Transition SST Research Articles

A three-dimensional refined numerical simulation of cross-flow induced vibration mechanism in the tube bundle

Cross-flow induced vibration causes many accidents in the nuclear steam generator tube bundle. An accurate and refined cross-flow induced vibration numerical simulation can help avoid accidents in the designed bundle for different geometries, and provide insights into flow-induced vibration mechanism. In this paper, a three-dimensional refined numerical simulation model considering the fluid viscous damping was established and validated. First, we validated the simulation of the viscous damping that structure suffered in the fluid, and studied the relationship between the fluid viscous damping and the structural spring damping in tube bundle coupling with fluid. The results showed that fluid viscous damping coefficient and the structural spring damping coefficient can be directly added to equal the total damping coefficient in the coupling system between the tube bundle and fluid. Then, a three-dimensional simulation based on SST-SAS (the Transition SST combined with the Scale Adaptive Simulations (SAS) turbulence model) was used to study flow-induced vibration for the literature experiment tube bundle. Simulation of flow-induced vibration had the same mass-damping parameters with the literature experiment. The vibration amplitude trend and spectra of the simulation were basically consistent with that of the experiment. Simulation accurately captured the onset of the vortex-induced resonance and the transition from the vortex-induced resonance to the fluidelastic instability. And the different mechanisms and their transition were analyzed. Specially, the flow field and structure analysis showed that the local vortex-induced resonance of the front-row tubes caused the synchronous resonance of the whole tube bundle.

Influence of the Reynolds Number on the Aerodynamic Performance of a Small Rotor

The use of small rotors has increased due their applications in drones and UAVs. In order to improve the global performance of these aerial vehicles, it is necessary to understand the aerodynamics of small rotors, since this is related to the global energy consumption of such vehicles. Most of the computational fluid dynamics (CFD) studies found in the literature that are related to the analysis of small rotors employ fully turbulent models, despite the low-to-moderate Reynolds numbers of these applications. This paper presents CFD simulations for a small rotor at hover at different Reynolds numbers using fully turbulent and transitional SST k−ω turbulence models. Numerical results show that thrust and torque are close to experimental measurements, showing differences of less than 5% for both fully turbulent and transitional models. However, significant differences were observed between the fully turbulent and the transitional models when studying the boundary-layer development and separation. As the Reynolds number was increased, it was observed that at the tip of the blade, these differences were reduced, but at mid-span, the differences were more obvious.

Two-phase stratified flow in horizontal pipes: A CFD study to improve prediction of pressure gradient and void fraction

Improved understanding of flow regime effects on design-influencing engineering quantities is of primary importance. This work is focused on the numerical prediction of pressure gradient and void fraction in a horizontal pipe where gas-liquid stratified flow is present in different operating conditions. The problem was modeled with unsteady, multiphase CFD (computational fluid dynamics) simulations. Volume Of Fluid (VOF) method was used as multiphase model. To define the numerical methodology, this study provides details on the influence of discretization grid and turbulence model on the simulation accuracy. It shows that mesh density on pipe cross-section is the most important grid parameter to focus on. Different turbulence models are required depending on the gas velocity and on its turbulence flow regime. Transition SST is able to model all the operating conditions but Realizable k-ε is adopted to further increase the accuracy of the results. A general underestimation of the pressure gradient is reported with an average error of − 6.43 % and − 16.21 % for a liquid superficial velocity of 0.04 m/s and 0.06 m/s respectively. Comparison with two-fluid 1D models shows that CFD simulations are the most accurate tools for predicting the pressure gradient at gas superficial velocities lower than 1.3 m/s. The implementation of a drift flux model shows a good agreement between experimental results and CFD simulations concerning void fraction estimation. CFD results are also used to underline the physical phenomena limiting the performance of 1D models.

Repair Parameter Design of Outer Reinforcement Layers of Offshore Wind Turbine Blade Spar Cap Based on Structural and Aerodynamic Analysis

The influence of the outer reinforcement layers on the repair structure and aerodynamic performance was studied. Firstly, a continuous damage mechanics model was established, and the 3D Hashin criterion and cohesive zone material model were used to analyze the damage repair model. The failure load deviation was 5.5%. Secondly, on the basis of the γ−Reθ transition model and SST–ω turbulence model, the aerodynamic analysis model of DU300 airfoil was established. The numerical simulation results showed that the lift coefficient and pressure distribution at the angle of attack of 10° and 15° were deviated from the experimental values by 2%. Furthermore, 27 structural repair models, nine 2D aerodynamic repair models, and a 3D full-scale blade model were designed. It was found that, when the repair length accounted for 60% of the total model length, the failure load increased by 22%, but the aerodynamic power with the repair length of 10 m was decreased by 0.137%. When the repair area was large and the repair height was from 4 mm to 6 mm, the failure load was greatly increased by about 30%, and the aerodynamic pressure distribution and static pressure field fluctuated significantly. The results show that the structural and aerodynamic characteristics were closely related to the repair parameters.

Study on the Influence of Gradient Wind on the Aerodynamic Characteristics of a Two-Element Wingsail for Ship-Assisted Propulsion

It is well known that sail-assisted propulsion works under gradient wind conditions in the atmospheric boundary layer, and is an energy-saving device for fuel consumption. In order to study the aerodynamic characteristics of a wingsail in the atmospheric boundary layer above sea level, a transition SST turbulence model was used for numerical simulation of the wingsail with uniform and gradient wind conditions. We concluded that gradient wind conditions can delay the stall caused by an increased angle of attack. This is because the airflow on the suction surface of the wingsail in the spanwise direction exerts an acceleration towards the top of the wingsail. At the same time, supplementary airflow compresses the separated vortex, thus delaying the stall of the two-element wingsail. Under gradient wind conditions, the flow separation of the wingsail develops rapidly in the stall angles. Once a flat separation vortex is formed at the trailing edge of the wingsail, with the slow increase of flap deflection angle, flow separation rapidly expands and a deep stall occurs. Therefore, a small change of the flap deflection angle in the near-stall angles may lead to a deep stall of the wingsail, which should be avoided in engineering applications. Finally, the influence of the average speed of the gradient wind on the aerodynamic performance of the two-element wingsail was analyzed.

Numerical Simulation of the Dispersion of Exhaled Aerosols from a Manikin with a Realistic Upper Airway

Basic analysis of the flow field and aerosol deposition under different conditions when a spreader contains an upper airway tract is important to accurately predict the transmission of virus-laden aerosols. An upper airway was included to simulate aerosol transport and deposition. A flow field was simulated by the Transition SST model for validation. The simulation results show that, in the absence of the upper airway structure, an over-predicted aerosol deposition rate will occur. Higher upper-stream air velocity enhanced the intensity but added complexity to the recirculating flow between two manikins and increased the deposition rate of aerosol in the disseminator. A low-temperature environment can reduce the deposition rate of aerosol particles on the body of the disseminator due to a strong thermal plume. Therefore, the structure of the upper airway should be considered when predicting respiratory aerosol in order to increase the accuracy of aerosol propagation prediction.

Airframe design and CFD analysis of light unmanned reconnaissance aircraft

This work deals with a comparative numerical finite volume method of airflow for a 3D airframe model. The analyzed airframe model allowed 3-vector thrust directing while using the geometry of the inverted delta, which increases lift force area, allows for vertical take-off and landing, as well as full control of its flight using rotating propulsion nacelles and an airframe control system. The airframe model dimensions were 3900 x 3250 x 915 mm, enabling the installation of components of specific dimensions. CFD analysis using a four-equation transition SST model with automatic surface roughness and initial conditions: T = 288K, viscosity η= 1.7894∙ 10−5 and was carried out in the FLUENT module of ANSYS 16.0. For each simulation, 2000 iterations were performed with the intention of achieving a convergence of all residuals below 1∙10-3 using a calculation mesh consisting of 500,000 elements and 150,000 nodes. The model uses aerodynamic profile geometries: CLARK Y, NACA 6409, and NACA 2414, which are provided to obtain the optimal aerodynamic characteristics and determine the optimal range of angles of attack for the designed solution. Those angles of attack were in the range of α = 5 ÷ 10° in which the highest excellence coefficient of the carrier airfoil profile occurs. For those values of parameters optimal lift and drag forces were determined

Three-dimensional analysis of the thermal and hydraulic performance of finned and un-finned tubes in a staggered array

• Novel type of leeward cut fin is compared with a conventional circular fin. • Fin spacing was varied to evaluate thermo-hydraulic behaviour. • Leeward cut fin gives lower heat transfer rate and pressure drop than circular fin. • Performance study suggests the potential of leeward cut fins for material saving. A novel type of finned tube obtained by removing the downstream section of the conventionally used complete circular finned tube (CCFT) is studied. The resulting novel type of finned tube obtained is termed leeward cut finned tube (LCFT). The thermal and hydraulic behaviour of these novel finned tubes is compared with CCFT and un-finned tubes. Leeward cut fins are specifically studied to check their capability to give equivalent heat transfer like that of complete circular fins. This study is carried out in the Reynolds number range 4330 ≤ Re ≤ 8790 and fin spacing range 2 ≤ s ≤ 4 mm . The transition SST model is implemented to solve the RANS equations. Heat transfer coefficient at the downstream section of fins is found to be less than the upstream section; hence, it can be advantageous to remove some portion of the downstream section of the fin. The leeward cut finned tubes give a lower value of heat transfer rate and pressure drop when compared with complete circular finned tubes. The heat transfer Colburn factor j for leeward cut fins is higher than CCFT and un-finned tubes. The friction factor is the lowest for CCFT and the highest for un-finned tubes. Analysis of the effect of fin spacing showed an increment in heat transfer rate and a decrease in pressure drop when fin spacing is increased from 2 to 4 mm. The studied geometries are evaluated based on their thermo-hydraulic performance parameters ( PEC and Z/E ). The performance evaluation criterion PEC for LCFT is higher than CCFT by 30–46 % at fin spacing of 2 mm, whereas for spacing of 4 mm, it is 21–23 % higher. The ratio of heat transfer rate per unit temperature difference to power provided to the heat exchanger Z/E is lower for LCFT than CCFT by 5–8 % for fin spacing of 2 mm, whereas for fin spacing of 4 mm, it is lower by 9–12 %. Based on the results, CCFT performs better than LCFT, but they have more fin material requirements (∼50 %). Hence, the LCFT can be seen as a potential novel type of fin to give equivalent heat transfer with the advantage of material savings.

Modeling and simulation of one- and two-row six-bladed ducted fans

The problem of simulation of efficient ducted fan type propulsors is considered. From experience of operation of twin blades in fantails of helicopters, it is known that this configuration creates less noise compared to a uniform arrangement of the blades around the circumference. However, the flow behind such fan is less uniform than that of a conventional ducted fan. For multicopter-type unmanned aircraft and air taxis, the key problem is flight in take-off and landing modes as well as acoustic and vortex fields created by propulsors in these modes. The decrease in the noise level in propellers with twin blades can potentially be accompanied by an increase in non-stationary vortex effects on the aircraft as well as a decrease in specific thrust. The objectives were to develop a method for simulation of ducted fan propellers in the takeoff and landing mode, to determine the optimal angle between the blades, and to compare a ducted fan with twin X-shaped blades to conventional blade position. Turbulent flows were calculated using transient Reynold-averaged Navier-Stokes equations, complemented by SST turbulence model, and large eddy simulation with WALE subgrid viscosity model. The calculations used the modification γ–Reθ Transition SST of the Langtry-Menter turbulence model, where there are relations for the intermittency criterion, which made it possible to consider the laminar-turbulent transition and the appearance of thin laminar separation bubbles that affect both the thrust of the propeller and the non-uniformity of the flow behind it. Testing was carried out on four-bladed propellers according to the known results of the TsAGI reference experiments. Testing of the γ–Reθ Transition SST Langtry-Menter turbulence model showed that it reproduces the dependence of the thrust coefficient and power factor on the blade angle better than the standard SST model. Calculations have shown that there is a clearly defined optimum angle between the paired blades. A comparison of three-bladed, six-bladed single and six-bladed propellers with twin blades showed that the latter option has slightly better thrust characteristics and creates a significantly lower noise level on the ground. The studied characteristics of ducted fans demonstrate the prospects for the use of propellers with twin blades in aircraft with vertical takeoff and landing. The developed numerical method can be directly used for industrial calculations of propellers and fans.

Numerical investigation on the aerodynamic efficiency of bio-inspired corrugated and cambered airfoils in ground effect

This research numerically investigates the flapping motion effect on the flow around two subsonic airfoils near a ground wall. Thus far, the aerodynamic efficiency of the dragonfly-inspired flapping airfoil has not been challenged by an asymmetric cambered airfoil considering the ground effect phenomenon, especially in the MAV flight range. The analysis is carried out on the basis of an unsteady Reynolds-averaged Navier-stokes (URANS) simulation, whereby the Transition SST turbulence model simulates the flow characteristics. Dragonfly-inspired and NACA4412 airfoils are selected in this research to assess the geometry effect on aerodynamic efficiency. Moreover, the impacts of Reynolds number (Re), Strouhal number (St), and average ground clearance of the flapping airfoil are investigated. The results indicate a direct relationship between the airfoil’s aerodynamic performance (C_l/C_d) and the ground effect. The C_l/C_d increases by reducing the airfoil and ground distance, especially at h_{0}=c. At Re=5times 10^4, by increasing the St from 0.2 to 0.6, the values of C_l/C_d decrease from 10.34 to 2.1 and 3.22 to 1.8 for NACA4412 and dragonfly airfoils, respectively. As a result, the C_l/C_d of the NACA4412 airfoil is better than that of the dragonfly airfoil, especially at low oscillation frequency. The efficiency difference between the two airfoils at St=0.6 is approximately 14%, indicating that the C_l/C_d difference decreases substantially with increasing frequency. For Re=5times 10^3, the results show the dragonfly airfoil to have better C_l/C_d in all frequencies than the NACA4412 airfoil.

Burbujas de separación laminar en flujo en transición alrededor de perfiles Aerodinámicos

The purpose of this work is to apply the γ-Re θ turbulence model, which is one of the numerical methods of shear stress transport (SST) applicable to transient flow, to examine if it shows the expected laminar separation cells or bubbles. This condition is key in the way to guarantee that the numerical modeling of lift and drag forces in aerodynamic profiles is more faithful to corresponding experimental data. For this, several two-dimensional simulations implemented with OpenFOAM, a well-known Finite Volume Method (FVM) package, were carried out for a Reynolds number range between 1x10 4 and 5x10 , with the airfoils NACA0012, SG6043 and S826, in which the laminar separation bubbles usually form. Numerical results of lift and drag coefficients show correct prediction of experimental results and error is reduced by 3% when compared to other simulations. In particular, adequate performance of the model is observed for regions close to or greater than the angle of attack for which the aerodynamic profile stalls. On the other hand, the geometric footprint of the flow simulated with this γ-Re 5 transition SST model shows great improvement compared to previous studies regarding the formation of laminar separation bubbles, which in turn means better performance when calculating lift and drag coefficients. It is also concluded that laminar separation occurs in the three studied airfoils, being symmetric or asymmetric profiles.

Numerical simulation of propulsive aerodynamic profiles

The problem of creating high-lift propulsive aerodynamic is considered. A method was developed for constructing an aerodynamic profile by solving the inverse problem of aerodynamics. The dependence of the lifting force of this profile on the volume of air sucked from its upper surface and from the angle of attack is studied. The profile under study was developed on the basis of the well-known Griffin/Goldschmid profile with air suction at the upper critical point. Three aerodynamic profiles have been developed. The first profile has a flat lower surface to obtain the ground effect. The second profile is similar to the first but has a slit nozzle near the trailing edge. The third profile is similar to the second but has a non-flat bottom surface and increased thickness. The solution of the inverse problem of aerodynamics was used to construct aerodynamic profiles within the model of an ideal gas. The pressure distribution on the upper part of the profile, its construction height and the range of angles of attack are from 0° to 16°, as well as the degree of rarefaction up to 0.5 atm in the gap through which the air was taken were set. For the second and third profiles, the ratio of the amount of air ejected through the nozzle to the amount of air taken from the upper surface of the profile was set. This ratio ranged from 50 % to 200 %. Numerical calculations were performed for each variant using the Spalart-Allmaras turbulence models and the Transition Shear Stress Transport (SST) and Langtry model. The parameters of the turbulence models were adjusted according to known reference data. The Reynolds number was in the range of 1.5·105–1.5·106. The profiles have a high lift coefficient Cy = 3–3.4 which is achieved when creating a vacuum in the air intake of 0.5 atm. Cy depends on the angle of attack almost linearly up to the maximum values. The greater the air flow through the slot nozzle, the greater is the Cy at a vacuum in the air intake of 0.5 atm. Significance for practical application. The developed profiles have a large thickness and create traction. These profiles are convenient to use in aircraft with large internal volumes, for example, those running on hydrogen fuel.

Turbulence Model Comparative Study for Complex Phenomena in Supersonic Steam Ejectors with Double Choking Mode.

Scholars usually ignore the non-equilibrium condensing effects in turbulence-model comparative studies on supersonic steam ejectors. In this study, a non-equilibrium condensation model considering real physical properties was coupled respectively with seven turbulence models. They are the k-ε Standard, k-ε RNG, k-ε Realizable, k-ω Standard, k-ω SST, Transition SST, and Linear Reynolds Stress Model. Simulation results were compared with the experiment results globally and locally. The complex flow phenomena in the steam ejector captured by different models, including shock waves, choking, non-equilibrium condensation, boundary layer separation, and vortices were discussed. The reasons for the differences in simulation results were explained and compared. The relationship between ejector performance and local flow phenomena was illustrated. The novelty lies in the conclusions that consider the non-equilibrium condensing effects. Results show that the number and type of shock waves predicted by different turbulence models are different. Non-equilibrium condensation and boundary layer separation regions obtained by various turbulence models are different. Comparing the ejector performance and the complex flow phenomena with the experimental results, the k-ω SST model is proposed to simulate supersonic steam ejectors.

Capturing transition around low-Reynolds number hydrofoil with zero-equation transition model

Compared with the local correlation-based shear stress transport (SST) γ−Reθ transition model (where SST k−ω transport equations are coupled with intermittency γ and transitional momentum-thickness Reynolds number Reθ transport equations), relatively simple and convenient modifications are applied to the parent SST k−ω model for computing natural and separation-induced transitions over the hydrofoil at a low-Reynolds number (LRN). The curiosity toward hydrofoil performance at an LRN has been enhanced by increasing attention to autonomous marine systems, deserving numerical simulations for transitional flow using computational fluid dynamics. With the newly devised transitional SST (T-SST) model, the viscous sublayer blending function F2 is slightly modified, and a stress-intensity parameter as a function of eddy-to-laminar viscosity ratio RT is introduced; intended formulations are plausible and have significant impacts on the transition prediction. Owing to the inherent potential for predicting bypass transition, two anisotropic versions of the v¯2−f(V2F) turbulence model are selected to evaluate their competencies in capturing separation-induced and natural transitions. Results demonstrate that natural transition prediction is more challenging than separation-induced transition for the V2F model. Nonetheless, the T-SST model performs consistently well in replicating both transitional phenomena.

CFD Analysis of Convection Heat Transfer in Corrugated Channels for Different Inclination Angle

Three different geometries have been used in this study, which investigated the effect of inclination angle on convective heat transfer in corrugated channels. The corrugated channel geometries used have inclination angles of 30°, 45°, and 60°. The finite volume method has been used in the study with numerical methods. k-ω, SST, and transition SST have been used as turbulence models. The mesh file used in the analysis consists of 192000 cells. The results obtained from the calculations using a corrugated channel with a 30° inclination angle have been compared with the experimental data. As a result of this comparison, the turbulence model to be used for this study has been determined as SST. SST turbulence model has been used in the analyzes made using a corrugated channel with 45° and 60° inclination angles and the results have been compared with each other. The Reynolds number ranges from 2225 to 7380. The Nusselt number and friction factor have been calculated using the data obtained as a result of the analysis. Based on the calculated values, it has been determined that the heat transfer increases as the angle of inclination increases in the corrugated channels. It has been also observed that the Nusselt number increased as the Reynolds number increased. It has been also seen that the analyzes for high Reynolds number gave results closer to the experimental data.

Numerical Study of Different Models for Turbulent Flow in 90° Pipe Bend

The investigation of the turbulence statistics for single-phase turbulent flow around pipe bends have mainly been experimental. Considering the cost-effectiveness of the numerical computational fluid dynamics (CFD) compared to experimental measurement, this work aims to study the accuracies of different CFD models, and establish their functionality and limitations. This paper investigates the capabilities of different numerical turbulence models and spatial discretization schemes for CFD analysis of a pipe bend. The pipe has a curvature radius which is seven times the inside diameter and a Reynolds number of 34132. The numerical modelling was developed on the commercial CFD software, ANSYS Fluent, evaluating the following viscous models:,, Spalart-Allmaras and Reynolds Stress Models. The streamwise velocities of the flow at cross-stream planes along the bend at 45º and 75º were computed for each of the turbulence models under different discretization schemes. The numerical results were compared against the existing experimental data for streamwise velocity, in order to investigate the accuracies of the different models. The results showed that the realizable K-E and Spalart-Allmaras models exhibited the best agreements with the experimental measurements, with respective average errors of 3.83% and 3.27% under the first-order spatial discretization scheme. It was also observed that the velocity profiles obtained through the K-W models (Standard and BSL), Transition SST and Reynolds Stress models exhibited better correlation with the experimental velocity profiles within the velocity transition region.

Aerodynamic Profile Modification of a NACA 0012 Aerofoil for Enhanced Lift-Drag Characteristics at Low Reynolds Number

This article discusses the enhanced lift-drag ratio of a geometrically modified National Advisory Committee for Aeronautics 0012 aerofoil at a low Reynolds number of 40000. The study involves validating the Reynolds Averaged Navier Stokes Transition Shear Stress Transport model for the analysis of flow around the subject aerofoil with the modified profile for angles of attack ranging from 0 to 10°. The coefficient of lift to drag increased by 70% for the modified aerofoil at an angle of attack of 6°. The extent of the laminar separation bubble on the modified airfoil is reduced by 40% compared to the standard aerofoil at an angle of attack of 8°. The modified aerofoil cross-section does not involve much manufacturing complexity and can be deployed in small-scale wind turbines operating at low wind speeds.

Numerical Investigation on the Effect of Asymmetry of Flow Velocity on the Wake Vortex of Hydrofoils

The Karman vortex street is a common flow phenomenon. In hydraulic machinery, it is usually located downstream of the guide vanes and the runner blades, which reduces hydraulic performance and may also cause fatigue damage to the structure. The latest research suggested that the difference in velocity gradient on each side of the blade trailing edge may have a significant impact on the strength of the wake vortex. The current work aims to verify the above conclusion and further explore the influence of asymmetry of flow velocity on the wake vortex. A numerical model with the velocity ratio, α, between the two sides of the hydrofoil as the only variable was designed, and the wake characteristics were solved by a computational fluid dynamics (CFD) method based on the finite volume. The unsteady Reynolds-average Navier–Stokes (URANS) equations were numerically solved by coupling with a transitional shear-stress transport (SST) turbulence model. The results showed that with the increase of α, the vortex shedding frequency decreased first, and then increased after reaching the critical velocity ratio αc1 ≈ 1.4. The vortex intensity first gradually decreased, and the vortex street suddenly disappeared after reaching the critical velocity ratio αc2 ≈ 2.2. The value of αc1 was affected by the thickness of the trailing edge, and αc2 was affected by the thickness and the Reynolds number. Besides, the asymmetry of the flow velocity also affected the effectiveness of the trailing-edge trimming. This research can provide references for the design of hydraulic machinery and other submerged structures.

AERODYNAMIC ANALYSIS OF DELTA WING AT LOW REYNOLDS NUMBER USING COMPUTATIONAL SIMULATIONS

The delta wing is best known for their contribution to stability and also, they have high structural advantages compared to other wings. Till now the delta wing has been used mostly in high speed or high Reynolds number flows. But no one concentrated on the low Reynolds number flows, here we have analyzed the flow at Re = 100000. Since we have taken the case of this Reynolds number range, the results obtained can be utilized in designing the Micro Air Vehicles (MAVs) which are mostly designed for the range of Reynolds number Re = 10000 to 100000. We have obtained Cl vs alpha and Cl/Cd vs alpha graphs using computational simulations. We used the CATIA software for designing the wing, it is a conceptual design based on delta wing and analyzed using XFLR 5 for ideal flows, here we used vortex lattice method – ring vortex method and ANSYS fluent software for realistic flows. We used Gamma – Re theta SST transition model for calculations in Ansys Fluent. We have expected CL to be start with smaller values and higher at higher angles of attack since, the delta wings have Low aspect ratio and also they have sweep back which induces leading edge vortices. But the Cl/Cd values will be at their minimum only.

Study of the airflow and vortex distributions in a long-narrow enclosed space

In an aircraft cabin, there is a great influence of indoor air quality on the physiological and mental health of passengers. To promote indoor air quality, this research performed experiments and CFD to analyze the flow field characteristics in an aircraft cabin. This study investigated the airflow characteristics of a full-scale cabin using a scaled model. The experimental results indicated that the supply air jet easily formed vortex structures around the chest and head zones of the occupants. The airflow was unstable at the cross-section and longitudinal scales. The Transition SST (4eqn) model could accurately simulate the flow field, and the supply air jet alternatively controlled the cross-section flow field, induced the unstable phenomena spatially and temporally. The vortex structures around the occupants produced and disappeared in both time and space. It showed the instability of the airflow in the aircraft cabin. And this instability of the airflow could induce the dissipation of vortex structures in the time series. This enhanced the unstable distribution of vortex structures. This study further clarifies the distribution of the velocity field and provides references for the futural design of airflow in aircraft cabins.