PSI - Issue 50

14

Popova, Popov, Samoylenko/ Structural Integrity Procedia 00 (2022) 000 – 000

Diana D. Popova et al. / Procedia Structural Integrity 50 (2023) 236–250 Fig. 15. The Mach number contour in relative motion at the working crown outlet.

249

Table 4 presents the working crown parameters of the two cases: the turbine rotor total torque, the working fluid total flow rate at the turbine stage inlet, the integral value of kinetic energy losses in the working rim and the integral value of the turbine stage efficiency determined by according to equation (5):

 G M n 0

,





(5)

st

k

  

  

 wc wc 1 k

k

*

* st

1

R

T









wc

a

0

1

k



wc

* 2 * 0

p p

is the stage expansion degree; M is torque; n is rotation frequency; 0 G is the flow rate at the

* st  

Where

a R is the gas constant of air; wc k is the adiabatic index in the stage; *

0 T is the total temperature at the

stage inlet; stage inlet.

Table 4. Turbine stage parameters Parameter Total pressure drop across the stage

1: ideal parallel clearance

2: real non-parallel gap

Difference, %

* st 

2.51

0

Loss of kinetic energy

9.84

9.33

-5.14 0.40

ξ, %

η st , %

Stage efficiency

91.32

91.69

10. Conclusion The tip clearance real shape is due to thermal and mechanical deformations of the rotor, stator and blades. For the stator, the deformation of the front part in the axial direction is greater as a result of the impact on the case of the continuous cover of the flame tube. For the disk and blade, the deformation of the rear part is greater, since the intermediate disk, which is more heated due to leakage behind the working blade, affects the disk, and the trailing edge of the blade is thinner and hotter. As a result, the shape of the tip clearance is obtained, which is in the axial direction from the input to the output edge - a diffuser channel, in the circumferential direction from the PS to the SS - also a diffuser channel. In the axial direction, the gap along the leading edge is greater than that along the trailing edge by almost 2.5 times. In the circumferential direction, the maximum excess of the movements of the SS over the movements of the PS is approximately 10%. According to the three-dimensional gas-dynamic analysis results, it was found that in the real tip clearance case, an increase in the total torque on the turbine rotor by 0.28%, a decrease in the flow rate of the working fluid through the turbine stage by 0.11%, and a total decrease in kinetic energy losses in the working crown by more than by 5% and an increase in turbine stage efficiency by 0.40%. Improving the parameters of the turbine stage is due to a decrease in the flow in the area of the tip clearance from the blade PS to the SS by more than 20%, thereby reducing the intensity and size of the vortex structures at the periphery of the interblade channel. References

Bondarchuk P.V., Tisarev A.U. & Lavruchin M.V. (2012) Development of a calculation method for control system of radial clearance in the turbine of gas turbine engine. Bulletin of Samara University. Aerospace and Mechanical Engineering, 3, 272-278.