $Ra=3\times 10^{13}$ and the Ekman number down to $Ek=5\times 10^{-9}$ ) indeed demonstrate all these diffusion-free scaling relations, in particular, that the dimensionless convective heat transport scales with the supercriticality parameter $\widetilde {Ra}\equiv Ra\, Ek^{4/3}$ as $Nu-1\propto \widetilde {Ra}^{3/2}$ , where $Nu$ is the Nusselt number. We further derive and verify in the DNS that with the decreasing $\widetilde {Ra}$ , the geostrophic turbulence regime undergoes a transition into another geostrophic regime, the convective heat transport in this regime is characterized by a very steep $\widetilde {Ra}$ -dependence, $Nu-1\propto \widetilde {Ra}^{3}$ .

Self-similarity in over-tripped turbulent boundary-layer flows

The scaling universality of structure functions is studied for artificially thickened turbulent boundary-layer flows in over-tripped impacts by using hot-wire measurement datasets. The self-similarity behaviours in the inner and outer regions are examined from the viewpoint of different flow mechanisms. In the inner region, the relative ratios between structure functions for the energy-containing range of scales exhibit universality behaviour, in accordance with Townsend's attached eddy hypothesis. This universality of the energy-containing range of scales extends further away from the wall by increasing the tripping intensity. On the other hand, the impact of the external intermittency on the self-similarity of small-scale turbulence is examined through the intermittent zone in over-tripped conditions. Towards the boundary-layer edge, the structure functions exhibit a growing departure from self-similarity and analytical prediction, and it is demonstrated that the departure is primarily due to external intermittency. Moreover, based on the conditional statistics concentrated in the turbulent regimes, it is revealed that the small scales in the turbulence regime are homogenized in a self-similar behaviour, which is independent of the current tripping conditions.

Cooling Efficiency of a NACA4412 airfoil: Numerical application

The temperatures imposed on the blades of the first stages of turbines are generally very high; these expose the latter to harmful thermal effects, pushing manufacturers to continually improve techniques for cooling the blades. It is true that by increasing the temperature of the gases at the inlet of the turbines, we increase the efficiency, the performance of the machines, and we improve the power and fuel consumption with a significant reduction in polluting gases. Thus, the current general trend among manufacturers is to design machines that operate at increasingly high inlet temperatures. This has led, therefore, to the constant search for new materials with high thermal resistance and to constantly improve cooling techniques. This task is conditioned by a good and deep understanding of the phenomenon of heat transfer in turbine blades. This study examines the three dimension numerical simulation of the flow and heat exchange inside an internal cooling channel of a gas turbine blade with the profile of NACA 4412. This channel plays an important role in increasing heat exchange between the cooling air and the walls of the blade. In the turbulent regime, we have investigated the cooling of a profile blade NACA 4412 using forced convection (V = 200, 250, 300, 350, and 400 m / s). determined that the value of the cold air's speed increases with the intensity of the secondary flow inside the morning. Results found that, The flow dynamics and kinematics of fluid particles alter significantly when the cooling air speed is increased, and the cooling level is enhanced.

Rozwiązanie problemu tworzenia się zatorów w rurociągach podczas transportu gazu poprzez proces automatycznego strumieniowania

The article presents the application of autoejection process to ensure efficient operation of pipeline systems and gas separation installations when it is impossible to remove and utilize the condensate from the pipelines. Thus, in the suggested ejector, a single common stream is separated into two streams, i.e., an active and a passive stream, as opposed to two separate independent streams in existing ejection devices. As a result, we refer to such an ejection process as autoejection, or a self-ejection process. Such a procedure is run in the pipeline with the goal of blowing and dusting the liquid phase through the central high-velocity nozzle in circumstances of mass blocking and coating rather than expelling the liquid from the pipes. On the cross-sectional area of the belts, the velocity profiles of flows in laminar and turbulent regimes are known to differ greatly from one another. The adhesion forces acting from the tube's central axis outwards, towards its walls cause the flow rate to decrease. There is a cross-sectional interaction of flows in this mode, according to experimental studies of turbulent flows. As a result, compared to the laminar domain, the flow velocities in this regime are more equally distributed across the cross-section of the flow, and their values are roughly equal to the flow's average value. In this case, based on the dependences of the flow ∆p = f(W), it is known from the calculations and the table that at such velocity limits of the flows, the “braking” pressure (p0) of the liquid coating on the pipe walls corresponds to the maximum velocity of the central gas flow. The autoejection process can occur due to the difference between the static pressures. Unsaturated absorbent coatings can be blasted off the tube absorber's walls using this technique and blended back into the main gas stream. Gas-liquid autoejectors installed along the pipe absorber's length make it possible to use this method. The purpose and principles of autoejectors’ operation are considered and a perspective of their application in tube absorbers is noted.

Experimental setup for researching the stability of fluid flow

The problem of studying the stability of the flow of a thermoviscous liquid is relevant in connection with the need to develop methods for controlling flow regimes in industrial condensers and heat exchange devices. These devices play an important role in a variety of technological processes, from food production to materials processing, and their effectiveness is directly dependent on the flow regime they establish. Awareness of the importance of both laminar and turbulent flow regimes leads to the need to balance between energy efficiency, which is often preferable to laminar flow, and heat and mass transfer efficiency, which is characteristic of turbulent flow. This makes it important to study and control the stability of the flow. As the speed of fluid flow increases, laminar flow loses stability and disturbances arise, which can lead to the formation of a secondary nonlinear regime that preserves the main characteristics of laminar flow, or to flow turbulization, which in turn can have a significant impact on the efficiency of technical devices. Although a lot of work has been done to study the stability of the flow of homogeneous liquids in channels and their spectral characteristics, the importance of taking temperature differences into account is often overlooked. However, it is the dependence of liquid viscosity on temperature that plays a significant role in determining flow patterns and requires additional study. Despite the ongoing numerical studies of the stability of fluid flow, there remains a need to compare experimental data with the results of numerical modeling to obtain a more complete understanding of the processes occurring in the system. In this regard, within the framework of this work, an experimental setup of an annular channel was developed and assembled in order to conduct a detailed experimental study of the stability of fluid flow and subsequently compare the results obtained with numerical simulations, which will provide more accurate data for further improving the design and operation of industrial devices.

The Okubo–Weiss-type topological criteria in two-dimensional magnetohydrodynamic flows

The Okubo–Weiss (Okubo, Deep-Sea Res., vol. 17, issue 3, 1970, pp. 445–454; Weiss, Physica D, vol. 48, issue 2, 1991, pp. 273–294) criterion has been widely used as a diagnostic tool to divide a two-dimensional (2-D) hydrodynamical flow field into hyperbolic and elliptic regions. This paper considers extension of these ideas to 2-D magnetohydrodynamic (MHD) flows, and presents an Okubo–Weiss-type criterion to parameterize the magnetic field topology in 2-D MHD flows. This ensues via its topological connections with the intrinsic metric properties of the underlying magnetic flux manifold, and is illustrated by recasting the Okubo–Weiss-type criterion via the 2-D MHD stationary generalized Alfvénic state condition to approximate the slow-flow-variation ansatz imposed in its derivation. The Okubo–Weiss-type parameter then turns out to be related to the sign definiteness of the Gaussian curvature of the magnetic flux manifold. A similar formulation becomes possible for 2-D electron MHD flows, by using the generalized magnetic flux framework to incorporate the electron-inertia effects. Numerical simulations of quasi-stationary vortices in 2-D MHD flows in the decaying turbulence regime are then given to demonstrate that the Okubo–Weiss-type criterion is able to separate the MHD flow field into elliptic and hyperbolic field configurations very well.

Entanglement-Based CV-QKD with Information Reconciliation over Entanglement-Assisted Link.

An entanglement-based continuous variable (CV) QKD scheme is proposed, performing information reconciliation over an entanglement-assisted link. The same entanglement generation source is used in both raw key transmission and information reconciliation. The entanglement generation source employs only low-cost devices operated in the C-band. The proposed CV-QKD scheme with information reconciliation over an entanglement-assisted link significantly outperforms the corresponding CV-QKD scheme with information reconciliation over an authenticated public channel. It also outperforms the CV-QKD scheme in which a classical free-space optical communication link is used to perform information reconciliation. An experimental demonstration over the free-space optical testbed established at the University of Arizona campus indicates that the proposed CV-QKD can operate in strong turbulence regimes. To improve the secret key rate performance further, adaptive optics is used.

Enhanced Aerodynamic Performance of a Two-Dimensional Airfoil Using Moving Boundaries

The effects of moving boundary conditions on the aerodynamic performance of a two-dimensional NACA 0012 airfoil at different angles of attack (α) in a uniform freestream at a Reynolds number of 10,000 are numerically studied. The moving boundary conditions are motivated by inviscid potential flow around the airfoil, which also satisfies the viscous equations of motion. In this study, the wall is moved at the slip velocity of the inviscid flow, or a fraction of it. These prescribed moving boundary conditions are shown to suppress vortex shedding, thus allowing the drag to go toward zero and the lift coefficient toward 2πα over a wide range of angles of attack (α≤20°) even in the separated flow regime. It is shown that moving boundary conditions are effective over a wide range of their strengths with respect to the overall power required (required to overcome aerodynamic drag and move the airfoil boundary). This power is shown to attain a minimum near the inviscid flow moving boundary condition, which is around 10% or less of the power required for the stationary boundary condition. Finally, the effectiveness of the moving boundary conditions is demonstrated for fully turbulent flow regimes at Re=6 million as well.

IMPACT OF SOLID BOUNDARIES AND VISCOSITY OF THE MEDIUM ON THE CONTRIBUTION OF THE INERTIAL AND VORTEX COMPONENTS OF THE NORMAL FORCE OF A ROTATING PLATE. PART 2

Within the framework of the improved method of discrete vortices, generalized for viscous media, a method has been developed for determining the contribution of forces of inertial, vortex and circulation nature to the normal force of a plate moving in a stationary viscous boundless medium accord- ing to an arbitrary law, in the presence of a wall and in a channel. The developed method was tested for the case of instantaneous angular start of the plate and subsequent constant angular speed of rotation (Wagner's problem) in a viscous boundless medium, in the presence of a wall and in a channel, in laminar and turbulent modes. The application of approximate analytical formulas for the components of the induced velocity from a discrete vortex in a viscous medium near the wall and in the channel made it possible to obtain velocity fields that visualize two vortices separated from the edges of the plate and the dynamics of their dispersion in laminar and turbulent regimes of rotation of the plate near the wall and in the channel. The inertial- vortical nature of the normal force of the plate (with the dominance of inertial forces) is confirmed, which rotates after an instantaneous start with the separation of the flow from both its edges, regardless of the presence of solid boundaries and laminar or turbulent flow regimes. It was found that in the case of the laminar regime, the effect of the presence of the wall on the reduced inertial component of the normal force of the plate is insignificant, but the influence of the channel leads to a faster departure of the laminar vortex from the moving edge of the plate, which leads to a gradual increase in the contribution of the inertial component of the normal force of the plate up to 100 % and more when turning the plate perpendicular to the channel walls. Approximately the same happens in the case of the absence of solid boundaries, when a turbulent vortex of a larger size and intensity than the corresponding laminar one moves away from the moving edge of the plate.

Thermo-hydraulic and entropy generation analysis of nanofluid flow with variable properties in various duct cross sections: a 3-D two-phase approach

A three-dimensional computational fluid dynamics (CFD) study is carried out to explore the effect of duct cross section on the thermo-hydraulic performance of various ducts. A finite volume-based scheme with an SST k-omega model and mixture model (two-phase model) was used to obtain more realistic results. A two-phase mixture model was used to consider the movement between base fluid and nanoparticles. Al2O3 nanoparticle having a volume fraction of 0.01% and 42 nm as particle size, the heat transfer and friction factor characteristic are studied for turbulent flow regime (3000 < Re < 9000) with variable thermo-physical properties. A maximum enhancement of 86% in heat transfer rate is obtained for the serpentine duct compared to the conventional circular duct at Re = 4500. Owing to a significantly lower increase in pressure drop, the elliptical duct has the highest thermo-hydraulic performance parameter of 1.54 relative to the circular duct. Further, to analyze the heat transfer quality, the entropy generation rate is studied, and it is observed that the square duct reported the highest with an increase of 60% and the elliptical duct the lowest with a reduction of 54% relative to the circular duct. This study can aid in choosing the duct geometry to enhance the heat transfer rate with nanofluid for applications such as solar-thermal, heat exchangers, etc.

Thermal effectiveness enhancement in heat exchange tube using louver-punched V-baffles

An efficient technique for reducing frictional loss by punching holes on the surface of vortex generators has been extensively researched, particularly in the form of louver-punched holes. This article describes an experimental and numerical examination of thermal effectiveness in a heat exchange tube with louvered baffle vortex generators (LBVG). As air was directed to the LBVG-inserted tube with a consistent heat flux, the flow was measured in a turbulent regime. The LBVGs were set at 30° attack angle (α) and mounted at regular intervals on a two-sided flat tape with one relative baffle height (b/D = RB = 0.25) and pitch (P/D= RP = 1) at the first step. The baffles had five different louver angles (θ = 0 ˗ 90°) and three different relative louver sizes (LR= e/b = 0.4, 0.56, and 0.72). The Nusselt number ratio (NuR), friction factor ratio (fR), and thermal effectiveness factor (TEF) were utilized to quantify the performance of LBVGs. The findings showed that LBVGs had much lower fR values than solid baffles (without holes), whereas NuR values decreased slightly. When θ and LR were reduced, the fR and NuR for LBVGs increased until they resembled those for solid baffles. Through numerical simulations using the realizable k-ε turbulent model based on the finite volume method, the flow and temperature fields of various cases were generated; their results were verified via analysis of the fluid flow patterns. The computational findings revealed that the jet flow from the louver hole could boost heat transfer, and TEF of LBVGs varied depending on the placement of the hole. According to the computations, the optimal TEF at RP = 0.75, LR = 0.4, and θ1 = 20° is roughly 2.64, and the hole should be placed toward the baffle ends rather than in the middle.

Symmetries of the Large Scale Structures of the Universe as a Phenomenology of a Fractal Turbulence: The Role of the Plasma Component

We present a new perspective on the symmetries that govern the formation of large-scale structures across the Universe, particularly focusing on the transition from the seeds of galaxy clusters to the seeds of galaxies themselves. We address two main features of cosmological fluid dynamics pertaining to both the linear and non-linear regimes. The linear dynamics of cosmological perturbations within the Hubble horizon is characterized by the Jeans length, which separates stable configurations from unstable fluctuations due to the gravitational effect on sufficiently large (and therefore, massive enough) overdensities. On the other hand, the non-linear dynamics of the cosmological fluid is associated with a turbulent behavior once the Reynolds numbers reach a sufficiently high level. This turbulent regime leads to energy dissipation across smaller and smaller scales, resulting in a fractal distribution of eddies throughout physical space. The proposed scenario suggests that the spatial scale of eddy formation is associated with the Jeans length of various levels of fragmentation from an original large-scale structure. By focusing on the fragmentation of galaxy cluster seeds versus galaxy seeds, we arrived at a phenomenological law that links the ratio of the two structure densities to the number of galaxies in each cluster and to the Hausdorff number of the Universe matter distribution. Finally, we introduced a primordial magnetic field and studied its influence on the Jeans length dynamics. The resulting anisotropic behavior of the density contrast led us to infer that the main features of the turbulence could be reduced to a 2D Euler equation. Numerical simulations showed that the two lowest wavenumbers contained the major energy contribution of the spectrum.

Influence of ion-to-electron temperature ratio on tearing instability and resulting subion-scale turbulence in a low- β e collisionless plasma

A two-field gyrofluid model including ion finite Larmor radius (FLR) corrections, magnetic fluctuations along the ambient field, and electron inertia is used to study two-dimensional reconnection in a low βe collisionless plasma, in a plane perpendicular to the ambient field. Both moderate and large values of the ion-to-electron temperature ratio τ are considered. The linear growth rate of the tearing instability is computed for various values of τ, confirming the convergence to reduced electron magnetohydrodynamics predictions in the large τ limit. Comparisons with analytical estimates in several limit cases are also presented. The nonlinear dynamics leads to a fully developed turbulent regime that appears to be sensitive to the value of the parameter τ. For τ = 100, strong large-scale velocity shears trigger Kelvin–Helmholtz instability, leading to the propagation of the turbulence through the separatrices, together with the formation of eddies of size of the order of the electron skin depth. In the τ = 1 regime, the vortices are significantly smaller and their accurate description requires that electron FLR effects be taken into account.

A Study of the Influence of Fin Parameters on Porous-Medium Approximation

The porous-medium approximation (PM) approach is extensively employed in large-quantity grid simulations of heat exchangers, providing a time-saving approach in engineering applications. To further investigate the influence of different geometries on the implementation of the PM approach, we reviewed existing experimental conditions and performed numerical simulations on both straight fins and serrated fins. Equivalent flow and heat-transfer factors were obtained from the actual model, and computational errors in flow and heat transfer were compared between the actual model and its PM model counterpart. This exploration involved parameters such as aspect ratio (a*), specific surface area (Asf), and porosity (γ) to evaluate the influence of various geometric structures on the PM approach. Whether in laminar or turbulent-flow regimes, when the aspect ratio a* of straight fins is 0.98, the flow error (δf) utilizing the PM approach exceeds 45%, while the error remains within 5% when a* is 0.05. Similarly, for serrated fins, the flow error peaks (δf &gt; 25%) at higher aspect ratios (a* = 0.61) with the PM method and reaches a minimum (δf &lt; 5%) at lower aspect ratios (a* = 0.19). Under the same Reynolds numbers (Re), employing the PM approach results in an increased heat-transfer error (δh)with rising porosity (γ) and decreasing specific surface area (Asf), both of which remained under 10% within the range of this study. At lower aspect ratios (a*), the fin structure becomes more compact, resulting in a larger specific surface area (Asf) and smaller porosity (γ). This promotes more uniform flow and heat transfer within the model, which is closer to the characteristics of PM. In summary, for straight fins at 0 &lt; a* &lt; 0.17 in the laminar regime (200 &lt; Re &lt; 1000) and in the turbulent regime (1200 &lt; Re &lt; 5000) and for serrated fins at 0 &lt; a* &lt; 0.28 in the laminar regime (400 &lt; Re &lt; 1000) or 0 &lt; a* &lt; 0.32, in the turbulent regime (2000 &lt; Re &lt; 5000), the flow and heat-transfer errors are less than 15%.

Radiative Particle-in-Cell Simulations of Turbulent Comptonization in Magnetized Black-Hole Coronae.

We report results from the first radiative particle-in-cell simulations of strong Alfvénic turbulence in plasmas of moderate optical depth. The simulations are performed in a local 3D periodic box and self-consistently follow the evolution of radiation as it interacts with a turbulent electron-positron plasma via Compton scattering. We focus on the conditions expected in magnetized coronae of accreting black holes and obtain an emission spectrum consistent with the observed hard state of Cyg X-1. Most of the turbulence power is transferred directly to the photons via bulk Comptonization, shaping the peak of the emission around 100keV. The rest is released into nonthermal particles, which generate the MeV spectral tail. The method presented here shows promising potential for abinitio modeling of various astrophysical sources and opens a window into a new regime of kinetic plasma turbulence.

Evaluating the advantage of turbulent flow to diminish concentration polarization in Roto-dynamic RO system

Concentration polarization (CP) is the major shortcoming of the reverse osmosis (RO) system for brackish/seawater desalination. The present study aims to understand the effect of induced shear stress, enhanced flow dynamics, and eddy diffusivity on CP, when the flow is turbulent. In roto-dynamic RO system turbulence can be easily generated by controlling the angular speed of the rotor without increasing the feed discharge. We have numerically simulated the salt rejection by the RO membrane and concentration polarization at the seawater salinity of 500 mol/m3 for two different configurations of roto-dynamic RO system when the flow is turbulent. We have used Reynolds stress model (RSM) and eddy viscosity-dependent eddy diffusivity models for salt transport. In turbulent flow regime, eddy diffusion enhances the mixing. In laminar flow regime, salt concentration over the membrane increases by 60%–110% for 70 bar feed pressure. In contrast, the increment of salt concentration is only about 3%–4% once the flow becomes turbulent, leading to 3–4 times higher permeate discharge for roto-dynamic RO system. Thus, it can increase the longevity of the membrane and improve overall performance of the RO module by delaying membrane scaling and fouling.

Advanced numerical simulation of hydrogen/air turbulent non-premixed flame on model burner

A numerical investigation of hydrogen (H2)/air turbulent non-premixed flame on the model burner was conducted. A large eddy simulation of reacting flow with partial and detailed chemical kinetic mechanisms was employed to obtain a high-resolution and accurate prediction of thermochemical states inside the combustion chamber, including pollutant NO, which have not been adequately predicted until now. This study employed temperature and species mass fraction data from two combustion cases of fully developed turbulent and transition regimes with a fuel composition of 50 % H2 and 50 % N2, experimentally measured by the German Aerospace Center (DLR) and TU Darmstadt. A reactor-based partially-stirred reactor (PaSR) model was used to handle the turbulence chemistry interaction. The employed chemical mechanisms included GRI-Mech 3.0 and partial Mevel mechanism. The effects of chemical mechanism and inlet jet velocity on simulation accuracy were discussed. The more elaborative nitrogen reactions in GRI-Mech 3.0 result in a better NO prediction compared to the partial Mevel mechanism. The implementation of finite rate chemistry in a PaSR model yields a significantly improved prediction of NO from the flamelet probability density function approach with less than 1 % root mean square deviation from experimental data. The performed simulation successfully captured the thermochemical profile of a fully developed turbulent flame; however, further improvement on boundary condition modeling is still required for a flame undergoing a transition from laminar to turbulent regimes. Finally, using the partial Mevel mechanism leads to a computational cost reduction of 32.66 % compared to the GRI-Mech 3.0 mechanism, which confirms the proportional relation between the size of the mechanism and computational cost.

Particle tracking schemes for micron particle deposition in a 90° pipe bend and nasal airway geometry

Computational studies of micron particle deposition is used to predict inhaled particles through the nasal cavity for understanding drug delivery or toxicology risks. To ensure reliable results in future studies, this study evaluated particle tracking schemes and determined the most appropriate settings for predicting micron particle deposition in a pipe bend and nasal cavity geometry. Micron particles were injected into a fully developed 90° pipe bend under a turbulent flow regime with Reynolds number, Re = 10,000, for comparison with existing data in the literature. Similarly, the micron particles were released into a more complex geometry, a human nasal cavity.The study found that although the high-resolution tracking is the default and preferred option set out by Ansys-Fluent, the 5μm particle tested travelled further than when the high-resolution tracking was off. This was rectified by setting the wall nodal velocity to zero. All particle tracking schemes performed well and were suitable for predicting deposition for particle diameters >5μm, with high-resolution tracking and setting the wall nodal velocity to zero. However, the results become sensitive to the particle scheme when dealing with particle diameters ¡ 5μm. The lower-order schemes overpredict deposition, while the higher-order schemes have zero deposition in the pipe bend unless the wall nodal velocity is set to zero. This study provides a list of recommended settings to best simulate particle deposition efficiency in Ansys Fluent (version 2023R2), although future releases of the CFD software may incorporate these settings as default options.

On the maximum velocity profile of wave boundary layer flows in the very rough turbulent regime

The maximum velocity profile in turbulent wave boundary layer flows has been experimentally investigated under both regular and irregular wave conditions. Four types of seabed models are adopted, i.e., smooth, sand-covered, uniform-sphere-covered and nonuniform-stone covered. The results show that the maximum overshoot increases with the decreasing A/ks (A is the semi-excursion of fluid particles in the free stream and ks is the bottom roughness), but it is not notably influenced by the irregularity of the waves nor the nonuniformity of bottom roughness elements. Two-dimensional numerical simulations are carried out to reveal the physics behind the large overshoot behavior. It is found that the gap flow accelerates around roughness elements and subsequently contributes to the overshoot. A three-parameter defect function is proposed that well describes the maximum velocity profile, and all three model parameters are correlated with the governing flow parameter A/ks.

Phase fluctuations-induced bit error ratio of deep-space optical communication systems during superior solar conjunction

Deep-space optical communication has garnered increasing attention for its high data transfer rate, wide bandwidth, and high transmission speed. However, coronal plasma turbulence severely degrades optical signals during superior solar conjunction. In this study, we introduce the models for plasma density and generalized non-Kolmogorov turbulence power spectrum. Based on these models, we derive the variance of the phase fluctuations with the assistance of the Rytov theory in the weak turbulence regime involving various variables, such as turbulence outer scale, spectral index, relative fluctuation factor, and wavelength. Subsequently, we evaluate the bit error ratio (BER) performance of the deep-space optical communication system, considering phase fluctuations and intensity scintillations, under binary phase shift keying modulation. Numerical calculations reveal that small heliocentric distance, large relative fluctuation factor and spectral index, could induce severe phase fluctuations and high BER. Fortunately, the effects of the plasma irregularities on the BER performance can be mitigated by short optical wavelength under large outer scale.