Profile Loss of Ultra-Highly Loaded Turbine Cascade at Transonic Flow Condition

2019 ◽  
Author(s):  
Hoshio Tsujita ◽  
Masanao Kaneko
Keyword(s):  
Mach Number ◽  
Transonic Flow ◽  
Compressible Flows ◽  
Detailed Examination ◽  
Aerodynamic Performance ◽  
Turbine Cascade ◽  
Wide Range ◽  
Exit Mach Number ◽  
Profile Loss ◽  
Highly Loaded

Abstract The aerodynamic performance of turbine components constituting the gas turbine engine is seriously required to be improved in order to reduce environmental load. The energy recovery efficiency in turbine component can be enhanced by the increase of turbine blade loading. In this study, as the first stage to investigate the aerodynamic performance of an ultra-highly loaded turbine cascade (UHLTC) with a turning angle of 160 degrees at transonic flow regime, two-dimensional steady compressible flows in UHLTC were analyzed numerically by using a commercial CFD code to focus on the profile loss. In the computations, the isentropic exit Mach number was varied in the wide range from 0.3 to 1.8 in order to examine the effects of exit Mach number on the shock wave formation and the associated profile loss generation. The computed results were examined in detail by comparing with those for a typical transonic turbine cascade. The detailed examination for the present computed results clarified the variation of shock pattern with the increase of exit Mach number and the loss “plateau” behavior in the present UHLTC.

The Effect of Pulsed Blowing on the Boundary Layer of a Highly Loaded Low Pressure Turbine Blade

2013 ◽  
Author(s):  
Marion Mack ◽  
Roland Brachmanski ◽  
Reinhard Niehuis
Keyword(s):  
Boundary Layer ◽  
Reynolds Number ◽  
Mach Number ◽  
Suction Side ◽  
Reynolds Numbers ◽  
Low Pressure ◽  
Trailing Edge ◽  
Low Pressure Turbine ◽  
Wide Range ◽  
Highly Loaded

The performance of the low pressure turbine (LPT) can vary appreciably, because this component operates under a wide range of Reynolds numbers. At higher Reynolds numbers, mid and aft loaded profiles have the advantage that transition of suction side boundary layer happens further downstream than at front loaded profiles, resulting in lower profile loss. At lower Reynolds numbers, aft loading of the blade can mean that if a suction side separation exists, it may remain open up to the trailing edge. This is especially the case when blade lift is increased via increased pitch to chord ratio. There is a trend in research towards exploring the effect of coupling boundary layer control with highly loaded turbine blades, in order to maximize performance over the full relevant Reynolds number range. In an earlier work, pulsed blowing with fluidic oscillators was shown to be effective in reducing the extent of the separated flow region and to significantly decrease the profile losses caused by separation over a wide range of Reynolds numbers. These experiments were carried out in the High-Speed Cascade Wind Tunnel of the German Federal Armed Forces University Munich, Germany, which allows to capture the effects of pulsed blowing at engine relevant conditions. The assumed control mechanism was the triggering of boundary layer transition by excitation of the Tollmien-Schlichting waves. The current work aims to gain further insight into the effects of pulsed blowing. It investigates the effect of a highly efficient configuration of pulsed blowing at a frequency of 9.5 kHz on the boundary layer at a Reynolds number of 70000 and exit Mach number of 0.6. The boundary layer profiles were measured at five positions between peak Mach number and the trailing edge with hot wire anemometry and pneumatic probes. Experiments were conducted with and without actuation under steady as well as periodically unsteady inflow conditions. The results show the development of the boundary layer and its interaction with incoming wakes. It is shown that pulsed blowing accelerates transition over the separation bubble and drastically reduces the boundary layer thickness.

Effects of Shock Wave Development on Secondary Flow Behavior in Linear Turbine Cascade at Transonic Condition

2020 ◽  
Author(s):  
Hoshio Tsujita ◽  
Masanao Kaneko
Keyword(s):  
Shock Wave ◽  
Mach Number ◽  
Secondary Flow ◽  
Turbine Blade ◽  
Gas Turbines ◽  
Flow Behavior ◽  
Turbine Cascade ◽  
Blade Loading ◽  
Passage Vortex ◽  
Exit Mach Number

Abstract Gas turbines widely applied to power generation and aerospace propulsion systems are continuously enhanced in efficiency for the reduction of environmental load. The energy recovery efficiency from working fluid in a turbine component constituting gas turbines can be enhanced by the increase of turbine blade loading. However, the increase of turbine blade loading inevitably intensifies the secondary flows, and consequently increases the associated loss generation. The development of the passage vortex is strongly influenced by the pitchwise pressure gradient on the endwall in the cascade passage. In addition, a practical high pressure turbine stage is generally driven under transonic flow conditions where the shock wave strongly influences the pressure distribution on the endwall. Therefore, it becomes very important to clarify the effects of the shock wave formation on the secondary flow behavior in order to increase the turbine blade loading without the deterioration of efficiency. In this study, the two-dimensional and the three-dimensional transonic flows in the HS1A linear turbine cascade at the design incidence angle were analyzed numerically by using the commercial CFD code with the assumption of steady compressible flow. The isentropic exit Mach number was varied from the subsonic to the supersonic conditions in order to examine the effects of development of shock wave caused by the increase of exit Mach number on the secondary flow behavior. The increase of exit Mach number induced the shock across the passage and increased its obliqueness. The increase of obliqueness reduced the cross flow on the endwall by moving the local minimum point of static pressure along the suction surface toward the trailing edge. As a consequence, the increase of exit Mach number attenuated the passage vortex.

Blade Bowing Effect on Aerodynamic Performance of a Highly Loaded Turbine Cascade

2010 ◽  
Vol 26 (3) ◽  
pp. 604-608 ◽  
Author(s):  
Chunqing Tan ◽  
Hualiang Zhang ◽  
Hongde Xia ◽  
Haisheng Chen ◽  
Atsumasa Yamamoto
Keyword(s):  
Aerodynamic Performance ◽  
Turbine Cascade ◽  
Highly Loaded

Experimental Investigation of Pressure Side Flow Separation on the T106C Airfoil at High Suction Side Incidence Flow

2016 ◽  
Author(s):  
Stephan Stotz ◽  
Reinhard Niehuis ◽  
Yavuz Guendogdu
Keyword(s):  
Mach Number ◽  
Wind Tunnel ◽  
Separation Bubble ◽  
Suction Side ◽  
Pressure Side ◽  
Blade Passage ◽  
Wide Range ◽  
Profile Losses ◽  
Exit Mach Number ◽  
Side Flow

The objective of this work is to study the influence of a pressure side separation bubble on the profile losses and the development of the bubble in the blade passage. For the experimental investigations the T106 profile is used, with an increased loading due to an enlarged pitch to chord ratio from 0.799 to 0.95 (T106C). The experiments were performed at the high-speed cascade wind tunnel of the Institute of Jet Propulsion at the University of the Federal Armed Forces Munich. The main feature of the wind tunnel is to vary Reynolds and Mach number independently to achieve realistic turbomachinery conditions. The focus of this work is to determine the influence of a pressure side separation on the profile losses and hence the robustness to suction side incidence flow. The cascade is tested at four incidence angles from 0° to −22.7° to create separation bubbles of different sizes. The influence of the Reynolds number is investigated for a wide range at constant exit Mach number. Therefore a typical exit Mach number for low pressure turbines in the range of 0.5–0.8 is chosen in order to consider compressible effects. Furthermore, two inlet turbulence levels of about 3% and 7.5% have been considered. The characteristics of the separation bubble are identified by using the profile pressure distributions, whereas wake traverses with a five hole probe are used to determine the influence of the pressure side separation on the profile losses. Further, time-resolved pressure measurements near the trailing edge as well as single hot wire measurements in the blade passage are conducted to investigate the unsteady behavior of the pressure side separation process itself and also its influence on the midspan passage flow.

Criterion Prediction of Changes of Shock-Wave Structure at Transonic Flow Around Airfoils with Local Impulse Energy

2014 ◽  
Vol 9 (1) ◽  
pp. 39-48
Author(s):  
Sergey Aulchenko ◽  
Vladimir Zamuraev ◽  
Anna Kalinina
Keyword(s):  
Shock Wave ◽  
Numerical Modeling ◽  
Mach Number ◽  
Pulse Energy ◽  
Transonic Flow ◽  
Energy Supply ◽  
Wave Structure ◽  
Shock Wave Structure ◽  
Wide Range ◽  
Comparison Of The Results

The results of numerical modeling of transonic streamline of profile with a local pulse energy supply were generalized in terms of criteria analysis for a wide range of parameters. Defined set of criteria allows predicting not only the degree, but the features of the flow transformation. A comparison of the results of the criteria analysis with numerical calculations of transonic streamline (Mach number M∞ = 0,85) of a symmetrical profile NASA-0012 were performed for energy supply in areas such as narrow and compact form

scholarly journals Mach Number Effects on Secondary Flow Development Downstream of a Turbine Cascade

1989 ◽  
Author(s):  
Antonio Perdichizzi
Keyword(s):  
Mach Number ◽  
Secondary Flow ◽  
Three Dimensional ◽  
Expansion Ratio ◽  
Turbine Cascade ◽  
Low Velocity ◽  
Flow Angle ◽  
Local Loss ◽  
Flow Development ◽  
Wide Range

The results of an investigation of the three-dimensional flow downstream of a transonic turbine cascade are presented. The investigation was carried out for a wide range of Mach numbers, extending from M2is = 0.2 up to 1.55. Measurements were made in five planes at different axial locations downstream of the trailing edge (covering more than one chord length), by using a miniaturized five hole probe especially designed for transonic flows. The results are presented in terms of local loss coefficient, vorticity and secondary velocity plots; these plots give a detailed picture of the secondary flow development downstream of the cascade and show how flow compressibility influences the vortex configuration. As Mach number increases, the passage vortex is found to migrate towards the endwall and secondary flow effects are more confined in the endwall region. The pitchwise mass averaged loss and flow angle distributions along the blade height appear to be affected by the expansion ratio; at high Mach number both underturning and overturning angles are found to be smaller than in low velocity flows. Overall losses, vorticity and secondary kinetic energy versus Mach number are also presented and discussed.

scholarly journals A Compact Diffuser System for Annular Combustors

1983 ◽  
Author(s):  
R. C. Adkins ◽  
J. O. Yost
Keyword(s):  
High Pressure ◽  
Mach Number ◽  
Pressure Loss ◽  
Total Pressure ◽  
Aerodynamic Performance ◽  
Total Pressure Loss ◽  
Pressure Recovery ◽  
Analytical Relationship ◽  
Exit Mach Number ◽  
Aerodynamic Simulation

Airflow tests have been conducted on an aerodynamic simulation of a combustor with pre-diffuser of compact configuration. The inlet Mach number throughout the tests was 0.35. The configuration was successful because of the attainment of a high pressure recovery, (Cp = 0.80), coupled with an exceptionally low total pressure loss (λ = 0.04). A useful analytical relationship is derived between the aerodynamic performance of combustor, compressor exit Mach number and diffuser performance.

Aerodynamic Performance of a Family of Three High Pressure Transonic Turbine Blades at Off-Design Incidence

2005 ◽  
Author(s):  
D. Corriveau ◽  
S. A. Sjolander
Keyword(s):  
High Pressure ◽  
Mach Number ◽  
Turbine Blades ◽  
Reynolds Numbers ◽  
Aerodynamic Performance ◽  
Navier Stokes ◽  
Blade Loading ◽  
Design Values ◽  
Outlet Flow ◽  
Exit Mach Number

Linear cascade measurements for the aerodynamic performance of three transonic High Pressure (HP) turbine blades have been presented previously by Corriveau and Sjolander [1] [2] for the design incidence. The airfoils were designed for the same inlet and outlet velocity triangles but varied in their loading distributions. Results from the earlier studies indicated that by shifting the loading towards the rear of the airfoil an improvement in the profile loss performance of the order of 20% could be obtained near the design Mach number of 1.05. The measurements have been extended to off-design incidence to investigate the effects of incidence on the performance of HP turbine blades having differing loading distributions. The additional measurements were performed for incidence values of −10.0°, +5.0°, and +10.0° relative to the design incidence. In addition, two-dimensional Navier-Stokes numerical simulations of the cascade flow were performed in order to help in the interpretation of the experimental results. The exit Mach number was kept at the design value of 1.05. The corresponding Reynolds numbers, based on outlet velocity and true chord, is roughly 10 × 105. The measurements include midspan losses, outlet flow angles, blade loading distributions and base pressures. The results show that the superior loss performance of the aft-loaded profile, observed at design incidence and Mach number, could also be seen for off-design values of incidence ranging from about −5.0° to +5.0°. However, it was found that for incidences greater than about +5.0° the performance of the aft-loaded blade deteriorated rapidly. The front-loaded airfoil showed generally similar performance to that of the baseline mid-loaded airfoil up to an incidence of +5.0°, at which point its performance also deteriorates significantly.

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