Surge-Induced Structural Loads in Gas Turbines

1980 ◽  
Vol 102 (1) ◽  
pp. 162-168 ◽  
Author(s):  
R. S. Mazzawy
Keyword(s):  
Gas Turbines ◽  
Pressure Ratio ◽  
Axial Flow ◽  
Turbine Engine ◽  
Compression System ◽  
Engine Design ◽  
Steady State Levels ◽  
Flow Compression ◽  
Engine Components ◽  
Bypass Ratio

The axial flow compression system of a modern gas turbine engine normally delivers a large quantity of airflow at relatively high velocity. The sudden stoppage (and reversal) of this flow when an engine surges can result in structural loads in excess of steady state levels. These loads can be quite complex due to inherent asymmetry in the surge event. The increasing requirements for lighter weight engine structures, coupled with the higher pressure ratio cycles required for minimizing fuel consumption, make the accurate prediction of these loads an important part of the engine design process. This paper is aimed toward explaining the fluid mechanics of the surge phenomenon and its impact on engine structures. It offers relatively simple models for estimating surge-induced loads on various engine components. The basis for these models is an empirical correlation of surge-induced inlet overpressure based on engine pressure ratio and bypass ratio. An approximate estimate of the post-surge axial pressure distribution can be derived from this correlation by assuming that surge initiation occurs in the rear of the compression system.

Analysis of Indirectly Fired Gas Turbine Power Systems

2007 ◽  
Author(s):  
J. E. Donald Gauthier
Keyword(s):  
Power Generation ◽  
Power Systems ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Turbine Engines ◽  
Inlet Temperature ◽  
Turbine Engine ◽  
Engine Design ◽  
Wide Range ◽  
System Configurations

This paper describes the results of modelling the performance of several indirectly fired gas turbine (IFGT) power generation system configurations based on four gas turbine class sizes, namely 5 kW, 50 kW, 5 MW and 100 MW. These class sizes were selected to cover a wide range of installations in residential, commercial, industrial and large utility power generation installations. Because the IFGT configurations modelled consist of a gas turbine engine, one or two recuperators and a furnace; for comparison purpose this study also included simulations of simple cycle and recuperated gas turbine engines. Part-load, synchronous-speed simulations were carried out with generic compressor and turbine maps scaled for each engine design point conditions. The turbine inlet temperature (TIT) was varied from the design specification to a practical value for a metallic high-temperature heat exchanger in an IFGT system. As expected, the results showed that the reduced TIT can have dramatic impact on the power output and thermal efficiency when compared to that in conventional gas turbines. However, the simulations also indicated that several configurations can lead to higher performance, even with the reduced TIT. Although the focus of the study is on evaluation of thermodynamic performance, the implications of varying configurations on cost and durability are also discussed.

The Influence of Fan Root Flow on the Aerodynamics of a Low-Pressure Compressor Transition Duct

2019 ◽  
Author(s):  
A. D. Walker ◽  
I. Mariah ◽  
D. Tsakmakidou ◽  
H. Vadhvana ◽  
C. Hall
Keyword(s):  
Gas Turbines ◽  
Pressure Ratio ◽  
Axial Compressor ◽  
Pressure Profile ◽  
Low Pressure ◽  
Secondary Flows ◽  
Test Facility ◽  
Inlet Flow ◽  
Flat Profile ◽  
Bypass Ratio

Abstract To reduce fuel-burn and CO2 emissions from aero gas turbines there is a drive towards very-high bypass ratio and smaller ultra-high-pressure ratio core engine technologies. However, this makes the design of the ducts connecting various compressor spools more challenging as the higher required radius change increases their aerodynamic loading. This is exacerbated for the duct which feeds the engine core as it must accept the relatively low-quality flow produced by the fan root. This is characterised by a hub-low pressure profile and large secondary flow structures which will inevitably increase loss and the likelihood of flow separation. Additionally, the desire for shorter, lighter nacelles means that the engine intake may be unable provide a uniform inlet flow to the fan when the aircraft is at an angle of attack or subject to cross winds. Any inlet distortion this generates can also further degrade the quality of the flow entering the core of the engine. This paper uses a combination of experiments and CFD to examine the effects of the inlet flow on the aerodynamics of an engine section splitter and transition duct designed to feed the low-pressure spool of a high bypass ratio turbofan. A fully annular test facility incorporating a 1½ stage axial compressor was used to compare the system performance of a rotor that produced a nominally flat profile with one that had a notably hub deficient flow. A RANS CFD model, employing a mixing plane between the rotor and Engine Section Stator (ESS) and a Reynolds Stress turbulence model, was then validated and used to further investigate the effects of increased inlet boundary layer thickness and bulk swirl distortion at rotor inlet. Overall, changes to the inlet condition were seen to have a surprisingly small effect on the flow at duct exit — i.e. the flow presented to the downstream compressor. Changes to the inlet did, however, generate increased secondary flows and degrade the performance of the ESS. This resulted in notably increased total pressure loss; in excess of 12% for the hub-low inlet and in excess of 30% at high inlet swirl where the flow in the ESS separated. However, the increased ESS wake structures, and the enhanced mixing, delayed separation in the duct suggesting that, overall the design was reasonably robust, albeit with a significant penalty in system loss.

Undergraduate Gas Turbine Engine Design Using Spreadsheets and Commercial Software

2000 ◽  
Author(s):  
Kenneth W. Van Treuren ◽  
Brenda A. Haven
Keyword(s):  
Gas Turbine ◽  
Fuel Consumption ◽  
Pressure Ratio ◽  
Sensitivity Study ◽  
Commercial Software ◽  
Turbine Engine ◽  
Mission Analysis ◽  
Engine Design ◽  
Student Team ◽  
Engine Cycle

A unique, three-part undergraduate gas turbine engine design project was developed to acquaint students, working in teams of two or three, with the process of engine cycle selection. The design application is a low-flying, Close Air Support (CAS) aircraft using a separate exhaust turbofan engine. Both spreadsheets and commercial software are used. The commercial software is included with the course textbook, “Elements of Gas Turbine Propulsion” by Dr Jack D. Mattingly. Using commercial software, reinforced by classroom lectures, allows the students to focus on the design decisions. The first part of the project is Mission Analysis which introduces the student teams to the design problem. A spreadsheet template is given to each student team that includes aircraft and mission profile specifications. The students must complete the spreadsheet and develop the relationships for lift, drag, thrust required, and fuel burn to calculate a useable fuel remaining at the end to the mission. The spreadsheet allows the students to obtain an average specific fuel consumption that results in 1500 lbm of fuel remaining at the end of the mission. This target value is used in the second part of the design process, on-design Parametric Cycle Analysis (PCA), as a basis for engine cycle selection. Parametric Cycle Analysis is accomplished using the program PARA.EXE. PARA.EXE generates a carpet plot of possible engine design choices by varying the compressor pressure ratio, bypass ratio, and fan pressure ratio. From these carpet plots the students must identify three possible engine cycles that meet the target value for specific fuel consumption found during the mission analysis. Tradeoffs between thrust and fuel consumption are discussed and the students are required to justify their choices for the engine cycle. The last part of the project is the off-design Engine Performance Analysis (EPA) using the program PERF.EXE. The chosen engines must fly the mission and meet the required performance and mission constraint. Based on the overall mission performance, the students narrow the field of three possible engine cycles to one. Each student team then does a sensitivity study to determine if there is an additional benefit for slight changes in the design choices. The result of this sensitivity study is the students’ final engine cycle. With this cycle, an additive drag calculation is made using the program DADD.EXE to account for losses (off-design) and these losses are then factored back into the performance spreadsheet to check the engine’s capabilities for completing the mission. The iterative nature of the design process is emphasized throughout but only one pass through the process is accomplished. Units are given in English Engineering, as that is what is required for the project. Both SI and English Engineering units are taught in the course.

Technological Trend of Aircraft Gas Turbines and its Effect on the Development for Ship Propulsion Plants

1970 ◽  
Author(s):  
N. K. H. Scholz
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Pressure Ratio ◽  
Gas Turbine Engine ◽  
Design Parameters ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Compression Pressure ◽  
Turbine Engine ◽  
Ship Propulsion

The effect of the main design parameters of the aero gas turbine engine cycle, namely combustion temperature and compression pressure ratio, on the specific performance values is discussed. The resulting development trend has been of essential influence on the technology. Relevant approaches are outlined. The efforts relating to weight and manufacturing expense are also indicated. In the design of aero gas turbine engines increasing consideration is given to the specific flight mission requirements, such as for instance by the introduction of the by-pass principle. Therefore direct application of aero gas turbine engines for ship propulsion without considerable modifications, as has been practiced in the past, is not considered very promising for the future. Nevertheless, there are possibilities to take advantage of aero gas turbine engine developments for ship propulsion systems. Appropriate approaches are discussed. With the experience obtained from aero gas turbine engines that will enter service in the early seventies it should be possible to develop marine gas turbine engines achieving consumptions and lifes that are competitive with those of advanced diesel units.

Engine Component Life Prediction Methodology for Conceptual Design Investigations

1986 ◽  
Author(s):  
John D. Cyrus
Keyword(s):  
Life Prediction ◽  
Preliminary Design ◽  
Design Decisions ◽  
Turbine Engine ◽  
Detailed Consideration ◽  
Engine Design ◽  
Engine Component ◽  
Fundamental Understanding ◽  
Engine Components ◽  
The Impact

The increasing emphasis on engine durability requires that an analytical capability be acquired to assess engine component lives during the conceptual/preliminary design phases. A generalized methodology has been developed to provide a fundamental understanding of the impact of engine design decisions, material selections, and a detailed consideration of engine usage for critical gas turbine engine components.

Optimization of Gas Turbine Engine Elements by Probability Criteria

1993 ◽  
Author(s):  
I. N. Egorov ◽  
G. V. Kretinin
Keyword(s):  
Stochastic Optimization ◽  
Gas Turbine ◽  
Axial Flow ◽  
Gas Turbine Engine ◽  
Design Parameters ◽  
Technical Object ◽  
Turbine Engine ◽  
Flow Compressor ◽  
Engine Components ◽  
Stochastic Setting

Procedure for the stochastic optimization of design parameters of gas turbine engine components for a prescribed level of production technology is discussed. Such combined criteria of the stochastic optimization as effectiveness-probability of realizing a design of an intricate technical object are proposed. With reference to the task of optimum designing the rows of a multistage axial flow compressor, there are presented the results, obtained for various probability criteria, in parallel with conducting their comparative analysis, and there are also investigated optimum stable (robust) characteristics of designs obtained for various levels of technology. There are also demonstrated a possibility of a significant increase in probability to realize in actual practice the design, obtained in stochastic setting, as compared to the design, obtained in deterministic setting.

Status of the Automotive Ceramic Gas Turbine Development Progrem: Year Four Progress

1995 ◽  
Author(s):  
Tsubura Nishiyama ◽  
Masumi Iwai ◽  
Norio Nakazawa ◽  
Masafumi Sasaki ◽  
Haruo Katagiri ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Inlet Temperature ◽  
Rotor Speed ◽  
Turbine Inlet Temperature ◽  
Turbine Engine ◽  
Turbine Inlet ◽  
Basic Engine ◽  
Energy Center ◽  
Engine Components

The seven-year program, designated “Research & Development of Automotive Ceramic Gas Turbine Engine (CGT Program)”, was started in 1990 with the object of demonstrating the advantageous potentials of ceramic gas turbines for automotive use. This CGT Program is conducted by Petroleum Energy Center. The basic engine is a 100kW, single-shaft regenerative engine having turbine inlet temperature of 1350°C and rotor speed of 110000rpm. In the forth year of the program, the engine components were experimentally evaluated and improved in the various test rigs, and the first assembly test including rotating and stationary components, was performed this year under the condition of turbine inlet temperature of 1200°C.

Experimental Study on Pressure Losses in Porous Materials

2018 ◽  
Author(s):  
Giacomo Fantozzi ◽  
Mats Kinell ◽  
Sara Rabal Carrera ◽  
Jenny Nilsson ◽  
Yves Kuesters
Keyword(s):  
Discharge Coefficient ◽  
Pressure Ratio ◽  
Inlet Temperature ◽  
Turbine Engine ◽  
Geometrical Properties ◽  
Pressure Losses ◽  
Technological Advances ◽  
Pore Radius Distribution ◽  
Engine Components ◽  
Test Objects

Recent technological advances in the field of additive manufacturing have made possible to manufacture turbine engine components characterized by controlled permeability in desired areas. These have shown great potential in cooling application such as convective cooling and transpiration cooling and may in the future contribute to an increase of the turbine inlet temperature. This study investigates the effects of the pressure ratio, the thickness of the porous material and the hatch distance used during manufacturing on the discharge coefficient. Moreover, two different porous structures were tested and in total 70 test objects were investigated. Using a scanning electron microscope, it is shown that the porosity and pore radius distribution, which are a result from the used laser power, laser speed and hatch distance during manufacturing, will characterize the pressure losses in the porous sample. Furthermore, the discharge coefficient increases with increasing pressure ratio, while it decreases with increasing thickness to diameter ratio. The obtained experimental data was used to develop a correlation for the discharge coefficient as a function of the geometrical properties and the pressure ratio.

On-Design and Off-Design Performance Analysis of a Gas Turbine Combined Cycle Using the Exergy Method

2000 ◽  
Author(s):  
Alcides Codeceira Neto ◽  
Pericles Pilidis
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Exergy Analysis ◽  
Pressure Ratio ◽  
Calorific Value ◽  
Combined Cycle ◽  
Exergy Destruction ◽  
Turbine Engine ◽  
Design Point

The present paper describes an on-design and an off-design performance study of gas turbine combined cycle based power plants. The exergy analysis has been carried out along with the performance assessment, considering the overall plant exergetic efficiency and the exergy destruction in the various components of the plant. The exergy method highlights irreversibility within the plant components, and it is of particular interest in this investigation. A computational analysis has been carried out to investigate the effects of compressor pressure ratio and gas turbine entry temperature on the thermodynamic performance of combined gas / steam power cycles. The exergy analysis has been performed for on-design point calculations, considering single shaft gas turbines with different compressor pressure ratios and turbine entry temperatures. Nearly 100 MW shaft power gas turbine engines burning natural gas fuel have been selected in this study. The off-design calculations have been performed for one of the gas turbines selected from the on-design point studies. For this particular gas turbine engine, fuel has been changed from natural gas to a low calorific value fuel gas originated from the gasification of wood. The exergy analysis indicates that maximum exergy is destroyed in the combustor, in the case of combined gas / steam cycles burning natural gas. For these studies on-design point, the exergy destruction in the combustor is found to decrease with increasing compressor pressure ratio to an optimum value and with increasing turbine entry temperature. In the off-design case the gas turbine engine is burning low calorific value fuel originated from the gasification of wood. The maximum exergy destruction occurs in the gasification process, followed by the combustion process in the gas turbine.

The Fouling of Axial Flow Compressors: Causes, Effects, Susceptibility, and Sensitivity

2009 ◽  
Author(s):  
Cyrus B. Meher-Homji ◽  
Mustapha Chaker ◽  
Andrew F. Bromley
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Simulation Analysis ◽  
Pressure Ratio ◽  
Axial Flow ◽  
Design Parameters ◽  
Comprehensive Treatment ◽  
Performance Deterioration ◽  
And Control ◽  
The Impact

Increased fuel costs have created a strong incentive for gas turbine operators to understand, minimize and control performance deterioration. The most prevalent deterioration problem faced by gas turbine operators is compressor fouling. Fouling causes a drop in airflow, pressure ratio and compressor efficiency, resulting in a “re-matching” of the gas turbine and compressor and a drop in power output and thermal efficiency. This paper addresses the causes and effects of fouling and provides a comprehensive treatment of the impact of salient gas turbine design parameters on the susceptibility and sensitivity to compressor fouling. Simulation analysis of ninety two (92) gas turbines of ranging from a few kW to large engines rated at greater than 300 MW has been conducted. It is hoped that this paper will provide practical information to gas turbine operators.

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