Steady State and Transient Modeling of a Micro-Turbine With Comparison to Operating Engine

Volume 6: Turbo Expo 2004 ◽

10.1115/gt2004-53378 ◽

2004 ◽

Cited By ~ 3

Author(s):

Craig R. Davison ◽

A. M. Birk

Keyword(s):

Steady State ◽

Full Range ◽

Transient Behavior ◽

Operating Point ◽

Engine Operation ◽

Operating Data ◽

Steady State Model ◽

Acceleration And Deceleration ◽

Micro Turbine ◽

Component Faults

Steady state and transient computer models of a micro turbine were produced. The engine under study was a micro-jet engine that when tested at 126,000 RPM provided 95 N thrust. The aero-thermal model uses generic performance maps for the compressor and turbine which were modified, based on operating data, to represent the components in the engine under study. The model also includes the inlet ducting connected to the engine. It simulates engine operation from idle to full power over the expected operating range of ambient temperature, pressure and humidity. A comparison of steady state model results to actual engine operating data is presented over the full range of speeds. The effect of ambient humidity on the engine operating point is examined for a micro-engine, in particular at temperatures above 30° Celsius. The techniques for introducing component faults are given and their effect on the engine operation is presented. The degraded components are the turbine and inlet flow passages. The methods for modeling the transient behavior of the engine are also presented. Results are presented for both acceleration and deceleration of the engine between steady state operating point. These results are also compared to the operating engine.

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Model-Based Dynamic In-Cylinder Air Charge, Residual Gas and Temperature Estimation for a GDI Spark Ignition Engine Using Cylinder, Intake and Exhaust Pressures

Volume 2: Intelligent Transportation/Vehicles; Manufacturing; Mechatronics; Engine/After-Treatment Systems; Soft Actuators/Manipulators; Modeling/Validation; Motion/Vibration Control Applications; Multi-Agent/Networked Systems; Path Planning/Motion Control; Renewable/Smart Energy Systems; Security/Privacy of Cyber-Physical Systems; Sensors/Actuators; Tracking Control Systems; Unmanned Ground/Aerial Vehicles; Vehicle Dynamics, Estimation, Control; Vibration/Control Systems; Vibrations ◽

10.1115/dscc2020-3280 ◽

2020 ◽

Author(s):

Amir Khameneian ◽

Xin Wang ◽

Paul Dice ◽

Mahdi Shahbakhti ◽

Jefferey D. Naber ◽

...

Keyword(s):

Steady State ◽

Gas Flow ◽

Transient Behavior ◽

Spark Ignition ◽

Ideal Gas ◽

Spark Ignition Engine ◽

Exhaust Gas ◽

Engine Operation ◽

Trapped Air ◽

Residual Gas

Abstract The in-cylinder trapped air, residual gas, and temperature directly impact Spark Ignition (SI) engine operation and control. However, estimation of these variables dynamically is difficult. This study proposes a dynamic cycle-by-cycle model for estimation of the in-cylinder mixture temperature at different events such as Intake Valve Closed (IVC), as well as mass of trapped air and residual gas. In-cylinder, intake and exhaust pressure traces are the primary inputs to the model. The mass of trapped residual gas is affected by valve overlap increase due to the exhaust gas backflow. Of importance to engines with Variable Valve Timing (VVT), the compressible ideal-gas flow correlations were applied to predict the exhaust gas backflow into the cylinder. Furthermore, 1D GT-Power Three Pressure Analysis (TPA) was used to calibrate and validate the designed model under steady-state conditions. To minimize the calibration efforts, Design of Experiments (DOE) analysis methodology was used. The transient behavior of the model was validated using dynamometer dynamic driving cycle. The cycle-based output parameters of the developed model are in good agreement with transient experimental data with minimal delay and overshoot. The predicted parameters follow the input dynamics propagated in the in-cylinder, intake and exhaust pressure traces with a 1.5% average relative steady-state prediction error.

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Transient Dynamics of Gas Turbine Engines

Volume 3C: General ◽

10.1115/93-gt-353 ◽

1993 ◽

Cited By ~ 3

Author(s):

A. R. Ganji ◽

M. Khadem ◽

S. M. H. Khandani

Keyword(s):

Steady State ◽

Differential Equations ◽

Gas Turbine ◽

Initial Conditions ◽

Transient Behavior ◽

Operating Point ◽

Turbine Engines ◽

Gas Turbine Engines ◽

Linear Ordinary Differential Equations ◽

General Methodology

Transient response of gas turbine engines depends on several parameters including engine type, components’ characteristics, and operational condition. This paper briefly describes the general methodology and approach for transient sensitivity analysis of various gas turbine engines, and the results of a computer program for analysis of the transient behavior of a single spool turbojet. Based on the method of intercomponent volumes, the general methodology applicable to transient analysis of any gas turbine based system has been developed. The method results in a set of stiff, time dependent non-linear ordinary differential equations (ODE) which can be solved by an appropriate ODE solver. The coefficients of the differential equations depend on the design and operational condition of the components represented by the component maps. The initial conditions of the ODE can be any steady state operating point of the engine. A steady state engine model provides these initial conditions. The program has the capability to match the components, and obtain a steady state operating point for the engine, accept a fuel protocol and predict the transient behavior of the engine. The program has produced satisfactory results for step, ramp and sinusoidal fuel inputs, as well as ramp variation in nozzle exit area.

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