Tip Leakage Flow Research Articles

Impact of complex flow structures on the turbine blade tip region mixing

Mixing of the turbine blade tip leakage and mainstream flows causes considerable aerodynamic loss. Its understanding is crucial to raise a consequential improvement of the turbine performance. In the present paper, a typical high pressure turbine rotor flow is simulated by detached eddy simulation. The complex mixing in the blade tip region is assessed by the dilution index algorithm in the streamwise direction. Influences of typical parameters on mixing are consecutively identified and analyzed. Relating the influences to flow structures, the mixing mechanism is obtained. It is revealed that the normal effective diffusion coefficient is key in mixing and is correlated with the unsteady tip leakage flow stick vortices. The latter induced by the Kelvin–Helmholtz instability can significantly enhance the local mass and energy transfer and hence diffusion. As a result, mixing is strengthened. Furthermore, the tip region is knowingly divided into the juxtaposing near and far fields. The former contains the tip leakage vortex, leakage jet, mainstream flow, and two entrainment zones. Meanwhile, the latter contains the leakage jet, mainstream flow, and entrainment zone. It was found that the entrainment zone is mixed to a high-degree, whereas the leakage jet is barely mixed.

Influence of Tip Clearance on Cavitation Characteristics of an Inducer of Turbopump: CFD Study

The tip clearance, a compact gap between the inducer blade tip and casing wall, is critical to both the liquid leakage and cavitation-induced forces of a turbopump. In this study, we numerically investigate the effect of tip clearance on the cavitation characteristics of an inducer. Six different tip clearances, 0.1, 0.3, 0.5, 1.0, 1.5, and 2 mm, namely Models A–F, were designed to evaluate the cavitation performance, cavity structure, blade loading, radial force, etc. Model D (1.0 mm) had the relatively highest head coefficient and smallest cavity area on each blade as compared to all other models. The pressure coefficient distribution and blade loading further confirmed that Model D can maintain a higher pressure head and better suppress the cavitation onset than the other models. The radial force signals in the time and frequency domains show that Model D has an intermediate force magnitude with slightly higher noises at the rotating frequency and its harmonic frequencies. Model D also has a relatively smaller vortex region and smaller vortex strength (λ2 criterion). In short, all results show that Model D is the best alternative to balance the complex interactions of the bulk flow and tip leakage flow, compromising the hydraulic head and rotating cavitation.

Effect of differential tip clearance on the performance and noise of an axial compressor

Rotor tip clearance (TC) shows significant effects on the stability and performance of aero-engine compressors. TC is also related to the producing of noise and tip leakage flow which is an indicator of critical operating conditions for rotating stall or surge. In this paper, the effect of TC on stall evolution process under different TC values is studied on a single-stage compressor with low speed and high load, and a frequency-domain interferometer diastimeter for high-resolution measurements is applied to accurately measure the TC value. In the present study, a soft-wall casing made of grindable material is applied to achieve the “zero clearance” condition, and casings with different diameters are adopted to reach different clearance values. Experimental results show that pressure rise and efficiency are improved with a small TC. With the TC varying from zero to a certain large scale, experimental results have proved that there is an optimal TC with the presence of maximum flow margin. In addition, eighty measurement points are evenly distributed around the casing circumferentially at the leading edge of the blade to analyze the circumferential flow characteristics of the tip flow field. And twenty wall-flush mounted microphones are evenly distributed circumferentially to monitor the induct sound field of the compressor, and the experimental results show that the sound pressure level (SPL) of the compressor is lowest at a relatively small TC rather than zero. The influence of different TC values on compressor is discussed based on the analysis of the pressure fields, stall process, and the acoustic signal. Furthermore, a detailed discussion of rotating instability (RI) brought about by large clearances is provided.

Numerical Analysis of the Effects of Different Rotor Tip Gaps in a Radial Turbine Operating at High Pressure Ratios Reaching Choked Flow

To operate, radial turbines used in turbochargers require a minimum tip gap between the rotor blades and the stationary wall casing (shroud). This gap generates leakage flow driven by the pressure difference between the pressure and suction side. The tip leakage flow is largely unturned, which translates into a reduction of the shaft work due to the decrease in the total pressure. This paper investigates the flow through the rotor blade tip gap and the effects on the main flow when the turbine operates at a lower and higher pressure ratio with the presence of supersonic regions at the rotor trailing edge for two rotational speeds using computational fluid dynamics (CFD). The rotor tip gap has been decreased and increased up to 50% of the original tip gap geometry given by the manufacturer. Depending on the operational point, the results reveal that a reduction of 50% of the tip gap can lead to an increase of almost 3% in the efficiency, whereas a rise in 50% in the gap penalty the efficiency up to 3%. Furthermore, a supersonic region appears in the tip gap just when the flow enters through the pressure side, then the flow accelerates, leaving the suction side with a higher relative Mach number, generating a vortex by mixing with the mainstream. The effects of the vortex with the variation of the tip gap on the choked area at the rotor trailing edge presents a more significant change at higher than lower speeds. At a higher speed, the choked region closer to the shroud is due to the high relative inlet flow angle and the effects of the high relative motion of the shroud wall. Furthermore, this relative motion forces the tip leakage vortex to stay closer to the tip suction side, generating a subsonic region, which increases with the tip gap height. The leakage flow at lower and higher rotational speed does not affect the main flow close to the hub. However, close to the shroud, the velocity profile changes, and the generated entropy increases when the flow goes through the tip gap.

A novel approach for suppressing leakage flow through turbine blade tip gaps

Tip clearance leakage flow of the turbine bade is an important factor limiting the augment of the high pressure turbine efficiency, which should be suppressed utilizing certain methods. However, the passive control method with the traditional structure is more and more difficult to satisfy the suppressing ability of the advanced turbine demand. In the present paper, a synergetic suppressing method by combining the approach of blade shape modification and spontaneous injection is adopted, to construct a novel tip structure. The aerodynamic characteristics of the tip leakage flow (TLF) with different blade tip configurations, such as the squealer, squealer-winglet (SW) and squealer-winglet-spontaneous injection holes (SWS) composite configurations, are numerically investigated. The impacts of several key geometric parameters, such as the winglet width and the space ng of spontaneous injection holes, are also discussed. Due to the adjustment of the winglet, the SW tip configuration can get better suppressing effect on TLF than the squealer tip. The SWS synergetic suppression tip decrease the leakage flow rate and the leakage mixing loss on the basis of the SW tip due to the blocking effect of the spontaneous injection flow. The key geometric parameters study shows that the suppressing effect of the TLF can be improved by reasonably increasing the winglet width and reducing the spacing between spontaneous injection holes.

Unsteady Structure of Compressor Tip Leakage Flows

Abstract Direct numerical simulations (DNS) are performed of a cantilevered stator blade to identify the unsteady and turbulent flow structure within compressor tip flows. The simulations were performed with clearances of 1.6% and 3.2% of chord. The results show that the flow both within the gap and at the exit on the suction side highly unsteady phenomena controlled by fine-scale turbulent structures. The signature of the classical tip-leakage vortex is a consequence of time-averaging and does not exist in the true unsteady flow. Despite the complexity, we are able to replicate the flow within the tip gap using a validated quasi-three-dimensional (Q3D) model. This enables a wide range of Q3D DNS simulations to study the effects of blade tip corner radius and Reynolds number. Tip corner radius is found to radically alter the unsteady flow in the tip; it affects both separation bubble size and shape, as well as transition mechanisms in the tip flow. These effects can lead to variations in tip mass flow of up to 10% and a factor of 2 variation in dissipation within the tip gap.

Pulsed suction towards unsteady active flow control in an axial compressor cascade including clearance leakage effects

Tip leakage flow (TLF) induced by the gap between the stationary and rotating components brings complex flow structures, and this leads to a considerable loss in the compressor. Boundary layer suction is considered an efficient method to compensate the disadvantages brought by the TLF. In this study, the effect of hole-type pulsed suction (PS) on the TLF in a compressor cascade is investigated through a series of wind-tunnel experiment. PS is a more advanced technology over the constant suction (CS), and it considers improving of the compressor flow field from both spatial and frequency domain. The results indicate that the optimal aerodynamic performance is obtained when using PS at 25 % cx with a mass flow rate of 0.66 % and an excitation frequency of 100 Hz. First, flow control mechanisms are analyzed in terms of flow structures based on oil visualization and dynamic pressure results. The PS technique can induce significant periodic features and increase local intermittently momentum exchange. A connection between the local intensity of the excitation frequency and loss reduction at the cascade outlet is observed. Subsequently, the influence of the PS hole axial position is investigated, and the PS is found to contribute further control to the vortex structures than the CS. Finally, the effectiveness of the PS technique at different tip clearance sizes and inlet incidences is assessed to confirm its superiority over the CS technique in controlling TLF.

Investigation on leakage vortex cavitation and corresponding enstrophy characteristics in a liquid nitrogen inducer

A modified thermal cavitation model was employed to study the thermodynamic cavitation and effects of tip leakage vortex (TLV) on hydraulic losses in a three-blade inducer. Comparative analyses for TLV cavitation under different temperatures were presented. The tip leakage flow was spirally distributed, and its shape was negatively correlated with the nitrogen temperature. Thermodynamic effects reduced the vapor volume in the cavitation region and vorticity primarily at the leading edge, thus inhibiting the development of TLV. Enstrophy analysis was proposed to reveal the energy losses on TLV, and the enstrophy dissipation rate showed good predictability for TLV evolution. With the increasing temperature, the intensity of energy losses was reduced due to the thermal effects combined with weak cavitation intensity. Moreover, the change of temperature mainly influenced the primary tip leakage vortex (PTLV) but had minimal impact of the secondary tip leakage vortex. The energy losses were positive correlated with TLV, and PTLV was offset to the hub of the inducer due to the thermodynamic effects. Thus, the tip leakage can be considered as a key parameter to minimize the occurrence of thermodynamic cavitation in a liquid nitrogen inducer toprovide a reference for the design of the inducer.

Augmented cooling performance in gas turbine blade tip with slot cooling

The blade tip is one of the most susceptible parts of gas turbine blade due to the thermally induced failure caused by a hot gas tip leakage flow through tip clearance. A highly sophisticated and efficient blade tip cooling scheme plays a crucial role in reliable operation of a gas turbine blade. In the present study, we adopted a special slot cooling scheme in turbine blade tip. The film cooling effectiveness (FCE) and flow characteristics of turbine blade tip were investigated according to the cooling flow through the slot gap in blade tip rim. A linear cascade was fabricated to measure and evaluate the cooling performance of the blade tip with the film cooling through a slotted rim versus the blade tip with cooling holes. The local FCE values of the blade tip floor and rim upper surface were measured using the pressure-sensitive paint (PSP) method. The Reynolds number based on the axial chord length and the inlet velocity in the experiment was set at 192,000. The tip clearance was varied from 1 to 3% of the blade span and the coolant mass flow rate ranged from 0.3 to 0.7% of the main flow. The slot cooling in the blade tip, which can be incorporated through an additive manufacturing, showed highly enhanced cooling performance ranging from 53 to 116% compared to that of the blade tip with film cooling holes for various tip gaps and coolant mass flow rates. The slot cooling in the blade tip is expected to improve the thermal durability and reliability of blade tip with better coolant coverage and additional convective cooling through the internal cooling passage in the narrow squealer rim.

Effect of multiple cavities and tip injection on the aerothermal characteristics of the squealer tip in turbine stage

For modern gas turbines, the blades of the first-stage high-pressure turbines are subject to significant aerodynamic and thermal loads. As the region where the aerothermal environment is most severe, the aerothermal performance of the blade tip is crucial. Either the tip injection or squealer tip with ribs can effectively improve the tip leakage flow distribution, and thus reduce the tip thermal loads, while the effect of the combination of the two remains to be explored, especially when the number of ribs increases. To further understand the combined effects of the rib number and the tip injections on the aerothermal characteristics, steady-state numerical simulations of the first stage turbine aerothermal field are carried out with varied rib numbers and tip injection configurations in the current study. The kω SST turbulence model was used to solve the 3D Reynolds-Averaged Navier-Stokes (RANS) equations. The heat transfer coefficient distributions and the leakage flow rate distributions are compared with those of the conventional squealer tip case. The results show that adding a rib inside the tip cavity would reduce the size of the reflux vortex near the leading edge of the blade (LE), and effectively reduce the averaged heat transfer coefficient on the tip. In addition, an increase in the rib number would make the coolant accumulate in the cavities, thus increasing the cooling performance. The averaged heat transfer coefficient of the coolant injected squealer tip with three ribs (Rib3C) decreases by 19.55%, compared with the performance of the conventional squealer tip, due to the combined action of adding the multiple ribs and the coolant injection. Comprehensively considering both improving the aerodynamic performance and reducing the blade tip heat load using TOPSIS analysis, the coolant injected squealer tip with two ribs (Rib2C) achieves the best overall performance. In general, ribs arranged in the upstream region of the blade would improve the coolant coverage by blocking the separation region at the cavity bottom. To improve the harsh tip thermal environment and reduce the tip aerodynamic loss, optimizing the rib layout inside the cavity and the coolant injection configurations is a practical solution.

Casing Treatment: Its Potential and Limitations

Abstract Casing treatment is an advanced design feature intended to improve the stability of a compressor. Various investigations have been conducted based on both experimental and numerical studies at least over the last 50 years. In general, it has been demonstrated that a careful design of a casing treatment can substantially improve the stall margin of a tip-limited compressor although this generally comes with an aerodynamic efficiency penalty. This review paper revisits important past studies on casing treatments to clarify findings on the sometimes-conflicting results and understand what lessons are generally applicable to a wider group of machines. Circumferential grooves over a rotor tip have been in use for some time. Much recent work has focused on axial slots over a rotor tip, because of the significant stall margin improvement and the better efficiency potential of this configuration. This paper includes both configurations, with more emphasis on the latter. The paper concludes that casing treatment offers powerful benefits to a compressor and deserves continuing research and development. Good benefits result from axial slots which start ahead of the rotor leading edge and cover the front part of the rotor tip and include skew (tangential lean in the direction of rotation). Contributing physical mechanisms include increasing the axial momentum of the casing flow casing and reducing the aerodynamic blockage to improve the casing boundary layer and the tip leakage flow. The role of impacting unsteadiness is yet to be further clarified. Areas of further research are recommended, both experimental and analytical, including further work to understand and control the loss mechanisms, studying and controlling stage interaction effects in multistage compressors, and the simultaneous design optimization of the rotor blade with the casing treatment. Multi-disciplinary issues such as manufacturing cost, weight, length, durability, aeromechanics effects, and tolerance to dust and ice also deserve further attention.

Effects of the inclination angle of oval film holes on the aero-thermal performance of a squealer blade tip

The investigation and study on the characteristics of the flow and wall heat transfer on the squealer tip is of vital importance to the safe and durable operation of a turbine rotor. The numerical model of the blade squealer tip with discrete film cooling holes (round and oval holes) was constructed and validated in this paper. The effects of the radial and axial inclination of oval-holes on aero-thermal performance were systematically investigated, which received little attentions in previous studies. The result shows that the streamline deflection produced by negative inclination structures significantly improves the coverage of film, but the development of the jet vortex leads to an enhancement in leakage flow. The lift-off of film is effectively restrained by positive inclination structures, however, the jet outflow contraction limits the expansion of film coverage. Besides, the scraping between tip cavity flow and leakage flow is also an important factor to the leakage flow control, which can reduce the momentum of leakage flow. Overall, the negative radial inclination structure achieves the optimal performance of film cooling, whose tip average cooling effectiveness at 0.5 blowing ratio is even 132% higher than that in the round hole reference at 1.5 blowing ratio. The highest relative reduction of leakage flow is obtained by the positive axial inclination structure with 62.79% at the blowing ratio of 1.5.

Stall Margin Improvement in a Transonic Compressor With a Casing Treatment: Flow Mechanism

Abstract A compressor casing treatment with circumferential casing grooves (CCGs) is studied in detail. The primary objective of the current paper is to unearth the main driving fluid mechanism that changes the stall margin in a transonic compressor with CCGs. Large eddy simulation (LES) is applied to calculate the transonic compressor flow fields with and without CCGs. The present investigation shows that CCGs reduce the mass flow through the tip gap by about 16% near the stall condition. Calculated flow fields show that most of this reduction of tip leakage flow occurs near the CCGs. Reinjected flow from the CCGs pushes the tip leakage flow radially inward below the casing and changes how the tip leakage flow collides with the incoming main passage flow. However, a detailed examination of the calculated flow in the tip region shows that the reinjected flow does not contribute to the reduction of the overall blockage generation. The primary driver for reducing blockage generation with CCGs is the reduction of overall mass flowrate through the tip gap. In the present investigation, measurements show a very small decrease in efficiency with CCGs at the design flow condition, although the difference in efficiency is within the measurement uncertainty. Results from the LES simulation at the design condition with CCGs show that the tip leakage vortex (TLV) is pulled toward the blade suction side and double leakage flow is eliminated. The result is that the simulated efficiencies with and without CCGs are almost the same.

Interaction mechanism between the tip leakage flow and inlet boundary layer in a highly loaded compressor cascade based on scale-adaptive simulation

Based on the scale-adaptive simulation, the interaction mechanism between the tip leakage flow (TLF) and the inlet boundary layer (IBL) and its effects on the tip flow field and aerodynamic performance of the compressor cascade were investigated. The time-averaged results show that the IBL reduces the blade tip load near the leading edge region, decreases the axial momentum of the TLF, and inhibits the development of the TLF to a certain extent. On the other hand, the IBL promotes the coupling of the tip leakage vortex, secondary vortex, and separation vortex and induces breakdown, resulting in a large area of severe flow separation in the corner region, greatly reducing the diffusion capacity and significantly increasing the flow loss in the tip region. The analysis of the unsteady transient flow fields indicates that the unsteady fluctuation in the tip region is mainly caused by the tip leakage vortex and flow separation near the blade trailing edge. The former is suppressed under the influence of the IBL, while the latter is amplified. The high-intensity oscillation due to the breakdown and decomposition of the tip vortex structures plays a critical role in the fluctuation of the cascade performance. By means of proper orthogonal decomposition, it is found that the IBL enhances the fluctuation of small-scale vortex structures related to flow separation and leakage flow and makes the stability of the tip flow field worse.

Using Tip Injection to Stability Enhancement of a Transonic Centrifugal Impeller with Inlet Distortion

This paper aims to understand the effects of circumferential inlet distortion and tip injection on a transonic impeller performance and flow field. For distorted inflow, the impeller is subjected to a stationary 120-degrees circumferential total pressure distortion. Full annulus unsteady three-dimensional analysis has been used to study the inlet distortion and tip injection effects on the impeller performance, stability and flow field. The results show that the circumferential inlet distortion reduces the impeller total pressure ratio and adiabatic efficiency; however, it has no significant impact on the safe operating range. Unlike the inlet distortion, the tip injection considerably increases the operating range. According to the results, the distortion and tip injection effect on the compressor performance is mainly due to changes in tip leakage flow. The inlet distortion has unfavorable influences on the flow field, especially near the impeller tip; however, the tip injection ameliorates the flow field in this region. In both the clean and distorted inflow, the tip injection causes downstream shock transmission, weakening the shock-tip leakage interaction. Hence, stall inception is postponed, and the impeller stability is improved in the presence of the tip injection.

Analysis and modeling of the tip leakage flow on the performance of small-scale turbopumps for ORC applications

• An automated design model is developed to generate impeller geometries suitable for organic Rankine cycles. • The influence of tip clearance is investigated and modeled. • At high blade outlet angles, the effects of tip clearance and flow rate on the slip factor diminish. • The head rise decreases with the tip clearance ratio. • Feedforward neural networks are trained to model the slip factor and head loss coefficient of unshrouded centrifugal pumps. In this paper, the influence of tip clearance on the performance of small-scale turbopumps is studied numerically on extensive parameter ranges suitable for organic Rankine cycle applications. A novel and fully parameterized design model is developed and used to generate a wide range of turbopumps and their fluid domains to carry out three-dimensional computations across the impeller stage. Impellers are investigated at different operating conditions, and the accomplished results are analyzed to characterize the performance at design and off-design conditions. The CFD calculations demonstrate that the slip factor is dependent not only on its geometrical parameters, as considered by most correlations, but also on its operating conditions. The slip factor decreased almost linearly as the flow rate increased. In addition, the tip clearance ratio influences the slip factor, and its influence is non-linear. The head rise decreases as the tip clearance ratios increase. However, for radial impellers, a higher head rise was observed for small tip clearance ratios (<0.10). The numerical data is employed to infer reduced-order models for considering the tip clearance effect in the early-phase design process of small-scale turbopumps. The models predict the CFD data with an average relative deviation of 3.6 % and 5.8 % for the slip factor and the head loss coefficient, respectively.

Research on the Influence of Impeller Tip Clearance on the Internal Flow Loss of Axial Circulating Pump Under Unpowered Driven Condition

Abstract An axial-flow pump (AFP) a key hydraulic component in the circulating water system of large ships. When the speed of a large ship meets certain requirements, the AFP operates in the unpowered driven condition and has the characteristics of low speed, positive rotation and driven rotation, thereby achieving energy recovery efficiency without investing in the driving device. The unsteady internal flow characteristics of the AFP under the unpowered driven condition differ from those of conventional conditions. The blade tip clearance (TC) is an essential basis for the comprehensive technical indicators of the lift pump and the safe and stable operation of the circulating water system. In this study, the performance of the AFP with different TCs under the unpowered driven condition is investigated based on experimental tests and numerical simulations. Based on the entropy production theory, the energy loss characteristics of the AFP with different TCs are studied, and it is concluded that increasing the TC increases the strength of tip leakage flow. Particularly at large TCs, the energy loss of the pump increases significantly, causing flow separation on the blade surface and the formation of large-area vortex structures on the blade. In addition, under the large spacing TC, the instantaneous entropy production of the pump is unstable, and the entropy production frequency and amplitude are much larger than those of the conventional TC.

Free-Windmilling Speed Prediction Based on Aerodynamic Similarity of an Axial Wide-Chord Fan

This paper explores the windmilling operational boundary and aerodynamic characteristics of an axial wide-chord fan rotor according to the zero-torque characteristic. The interesting results show the radial profiles of the aerodynamic parameters at the rotor exit nearly collapse to the same curve for different windmilling speeds, which indicate that windmilling flow has a strong similarity. Meanwhile, there are three different operating modes along the blade span. The formation mechanism and evolution process of the tip leakage flow at the windmill are also analyzed. The reversal of the pressure difference will generate two kinds of tip leakage flows in opposite directions. A clear blockage zone appears near the blade tip under the joint action of the two kinds of tip leakage flows. Finally, this study proposes a mathematical model to predict the windmilling speed of a high-bypass-ratio turbofan based on the aerodynamic similarity of windmilling flow and the one-dimensional semiempirical windmilling mass flow function. This can be applied to the early stages of high-bypass-ratio turbofan development and can evaluate safety characteristics during engine windmilling operations.

Flow effects of microperforated-panel casing treatments in a contra-rotating fan

The flow effects of microperforated-panel (MPP) casing treatments installed over the front rotor of a small contra-rotating (CR) fan are numerically studied, with emphasis put on the reshaped front-rotor tip leakage flow, the blade response to rotor-rotor interaction, and the unsteadiness of static pressure on blade surfaces. It is found that the secondary flow through the sub-millimeter holes of the MPP hinders the formation of the front-rotor tip leakage flow and reduces its circumferential stretching, resulting in an improved inflow to the rear rotor. Consequently, the unsteady characteristics of static pressure and lift force on the rear rotor are generally attenuated. An enlarged back cavity can enhance such attenuation, in which case a 14.5% decrease in pressure unsteadiness is observed. The first, second, and third harmonics of the unsteady lift force experience reductions of 15.6%, 37.4%, and 60.9%, respectively. However, the unsteady characteristics on the front rotor dominated by potential interaction are not significantly influenced by the MPP. Furthermore, analysis of blade-to-blade phase differences shows that, whether the CR fan is treated with the MPP or not, the phase differences are not precisely repeated but vary randomly and that the higher the order of the force harmonic, the more likely the phase relationship is disturbed by the treatments. The varying nature of the phase relationship would render the acoustic energy of an induced interaction tone leaked into shaft tones and broadband noise. Radiation efficiency analysis of force harmonics demonstrates that the front rotor is not an efficient contributor to interaction noise compared with the rear rotor, which radiates more interaction tones with much higher efficiency. The current work is expected to be useful not only for devising effective MPP casing treatments to control small CR fan noise but also for understanding their underlying flow effects on rotor-rotor interaction.

Effects of combined sweeping jet actuator and winglet tip on aerodynamic performance in a turbine cascade

Compared with steady injection, the unsteady flow control techniques have received more attention in recent years and are considered to be more hopeful for reducing secondary flow losses in turbine stages. In particular, the sweeping jet actuator (SJA) is gradually being applied to reduce losses in turbomachinery due to its larger sweeping range. The objective of this study is to investigate the effect of combined flow control of SJA and the winglet tip structure on the aerodynamic performance and tip leakage flow of the turbine cascade through experimental and numerical methods. The effect of blade tip geometry on aerodynamic performance enhancement is discussed in detail by comparing flat and groove tips. The effect of injection flow on aerodynamic performance and secondary flow of turbine cascade with different blade tip structures is discussed by comparing SJA and hole-style steady jet actuator (HSJA). Compared with the flat tip without injection case, the combination of the winglet tip and SJA results in a maximum reduction of 20.1% in the total pressure loss at the cascade outlet, which is significantly better than the combination of the winglet tip and HSJA (16.2%). The results of the validated CFD calculations are also reported to help analyze the flow field and secondary flow loss mechanisms.