Investigation of the Combined Effect of Variable Inlet Guide Vane Drift, Fouling, and Inlet Air Cooling on Gas Turbine Performance

Abstract

Variable geometry gas turbines are susceptible to various malfunctions and performance deterioration phenomena, such as variable inlet guide vane (VIGV) drift, compressor fouling, and high inlet air temperatures. The present study investigates the combined effect of these performance deterioration phenomena on the health and overall performance of a three-shaft gas turbine engine (GE LM1600). For this purpose, a steady-state simulation model of the turbine was developed using a commercial software named GasTurb 12. In addition, the effect of an inlet air cooling (IAC) technique on the gas turbine performance was examined. The design point results were validated using literature results and data from the manufacturer's catalog. The gas turbine exhibited significant deterioration in power output and thermal efficiency by 21.09% and 7.92%, respectively, due to the augmented high inlet air temperature and fouling. However, the integration of the inlet air cooling technique helped in improving the power output, thermal efficiency, and surge margin by 29.67%, 7.38%, 32.84%, respectively. Additionally, the specific fuel consumption (SFC) was reduced by 6.88%. The VIGV down-drift schedule has also resulted in improved power output, thermal efficiency, and the surge margin by 14.53%, 5.55%, and 32.08%, respectively, while the SFC decreased by 5.23%. The current model can assist in troubleshooting the root cause of performance degradation and surging in an engine faced with VIGV drift and fouling simultaneously. Moreover, the combined study also indicated the optimum schedule during VIGV drift and fouling for performance improvement via the IAC technique.Entropy 2019, 21, 1186 2 of 26 mechanism ensure stability and improve performance by alleviating surge in the axial compressor. In addition, the new generation of gas turbines face highly significant performance decline (deterioration) due to nonlinear and complex dynamics. Deterioration may also be triggered by some other factors such as malfunctions induced in the variable geometry mechanism, fouling in the axial compressor, and increased ambient temperature [5].The VIGVs are controlled by an actuating mechanism via different linkages connected to guide vanes [6]. The VIVGs may encounter some malfunctions such as drifting of VIGVs away from the normal operational envelope. These malfunctions and faults lead to surging and choking in the compressor stages and eventually cause an accidental shutdown. Ishak and Ahmad [7] categorized the common phenomena responsible for VIGV drift as (i) high-speed stop, (ii) low-speed stop, (iii) hydraulic ram leakage, and (iv) Rotary variable displacement transducer (RVDT) misalignment. Similarly, Tsalavoutas et al. [8] stated that VIGVs are drifted outside from their normal schedule due to some other reasons: Wearing of actuation mechanism linkages and mispositioning/stacking of vanes due to loosed bolts. In order to avoid the occurrence of these faults, there is a need to continuously monitor and ensure that the movement and position of ...

Development of a method to improve the calculation accuracy of specific fuel consumption for performance modeling of air-breathing engines

“…The influence of pressure (reaching 3 MPa) and thermal dissociation (outlet temperature of the combustion chamber T>1,600 K) also was not taken into account. In [10], a study of the influence of the variable inlet guide vane and air cooling at the compressor inlet on the GTE performance is carried out. The specific isobaric heat capacity of the air components and combustion products is represented by the second-degree temperature polynomials.…”

“…The specific isobaric heat capacity of the air components and combustion products is represented by the second-degree temperature polynomials. The advantage of [10] is that air and combustion products are presented as a mixture of individual components. The disadvantage of this work is the modeling of the heat capacity of the components by the second-degree temperature polynomial.…”

Transient Behavior in Variable Geometry Industrial Gas Turbines: A Comprehensive Overview of Pertinent Modeling Techniques

“…The transient factors that are leading to instability of the engine can be rectified by incorporating variable geometry features in the gas turbines, i.e., variable inlet guide vanes (VIGVs), variable stator vanes (VSV), variable bleed valve (VBV), and variable area nozzle (VAN). In this case, the instability of compressor in form of surging and choking can be reduced using the modulation of VIGVs [ 11 , 12 , 13 , 14 , 15 ]. A group of researchers have well reviewed the transient models revealing their scope in variety of applications such as system performance analysis, fault identification, effective controller design, condition monitoring, diagnostics and prognostics purposes [ 16 ].…”

Variable Guide Vane Scheduling Method Based on the Kinematic Model and Dual Schedule Curves

“…Thus, analysis of the link mechanisms should be performed to define the actuator requirements: such as stroke or load capacity, and the precise vane and actuator control logic should be also needed to obtain exact angles of vanes according to VGV schedule. However, most of studies focused on the effect of the misaligned vane angle on the compressor performance and the fault diagnosis of the compressor [10][11][12][13][14]. Compared to that, precise control and compensation methods for mechanical drifting or hysteresis of the VGVs link mechanisms have still been rarely studied.…”

“…The control algorithm based on dual schedule curves is presented to Link mechanisms are usually designed with redundancy degrees of freedoms (DOFs) in three-dimensional space to produce well, the rotational motion of lever arms from the linear motion of actuators. With this redundancy DOF, manufacturing tolerance, wearing of actuation link mechanism, and loosening of bolts cause drifting from the vane schedule and hysteresis between the actuator strokes and vane angles [10,12]. To compensate this hysteresis additional mechanical compensations are needed to the VGV link mechanisms such as pre-loading springs or flexible bushings.…”