scholarly journals Superhybrid Composite Blade Impact Studies

1981 ◽  
Vol 103 (4) ◽  
pp. 731-738 ◽  
Author(s):  
C. C. Chamis ◽  
R. F. Lark ◽  
J. H. Sinclair
Keyword(s):  
Structural Integrity ◽  
Mechanical Design ◽  
Impact Resistance ◽  
Leading Edge ◽  
Operating Conditions ◽  
Turbine Engine ◽  
Design Concepts ◽  
Composite Blade ◽  
Bird Impact ◽  
Small Bird

An investigation was conducted to determine the feasibility of superhybrid composite blades for meeting the mechanical design and impact resistance requirements of large fan blades for aircraft turbine engine applications. Two design concepts were evaluated: (1) leading edge spar (TiCom) and (2) center spar (TiCore), both with superhybrid composite shells. The investigation was both analytical and experimental. The results obtained show promise that superhybrid composites can be used to make light-weight, high-quality, large fan blades with good structural integrity. The blades tested successfully demonstrated their ability to meet steady-state operating conditions, overspeed, and small bird impact requirements.

Evaluation of Fuel Preparation Systems for Lean Premixing-Prevaporizing Combustors

1986 ◽  
Vol 108 (2) ◽  
pp. 391-395
Author(s):  
W. J. Dodds ◽  
E. E. Ekstedt
Keyword(s):  
System Design ◽  
Large Scale ◽  
Fuel Injection ◽  
Operating Conditions ◽  
Turbine Engine ◽  
Fuel Injectors ◽  
Design Concepts ◽  
Mixture Preparation ◽  
Design Variables ◽  
System Length

A series of tests was conducted to provide data for the design of premixing-prevaporizing fuel-air mixture preparation systems for aircraft gas turbine engine combustors. Fifteen configurations of four different fuel-air mixture preparation system design concepts were evaluated to determine fuel-air mixture uniformity at the system exit over a range of conditions representative of cruise operation for a modern commercial turbofan engine. Operating conditions, including pressure, temperature, fuel-air ratio, and velocity had no clear effect on mixture uniformity in systems which used low-pressure fuel injectors. However, performance of systems using pressure atomizing fuel nozzles and large-scale mixing devices was shown to be sensitive to operating conditions. Variations in system design variables were also evaluated and correlated. Mixture uniformity improved with increased system length, pressure drop, and number of fuel injection points per unit area. A premixing system compatible with the combustor envelope of a typical combustion system and capable of providing mixture nonuniformity (standard deviation/mean) below 15% over a typical range of cruise operating conditions was demonstrated.

Tensile Characterization of a GTAW Bimetallic Weld Mod 9Cr-1Mo–316L(N) With a New Measurement System for Tensile Testing

2011 ◽  
Author(s):  
O. Ancelet ◽  
G. Perez ◽  
L. Forest
Keyword(s):  
Measurement System ◽  
Tensile Testing ◽  
Structural Integrity ◽  
Mechanical Design ◽  
Operating Conditions ◽  
Curvature Radius ◽  
Local Behavior ◽  
Stainless Steel 316L ◽  
Minimum Diameter ◽  
Gtaw Process

Mod 9Cr-1Mo steel (T91) is a candidate material for steam generator of SFR (Sodium Fast Reactors). In order to validate this choice, it is necessary, firstly to verify that it is able to withstand the planned environmental and operating conditions, and secondly to check if it is covered by the existing design codes, concerning its procurement, fabrication, welding, examination methods and mechanical design rules. A large R&D program on mod 9Cr-1Mo steel has been undertaken at CEA in order to characterize the behavior of this material and of its welded junctions. In this frame, a new measurement system for tensile testing was developed in the laboratory of structural integrity and standards (LISN) of the CEA (French atomic commission), in order to characterize the local behavior of the material during a whole tensile testing. Indeed, with the conventional measurement system (typically an extensometer), the local behavior of the material can only be determined during the stable step of the testing. So, usually the behavior of the material during the necking step of the step is unknown. This new measurement is based on the use of some laser micrometers which allow measuring the minimum diameter of the specimen and the curvature radius during the necking phase with a great precision. Thanks to the Bridgman formula, we can evaluate the local behavior of the material until the failure of the specimen. This new system was used to characterize the tensile propriety of a bimetallic welded junction of Mod 9Cr-1Mo steel and austenitic stainless steel 316L(N) realized with GTAW process and inconel filler metal. These works lead to propose a tensile curve for each materials of the welded junction.

Finite Element Transient Modelling for Aero-Thermo-Mechanical Analysis of Whole Gas Turbine Engine

2019 ◽  
Author(s):  
Sabrina Giuntini ◽  
Antonio Andreini ◽  
Bruno Facchini
Keyword(s):  
Gas Turbines ◽  
Structural Integrity ◽  
Numerical Procedure ◽  
Mechanical Analysis ◽  
Operating Conditions ◽  
Test Case ◽  
Large Power ◽  
Turbine Engine ◽  
Air System ◽  
Secondary Air

Abstract It is here proposed a numerical procedure aimed to perform transient aero-thermo-mechanical calculations of large power generation gas turbines. Due to the frequent startups and shutdowns that nowadays these engines encounter, procedures for multi-physics simulations have to take into account the complex coupled interactions related to inertial and thermal loads, and seal running clearances. In order to develop suitable secondary air system configurations, guarantee structural integrity and maintain actual clearances and temperature peaks in pre-established ranges, the overall complexity of the structure has to be reproduced with a whole engine modelling approach, simulating the entire machine in the real operating conditions. In the proposed methodology the aerodynamic solution providing mass flows and pressures, and the thermo-mechanical analysis returning temperatures and material expansion, are performed separately. The procedure faces the aero-thermo-mechanical problem with an iterative process with the aim of taking into account the complex aero-thermo-mechanical interactions actually characterizing a real engine, in a robust and modular tool, combining secondary air system, thermal and mechanical analysis. The heat conduction in the solid and the fluid-solid heat transfer are computed by a customized version of the open source FEM solver CalculiX®. The secondary air system is modelled by a customized version of the embedded CalculiX® one-dimensional fluid network solver. In order to assess the physical coherence of the presented methodology the procedure has been applied to a test case representative of a portion of a real engine geometry, tested in a thermal transient cycle for the assessment of the interaction between secondary air system properties and geometry deformations.

Mechanical Behaviour of SFR Materials: Proposition of Fatigue Weld Joint Coefficient for Mod9Cr-1Mo

2011 ◽  
Author(s):  
O. Ancelet ◽  
Ph. Matheron
Keyword(s):  
Weld Joint ◽  
Structural Integrity ◽  
Mechanical Design ◽  
Operating Conditions ◽  
Design Codes ◽  
Fast Reactors ◽  
Defect Assessment ◽  
Examination Methods ◽  
Assessment Procedures

Mod 9Cr-1Mo steel (T91) is a candidate material for steam generator of SFR (Sodium Fast Reactors). In order to validate this choice, it is necessary, firstly to verify that it is able to withstand the planned environmental and operating conditions, and secondly to check if it is covered by the existing design codes, concerning its procurement, fabrication, welding, examination methods and mechanical design rules. A large R&D program on mod 9Cr-1Mo steel has been undertaken at CEA in order to characterize the behavior of this material and of its welded junctions. In this program, the role of the Laboratory for structural Integrity and Standards (LISN) is to develop high temperature defect assessment procedures under fatigue and creep loadings. In this frame, complementary studies are conducted in order to validate the existing methods (developed for the fast reactors) and to get new experimental data on Mod 9Cr-1Mo steel. In particular, some new experiments are conducted on specimen with a weld joint and compared with classical experiments on base metal specimen. These results associated with finite element modeling allow to propose a weld joint coefficient at 550°C for the Mod9Cr 1Mo steel.

Reliability and Durability of Ceramic Regenerators in a Gas Turbine

1978 ◽  
Vol 100 (1) ◽  
pp. 73-81 ◽  
Author(s):  
C. J. Rahnke ◽  
J. K. Vallance
Keyword(s):  
Thermal Stress ◽  
Gas Turbine ◽  
Mechanical Design ◽  
Ceramic Materials ◽  
Aluminum Silicate ◽  
Turbine Engine ◽  
Design Concepts ◽  
Chemical Attack ◽  
Magnesium Aluminum Silicate ◽  
Regenerator System

The two major causes of failure of ceramic regenerators in a gas turbine engine are excessive thermal stress and chemical attack of the basic ceramic material. Data are presented which show that regenerator life can be correlated on the basis of rim thermal-stress safety factor. Durability gains can be achieved through improved mechanical design of the regenerator system, as well as through improved ceramic materials. The test results from almost 50,000 hr of gas turbine operation on several different candidate materials and design concepts are also presented. Two materials, aluminum silicate and magnesium aluminum silicate, show promise of achieving the durability goals required for automotive and industrial turbine applications.

Impact of Variable-Geometry Stator Hub Leakage in a Low Speed Axial Compressor

1998 ◽  
Author(s):  
Wendy S. Barankiewicz ◽  
Michael D. Hathaway
Keyword(s):  
Mechanical Design ◽  
Axial Compressor ◽  
Leading Edge ◽  
Operating Conditions ◽  
Variable Geometry ◽  
Turning Angle ◽  
Blade Loading ◽  
Axial Compressors ◽  
The Impact ◽  
Variable Stator

The impact of hub leakage flow associated with the clearance gaps of hub-shrouded variable-geometry stator rows in axial compressors is investigated experimentally. The objectives of this work are to investigate the sensitivity of performance to chordwise leakage location and to provide guidance for the mechanical design of variable stator hub trunions. Although blade loading near the hub is increased when leakage occurs at the leading edge, losses also increase for both design and off-design operating conditions. Leading edge leakage also causes a greater spanwise variation in absolute turning angle over the first 20% of span from the hub. Results show that for a moderately separated stator, the optimum leakage configuration features trailing edge leakage with the leading edge sealed. This confirms the current practice of most engine companies in placing the hub trunion at the blade leading edge.

Unsteady simulations of migration and deposition of fly-ash particles in the first-stage turbine of an aero-engine

2021 ◽  
pp. 1-21
Author(s):  
Z. Hao ◽  
X. Yang ◽  
Z. Feng
Keyword(s):  
Fly Ash ◽  
Film Cooling ◽  
Particle Deposition ◽  
Flow Characteristics ◽  
Leading Edge ◽  
Velocity Model ◽  
Operating Conditions ◽  
Inlet Temperature ◽  
Internal Cooling ◽  
Aero Engine

Abstract Particulate deposits in aero-engine turbines change the profile of blades, increase the blade surface roughness and block internal cooling channels and film cooling holes, which generally leads to the degradation of aerodynamic and cooling performance. To reveal particle deposition effects in the turbine, unsteady simulations were performed by investigating the migration patterns and deposition characteristics of the particle contaminant in a one-stage, high-pressure turbine of an aero-engine. Two typical operating conditions of the aero-engine, i.e. high-temperature take-off and economic cruise, were discussed, and the effects of particle size on the migration and deposition of fly-ash particles were demonstrated. A critical velocity model was applied to predict particle deposition. Comparisons between the stator and rotor were made by presenting the concentration and trajectory of the particles and the resulting deposition patterns on the aerofoil surfaces. Results show that the migration and deposition of the particles in the stator passage is dominated by the flow characteristics of fluid and the property of particles. In the subsequential rotor passage, in addition to these factors, particles are also affected by the stator–rotor interaction and the interference between rotors. With higher inlet temperature and larger diameter of the particle, the quantity of deposits increases and the deposition is distributed mainly on the Pressure Side (PS) and the Leading Edge (LE) of the aerofoil.

scholarly journals Mode I Crack Propagation Experimental Analysis of Adhesive Bonded Joints Comprising Glass Fibre Composite Material under Impact and Constant Amplitude Fatigue Loading

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4380
Author(s):  
Alirio Andres Bautista Villamil ◽  
Juan Pablo Casas Rodriguez ◽  
Alicia Porras Holguin ◽  
Maribel Silva Barrera
Keyword(s):  
Crack Propagation ◽  
Structural Integrity ◽  
Crack Propagation Rate ◽  
Fatigue Loading ◽  
Propagation Rate ◽  
Operating Conditions ◽  
Impact Testing ◽  
Mode I ◽  
Mode I Crack ◽  
Constant Amplitude

The T-90 Calima is a low-wing monoplane aircraft. Its structure is mainly composed of different components of composite materials, which are mainly bonded by using adhesive joints of different thicknesses. The T-90 Calima is a trainer aircraft; thus, adverse operating conditions such as hard landings, which cause impact loads, may affect the structural integrity of aircrafts. As a result, in this study, the mode I crack propagation rate of a typical adhesive joint of the aircraft is estimated under impact and constant amplitude fatigue loading. To this end, effects of adhesive thickness on the mechanical performance of the joint under quasistatic loading conditions, impact and constant amplitude fatigue in double cantilever beam (DCB) specimens are experimentally investigated. Cyclic impact is induced using a drop-weight impact testing machine to obtain the crack propagation rate (da/dN) as a function of the maximum strain energy release rate (GImax) diagram; likewise, this diagram is also obtained under constant amplitude fatigue, and both diagrams are compared to determine the effect of each type of loading on the structural integrity of the joint. Results reveal that the crack propagation rate under impact fatigue is three orders of magnitude greater than that under constant amplitude fatigue.

Analysis of High Velocity Impact on Composite Structures

2014 ◽  
Vol 617 ◽  
pp. 104-109 ◽  
Author(s):  
Milan Žmindák ◽  
Zoran Pelagić ◽  
Maroš Bvoc
Keyword(s):  
Carbon Fibers ◽  
Composite Structures ◽  
Impact Resistance ◽  
Leading Edge ◽  
Layered Composite ◽  
Bird Strike ◽  
Out Of Plane ◽  
The Matrix ◽  
Composite Wing ◽  
Considerable Damage

In the recent years a big focus is subjected to the response of structures subjected to out-of-plane loading such as blasts, impact, etc. not only to homogenous materials, but also to heterogeneous materials, such as composites. Such form of loading can cause considerable damage to the structure. In the case of layered composite materials the damage can have several forms, starting from damage in layers up to delamination and full damage of the construction. This paper describes the investigation of shockwave propagation in composite structures caused by impact loading. The composite consists of carbon fibers in a polymer matrix, in which the fibers are much stiffer then the matrix. Finite element simulations were carried out for a “bird” strike impact on a composite wing leading edge. Results show a good impact resistance and good damping abilities of shockwaves.

Numerical Investigation of the Solidity Effect on Linear Compressor Cascades

2014 ◽  
Author(s):  
J. Sans ◽  
M. Resmini ◽  
J.-F. Brouckaert ◽  
S. Hiernaux
Keyword(s):  
Numerical Investigation ◽  
State Of The Art ◽  
Leading Edge ◽  
Operating Conditions ◽  
Compressor Cascade ◽  
Minimum Loss ◽  
Low Speed ◽  
High Mach ◽  
The Stability ◽  
The Impact

Solidity in compressors is defined as the ratio of the aerodynamic chord over the peripheral distance between two adjacent blades, the pitch. This parameter is simply the inverse of the pitch-to-chord ratio generally used in turbines. Solidity must be selected at the earliest design phase, i.e. at the level of the meridional design and represents a crucial step in the whole design process. Most of the existing studies on this topic rely on low-speed compressor cascade correlations from Carter or Lieblein. The aim of this work is to update those correlations for state-of-the-art controlled diffusion blades, and extend their application to high Mach number flow regimes more typical of modern compressors. Another objective is also to improve the physical understanding of the solidity effect on compressor performance and stability. A numerical investigation has been performed using the commercial software FINE/Turbo. Two different blade profiles were selected and investigated in the compressible flow regime as an extension to the low-speed data on which the correlations are based. The first cascade uses a standard double circular arc profile, extensively referenced in the literature, while the second configuration uses a state-of-the-art CDB, representative of low pressure compressor stator mid-span profile. Both profiles have been designed with the same inlet and outlet metal angles and the same maximum thickness but the camber and thickness distributions, the stagger angle and the leading edge geometry of the CDB have been optimized. The determination of minimum loss, optimum incidence and deviation is addressed and compared with existing correlations for both configurations and various Mach numbers that have been selected in order to match typical booster stall and choke operating conditions. The emphasis is set on the minimum loss performance at mid-span. The impact of the solidity on the operating range and the stability of the cascade are also studied.

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