Test Rig for Turbine Vanes Aerodynamic Study
Aerospace propulsion engineering
Company «Aviadvigatel», 93, Komsomolsky avenue, Perm, GSP, 614990, Russia
This paper is focused on development of the test rig dedicated to aircraft engine turbine vanes study with various design measures to optimize turbine vane passage flow aerodynamics.
First test cycle was conducted for nozzle guide vanes (NGV) sector using advanced optimization technology for secondary turbulent flows near the walls with application of non-axisymmetric end walls. NGV sector was designed based on computational study conducted as part of the work .
The rig was designed to meet the below required performance and boundary conditions for tested NGV:
a) required flow quality at tested NGV inlet: uniform parameters profile, required boundary layer thickness and NGV gas stagnation angles;
b) required flow quality at tested NGV exit: no deviation of parameters across turbine passages, required radial distribution of parameters.
The rig was designed using, among other methods, up-to-date numeric flow modelling techniques. First test cycle steady-state modelling was conducted using ANSYS CFX 14.0 to estimate rig flow parameters.
This test rig is a wind tunnel consisting of the following key modules:
a) inlet duct: diffuser, settling chamber, straightening grid and three screens, contraction, NGV sector of 7 vanes (7-NGV sector);
b) test item: 7-NGV sector;
c) exhaust duct: test item exhaust duct, rig case, radial traverse, window.
Rig basic components are manufactured using rapid prototyping (RP) technology.
Required pressure ratio adjustments for the test item is reached using compressed air source (compressor) as well as control and bleed valves in working fluid supply and discharge lines.
Required boundary conditions for the test item are provided using dedicated design features as follows: flow straightening grid and screens, NGV, boundary layer bleed plates, optimized test item exhaust duct, exhaust duct ring step etc.
Various flow measuring and visualizing devices were integrated into the rig to study aerodynamics of vanes, secondary flows in vane passages and total pressure and momentum losses through the rows:
a) measurement of flow velocity and turbulence profiles using LDA (Laser Doppler Anemometry);
b) measurement of static pressure (up to 300 points) throughout the vane passages using AIR-20 pressure transmitters;
c) visualization of smoke particles movement paths in vane passages using high-speed video camera;
d) visualization of vane and end walls streamlines using oil film;
e) measurement of total and static pressure profiles and test item gas exit angles using automated system combining industrial robot, laser tracker and 5-hole probe.
The rig provides wide-range test capabilities focused on assessment of various methods of vane and vane passage 3D geometry optimization, such as:
a) non-axisymmetric vane passage end walls;
b) trailing adge local divergence (flow exit angle increase);
c) flow path mean line optimization;
d) vane lean angle change;
e) using bowed vane configuration;
f) arc-shape trailing edges etc.
Besides the above mentioned, there are also capabilities to study present-day aerodynamics issues, particularly: effects of roughness of the thermal barrier coating, Reynolds numbers, effects of vane nozzles cooling flow and geometry on NGV losses. Design and implementation of test rig dedicated to turbine vanes study featuring various design measures to optimize turbine vane passages flow aerodynamics is completed.
Keywords:test rig, design, test, aerodynamics, turbine vane, non-axisymmetric end walls, secondary flows
References1. Inozemtsev A.A., Samokhvalov N.Yu., Tikhonov A.S. Teploenergetika, 2012, no. 9, pp. 22-26.