Development and Integration of Rain Ingestion Effects in Engine Performance Simulations

Abstract

Rain ingestion can significantly affect the performance and operability of gas turbine aero-engines. In order to study and understand rain ingestion phenomena at engine level, a performance model is required that integrates component models capable of simulating the physics of rain ingestion. The current work provides, for the first time in the open literature, information about the setup of a mixed-fidelity engine model suitable for rain ingestion simulation and corresponding overall engine performance results. Such a model can initially support an analysis of rain ingestion during the predesign phase of engine development. Once components and engine models are validated and calibrated versus experimental data, they can then be used to support certification tests, the extrapolation of ground test results to altitude conditions, the evaluation of control or engine hardware improvements and eventually the investigation of in-flight events. In the present paper, component models of various levels of fidelity are first described. These models account for the scoop effect at engine inlet, the fan effect and the effects of water presence in the operation and performance of the compressors and the combustor. Phenomena such as velocity slip between the liquid and gaseous phases, droplet breakup, droplet–surface interaction, droplet and film evaporation as well as compressor stages rematching due to evaporation are included in the calculations. Water ingestion influences the operation of the components and their matching, so in order to simulate rain ingestion at engine level, a suitable multifidelity engine model has been developed in the Proosis simulation platform. The engine model's architecture is discussed, and a generic high bypass turbofan is selected as a demonstration test case engine. The analysis of rain ingestion effects on engine performance and operability is performed for the worst case scenario, with respect to the water quantity entering the engine. The results indicate that rain ingestion has a strong negative effect on high-pressure compressor surge margin, fuel consumption, and combustor efficiency, while more than half of the water entering the core is expected to remain unevaporated and reach the combustor in the form of film.

Numerical study on wet compression in a supercritical air centrifugal compressor

“…The factors of work reduction (derived from evaporative cooling) and work increment (derived from droplet motion) of droplets together determine whether the work is reduced or the magnitude of work reduction. For traditional water ingestion studies such as wet gas compression 4 and rain ingestion, 5 the droplet sizes (typical range 50–1500 µm) are so large that the additional droplet losses may exceed the effect of evaporative cooling. But for wet compression, its tiny droplet sizes (5 µm for this study) are much smaller than above, which significantly enhances the influence of evaporative cooling.…”

“…Currently, a technology called wet compression has been widely applied in gas turbines to reduce compression work and improve thermal efficiency. Unlike traditional water ingestion studies (typical droplet sizes range 50–1500 µm), 4–6 wet compression requires very fine droplets (≤15–20 µm) 7 with a large surface area to volume ratio, which makes evaporation faster. By injecting tiny water droplets into the compressor, the terminal temperature decreases by the evaporative cooling during the compression process, thereby reducing the compression work.…”

Turbofan Engine Health Assessment From Flight Data

“…proosis is a tool capable of modeling any gas turbine engine configuration using the default and/or any user-defined library of gas turbine engine components. The tool also has the capability to perform mul tisystem, mixed-fidelity, multidisciplinary, and distributed simulations [18][19][20], Last but not least, different types of customer decks can be automatically generated for a variety of platforms while a standard interface is available for some applications (e.g. and editing their attributes [17], The associated mathematical model (partition) can then be defined through the specification of appropriate boundary and iteration (algebraic) variables.…”

Effects of water ingestion on the tip clearance flow in compressor rotors

“…3 In addition, the existence of liquid water in the engine will pose some threats to the operational stability of compressor, combustion chamber, and turbine, which leads to local temperature reduction, pressure losses, mechanical losses, surge, and even flame-out. 4–7…”

“…3 In addition, the existence of liquid water in the engine will pose some threats to the operational stability of compressor, combustion chamber, and turbine, which leads to local temperature reduction, pressure losses, mechanical losses, surge, and even flame-out. [4][5][6][7] It is obvious that the ingestion of water droplets will move together with the main airflow to the compression component. 8 Following the movement of water droplets in compressor, the heat and mass transfer processes between water and the surrounding air are constantly occurring, which changes the working environment of the compression system.…”