Aerodynamic Performance Measurements of a Fully-Scaled Turbine in a Short Duration Facility

2000 ◽  
Author(s):  
R. C. Keogh ◽  
G. R. Guenette ◽  
T. P. Sommer
Keyword(s):  
Short Duration ◽  
Mass Flow ◽  
Low Cost ◽  
Turbine Stage ◽  
Performance Measurements ◽  
Turbine Efficiency ◽  
Transonic Turbine ◽  
Absolute Measurements ◽  
Relative Measurements ◽  
Isentropic Efficiency

This paper describes the implementation and results of an experiment to measure the isentropic efficiency of a fully scaled transonic turbine stage in a short-duration blowdown type facility. Short duration test facilities offer the potential for low cost, high accuracy testing of turbomachinery components under fully scaled conditions. The method developed employs the ‘brake’ approach for turbine efficiency measurement. This paper describes newly developed techniques to measure the turbine torque and mass flow in this type of facility. The isentropic efficiency was measured over a test window of 400 to 500 milliseconds. The estimated measurement uncertainty (U95) is 0.45% for absolute measurements, and 0.25% for relative measurements. Corrected mass flow and isentropic efficiency measurements are presented for a range of corrected speed (97–112%) and compared with CFD predictions. Close agreement was observed both in overall magnitudes and trends between the measured data and predictions.

Analysis of the Mixing Plane Interface Between Stator and Rotor of a Transonic Axial Turbine Stage

2000 ◽  
Author(s):  
P. Giangiacomo ◽  
V. Michelassi ◽  
F. Martelli
Keyword(s):  
Mass Flow ◽  
Static Pressure ◽  
Three Dimensional ◽  
Turbine Stage ◽  
Flow Rates ◽  
Tip Leakage ◽  
Mass Flow Rates ◽  
Stator Blade ◽  
Transonic Turbine ◽  
Rotor Mass

A three-dimensional transonic turbine stage is computed by means of a numerical simulation tool. The simulation accounts for the coolant ejection from the stator blade and for the tip leakage of the rotor blade. The stator and rotor rows interact via a mixing plane, which allows the stage to be computed in a steady manner. The analysis is focused on the matching of the stator and rotor mass flow rates. The computations proved that the mixing plane approach allows the stator and rotor mass flow rates to be balanced with a careful choice of the stator-rotor static pressure interface. At the same time, the pitch averaged distribution of the transported quantities at the interface for the stator and rotor may differ slightly, together with the value of the static pressure at the hub.

Improving Accuracy and Comparability of Turbocharger Performance Measurements

2019 ◽  
Author(s):  
Mario Schinnerl ◽  
Mathias Bogner ◽  
Jan Ehrhard
Keyword(s):  
Turbine Stage ◽  
Performance Measurements ◽  
Cfd Simulations ◽  
Operating Range ◽  
Turbine Efficiency ◽  
Run Up ◽  
Improving Accuracy ◽  
Compressor Power ◽  
The Impact ◽  
Operating Points

Abstract The reduction of fuel consumption and emissions is the most dominant challenge in powertrain development. Therefore, engine and turbocharger have to be matched with high accuracy to achieve optimum powertrain efficiencies. With respect to relevant engine operating points, compressor maps can be measured in full operating range on a standard hot gas test bench. Even though there is no need for extrapolation of the operating range, they have to be corrected for the impact of heat transfer to represent the adiabatic performance of the compressor stage. The common approach to evaluate the turbine efficiency is to apply the energy balance of the entire turbocharger where the turbine power is the sum of the compressor power and the friction losses of the radial and axial journal bearings. The adiabatic compressor power in combination with the calculation of the friction losses by using validated run-up simulations enables the evaluation of the isentropic turbine efficiency and the comparability to CFD simulations of the turbine stage. For reasons of comparability to CFD simulations, which can predict a wide operating range of the turbine stage, the limited measureable turbine operating range is enhanced by a so-called compressor closed loop unit (CCLU). This additional test device enables to vary the demand of compressor power for the same operating points as in the standard mapping and therefore to enlarge the measureable turbine operating range. In combination with proper extrapolation methods, the isentropic turbine efficiency can now be compared to CFD simulations.

Influence of Tip Geometry on Over Tip Leakage in Shrouded Rotor Blades With Cooling

2017 ◽  
Author(s):  
Jeffrey Tessier ◽  
Gregory Vogel
Keyword(s):  
Gas Turbine ◽  
Mass Flow ◽  
Turbine Blades ◽  
Honeycomb Structure ◽  
Rotor Blades ◽  
Turbine Stage ◽  
Turbine Efficiency ◽  
Physical Effects ◽  
Efficiency Effects ◽  
Stage Efficiency

Gas turbine blades can be shrouded and designed with “knife edges” to reduce over tip leakages as an attempt to improve turbine stage efficiency. The smaller the tip gap is, the less the amount of leakage and consequently the higher the turbine efficiency. However a zero tip gap between the rotating blade and the stationary casing is simply not practical and not achievable for typical engine operations. One approach often consists of making the stationary shroud at the casing of abradable coating or of softer material in a honeycomb structure. In some cases, it is also common practice to pretrench the honeycomb structure to a certain height to reduce rubbing that could naturally occur with brand new hardware. This paper details the physical effects occurring between trenched and un-trenched configurations and quantifies the potential loss in turbine stage efficiency and power under such changes. Because front turbine stages are also cooled, this paper is also detailing the physical effects that are occurring between trenched and un-trenched configurations for a shrouded cooled turbine blade and the associated impact on performance. Since gas turbine are set to run at a specific gas mass flow, the differences between un-trenched and trenched for un-cooled and cooled are compared at the same given gas mass flow conditions. The paper concludes with key considerations for cooled turbine stage efficiency effects with and without trench.

Effect of Active Modulation of Through-Casing Coolant Injection on Turbine Efficiency

2017 ◽  
Author(s):  
Brian M. T. Tang ◽  
Marko Bacic ◽  
Peter T. Ireland
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Total Pressure ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Tip Leakage ◽  
Turbine Efficiency ◽  
Coolant Injection ◽  
Cooling Air

This paper presents a computational investigation into the impact of cooling air injected through the stationary over-tip turbine casing on overall turbine efficiency. The high work axial flow turbine is representative of the high pressure turbine of a civil aviation turbofan engine. The effect of active modulation of the cooling air is assessed, as well as that of the injection locations. The influence of the through-casing coolant injection on the turbine blade over-tip leakage flow and the associated secondary flow features are examined. Transient (unsteady) sliding mesh simulations of a one turbine stage rotor-stator domain are performed using periodic boundary conditions. Cooling air configurations with a constant total pressure air supply, constant mass flow rate and actively controlled total pressure supply are assessed for a single geometric arrangement of cooling holes. The effects of both the mass flow rate of cooling air and the location of its injection relative to the turbine rotor blade are examined. The results show that all of the assessed cooling configurations provided a benefit to turbine row efficiency of between 0.2 and 0.4 percentage points. The passive and constant mass flow rate configurations reduced the over-tip leakage flow, but did so in an inefficient manner, with decreasing efficiency observed with increasing injection mass flow rate beyond 0.6% of the mainstream flow, despite the over-tip leakage mass flow rate continuing to reduce. By contrast, the active total pressure controlled injection provided a more efficient manner of controlling this leakage flow, as it permitted a redistribution of cooling air, allowing it to be applied in the regions close to the suction side of the blade tip which more directly reduced over-tip leakage flow rates and hence improved efficiency. Cooling air injected close to the pressure side of the rotor blade was less effective at controlling the leakage flow, and was associated with increased aerodynamic loss in the passage vortex.

Transonic Turbine Stage Heat Transfer Investigation in Presence of Strong Shocks

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
A. de la Loma ◽  
G. Paniagua ◽  
D. Verrastro ◽  
P. Adami
Keyword(s):  
Heat Transfer ◽  
Rotor Blade ◽  
Shock Interaction ◽  
Turbine Stage ◽  
Test Rig ◽  
Unsteady Heat Transfer ◽  
Tube Test ◽  
Stator Blade ◽  
Transonic Turbine ◽  
Layered Thin Film

This paper reports the external convective heat transfer distribution of a modern single-stage transonic turbine together with the physical interpretation of the different shock interaction mechanisms. The measurements have been performed in the compression tube test rig of the von Karman Institute using single- and double-layered thin film gauges. The three pressure ratios tested are representative of those encountered in actual aeroengines, with M2,is ranging from 1.07 to 1.25 and a Reynolds number of about 106. Three different rotor blade heights (15%, 50%, and 85%) and the stator blade at midspan have been investigated. The measurements highlight the destabilizing effect of the vane left-running shock on the rotor boundary layer. The stator unsteady heat transfer is dominated by the fluctuating right-running vane trailing edge shock at the blade passing frequency.

Design of a Transonic High-Pressure Turbine Stage 2D Section With Reduced Rotor/Stator Interaction

2004 ◽  
Author(s):  
Michele Vascellari ◽  
Re´my De´nos ◽  
Rene´ Van den Braembussche
Keyword(s):  
Rotor Blade ◽  
Static Pressure ◽  
Aerodynamic Force ◽  
Pressure Fluctuations ◽  
Uniform Field ◽  
Turbine Stage ◽  
Rotor Stator Interaction ◽  
Transonic Turbine ◽  
Blade Failure ◽  
Rotor Profiles

In transonic turbine stages, the exit static pressure field of the vane is highly non-uniform in the pitchwise direction. The rotor traverses periodically this non-uniform field and large static pressure fluctuations are observed around the rotor section. As a consequence the rotor blade is submitted to significant variations of its aerodynamic force. This contributes to the high cycle fatigue and may result in unexpected blade failure. In this paper an existing transonic turbine stage section is redesigned in the view of reducing the rotor stator interaction, and in particular the unsteady rotor blade forcing. The first step is the redesign of the stator blade profile to reduce the stator exit pitchwise static pressure gradient. For this purpose, a procedure using a genetic algorithm and an artificial neural network is used. Next, two new rotor profiles are designed and analysed with a quasi 3D Euler unsteady solver in order to investigate their receptivity to the shock interaction. One of the new profiles allows reducing the blade force variation by 50%.

scholarly journals The Design and Evaluation of a High Pressure Ratio Radial Turbine

1992 ◽  
Author(s):  
K. R. Pullen ◽  
N. C. Baines ◽  
S. H. Hill
Keyword(s):  
High Pressure ◽  
High Speed ◽  
Pressure Ratio ◽  
Performance Measurements ◽  
Turbine Engine ◽  
High Pressure Ratio ◽  
Turbine Efficiency ◽  
Wide Range ◽  
Dimensional Parameters ◽  
Very High

A single stage, high speed, high pressure ratio radial inflow turbine was designed for a single shaft gas turbine engine in the 200 kW power range. A model turbine has been tested in a cold rig facility with correct simulation of the important non-dimensional parameters. Performance measurements over a wide range of operation were made, together with extensive volute and exhaust traverses, so that gas velocities and incidence and deviation angles could be deduced. The turbine efficiency was lower than expected at all but the lowest speed. The rotor incidence and exit swirl angles, as obtained from the rig test data, were very similar to the design assumptions. However, evidence was found of a region of separation in the nozzle vane passages, presumably caused by a very high curvature in the endwall just upstream of the vane leading edges. The effects of such a separation are shown to be consistent with the observed performance.

The theoretical and experimental research on the thermodynamic process in transcritical carbon dioxide piston compressor

2018 ◽  
Vol 233 (2) ◽  
pp. 267-279
Author(s):  
Yulong Song ◽  
Qinfei Sun ◽  
Shuo Yang ◽  
Qijing Xing ◽  
Ling Cheng ◽  
...  
Keyword(s):  
Pressure Ratio ◽  
Piston Compressor ◽  
Volumetric Efficiency ◽  
Thermodynamic Process ◽  
Height Ratio ◽  
General Mathematical Model ◽  
Simulation Results ◽  
Transcritical Carbon Dioxide ◽  
Relative Measurements ◽  
Isentropic Efficiency

The general mathematical model of the transcritical CO2 compressor was presented to assess the compressor efficiencies including isentropic efficiency and volumetric efficiency based on the thermodynamic theories and compressor structures. Furthermore, the prototype of the transcritical CO2 system was established and relative measurements were carried out to evaluate the precision of the simulation. Results showed that the volumetric efficiency of the compressor kept decreasing while the isentropic efficiency increased first and then kept almost constant and even declined with the increase in the pressure ratio. Besides, the indicated efficiency and volumetric efficiency declined slightly with the decrease in the suction density corresponding to the increase in suction superheating. As for the effects of compressor structures on the performances, the indicated efficiency increased sharply and then decreased gradually, while the volumetric efficiency kept declining with the increase in the cylinder diameter-to-height ratio, respectively.

A comparative study of the performance of the mixed flow and radial flow variable geometry turbines for an automotive turbocharger

2018 ◽  
Vol 233 (8) ◽  
pp. 2696-2712 ◽  
Author(s):  
K Ramesh ◽  
BVSSS Prasad ◽  
K Sridhara
Keyword(s):  
Mass Flow ◽  
Flow Parameter ◽  
Radial Flow ◽  
Velocity Ratio ◽  
Variable Geometry ◽  
Flow Variable ◽  
Mixed Flow ◽  
Turbine Efficiency ◽  
Variable Geometry Turbine ◽  
Specific Speed

A new design of a mixed flow variable geometry turbine is developed for the turbocharger used in diesel engines having the cylinder capacity from 1.0 to 1.5 L. An equivalent size radial flow variable geometry turbine is considered as the reference for the purpose of bench-marking. For both the radial and mixed flow turbines, turbocharger components are manufactured and a test rig is developed with them to carry out performance analysis. Steady-state turbine experiments are conducted with various openings of the nozzle vanes, turbine speeds, and expansion ratios. Typical performance parameters like turbine mass flow parameter, combined turbine efficiency, velocity ratio, and specific speed are compared for both mixed flow variable geometry turbine and radial flow variable geometry turbine. The typical value of combined turbine efficiency (defined as the product of isentropic efficiency and the mechanical efficiency) of the mixed flow variable geometry turbine is found to be about 25% higher than the radial flow variable geometry turbine at the same mass flow parameter of 1425 kg/s √K/bar m2 at an expansion ratio of 1.5. The velocity ratios at which the maximum combined turbine efficiency occurs are 0.78 and 0.825 for the mixed flow variable geometry turbine and radial flow variable geometry turbine, respectively. The values of turbine specific speed for the mixed flow variable geometry turbine and radial flow variable geometry turbine respectively are 0.88 and 0.73.

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