AbstractThe results of a special methodology design for technical performance of a gas turbine with variable nozzles are presented in the paper. The data are provide for the industrial implementation experience and special heat engineering tests on appropriate machines. The methodology was designed with the use of approximated manufacturer characteristics where dependencies from initial conditions and GT load were adopted

Blinov, V. L.

Komarov, O. V.

Sedunin, V. A.

Komarov, O.V.

Blinov, V.L.

Sedunin, V.A.

Elsevier - Publisher Connector 

 Procedia Engineering  150 ( 2016 )  1378 – 1383 
1877-7058 © 2016 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license 
(http://creativecommons.org/licenses/by-nc-nd/4.0/).
Peer-review under responsibility of the organizing committee of ICIE 2016
doi: 10.1016/j.proeng.2016.07.332 
ScienceDirect
Available online at www.sciencedirect.com
International Conference on Industrial Engineering, ICIE 2016 
On Technical Performance Estimation of a Gas Turbine with 
Variable Power Turbine Vanes 
O.V. Komarov, V.L. Blinov, V.A. Sedunin* 
Ural Federal University, 19 Mira sreet, Yekaterinburg, 620002, Russia 
Abstract 
The results of a special methodology design for technical performance of a gas turbine with variable nozzles are presented in the 
paper. The data are provide for the industrial implementation experience and special heat engineering tests on appropriate 
machines. The methodology was designed with the use of approximated manufacturer characteristics where dependencies from 
initial conditions and GT load were adopted.  
© 2016 The Authors. Published by Elsevier Ltd. 
Peer-review under responsibility ofthe organizing committee of ICIE 2016. 
Keywords:Gas Turbines; Technical performance estimation; Opeartion of Gas Turbines; Variable geometry in turbomachinery 
1. Introduction 
Technical performance estimation is one of the most important task during Gas Compressor machine with Gas 
Turbine drive. Based on so called coefficients of technical performance (CTP) by power and efficiency key 
solutions to be made regarding operational mode of the machine and the whole plant. It also can be used for pipeline 
loading, maintenance forecast and appropriate financial planning [1-3].  
There are more than 90 machines in Gas Transportation company fleet, that were made with variable nozzles of 
Power Turbine. These machines are GTK-25I (MS5002B) and GTK-10I (MS3002B). For such machines technical 
performance estimation brings some difficulties, since the classical method that implies comparison to nominal 
mode has one more uncertainty: variable nozzle position. Due to that fact currently CTP online estimation for these 
machines has some uncertainties and the operation personnel has no instruments to solve it. Currently there are 
 
 
* Corresponding author. Tel.: +7-343-375-48-51; fax: +7-343-375-48-51. 
E-mail address: lerr@bk.ru 
 2016 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license 
(http://creativecommon .org/licenses/by-nc-nd/4.0/).
Peer-review under responsibility of the organizing committee of ICIE 2016
1379 O.V. Komarov et al. /  Procedia Engineering  150 ( 2016 )  1378 – 1383 
methods for CTP estimation of such machines but it needs proper additional instrumentation and significant labor 
consumption, so it can be done only during special test, but not online [4, 5].  
Meanwhile the problem becomes more important since the age of these machines is close to its limit and failure 
risk grows rapidly. 
 
Nomenclature 
N power 
k coefficient 
T temperature 
P pressure 
n rotation speed;total number of measured points 
Ș efficiency 
ȟ losses 
 
Subscripts 
2 parameters at power turbine 
a ambient condition 
in inlet 
out outlet 
nom nominal value 
e effective 
T turbine 
C compressor 
 
Superscript 
cha characteristic 
i value at ideal engine condition 
r value at real engine condition 
 
Abbreviations 
CTP Coefficient of technical performance 
GT Gas Turbine 
GTK Gas Turbo Compressor (Russian acronym) 
PT Power Turbine 
2. Method description 
The method is based on comparison of real engine power that is produced at real engine on site and one that 
should be provided by brand new engine but at the same atmospheric conditions. So the real power value includes 
losses due to weariness, higher tip clearances, dust on blades and so on. The proportion of this two values is called 
the coefficient of technical performance by power. Similar CTP can be calculated by efficiency comparison [4]. 
First of all one remark should be added. The method is very much rely on engine characteristics provided by 
producer for brand new engine. There are several reasons why this data should be properly processed and presented 
values may not be reached on real Gas Compressor Plant. First, the inlet and outlet conditions of GTU are not in the 
scope of turbine producer, so the engine characteristic can be provided for ISO conditions and should be adopted for 
different filtration and exhaust systems pressure losses. Second, the engine can be modified during its operation in 
order to have better emissions, higher efficiency or reliability.  
Therefore the most important result of producer characteristic approximation is the behavior of the engine at part 
loads and varying atmospheric conditions, since that behavior can be realized in many ways and could not be 
1380   O.V. Komarov et al. /  Procedia Engineering  150 ( 2016 )  1378 – 1383 
guessed by any physical means. Once the position of variable nozzles, maximum available power and efficiency 
areknown, the CTP calculation can be performed. But only comparative analysis can be made. For example, before 
axial compressor washing the CTP was 0,8 and after washing - 0,83. So the relative gain is 3,75%. But this does not 
mean that the engine performance could be improved by 25% more, since the real maximum performance due to site 
limitations remains unknown. 
Real power value is gained by natural gas compressor which is for this case the only power consumer for Power 
Turbine. The value of ideal power is gained according to approximated producer characteristics. In current paper the 
dependencies for power and efficiency were used for the following types of machines: PGT-10, M5352(B), 
M5322R(B), M5352R(C) and can be presented as: 
 2, ,chae PT Ɍ CN f n T T   (1) 
 , ,cha chae PT e Cf n N TK    (2) 
where Necha - effective power of GTU according to producer's characteristic; Șecha – effective GT efficiency from 
characteristic; nPT– Power Turbine rotation speed; ɌɌ2 – exhaust gas temperature; ɌC – compressor inlet air 
temperature. 
On Figure 1 the characteristic is presented for M5352R(C) machine. 
The effective GT power at its best condition can be described as following: 
2
2 3
2 3 2
2 2 22 2 2
,chae
Ɍ Ɍ ɌɌ Ɍ Ɍ
c e f n h i n j nN a b n d n g n
T T TT T T
                (3) 
where n – Power Turbine shaft speed rpm; ɌɌ2 – exhaust gases temperature, Ʉ; a, b, c, d, e, f, g, h, i, j – variable 
coefficients, defined for every GT type and axial compressor inlet temperature. These coefficients can be defined as: 
1 2
1 2
1 2
1 2
,
,
,
...
,
C a a
C b b
C c c
C j j
a T k k
b T k k
c T k k
j T k k
  
  
  
  
  (4) 
where ɌC – axial compressor inlet temperature, Ʉ; ki – constant coefficients for GT type and prescribed axial 
compressor inlet temperature range. 
Effective power at ideal condition above is calculated regardless inlet duct and exhaust system pressure losses, so 
the inlet pressure is considered as 1,0132 bar. Therefore additional correction is added as following: 
,Pi cha in out ae e cha cha chaN N Ne e e
N N k k k[ [      (5) 
where Necha – power value, gained from producers characteristics; kȟin, kȟout, kPa – correction coefficients for inlet and 
exhaust losses and also for atmospheric pressure deviation.  
The correction coefficients for effective power for the following types M5352(B), M5322R(B)  ɢ M5352R(ɋ) 
are: 
1 0.000167in inchaNe
k[ [   ,   1 0,000069out outchaNe
k[ [   . (6) 
1381 O.V. Komarov et al. /  Procedia Engineering  150 ( 2016 )  1378 – 1383 
 
Fig.1.Machine operation characteristic for M5352R(C) type at ambient condition15 0ɋ. 
The same for PGT-10: 
1,000132 0,000171incha inNe
k[ [   ,  1,000075 0,00007out outchaNe
k[ [   , (7) 
wherevȟin, ȟout –  pressure losses in the inlet and outlet ducts correspondingly in mm of water. 
The correction coefficients for atmospheric pressure:  
760
P aa
chaNe
P
k  ,  (8) 
where Ɋɚ – real atmospheric pressure in mm Hg. 
The efficiency for engine at best condition according to approximated characteristics can be defined as: 
2 2
3 3 2 2
ln( ) ln( ) (ln( )) (ln( )) ln( ) ln( )
(ln( )) (ln( )) ln( ) (ln( )) (ln( )) ln( ),
cha cha cha cha
e e e e
cha cha cha
e e e
a b n c N d n e N f n N
g n h N i n N j n N
K             
         
 (9) 
where n – Power Turbine speed, rpm; Necha – effective power at best condition according to producers 
characteristics, kW; a, b, c, d, e, f, g, h, i, j – variable coefficients, defined for every GT type and axial compressor 
inlet temperature.  
1382   O.V. Komarov et al. /  Procedia Engineering  150 ( 2016 )  1378 – 1383 
For given current operational parameters the efficiency at best condition can be defined. So the coefficient of 
technical performance by efficiency can be defined as:  
r
e
TP i
e
N
k
N
 .  (10) 
In order to have reliable data regarding technical performance the series of calculation is needed at the wide 
range of power and atmospheric conditions. Then the averaged CTP can be calculated: 
' 1
n
TPi
i
TP
k
Ʉ
n
  
¦
,  (11) 
where i – the sequence number of measured point1 ;i nd d n – total number of measured points; kTPi – CTP for i-
mode. 
3. Experimental process and model verification 
Since the real tests were made on site the real operation conditions of the Compressor plant were respected as 
well as some limitations regarding wide instrumentation requirements [6-7]. The data was registered and recorded to 
the hard disk and then analyzed. Degradation curves were built up and controlled for each Turbine Unit on every 
Pumping station. The character and qualitative behavior of data collected lays in good agreement with [8]. Also very 
important notes and references regarding this problem are presented in [9]. 
It is very important to have stable mode to be recorded. If the parameters are still changing they should not be 
processed otherwise this will bring significant error later on. The parameters are considered to be stable if the 
deviation of parameters including variable nozzles position is less than 1% in one hour. Also the deviation of inlet 
and outlet temperatures of natural gas centrifugal compressor should be less than 0,1 degree in 10 minutes. 
The measurements were made for the control algorithm that does not include control of inlet variable guide vanes 
of axial compressor, so it remains at the same position. The method verification was made based on operational 
parameters registered for several Gas Turbines of GTK-25I type, that are working at different compressor plants at 
Gas Transportation company. As an example at figures 2 and 3 comparative characteristics are presented for real 
power value and one for GT best conditions at different operational modes. 
 
 
Fig.2.Real measured power (blue line) and power at ideal engine condition (red line) at different operational modes for GTK-25I, on Station 1: as 
function of exhaust gases temperature (a); as function of Power Turbine rotation speed (b). 
1383 O.V. Komarov et al. /  Procedia Engineering  150 ( 2016 )  1378 – 1383 
4. Conclusion 
According to special tests of real engine operation on site for GTK-25IR the methodology presented showed its 
ability for coefficient of technical performance estimation for Gas Turbines with variable nozzles of Power Turbine. 
Key factor of this estimation is the nozzle behavior as a function of atmospheric conditions and load. In the current 
work the engine producer characteristics gave reasonably good precision. 
The methodology is realized in in-house code distributed for on-site operational needs, that can be used for 
reduction of failure risks and maintenance forecast and preparations.  
Presented method can be applied for similar types of Gas Turbines with variable nozzles. In any case proper 
verification is needed by means of manufacturer documentation and proper instrumented test on site. 
 
 
Fig. 3.Real measured power (blue line) and power at ideal engine condition (red line) at different operational modes for GTK-25I, on Station 2: 
as function of exhaust gases temperature (a); as function of Power Turbine rotation speed (b). 
References 
[1] G.G. Olkhovsky, Termal test of Gas Turbine Engines, Energiya, Moscow, 1971. (in Russ.). 
[2] Z.T. Galiullin, S.Yu. Salnikov, V.A. Shurovskiy, Modern Gas Transport Technologies and systems, Gazprom VNIIGAZ, Moscow, 2014. (in 
Russ.). 
[3] O.V. Komarov, V.A. Sedunin, V.L. Blinov, A.V. Skorokhodov, Parametrical diagnostics of gas turbine performance on side at gas pumping 
plants based on standard measurements, in: Proceedings of the ASME Turbo Expo: Turbine Technical Conference and Exposition, GT 2014, 
Dusseldorf, Germany. 3B (2014) 1–8. 
[4] O.V. Komarov, V.L. Blinov, A.V. Skorokhodov, V.A. Sedunin, E.P. Sozonov, Design of the methodology of technical performance 
estimation of the gas turbine with variable flowpath geometry, in: Proceeding of LXII Science-technical session on the problem of Gas 
Turbines and CCPP, Moscow. (2014) 87–93. (in Russ.). 
[5] A.G. Vanchin, Evaluation methods of the technical conditions and forecasting of indicators of the gas-compressor plant GTK-25IR operation, 
Online scientific journal Neftegazovoe delo. 6 (2012) 184–197. (in Russ.). 
[6] GOSTR 52782-2007, Gas turbine units, Test methods, Acceptance tests, 2007. (in Russ.). 
[7] V.A. Shurovskiy, Yu.N. Sinicyn, V.I. Korneev, A.V. Cheremin, G.S. Stepanov, Methodological reccomendations on thermal and 
aerodynamic numerical processing of technical tests of the gas turbine gas compressor units, PR51-31323949-43-99, GAZPROM, VNIIGAZ, 
1999. (in Russ.). 
[8] F. Bainier, R. Belgodère, V. Routhieau, T. Pillay, R. Kurz, Management of gas turbine performance in GTRGAZ network in France, GT2012-
68333, in: Proceedings of ASME Turbo Expo 2012. (2012). 
[9] M. Venturini, D. Therkorn, Application of a Statistical Methodology for Gas Turbine Degradation Prognostics to Alstom Field Data, Journal 
of Engineering for Gas Turbines and Power. 135 (2013). 


On Technical Performance Estimation of a Gas Turbine with Variable Power Turbine Vanes 

O.V. Komarov

V.L. Blinov

V.A. Sedunin

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Procedia Engineering

On Technical Performance Estimation of a Gas Turbine with Variable Power Turbine Vanes

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On Technical Performance Estimation of a Gas Turbine with Variable Power Turbine Vanes

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