A Fully Coupled Approach for the Integration of 3D-CFD Component Simulation in Overall Engine Performance Analysis

Abstract

Due to a high degree of complexity and computational effort, overall system simulations of jet engines are typically performed as 0-dimensional thermodynamic performance analysis. Within these simulations and especially in the early cycle design phase, the usage of generic component characteristics is common practice. Of course these characteristics often cannot account for true engine component geometries and operating characteristics which may cause serious deviations between simulated and actual component and overall system performance. This leads to the approach of multi-fidelity simulation, often referred to as zooming, where single components of the thermodynamic cycle model are replaced by higher-order procedures. Hereby the consideration of actual component geometries and performance in an overall system context is enabled and global optimization goals may be considered in the engine design process. The purpose of this study is to present a fully automated approach for the integration of a 3D-CFD component simulation into a thermodynamic overall system simulation. As a use case, a 0D-performance model of the IAE-V2527 engine is combined with a CFD model of the appropriate fan component. The methodology is based on the DLR in-house performance synthesis and preliminary design environment GTlab combined with the DLR in-house CFD solver TRACE. Both, the performance calculation as well as the CFD simulation are part of a fully automated process chain within the GTlab environment. The exchange of boundary conditions between the different fidelity levels is accomplished by operating both simulation procedures on a central data model which is one of the essential parts of GTlab. Furthermore iteration management, progress monitoring as well as error handling are part of the GTlab process control environment. Based on the CFD results comprising fan efficiency, pressure ratio and mass flow, a map scaling methodology as it is commonly used for engine condition monitoring purposes is applied within the performance simulation. Hereby the operating behavior of the CFD fan model can be easily transferred into the overall system simulation which consequently leads to a divergent operating characteristic of the fan module. For this reason, all other engine components will see a shift in their operating conditions even in case of otherwise constant boundary conditions. The described simulation procedure is carried out for characteristic operating conditions of the engine.

Collaborative Aircraft Engine Preliminary Design using a Virtual Engine Platform, Part A: Architecture and Methodology

“…Although the general functionality to execute CFD processes within GTlab has already been demonstrated [22,23], the extension of the interfaces to the detailed engine design including aero-structure coupled simulations is one of the next objectives and will be addressed in the DLR internal projects SimBaCon (Simulation Based Certification) and VirTriP targeting the digitalization of the aircraft engine and stationary gas-turbine sector.…”

“…The advantages of the application of a central data model as infrastructure for the exchange of data during multi-fidelity simulation were demonstrated in Refs. [21][22][23].…”

A Matching Problem between the Front Fan and Aft Fan Stages in Adaptive Cycle Engines with Convertible Fan Systems

“…At present, the three-dimensional model [28][29][30] and zero-dimensional model [26,31,32] of an engine are commonly used in the numeric simulation processes. The steady-state performance numeric simulation with three-dimensional model is a method to simulate the engine by establishing a fine engine flow channel model according to the specific structure and size of the engine [28][29][30]33,34] and using computational fluid dynamics (CFD) technologies to carry out thermodynamical calculation of the whole engine [35][36][37]. This method has high complexity, requires a huge amount of calculation, and it depends on the specific structure of the engine, and the accuracy of both the model and the CFD algorithms will have a direct impact on the calculation results [35][36][37].…”

“…The steady-state performance numeric simulation with three-dimensional model is a method to simulate the engine by establishing a fine engine flow channel model according to the specific structure and size of the engine [28][29][30]33,34] and using computational fluid dynamics (CFD) technologies to carry out thermodynamical calculation of the whole engine [35][36][37]. This method has high complexity, requires a huge amount of calculation, and it depends on the specific structure of the engine, and the accuracy of both the model and the CFD algorithms will have a direct impact on the calculation results [35][36][37]. Moreover, in the demonstration stage of an engine concept, it is difficult to use this model to calculate the steady-state performance because there is neither specific structure nor accurate size data of the engine.…”

A Fully Coupled Body Force-Engine Performance Methodology For Boundary Layer Ingestion

“…In the literature, a method that couples aerodynamic and engine performance analysis is the so-called zooming approach, mainly aimed at improving the accuracy of individual component representation in overall performance models. This improvement is achieved through CFD calculations of a turbomachinery component, which can range from one-dimensional mean line calculations [17][18][19][20], to 3D CFD simulations [21][22][23], or some intermediate levels such as 2D streamline curvature models [24]. In these contributions, CFD data is used to re-scale component maps in the performance model, hence enhancing the predictions of the latter over a specific engine operation range.…”