Blade Roughness Effects on Compressor and Engine Performance—A CFD and Thermodynamic Study

Abstract

Degradation of compressors is a common concern for operators of gas turbine engines (GTEs). Surface roughness, due to erosion or fouling, is considered one of the major factors of the degradation phenomenon in compressors that can negatively affect the designed pressure rise, efficiency, and, therefore, the engine aero/thermodynamic performance. The understanding of the aerodynamic implications of varying the blade surface roughness plays a significant role in establishing the magnitude of performance degradation. The present work investigates the implications due to the degradation of the compressor caused by the operation in eroding environments on the gas turbine cycle performance linking, thereby, the compressor aerodynamics with a thermodynamic cycle. At the core of the present study is the numerical assessment of the effect of surface roughness on compressor performance employing the Computational Fluid Dynamics (CFD) tools. The research engine test case employed in the study comprised a fan, bypass, and two stages of the low pressure compressor (booster). Three operating conditions on the 100% speed-line, including the design point, were investigated. Five roughness cases, in addition to the smooth case, with equivalent sand-grain roughness (ks) of 15, 30, 45, 60, and 150 µm were simulated. Turbomatch the Cranfield in-house gas turbine performance simulation software, was employed to model the degraded engine performance. The study showed that the increase in the uniform roughness is associated with sizable drops in efficiency, booster pressure ratio (PR), non-dimensional mass flow (NDMF), and overall engine pressure ratio (EPR) together with rises in turbine entry temperature (TET) and specific fuel consumption (SFC). The performance degradation evaluation employed variables such as isentropic efficiency (ηis), low pressure compressor (LPC) PR, NDMF, TET, SFC, andEPR. The variation in these quantities showed, for the maximum blade surface degradation case, drops of 7.68%, 2.62% and 3.53%, rises of 1.14% and 0.69%, and a drop of 0.86%, respectively.

High-Temperature Solid Particle Erosion of Aerospace Components: Its Mitigation Using Advanced Nanostructured Coating Technologies

“…Since aerospace technology needs accuracy and high safety standards, before the experiment, several authors simulated the erosion and fouling conditions and their effects on gas turbine engine performance [44][45][46][47][48]. Alqallaf and Teixeira [44] reported degradation of the compressor performance due to eroding environments by linking the compressor aerodynamics with a thermodynamic cycle using Turbomatch, the Cranfield in-house gas turbine performance simulation software. They have uniformly increased blade surface roughness in the first two stages of a low-pressure compressor.…”

Quantifying the Economic Benefits of Using Erosion Protective Coatings in a Low-Pressure Compressor (Aero-Engine): A Case Study Evaluation

“…Such a process permits a substantial level of flexibility when investigating alternative operational arrangements for GTEs. A comprehensive explanation of the Turbomatch tool is presented in [5]. A schematic representation of the complete research engine model is shown in Figure 1.…”

“…The LPC comprises inlet guide vanes (IGV), second rotor (R2), second stator (S2), third rotor (R3) and third stator (S3), comprising a total of 458 blades. Comprehensive technical details of the research engine can be found in [5]. For the geometric details of the research engine showing the locations of the IGV and first two stages of the LPC, see Figure 2.…”

“…SPE-generated weakening of the blade surfaces reduces blade strength, which can adversely affect the structural integrity of the compressors. In addition, SPE has an impact on important variables of the cycle such as pressure ratio (PR), specific fuel consumption (SFC), non-dimensional mass flow (NDMF), turbine entry temperature (TET) and efficiency [5,6]. GTE performance is heavily dependent on LPC efficiency; thus, it is important to maintain the compressor at its best condition [5].…”

“…In addition, SPE has an impact on important variables of the cycle such as pressure ratio (PR), specific fuel consumption (SFC), non-dimensional mass flow (NDMF), turbine entry temperature (TET) and efficiency [5,6]. GTE performance is heavily dependent on LPC efficiency; thus, it is important to maintain the compressor at its best condition [5]. Consequently, much work has been undertaken to better understand the mechanisms by which SPE induces material loss [7][8][9][10], and to improve protective methods to enhance the lifetimes of components [11][12][13][14].…”