Static Pressure Recovery Research Articles

Flow investigation of two-stand ultrasonic flow meters in a wide dynamic range by numerical and experimental methods

The enhancement of two-stand ultrasonic flow meters relies upon obtaining a precise understanding and prediction of their complex flow physics throughout their entire dynamic range of operation. This study provides a comprehensive numerical and experimental investigation of the flow physics of a typical two-stand ultrasonic flow meter by industry standards. Predictions based on computational fluid dynamics simulations are employed to obtain numerical results, which are validated through experiments based on laser Doppler velocimetry and static pressure drop. Results indicate that no qualitative changes occur beyond an inflow Reynolds number of 104 in terms of coherent structures and flow dynamics. Analysis of the static pressure distribution across cross-sections reveals that the stands are the most influential areas contributing to pressure drop. In cases with turbulent inflow, there is a noticeable recovery of static pressure following significant pressure gradients across the stands, while such recovery is absent in scenarios with laminar inflow. Both numerical and experimental approaches yield excellent agreement in outcomes, accurately estimating the axial velocity within the flow meter’s measurement volume and the pressure drop across it, with deviations within experimental uncertainty ranges of 2 standard deviations. The developed numerical methodology demonstrates its potential to accurately evaluate complex internal-flow systems with similar flow features and Reynolds number ranges. The flow dynamics for a wide dynamic range of operation in two-stand ultrasonic flow meters are shown in detail in both laminar and turbulent flow regimes, displaying rolling vortices, detached flow, and recirculation zones.

Parametric optimization applied to design a high-performance vaneless-diffuser for CO2 centrifugal compressor

ABSTRACT Carbon-dioxide (CO2) centrifugal compressors are machines with high potential of usage in power generation plants and oil industry as it achieves high thermal efficiency in the Brayton cycles and contributes to oil production through the capture and storage of CO2 (CCS) in EOR (Enhanced Oil Recovery) systems. High levels of static pressure at the outlet are desired for EOR applications, which are usually obtained through the insertion of vanes in the diffuser. This work intends to increase vaneless-diffuser static pressure recovery by modifying only its meridional profile, ensuring a broader range of off-design operation when compared to vaned diffusers and attending to the fluctuations of mass flow and rotation expected in EOR practical applications. Therefore, a parametric optimization through surrogate model coupled to CFD was performed with three different objective functions that were submitted to single-optimization through the NSGA-II method: Maximize total-to-total polytropic efficiency, minimize total pressure loss coefficient or maximize static pressure recovery coefficient. Additionally, a sensitivity analysis was conducted using Morris Elementary Effects and SS-ANOVA. The results indicated that the optimized geometries increased the total-to-total polytropic efficiency by 2.9%, reduced the total pressure loss coefficient by 24.0% and increased the static pressure recovery coefficient at the design point by 11.4%, which is discussed in detail after a careful phenomenology assessment. The strategy adopted in the present work through a combination of Sensitivity Analysis, surrogate models and CFD increased the vaneless-diffuser static pressure recovery without the need of inserting vanes in the diffuser, which avoid instabilities in the equipment and would restrict its range of off-design operation.

Research on gas–liquid separation characteristics in the helico-axial multiphase pump

Due to the fact that it serves as both a pump and a compressor, the helico-axial multiphase pump is better suited for mixed-transport oil-gas two-phase flow and is frequently used for deep-sea oil extraction. The gas–liquid separation caused by the asynchrony of the gas–liquid two-phase medium is the primary cause of the damage or failure of the helico-axial multiphase pump in the project, resulting in the pump's damage or inability to operate. To investigate the variation of phase separation in the helico-axial multiphase pump under diverse operating conditions, a test system was designed and the theory of fluid flow mechanics was applied. The effects of different flow fields on the energy conversion characteristics of the pump were investigated. The results indicate that the gas–liquid separation position in the impeller occurs near the 2/3 of the airfoil bone line. After the gas–liquid separation, gas mass will be formed, pocket flow will be readily induced, and the gas block-up phenomenon will result in energy loss in the compression unit. Simulations indicate that the static pressure recovery and total pressure loss in a diffuser fluctuate over time. The static pressure recovery efficacy of the diffuser is highest when the imported gas volume fraction is 10% and lowest when the imported gas volume fraction is 60%. On the surface of the impeller blade, perpendicular to the flow direction, the separation phenomenon near the hub side is more severe than that near the rim. Along the flow direction, the pattern of phase separation is comparable.

Effects of Synthetic Jets on Swirl Inflow in a Variable-Geometry Twin Air-Intake

Air intakes are an integral part of contemporary passenger and military aircraft engines. Their impact on aerodynamic performance across the entire flight envelope is critical to aircraft flight safety, efficiency, and manoeuvrability, especially at high Mach numbers due to shock waves. The high demand for reductions in aircraft weight and size and enhancements in durability, comfort, and thermal and radar signatures compel researchers and engineers to explore new designs and develop efficient air intakes for high-performance aircraft engines. Although a number of studies on air intake have been conducted and reported in the open literature, there is little information available in the public domain on bifurcated twin air intakes using synthetic jet. As a result, the primary goal of this research is to use computational fluid dynamics modelling to investigate the effects of synthetic jets on swirl inflow variable geometry twin air intake aerodynamic performance over a range of Reynolds numbers. Some important parameters (distortion coefficient, non-uniformity index, swirl coefficient, and static and total pressure coefficients) were investigated. Both static and total pressure recovery have been increased at all swirl numbers. A significant decrease in distortion coefficient and swirl coefficient has also been achieved, reaching a 53% reduction in the distortion coefficient and a 62% reduction in the swirl coefficient. The reduction in the non-uniformity index is achieved by 62% for the controlled flow case. The findings show that synthetic jets are effective in controlling the flow separation in the twin air intakes and enhancing aerodynamic performance.

CFD simulation of a vortex-controlled diffuser for a jet engine burner

A computational flow analysis of an ideal vortex-controlled diffuser (VCD) was carried out. The simulation model used is the compressible Reynolds averaged Navier-Stokes equations(RANS), with the application of the RNG based k-ε turbulence model. The effects of important parameters like static pressure recovery, bleed fraction, position of bleed slot, have been studied and comparisons were made with respect to VCD without the bleed configuration and the following features were revealed: radial profiles of velocity at the inlet, mid-planes and exit planes, including diffuser effectiveness (i.e. static pressure recovery), diffuser efficiency, reattachment length and diffuser total pressure loss. Results obtained by applying the RNG turbulence model show an instantaneous improvement in the diffuser efficiency that happens at reasonably minimal suction rates. From the calculations, it has been verified and shown in the analysis that the effect of the bleed positioning offers advantages in relation to where it is located.

Potential of Static Pressure Recovery of Rotor-Only Low-Pressure Axial Fans

Typically installed in a rotor-only configuration, low-pressure axial fans discharge directly into a free atmosphere and the discharge shows a strong swirl component. Since such designs, without guide vanes, cannot convert the dynamic pressure in the swirl component back into static pressure, the dynamic pressure is usually considered a loss. However, the radial equilibrium shows that a significant part of the kinetic energy contained in this swirl component is recovered as static pressure in the free atmosphere. This additional pressure increase has been sparsely researched. A comparison between two configurations with and without outlet guide vanes allows for the formulation of an evaluation criterion of the rotor-only configuration. Utilizing this evaluation criterion, the investigation of velocity profiles corresponding to generic rotor designs shows promise in terms of pressure recovery for new designs.

Experimental Investigation of Flow Parameters in a Mild Curved S-shaped Diffusing Duct

The paper presents a detailed study of the performance of fully developed subsonic turbulent flow in a circular cross-section S-shaped centerline-diffusing duct. A precalibrated 5-hole pressure probe was used for the measurements. The diffuser cross-section was expanded to 2.25 area ratio (Ar) at the exit. The duct was fabricated by joining two 22.5º bends of curvature ratio (βt) 11.46 in reverse direction with a centerline offset of 0.2 of the axial length of the diffuser. The test was carried out with inlet Re=8.4x105, calculated based on diffuser inlet diameter. The experimental results indicated the generation of secondary flow in the form of a pair of counter rotating vortices in the first half, which changes its senses of rotation in the second half. The overall static pressure recovery of the diffuser was 40%.

A Novel Vane-twisted Conformal Diffuser for Compact Centrifugal Compressors

Compact aero-engines that use centrifugal compressors are in high demand due to their small size and cost-effectiveness. However, limited improvements in the aerodynamic performance of centrifugal impellers have led to a greater focus on improving the performance of diffusers. This paper introduces a novel vane conformal diffuser designed to match an impeller with a high pressure ratio. The diffuser utilizes a unique design method that creates transitions from a two-dimensional meridian to a three-dimensional configuration, to achieve a twisted design for the vane and hub. Eventually an integrated vane configuration is formed from the radial section to the bend and axial sections. The novel diffuser significantly reduces the radial size of the entire compressor compared with a conventional vaned diffuser. Different cross-section area distributions are studied to explore the reasonable static pressure recovery ability of the diffuser. To validate the new concept, the diffusers of two existing high-pressure centrifugal compressors are redesigned using the novel conformal diffuser configuration. The numerical results show that the aerodynamic performances of the two redesigned centrifugal compressors are improved in terms of both the total pressure ratio and the isentropic efficiency compared with their counterparts. These results demonstrate the effectiveness and applicability of the developed design method for the novel conformal diffuser.

Investigations on the Splitter Structure to Improve the Aerodynamic Performance of Gas Turbine Exhaust Diffuser at Different Swirl Angles

Abstract To weaken the flow separation in the exhaust diffuser under real operating conditions and increase the static pressure recovery coefficient of the exhaust diffuser, an exhaust diffuser structure with splitters was proposed. Based on verifying the reliability of the numerical method, the paper numerically explores the influence of the height and width of the splitter on the aerodynamic performance of the exhaust diffuser under three different inlet swirl angles by solving three-dimensional Reynolds-Averaged Navier–Stokes (RANS). The results show that the introduction of the splitter structure into the exhaust diffuser can effectively suppress the separation vortex near the strut, improve the flow state at the exhaust diffuser outlet, and further increase the static pressure recovery coefficient of the exhaust diffuser. The optimal splitter structure can be obtained by comparing the effects of the splitter height and width on the static pressure recovery performance of the exhaust diffuser under different inlet swirl angles. When the inlet swirl angles are 16 degs, 28 degs, and 38 degs, compared with the original exhaust diffuser without splitters, the optimal splitter structure can increase the static pressure recovery coefficient of the exhaust diffuser by 0.036, 0.096, and 0.146, respectively, with a relative increase of 7.3%, 34.2%, and 76.2%. The introduction of the splitter structure helps to improve the aerodynamic performance of the exhaust diffuser.

Design and Computational Analysis of the Conventional Vaned Diffuser for a Turbocharger Compressor

Abstract: A review of a study paper on centrifugal compressors revealed that the flow dynamics within them are extremely complex. The intensity of secondary flows and tip leakage flows will significantly alter depending on the vane loading, creating the low energy fluid zone on the impeller blade's suction surface. The flow finally becomes excessively viscous and non-uniform at the centrifugal impeller's exit due to this type of flow pattern. The goal of the current work is to comprehend the flow at the centrifugal impeller's exit and construct the conventional vaned diffuser (CVD) in accordance with that understanding in order to transfer the high kinetic energy already existing into a static pressure rise. A highly loaded centrifugal compressor with a newly developed conventional vaned diffuser (CVD) was subjected to numerical analysis using Ansys for an impeller tip mach number of 0.9. For design and off-design positions, respectively, key diffuser performance characteristics like pressure ratio and static pressure recovery are studied numerically, as qualitatively was Mach number. The pressure recovery of conventional vaned diffuser was showing 39.1 % more than the compressor with vaneless diffuser

Numerical investigation of air admission influence on the precessing vortex rope in a Francis turbine

Precessing vortex rope (PVR) plays a key role in inducing hydraulic resonance in Francis turbines operating at partial load, possibly degrading power plant stability and availability. Air injection into the runner cone is a suitable mitigating alternative; however, the influence mechanism of air injection on PVR remains unclear. The principal objective of this study was to establish response relationships between the characteristic parameters and air injection by the method of computational fluid dynamics (CFD) considering the fluid components of water, water vapour and air. The findings show that cavitation flow can be completely suppressed by slight air injection; however, the helical vortex structures are persisted at 1.0% and 2.0% air volume fractions, and the static pressure recovery is improved together with a slight increase in the hydraulic loss. At 3.0% air volume fraction, the vortex structure completely disappears, leaving an umbrella-shaped structure, with no pressure vibration arising in the turbine. Moreover, the physical mechanism of reducing the pressure amplitudes is clarified. This results clarify the influence mechanism of air injection on PVR, and contribute to steadily extending the flexibility of the operating range of the turbine during the engineering application.

Experimental and numerical study on the performance and mechanism of a vortex-broken electrocyclone

As the synthesis unit of a gas cyclone and electrostatic precipitator, electrocyclone has advantages in particle collection efficiency, capital outlay, and space occupation. This paper proposes a better combination of the gas cyclone and electric field based on the self-designed vortex-broken wing. The performances of the vortex-broken electrocyclone with different inlet velocities and working voltages were investigated by both experiments and numerical simulations. The flow field and electric field in the electrocyclone were obtained by large eddy simulation and solving the potential equation, respectively. The particles were modeled by the Lagrangian particle tracking model and the dynamic behavior of a representative particle was analyzed. The experimental results show that the vortex-broken electrocyclone can reduce the pressure drop and improve the collection efficiency simultaneously. However, the reduction in pressure drop is obvious at high inlet velocity, while the increment in collection efficiency is just the opposite. On the one hand, the simulated flow field reveals that the mechanism for the reduction in pressure drop is that the vortex-broken wing breaks up the inner vortex core, thereby yielding a static pressure recovery. On the other hand, the electric intensity and velocity have opposite directions in the key flow regions, thus affecting the force balance and changing particle trajectories. Further analysis of particle dynamics demonstrates that although the electric field force is far less than the drag force, the particle trajectory can be significantly changed over time. These findings can provide guidance for optimizing the technologies that incorporate electric fields and gas cyclones.

Investigations on the Aerodynamic Performance of a Gas Turbine Exhaust Diffuser With the Modified Shell Profile

Abstract In this paper, a shell profile design method based on diffuser flow area curve is proposed to improve the static pressure recovery coefficient of the exhaust diffuser over a range of inlet swirl angles. Based on verifying the reliability of the numerical method, the paper first explored the aerodynamic performance of the exhaust diffuser with the original structure and the modified structure by solving three-dimensional Reynolds-Averaged Navier–Stokes. Numerical results well capture the pressure distribution and flow characteristics in the exhaust diffuser. The numerical results show that the shell profile modification method effectively improves the aerodynamic performance of the exhaust diffuser. Compared with the original exhaust diffuser, the secondary vortex near the outer shell of the modified exhaust diffuser is weakened and the axial reverse pressure gradient near the strut is reduced. The static pressure recovery coefficient of the modified exhaust diffuser is significantly increased under different inlet swirl angles. Especially, under the normal working condition with a medium swirl angle (22 deg), the static pressure recovery coefficient increases by 0.034 with a relative increase of 7.6%. Under the extreme working conditions of a large swirl angle (35 deg), the static pressure recovery coefficient increases by 0.074 with a relative increase of 39%. A test rig for measuring the aerodynamic performance of the exhaust diffuser was built, and the validity of the shell profile design method is further verified through experimental measurements.

Flow distribution in the air cooler of HTGR passive cavity cooling system

Passive Cavity Cooling System (PCCS) is an important safety related system for High Temperature Gas-cooled Reactor (HTGR). Air cooler is one of the key components of this system. The non-uniform flow distribution is a common issue encountered in similar Parallel Tube Heat Exchanger (PTHX). Improving flow uniformity is favorable for both thermal hydraulic performance and structure safety. In this work, the flow distribution characteristics of a compact parallel tube air cooler with U-type header arrangement are theoretically and numerically investigated. First, a theoretical discrete model is proposed for flow distribution in PTHX. It reveals that the static pressure distributions in the headers are influenced by static pressure recovery, friction resistance and local pressure drop, which is directly related with flow uniformity. Then, the flow uniformity of Z-type and U-type header arrangements is numerically investigated and compared in detail. Moreover, the effects of thermal hydraulic parameter and geometrical parameter on flow uniformity are successively evaluated. Numerical results show that the flow uniformity of PCCS air cooler with U-type header arrangement is more excellent than that of Z-type header arrangement. Thermal hydraulic parameters, such as tube-side water temperature and mass flow rate, have little impact on flow uniformity. Nevertheless, the flow distribution characteristics are very sensitive to the geometrical parameters, including the insertion angle configuration, the flow area ratio of header to parallel heat transfer tubes (AR) and the cross-sectional area ratio of distribution header to collection header (DCR). Reasonable insertion angle configuration and decreasing AR can effectively enhance the flow uniformity of PCCS air cooler. For header match, it should be avoided that the distribution header diameter below the collection header diameter. As a result, the optimal structure design determined in this work is an air cooler with U-type header arrangement, where the inlet insertion angle is 0°, the outlet insertion angle is 180°, and the diameters of distribution header and collection header are both 120 mm. Its flow uniformity is improved by more than 50% compared with present design. This work reports a promising design modification, as the potential structure optimization for HTGR PCCS air cooler.

Performance Enhancement of a Centrifugal Compressor by Designing a Tandem Cascade Diffuser

The performance of a vane diffuser plays an important role in transforming the high kinetic energy into pressure energy at the impeller outlet of a centrifugal compressor. In this study, the performance enhancement of a centrifugal compressor is achieved by designing a tandem cascade diffuser. An optimum value of the total bending angle of a tandem cascade diffuser is obtained through numerical simulation. The total bending angle is defined as the angle between the tangent line of the front blade arc line at the leading edge point and the tangent line of the rear blade arc line at the trailing edge point. The range of the total bending angle increases from zero to 21°. The simulation results show that the variation of the total bending angle has a great impact on the performances of the compressor stage. The best performance is achieved by the 10° model, by which the minimum total pressure loss coefficient and the maximum static pressure recovery coefficient are obtained. The mechanism of performance improvement by choosing a reasonable total bending angle is that the separated flow zone in the diffuser is constrained and the distribution of radial velocity at the inlet and outlet of the diffuser is more uniformed. With the 10° model, the separated zone almost completely disappears in the diffuser and a distribution of more uniform radial velocity along the meridional section is obtained. Compared with the stage of the prototype with a single row of vane diffuser, the stage with the newly designed tandem vane diffuser (10° model) achieved performance improvement, the efficiency increased about 6%, and the total pressure ratio increased about 3.5% at the flow coefficient of 0.15.

Effects of the number of blades on impeller-volute interaction and flow instability of a centrifugal pump

Effects of the number of blades on the impeller-volute interaction and flow instability were studied for a centrifugal pump. The hydraulic performance and time-dependent flow field were analyzed by using the unsteady three-dimensional Reynolds-averaged Navier-Stokes equations with the k-ω based shear stress transport turbulence model. The grid dependence and temporal resolution were tested to evaluate the numerical uncertainties, and the numerical results were validated using experimental data. As the performance parameters, the stage total-to-static head coefficient, the impeller total-to-static head coefficient, and the volute static pressure recovery coefficient were selected to classify the cause of the impeller-volute interaction and flow instability observed inside components. Using the fast Fourier transform, fluctuations of the performance parameters were divided into three categories: the blade passing frequency and its harmonic frequencies, the fluctuations in the broadband frequency region, and the fluctuations in the low-frequency region. The results showed that the fluctuations of the performance parameters and local pressure were affected in various ways by the number of blades. The time-dependent flow structure was investigated to study the root causes of the differences in the impeller-volute interaction and flow instability by the number of blades.

Experimental and Numerical Investigation of Clearance Effects in a Transonic Centrifugal Compressor

Extensive research studying tip clearance effects on compressor performance has been conducted during the past few decades with significant progress achieved. However, most of the previous investigations focus on stage-level analysis at the design condition, with very limited studies at the component level or part speed conditions. To fill this gap, this paper investigates the effects of impeller tip clearance on the performance of a high-speed centrifugal compressor, at both stage and component levels, covering a variety of operating speeds resulting in subsonic to transonic inlet conditions. Experiments were conducted on the Single Stage Centrifugal Compressor facility at two different running tip clearances. With increased clearance, the stage and impeller pressure ratio, isentropic efficiency, and work factor drop, but the static pressure recovery coefficient in the diffuser increases. As the compressor transitions from subsonic to transonic operation from 60 to 85% corrected speed, the sensitivities of stage and impeller pressure ratio and efficiency reach their peak values. Lastly, numerical simulations at design speed showed that the computational fluid dynamics (CFD) model sufficiently predicts the sensitivities due to tip clearance for most of the parameters at the stage and component levels, indicating the potential of using CFD to investigate the flow physics.

CFD investigation of flow through a centrifugal compressor diffuser with splitter blades

The aerodynamic losses in centrifugal compressors are mainly associated with the separated flow on the suction sides of impeller and diffuser vanes. The overall performance of such compressors can be improved by adding splitter vanes. The present work examines the effect of varying the geometrical location of the splitter vanes in the diffuser on the overall performance of a high-speed centrifugal compressor stage of a small gas turbine. To increase the pressure recovery through the diffuser, two radial sets of vanes are used. The first set of vanes (diffuser-1) is equipped with splitter vanes, placed mid-distance between the main vanes, while the vanes of the second set (diffuser-2) are conventional vanes. Flow through the compressor was simulated using the ANSYS 19 workbench program. Flow characteristics and compressor performance were obtained and analyzed for different circumferential positions of the splitting vanes relative to the main vanes of diffuser-1. The study covered seven positions of the splitter vanes including the original design of the diffuser where the splitter vanes were located at mid-distance between the main vanes. The analysis shows that, at design conditions, selecting the position of the splitter vanes to be nearer to the pressure side of the main vanes improves the stage performance. In the present study, locating the splitters at 33% of the angular distance between the main vanes leads to the best performance, and a significant improvement in the overall stage performance is recorded. The pressure recovery coefficient is raised by about 17%, the pressure ratio is increased by about 1.13%, and the stage efficiency is increased by about 2.01%, compared to the original splitter position. Performance improvement is related to the suppression of the flow separation and the more uniformity of flow. On the contrary, further moving the splitter closer to the main blade, the pressure recovery coefficient is decreased by about 2% than the position of 33% of the angular distance, but still higher than the original position by about 15% and a limited improvement in the compressor performance is noticed. Moving the splitter far out the main blade annihilates the static pressure recovery of the diffuser by about 2:7% compared with the original position. So, for the investigated compressor, the best position of the splitter blade in the circumferential direction, which provides the best stage performance in our parametric analysis, is not necessary to be at the mid-angular distance between the diffuser’s main blades, but it is achieved by moving the splitter to about 33% of the angular distance where the diminished loss from the suppressed flow separation is more prevailing and the instigated friction losses from splitter surfaces are less critical.

Optimization of Sweep and Blade Lean for Diffuser to Suppress Hub Corner Vortex in Multistage Pump

The bowl diffuser is the main flow component in multistage submersible pumps; however, secondary flow fields can easily induce a separation vortex in the hub corner region of the bowl diffuser during normal operation. To explore the flow mechanism of the hub corner separation vortex and develop a method for suppressing hub corner separation vortices, the lean and sweep of the diffuser blade were optimized using computational fluid dynamics (CFD) simulations and central composite design. Diffuser efficiency, static pressure recovery coefficient, and non-uniformity were selected as the optimization objectives. Details of the internal flow were revealed and the collaborative response relationships between blade lean/sweep parameter equations and optimization objectives were established. The optimization results show that a greater pressure difference between the pressure surface and suction surface (PS–SS) at the inlet can offset transverse secondary flow, whereas a lower PS–SS pressure difference will cause a drop in low-energy fluid in the diffuser mid-section. The blade’s lean scheme suppresses the hub corner separation vortex, leading to an increase in pressure recovery and diffuser efficiency. Moreover, optimizing the sweep scheme can reduce the shroud–hub pressure difference at the inlet to offset spanwise secondary flow and enhance the hub–shroud pressure difference at the outlet, thus driving low-energy fluid further downstream. The sweep scheme suppresses the hub corner vortex, with a resulting drop in non-uniformity of 13.1%. Therefore, optimization of the diffuser blade’s lean and sweep can result in less low-energy fluid or drive it further away from hub, thereby suppressing the hub corner vortex and improving hydraulic performance. The outcomes of this work are relevant to the advanced design of bowl diffusers for multistage submersible pumps.

An Investigation of the Tapered Strut on Aerodynamic Performance of the Exhaust Diffuser Under Different Swirls

Abstract The strut structure directly affects the flow-field characteristics and aerodynamic performance of the gas turbine exhaust diffuser. Based on verifying the reliability of the numerical method, the exhaust diffuser with different struts was numerically calculated by solving three-dimensional Reynolds-averaged Navier–Stokes. The flow process and flow loss mechanism in the diffuser were analyzed, the influence of two different structures of tapered struts on the aerodynamic performance of the exhaust diffuser under different inlet preswirls was explored, and the aerodynamic performance of the exhaust diffuser with tapered struts was compared with a conventional exhaust diffuser with linear struts. The results show that, compared with the conventional linear strut, under different inlet preswirls, two different tapered struts can both weaken the flow separation in the exhaust diffuser, thereby reducing the total pressure loss. When the inlet preswirl is greater than 0.35, the total pressure loss coefficient of the exhaust diffuser with structure-C tapered struts decreases by up to 0.07. The two types of tapered struts also change the flow structure at the exhaust diffuser outlet, which affects the uniformity of the outlet airflow, and then affect the static pressure recovery coefficient. Under different inlet preswirls, two types of tapered struts can be effective to increase the static pressure recovery coefficient of the exhaust diffuser, for the exhaust diffuser with structure-C tapered struts, the static pressure recovery coefficient can be increased by up to 0.065, relative increase of 20%. The research in this paper shows that the tapered structure can significantly improve the aerodynamic performance of the exhaust diffuser under different inlet preswirls.