Showing papers on "Tip clearance published in 2008"

Hover and wind-tunnel testing of shrouded rotors for improved micro air vehicle design

Abstract: : The shrouded-rotor configuration has emerged as the most popular choice for rotary-wing Micro Air Vehicles (MAVs), because of the inherent safety of the design and the potential for significant performance improvements However, traditional design philosophies based on experience with large-scale ducted propellers may not apply to the low-Reynolds-number (20,000) regime in which MAVs operate An experimental investigation of the effects of varying the shroud profile shape on the performance of MAV-scale shrouded rotors has therefore been conducted Hover tests were performed on seventeen models with a nominal rotor diameter of 16 cm (63 in) and various values of diffuser expansion angle, diffuser length, inlet lip radius and blade tip clearance, at various rotor collective angles Compared to the baseline open rotor, the shrouded rotors showed increases in thrust by up to 94%, at the same power consumption, or reductions in power by up to 62% at the same thrust These improvements surpass those predicted by momentum theory, due to the additional effect of the shrouds in reducing the non-ideal power losses of the rotor Increasing the lip radius and decreasing the blade tip clearance caused performance to improve while optimal values of diffuser angle and length were found to be 10 and 50% of the shroud throat diameter, respectively With the exception of the lip radius, the effects of changing any of the shrouded-rotor parameters on performance became more pronounced as the values of the other parameters were changed to degrade performance Measurements were also made of the wake velocity profiles and the shroud surface pressure distributions The uniformity of the wake was improved by the presence of the shrouds and by decreasing the blade tip clearance, resulting in lower induced power losses For high net shroud thrust, a favorable pressure distribution over the inlet was seen to be more important than in the diffuser

Aircraft gas turbine engine blade tip clearance control

Abstract: A method and system adjusts blade tip clearance between rotating aircraft gas turbine engine blade tips and a surrounding shroud in anticipation of and before an engine command that changes an engine rotational speed. The method may include determining when to begin adjusting the tip clearance by expanding or contracting the shroud before the engine command and may be based on monitored aircraft and/or aircraft crew data indicative of the engine. The aircraft and/or aircraft crew data may include communications between aircraft crew and air traffic control authorities or air traffic control surrogates. Determining when to begin adjusting the tip clearance may include using learning algorithms which may use the aircraft gas turbine engine's operating experience and/or operating experience of other jet engines on an aircraft containing the aircraft gas turbine engine and/or on other aircraft.

Tip Clearance Vortex Oscillation, Vortex Shedding and Rotating Instabilities in an Axial Transonic Compressor Rotor

Abstract: Unsteady flow characteristics in a modern transonic axial compressor operating near stall are studied in detail. Measured data from high-response pressure probes show that the tip clearance vortex oscillates substantially near stall. Instantaneous flow structure varies substantially among different blade passages even with uniform inlet flow. Fast Fourier transformation of measured wall pressure shows a dominant frequency component that is between 30% and 40% of the rotor speed. To identify and analyze this phenomenon, computational studies based on a single passage and full annulus were carried out. The flow field in a transonic compressor near stall is heavily influenced by the unsteady motion of tip clearance vortices. Therefore, a Large Eddy Simulation (LES) was carried out to capture transient characteristics of the tip clearance vortex more realistically. The wall pressure spectrum from the current full annulus analysis also shows a dominant frequency when the rotor operates near stall. The calculated peak frequency is about 30% of the rotor frequency. The dominant frequency, which is non-synchronous with the rotor blade, is due to rotating flow instabilities. Flow interactions across blade passages due to synchronized tip clearance vortex oscillation seem to be the main cause.Copyright © 2008 by ASME

CFD Investigation on the Circumferential Grooves Casing Treatment of Transonic Compressor

Abstract: The performance of NASA Rotor 37 with Circumferential Grooves Casing Treatment (CGCT) is studied with an in-house CFD code NSAWET. Based on the stall mechanism analysis, a number of CGCT configurations have been proposed and numerically tested. The computation results show that the stall mechanisms are strongly related with the width of tip clearance. With a small tip clearance, the stall process is dominated by the trailing edge separation, while the leading edge tip leakage vortex breakdown induced blockage causes stall in a large tip clearance configuration. Circumferential grooves at appropriate axial locations can be beneficial to the stall margin in these two types of stall processes. The effects of the groove width and depth are presented. The mechanisms of CGCT for different tip clearances are also discussed.Copyright © 2008 by ASME

Flow Structure of Short-Length-Scale Disturbance in an Axial-Flow Compressor

Abstract: Short-length-scale disturbances, also called spikes, are often responsible in triggering rotating stall in axial-flow compressors. One hypothesis suggests that spikes can be the consequence of dynamic interaction among forward-spilled tip-leakage flow, the main throughflow, and the reversed flow. However, the transit process of such a dynamic interaction in the vicinity of the rotor tip clearance and, thus, the physical images of the flow structure of a spike are still unknown. In this paper, we present a numerical study with a novel scheme for a low-speed axial-How compressor by incorporating rotating inlet distortion. Because the inlet distortion will overload a portion of the blades while keeping the rest working normally, the short-length-scale disturbances can be observed without advocating the computational difficulty of simulating a fully stalled compressor. Two unsteady simulations using a commercial, three-dimensional, time-accurate, Reynolds-averaged Navier-Stokes solver are performed: one for a one-fourth rotor annulus with finer grids and the other for the entire rotor annulus with coarser grids. After the code is validated by comparing experimental results with the simulation for the entire rotor annulus, the one-fourth-annulus simulation is used to unveil the flow physics. As elucidated from the computational results, the complete birth-to-decay process of the short-length-scale disturbances is captured for the first time. The corresponding 3-D flow structure is also revealed. It is shown that the effects of dynamic How interaction at the tip extend beyond the tip region and deeply into the blade span. A horn-shaped vortex with one end at about 30% of the blade span and the other end at the casing is formed, which generates a low-pressure dip in the casing-pressure measurement. The spike, as identified from casing-pressure measurement, corresponds to a flow image in which the vortex rotates around the annulus.

Numerical investigation of relation between unsteady behavior of tip leakage vortex and rotating disturbance in a transonic axial compressor rotor

Abstract: The purpose of this study is to have a better understanding of the unsteady behavior of tip clearance flow at near-stall condition from a multi-passage simulation and to clarify the relation between such unsteadiness and rotating disturbance. This study is motivated by the following concern. A single passage simulation has revealed the occurrence of the tip leakage vortex breakdown at near-stall condition in a transonic axial compressor rotor, leading to the unsteadiness of the tip clearance flow field in the rotor passage. These unsteady flow phenomena were similar to those in the rotating instability, which is classified in one of the rotating disturbances. In other words it is possible that the tip leakage vortex breakdown produces a rotating disturbance such as the rotating instability. Three-dimensional unsteady RANS calculation was conducted to simulate the rotating disturbance in a transonic axial compressor rotor (NASA Rotor 37). The four-passage simulation was performed so as to capture a short length scale disturbance like the rotating instability and the spike-type stall inception. The simulation demonstrated that the unsteadiness of tip leakage vortex, which was derived from the vortex breakdown at near-stall condition, invoked the rotating disturbance in the rotor, which is similar to the rotating instability.Copyright © 2008 by ASME

Experiments and Computations on Large Tip Clearance Effects in a Linear Cascade

Abstract: Large tip clearances typically in the region of six percent exist in the high pressure stages of compressors of industrial gas turbines. Due to the relatively short annulus height and significant blockage, the tip clearance flow accounts for the largest proportion of loss in the HP. Therefore increasing the understanding of such flows will allow for improvements in design of such compressors, increasing efficiency, stability and the operating range. Experimental and computational techniques have been used to increase the physical understanding of the tip clearance flows through varying clearances in a linear cascade of controlled-diffusion blades. This paper shows two unexpected results. Firstly the loss does not increase with clearances greater than 4% and secondly there is an increase of blade loading towards the tip above 2% clearance. It appears that the loss production mechanisms of the pressure driven tip clearance jet do not increase as the clearance is increased to large values. The increase in blade force is attributed to the effect of the strong tip clearance vortex which does not move across the blade passage to the pressure surface, as is often observed for high stagger blading. These results may be significant for the design of HP compressors for industrial gas turbines.© 2008 ASME

Health risk assessment and prognosis of gas turbine blades by simulation and statistical methods

Abstract: Algorithmic approaches for failure risk assessment, anomaly detection and life prognosis of gas turbine blade are discussed. Modeling of blade tip clearance and Monte Carlo simulation considering creep, vibration and other damaging effects lead to two probabilistic distributions with blade tip clearance data. Failure risk can be determined during blade life usage based on blade tip tolerance limits. Statistical treatments considering percentile ranking of sample mean and regression analysis of blade tip clearance data for anomaly detection and usage life analysis respectively are also discussed.

Investigation of Blade Tip Interaction With Casing Treatment in a Transonic Compressor—Part I: Particle Image Velocimetry

Abstract: A single-stage transonic axial compressor was equipped with a casing treatment (CT), consisting of 3.5 axial slots per rotor pitch in order to investigate the predicted extension of the stall margin characteristics both numerically and experimentally. Contrary to most other studies the CT was designed especially accounting for an optimized optical access in the immediate vicinity of the CT, rather than giving maximum benefit in terms of stall margin extension. Part 1 of this two-part contribution describes the experimental investigation of the blade tip interaction with casing treatment using Particle image velocimetry (PIV). The nearly rectangular geometry of the CT cavities allowed a portion of it to be made of quartz glass with curvatures matching the casing. Thus the flow phenomena could be observed with essentially no disturbance caused by the optical access. Two periscope light sheet probes were specifically designed for this application to allow for precise alignment of the laser light sheet at three different radial positions in the rotor passage (87.5%, 95% and 99%). For the outermost radial position the light sheet probe was placed behind the rotor and aligned to pass the light sheet through the blade tip clearance. It was demonstrated that the PIV technique is capable of providing velocity information of high quality even in the tip clearance region of the rotor blades. The chosen type of smoke-based seeding with very small particles (about 0.5 μm in diameter) supported data evaluation with high spatial resolution, resulting in a final grid size of 0.5 × 0.5 mm. The PIV data base established in this project forms the basis for further detailed evaluations of the flow phenomena present in the transonic compressor stage with CT and allows validation of accompanying CFD calculations using the TRACE code. Based on the combined results of PIV measurements and CFD calculations of the same compressor and CT geometry a better understanding of the complex flow characteristics can be achieved, as detailed in Part 2 of this paper.Copyright © 2008 by ASME

Method and system for inspecting blade tip clearance

Abstract: A method for inspecting blade tip clearance between at least one rotor blade and a case spaced radially outward from the rotor blade is provided. The method includes inserting a probe into an aperture defined in the case and emitting electromagnetic energy into the case using the probe. The method also includes detecting electromagnetic energy reflected from a blade tip portion of the rotor blade and determining a blade tip clearance defined between the blade tip and the case based on the detected electromagnetic energy.

Compressor blade with forward sweep and dihedral

Abstract: An airfoil for use as rotor blades in compressors for turbomachines, such as gas turbine engines. The airfoil includes increased forward sweep and forward dihedral effective to reduce losses generated by interaction of tip clearance flow, secondary flows and passage shocks.

Turbine blade tip clearance system

Abstract: A system for adjusting a clearance between blade tips of a turbine and a shroud assembly encircling the turbine in a turbine engine is disclosed herein. The system includes a first fluid passageway operable to extend from a first source of fluid at a variable pressure to a shroud assembly of a turbine engine. The first fluid passageway directs a first stream of fluid to the shroud assembly. The system also includes a first valve positioned along the first fluid passageway and moveable between open and closed configurations. The first valve is biased to the open configuration and moved to the closed configuration passively and directly by a first predetermined level of pressure of the first stream of fluid. During periods of relatively low power production of the turbine engine, the first valve is in the open configuration and moves to the closed configuration when power production of the turbine engine increases from relatively low power production.

The Effect of Clearance Flow of Variable Area Nozzles on Radial Turbine Performance

Abstract: The flow behind the variable area nozzle for radial turbines was measured with a 3-hole yaw probe and calculated with CFD. Two nozzle throat-areas were investigated: the smallest and the largest opening for the variable nozzle. Test results agreed with the calculated results qualitatively. The leakage flow through the tip clearance of the nozzle vane significantly affected the flow field downstream of the nozzle vane with the smallest opening. However, the effect on leakage flow on the flow field downstream of the nozzle vane with the largest opening was very weak. In the flow field of the largest opening nozzle, the effect of wake s dominant. The effect of the clearance of the nozzle vane on the turbine performance was estimated by a 1D-model and the strong influence on the turbine efficiency was confirmed at smallest opening. The flow fields in the impeller downstream of the nozzle vane at the smallest opening with and without the nozzle clearance were investigated with CFD. The setting angle of the nozzle vane without clearance was adjusted to match the operating point of the turbine with the nozzle clearance. In order to extract the specific work from the impeller, the nozzle vane with the vane clearance requires the larger vane setting angle than that without clearance. The increase of the vane setting angle increases the incidence loss and deteriorates turbine efficiency.Copyright © 2008 by ASME

Investigation of a centrifugal compressor and study of the area ratio and TIP clearance effects on performance

Abstract: In this research, the centrifugal compressor of a turbocharger is investigated experimentally and numerically. Performance characteristics of the compressor were obtained experimentally by measurements of rotor speed and flow parameters at the inlet and outlet of the compressor. Three dimensional flow field in the impeller and diffuser was analyzed numerically using a full Navier-Stokes program with SST turbulence model. The performance characteristics of the compressor were obtained numerically, which were then compared with the experimental results. The comparison shows good agreement. Furthermore, the effect of area ratio and tip clearance on the performance parameters and flow field was studied numerically. The impeller area ratio was changed by cutting the impeller exit axial width from an initial value of 4.1 mm to a final value of 5.1 mm, resulting in an area ratio from 0.792 to 0.965. For the rotor with exit axial width of 4.6 mm, performance was investigated for tip clearance of 0.0, 0.5 and 1.0 mm. Results of this simulation at design point showed that the compressor pressure ratio peaked at an area ratio of 0.792 while the efficiency peaked at a higher value of area ratio of 0.878. Also the increment of the tip clearance from 0 to 1 mm resulted in 20 percent efficiency decrease.

Effect of Pin Tip Dual Clearance on Flow and Heat Transfer at Low Reynolds Numbers

Abstract: Cylindrical pin fins with tip clearances are investigated in the low Reynolds number range 5 100, both t* =0.2D* and 0.3D* were comparable in performance.

Microhaemodynamics within the blade tip clearance of a centrifugal turbodynamic blood pump

Abstract: A persistent challenge facing the quantitative design of turbodynamic blood pumps is the great disparity of spatial scales between the primary and auxiliary flow paths. Fluid passages within journals and adjacent to the blade tips are often on the scale of several blood cells, confounding the application of macroscopic continuum models. Yet, precisely in these regions there exists the highest shear stress, which is most likely to cause cellular trauma. This disparity has motivated these microscopic studies to visualize the kinematics of the blood cells within the small clearances of a miniature turbodynamic blood pump.A transparent model of a miniature centrifugal pump having an adjustable tip clearance (50–200μm) was prepared for direct optical visualization of the region between the impeller blade tip and the stationary housing. Synchronized images of the blood cells were obtained by a microscopic visualization system, consisting of an inverted microscope fitted with long-working-distance objective lens...

Unsteady Analysis of Blade and Tip Heat Transfer as Influenced by the Upstream Momentum and Thermal Wakes

Abstract: The effect of the upstream wake on the blade heat transfer has been numerically examined. The geometry and the flow conditions of the first stage turbine blade of GE s E3 engine with a tip clearance equal to 2 percent of the span was utilized. Based on numerical calculations of the vane, a set of wake boundary conditions were approximated, which were subsequently imposed upon the downstream blade. This set consisted of the momentum and thermal wakes as well as the variation in modeled turbulence quantities of turbulence intensity and the length scale. Using a one-blade periodic domain, the distributions of unsteady heat transfer rate on the turbine blade and its tip, as affected by the wake, were determined. Such heat transfer coefficient distribution was computed using the wall heat flux and the adiabatic wall temperature to desensitize the heat transfer coefficient to the wall temperature. For the determination of the wall heat flux and the adiabatic wall temperatures, two sets of computations were required. The results were used in a phase-locked manner to compute the unsteady or steady heat transfer coefficients. It has been found that the unsteady wake has some effect on the distribution of the time averaged heat transfer coefficient on the blade and that this distribution is different from the distribution that is obtainable from a steady computation. This difference was found to be as large as 20 percent of the average heat transfer on the blade surface. On the tip surface, this difference is comparatively smaller and can be as large as four percent of the average.

Effects of turbine tip clearance on gas turbine performance

Abstract: There are many different sources of loss in gas turbines. The turbine tip clearance loss is the focus of this work. In gas turbine components such as compressor and turbine the presence of rotating blades necessitates a small annular tip clearance between the rotor blade tip and the outer casing. This clearance, although mechanically necessary, may represent a source of large loss in a turbine. The gap height can be a fraction of a millimeter but can have a disproportionately high influence on the stage efficiency. A large space between the blades and the outer casing results in detrimental leakages, while contact between them can damage the blades. Therefore, the evaluation of the sources of the performance degradation independently presents useful information that can aid in the maintenance action. As part of the overall blade loss the turbine tip clearance loss arises because at the blade tip the gas does not follow the intended path and therefore does not contribute to the turbine power output and interacts with the outer wall boundary layer. Increasing turbine tip clearance causes performance deterioration of the gas turbine and therefore increases fuel consumption. The increase in turbine tip clearance may as a result of rubs during engine transients and the interaction between the blades and the outer casing. This work deals with the study of the influence of the turbine tip clearance on a gas turbine engine, using a turbine tip clearance model incorporated to an engine deck. Actual data of an existing engine were used to check the validity of the procedure. This paper refers to a single shaft turbojet engine under development, operating under steady state condition. Different compressor maps were used to study the influence of the curve shapes on the engine performance. Two cases were considered for the performance simulation: constant corrected speed and constant maximum cycle temperature.© 2008 ASME

Study on leakage flow characteristics of radial inflow turbines at rotor tip clearance

Abstract: Tip clearance leakage flow in a radial inflow turbine rotor for microturbines under the stage environment is investigated using a three-dimensional viscous flow simulation. The results indicate that the scraping flow caused by relative motion between casing and rotor tip, and the pressure difference between pressure side and suction side at rotor tip, play important roles in tip clearance leakage flow. The more the rotor tip speed increases and tip clearance height decreases, the more the scraping effect acts. Though the leakage velocity of tip clearance at midsection and exducer regions changes less when the rotor rotational speed is changing, the distance between passage vortex and rotor suction side varies in evidence. Main leakage flow rate of tip clearance takes place at region of exducer tip and some seal configurations will be quite effective for cutting leakage flow if these configurations are arranged over midsection and exducer of the radial inflow rotor.

Control of Short Length-Scale Rotating Stall Inception on a High-Speed Axial Compressor With Plasma Actuation

Abstract: This paper presents a computational assessment of the use of Single Dielectric Barrier Discharge (SDBD), or plasma, actuators for the suppression of short-length scale (spike) stall inception in a transonic axial compressor. Casing plasma actuation has the potential to provide a robust and effective stall suppression device without compromising compressor performance. The objective of this work is to determine the optimum actuator location and actuation strength needed to suppress spike stall inception at transonic speeds without imposing a penalty on compressor performance. This is done through the implementation of an actuator model in a turbomachinery CFD code for simulations of a transonic research compressor rotor passage to measure the effectiveness of casing plasma actuation in delaying the tip clearance flow criteria that are believed to lead to the formation of spike disturbances. Results show that the casing plasma actuator should be positioned near the rotor leading edge so as to optimize the impact on the interface between the incoming and tip clearance flows as well as for practical consideration. Simulations also indicate that the required actuator strength is higher than that of typical SDBD actuators while still remaining within practical achievable limits. These results will form the basis for experimental validation of the concept in the corresponding research compressor rig in the near future.Copyright © 2008 by ASME

Stall inception in a transonic axial fan

Abstract: The current paper reports a numerical investigation of stall inception in a transonic compressor rotor, NASA Rotor-67, by using the whole flow passages in the computations. Surface roughness is added to one of the blades in order to trigger rotating stall. During stall inception, the tip clearance vortex moved away from the suction surface of the roughened blade's upper neighbour, leading to vortex breakdown. The stall cell was found to propagate opposite the direction of the blade rotation at about 30 per cent of rotational speed. The effect of air bleeding on stabilizing the compressor is also studied in this work. The mean mass flowrate removed from the bleed valves was ∼1.2 per cent of the mainstream flowrate. This amount of bleeding was found to effectively suppress the stalling disturbances.

Investigation of Tip-Flow Based Stall Criteria Using Rotor Casing Visualization

Abstract: Recent stall inception investigations have indicated that short-length scale stall initiates when the interface between the tip gap flow and the approach flow spills forward of the leading edge of the adjacent blade. This hypothesis was investigated in the present work using both numerical and experimental results from a range of compressor geometries and speed. First, full annulus unsteady computations of R35 were used to generate contours of entropy at the casing. It was found that a large gradient in entropy, which marked the leakage fluid, was aligned with the leading edge plane at the stalling mass flow. It was also observed that the flow direction in the region of increased entropy was in the reverse axial direction. The interface between the approach fluid and the reverse-direction leakage flow was related to a region in which the axial component of the wall shear stress was zero. The axial location of this line was measured experimentally using a surface streaking method using two separate facilities. It was found that the location of this line is determined by a momentum balance between the approach fluid and the tip leakage fluid. Measurements were acquired with varied tip clearance, radial distortion, and centerline offset to support these conclusions. In all cases the zero axial shear line was found to move upstream with decreased flow coefficient, and was in close proximity to the rotor leading edge at the stalling mass flow.Copyright © 2008 by ASME

Tip Clearance Effects on Inlet Hot Streak Migration Characteristics in High Pressure Stage of a Vaneless Counter-Rotating Turbine

Abstract: In this paper, three-dimensional multiblade row unsteady Navier-Stokes simulations at a hot streak temperature ratio of 2.0 have been performed to reveal the effects of rotor tip clearance on the inlet hot streak migration characteristics in high pressure stage of a Vaneless Counter-Rotating Turbine. The hot streak is circular in shape with a diameter equal to 25% of the high pressure turbine stator span. The hot streak center is located at 50% of the span and the leading edge of the high pressure turbine stator. The tip clearance size studied in this paper is 2.0mm (2.594% high pressure turbine rotor height). The numerical results indicate that the hot streak mixes with the high pressure turbine stator wake and convects towards the high pressure turbine rotor blade surface. Most of hotter fluid migrates to the pressure surface of the high pressure turbine rotor. Only a few of hotter fluid rounds the leading edge of the high pressure turbine rotor and migrates to the suction surface. The migration characteristics of the hot streak in the high pressure turbine rotor are dominated by the combined effects of secondary flow, buoyancy and leakage flow in the rotor tip clearance. The leakage flow trends to drive the hotter fluid towards the blade tip on the pressure surface and to the hub on the suction surface. Under the effect of the leakage flow, even partial hotter fluid near the pressure surface is also driven to the rotor suction surface through the tip clearance. Compared with the case without rotor tip clearance, the heat load of the high pressure turbine rotor is intensified due to the effects of the leakage flow. And the results indicate that the leakage flow effects trend to increase the low pressure turbine rotor inlet temperature at the tip region. The air flow with higher temperature at the tip region of the low pressure turbine rotor inlet will affect the flow and heat transfer characteristics in the downstream low pressure turbine.Copyright © 2008 by ASME

Tip Clearance Effect on the Performance of a Shrouded Supersonic Impulse Turbine

Abstract: An experimental investigation of the effect of tip clearance on the performance of a shrouded supersonic impulse turbine was performed in this study. A single-staged axial flow impulse turbine designed to have a rotor inlet relative Mach number of 1.7 was used for the experiment. Turbine efficiency was measured at various settings of tip clearances, rotational speeds, and turbine pressure ratios to observe the characteristics of the efficiency gradient. The overall efficiency of the supersonic impulse turbine was largely affected by rotational speed. For a fixed rotational speed, local maximum efficiency was found near a turbine pressure ratio at which the turbine nozzle was fully expanded. At a reference test point, the linearly estimated efficiency gradient was 0.09. However, efficiency variation with respect to tip clearance was nonlinear, and relatively larger efficiency gradients were found at small tip clearances and high rotational speeds. It has been found that the efficiency gradient varies linearly with the cube of rotational speed and shows its minimum value near the reference turbine pressure ratio.

Effects of axial non-uniform tip clearances on aerodynamic performance of a transonic axial compressor

Abstract: This paper presents a numerical investigation of effects of axial non-uniform tip clearances on the aerodynamic performance of a transonic axial compressor rotor (NASA Rotor 37). The three-dimensional steady flow field within the rotor passage was simulated with the datum tip clearance of 0.356 mm at the design wheel speed of 17188.7 rpm. The simulation results are well consistent with the measurement results, which verified the numerical method. Then the three-dimensional steady flow field within the rotor passage was simulated respectively with different axial non-uniform tip clearances. The calculation results showed that optimal axial non-uniform tip clearances could improve the compressor performance, while the efficiency and the pressure ratio of the compressor were increased. The flow mechanism is that the axial non-uniform tip clearance can weaken the tip leakage vortex, blow down low-energy fluids in boundary layers and reduce both flow blockage and tip loss.