Life Calculation of First Stage Compressor Blade of a Trainer Aircraft

2012 ◽  
Author(s):  
J. S. Rao ◽  
Narayan Rangarajan ◽  
Rejin Ratnakar ◽  
R. Rzadkowski ◽  
M. Soliński ◽  
...  
Keyword(s):  
Air Force ◽  
Critical Speed ◽  
Iterative Solution ◽  
Nonlinear Damping ◽  
Equivalent Viscous Damping ◽  
Campbell Diagram ◽  
Compressor Rotor ◽  
Institute Of Technology ◽  
The Given ◽  
Damping Model

This paper is concerned with life estimation of a compressor rotor blade of an engine at the Air Force Institute of Technology in Warsaw used in a trainer aircraft. A bird strike is simulated by two or three blade passage blocks in the incoming flow and the pressure field is obtained from a CFD code. For the blade the Campbell diagram is prepared and the critical speeds are identified. The alternating pressures corresponding to the critical speed are obtained from an FFT. A nonlinear damping model is estimated using Lazan’s hysteresis law; the equivalent viscous damping model is determined as a function of reference strain amplitude in the given mode of vibration at the rotational speed. An iterative solution is developed with the nonlinear damping model and the resonant stress and location is determined. The life at this critical speed is determined using a cumulative damage criterion.

Crack Propagation Life Calculation of an Aircraft Compressor Blade due to Bird Ingestion

2014 ◽  
Author(s):  
Srinivasa R. Jammi ◽  
R. Rzadkowski
Keyword(s):  
Crack Propagation ◽  
Iterative Process ◽  
Reference Strain ◽  
Pressure Field ◽  
Nonlinear Damping ◽  
Compressor Blade ◽  
Viscous Damping ◽  
Equivalent Viscous Damping ◽  
The Given ◽  
Damping Model

Bird ingestion is simulated by blade passage blocks in the incoming flow and the pressure field is obtained from a CFD code. The alternating pressure field corresponding to the identified critical speed of the first stage rotor blade is obtained from an FFT. A nonlinear damping model is developed using Lazan’s hysteresis law; the equivalent viscous damping model is determined as a function of reference strain amplitude in the given mode of vibration at the rotational speed. An iterative process is developed with the nonlinear damping model and the resonant stress and location is determined. The Fracture Mechanics approach is used to estimate the crack propagation life of the blade.

Feasibility investigation of a compressor rotor supported by gas foil bearings with inhomogeneous bump foils

2021 ◽  
pp. 135065012110046
Author(s):  
Hao Li ◽  
Haipeng Geng ◽  
Bo Wang ◽  
Wei Zheng
Keyword(s):  
Critical Speed ◽  
Rotor System ◽  
Experimental Result ◽  
Test Results ◽  
Rotating Speed ◽  
Foil Bearings ◽  
Dynamic Coefficients ◽  
High Order Harmonic ◽  
Compressor Rotor ◽  
Operating Points

In this paper, a rotordynamic experiment on a compressor rotor system is presented and the feasibility of gas foil bearings with inhomogeneous bump foils is verified. A push–pull device is designed to obtain the stiffness curve and the nominal clearance of foil bearings. Operating points and dynamic coefficients of the rotor system at each rotating speed are predicted. In rotordynamic analysis, an alternative model of the impeller is proposed and the critical speed is predicted by employing the finite element method, in which the dynamic coefficients of inhomogeneous foil bearings are taken into account. Compared with the experimental result, the accuracy of the prediction for the critical speed is verified to be about 14% error. Two sets of foil bearings with 22 and 41 μm nominal clearance are manufactured and tested. Test results indicate that the vibration amplitude can be greatly reduced by diminishing the bearing clearance. When foil bearings with 22 μm clearance are used, the high-order harmonic frequencies of rotor vibration are significantly inhibited, and the amplitude of the rotating frequency is obviously restricted. Thus, the foil bearing with inhomogeneous bump foils tested in this paper can meet the speed requirement of the compressor when the nominal clearance is set at 22 μm.

Characterization of Shock Wave–Endwall Boundary Layer Interactions in a Transonic Compressor Rotor

1988 ◽  
Vol 110 (3) ◽  
pp. 386-392 ◽  
Author(s):  
D. C. Rabe ◽  
A. J. Wennerstrom ◽  
W. F. O’Brien
Keyword(s):  
Boundary Layer ◽  
Shock Wave ◽  
Air Force ◽  
Leading Edge ◽  
Transonic Compressor ◽  
Laser Measurements ◽  
Compressor Rotor ◽  
Boundary Layer Interaction ◽  
Air Force Base

The passage shock wave–endwall boundary layer interaction in a transonic compressor was investigated with a laser transit anemometer. The transonic compressor used in this investigation was developed by the General Electric Company under contract to the Air Force. The compressor testing was conducted in the Compressor Research Facility at Wright-Patterson Air Force Base, OH. Laser measurements were made in two blade passages at seven axial locations from 10 percent of the axial blade chord in front of the leading edge to 30 percent of the axial blade chord into the blade passage. At three of these axial locations, laser traverses were taken at different radial immersions. A total of 27 different locations were traversed circumferentially. The measurements reveal that the endwall boundary layer in this region is separated from the core flow by what appears to be a shear layer where the passage shock wave and all ordered flow seem to end abruptly.

scholarly journals The laboratory test rig with miniature jet engine to research aviation fuels combustion process

2015 ◽  
Vol 36 (1) ◽  
pp. 79-90 ◽  
Author(s):  
Bartosz Gawron ◽  
Tomasz Białecki
Keyword(s):  
Research And Development ◽  
Laboratory Test ◽  
Air Force ◽  
Combustion Process ◽  
Jet Engines ◽  
Test Rig ◽  
Jet Engine ◽  
Measurement Results ◽  
Institute Of Technology ◽  
Main Components

Abstract This article presents laboratory test rig with a miniature turbojet engine (MiniJETRig – Miniature Jet Engine Test Rig), that was built in the Air Force Institute of Technology. The test rig has been developed for research and development works aimed at modelling and investigating processes and phenomena occurring in full scale jet engines. In the article construction of a test rig is described, with a brief discussion on the functionality of each of its main components. Additionally examples of measurement results obtained during the realization of the initial tests have been included, presenting the capabilities of the test rig.

Capabilities of the FAM-C method to diagnose the accessory gearboxes and transmission -train assemblies of the MI-24 helicopters

2012 ◽  
Vol 30 (1) ◽  
pp. 199-220
Author(s):  
Sławomir Augustyn ◽  
Andrzej Gębura
Keyword(s):  
Air Force ◽  
Instantaneous Frequency ◽  
Rotational Speed ◽  
Diagnostic Method ◽  
Transmission System ◽  
Structural Components ◽  
Mechanical Measurements ◽  
Institute Of Technology ◽  
Non Destructive

The study has been intended to present some selected service-imposed issues with the transmission system of the Mi-24 combat helicopter. An attempt has been made to present predictions about possible threats/hazards to the transmission system of this helicopter. The forecast has been based on the FAM-C analysis of changes in instantaneous frequency against time and, to some extent, on mechanical measurements of disassembled structural components/subassemblies. The greatest emphasis has been laid on capabilities to identify and diagnose locations in structural components of the Mi-24 helicopter (where many and various hazards may arise) using the non-destructive diagnostic method FAM-C developed at ITWL (Air Force Institute of Technology). The method has been based on the tracking of parameters of modulation of airborne alternator produced frequencies. The testing requires no extra sensors, since the built-in airborne AC, DC, and tachogenerators themselves are the diagnostic transducers. While taking FAM-C measurements, the transmission system experiences no extra loads or rotational-speed distortions.

Investigations on corrosion of aircrafts in the aspect of prolonged service life and operation driven by their technical condition

2012 ◽  
Vol 30 (1) ◽  
pp. 59-72 ◽  
Author(s):  
Piotr Barszcz
Keyword(s):  
Service Life ◽  
Air Force ◽  
Atmospheric Corrosion ◽  
Protective Coatings ◽  
Technical Condition ◽  
Structural Components ◽  
Institute Of Technology ◽  
Corrosion Investigation ◽  
Prolonged Service ◽  
Research Studies

Research studies that are conducted by both the Air Force Institute of Technology (AFIT) and other domestic and foreign organizations indicate that investigations of corrosion phenomena present a very important factor with respect to prolongation of technical resources and operation of aircraft driven by their actual technical condition. The investigation of the corrosion degree and deterioration of protective coatings must be carried out in a systemic manner with thorough analysis of information that bring together the aircraft operation and the processes of corrosion and deterioration of protective coatings. The investigation must comprise measurements of the atmospheric corrosion in order to determine corrosive aggressiveness of the atmosphere and establish frequency and scope of corrosion inspection. Only the analysis of gathered information with its characteristics may guarantee safe operation of structural components of aircrafts according to their actual technical condition. This paper outlines the approach to corrosion investigation that is in place in AFIT.

Reduced-Order Nonlinear Damping Model: Formulation and Application to Postflutter Aeroelastic Behavior

AIAA Journal ◽  
2021 ◽  
pp. 1-11
Author(s):  
X. Q. Wang ◽  
Pengchao Song ◽  
Marc P. Mignolet ◽  
P. C. Chen
Keyword(s):  
Nonlinear Damping ◽  
Model Formulation ◽  
Reduced Order ◽  
Damping Model

Vibration Response of Functionally Graded Rotating Disk With a Circumferential Crack

2010 ◽  
Author(s):  
Rui Liu ◽  
Hamid Nayeb-Hashemi
Keyword(s):  
Critical Speed ◽  
Crack Depth ◽  
Rotating Disk ◽  
Vibration Characteristics ◽  
Functionally Graded ◽  
Mode Shapes ◽  
Campbell Diagram ◽  
Circumferential Crack ◽  
Inner Radius ◽  
The Galerkin Method

In this study, the vibration characteristics of a functionally graded rotating hollow disk with the circumferential surface crack are investigated. In order to simplify the problem, the circumferential crack of the rotating hollow disk is modeled as circumferential step indentation. The Galerkin Method is used to obtain the radial and hoop stresses for disks with clamped edge at the inner radius. Finite Difference scheme is adopted to solve the partial differential equation of motion of the rotating hollow disk to obtain the mode shapes and the Campbell Diagram. The first critical speed, which is one of the important parameters limiting the performance of the rotating disk, was obtained from the Campbell Diagram. The results show that the crack will reduce the stiffness and the critical speed of the rotating disk. Critical speed increases with decreasing the distance from inner radius to the crack and decreases with increasing crack depth. Furthermore, considering the functionally graded disk, the distribution of elastic modulus does not change significantly the effects of circumferential cracks on the vibration characteristics of the rotating.

An Efficient Technique for Design of Hydraulic Engine Mount via Design Variable-Embedded Damping Modeling

2005 ◽  
Vol 127 (1) ◽  
pp. 93-99 ◽  
Author(s):  
Jun-Hwa Lee ◽  
Kwang-Joon Kim
Keyword(s):  
Dynamic Characteristics ◽  
Low Frequency ◽  
High Amplitude ◽  
Nonlinear Damping ◽  
Efficient Design ◽  
Equivalent Viscous Damping ◽  
Damping Characteristics ◽  
Design Variables ◽  
Engine Mount ◽  
Stiffness And Damping

For an efficient design of hydraulic mounts, it is most important to have a good mathematical model available, which must be simple yet capable of representing dynamic characteristics of the hydraulic mounts accurately. Under high amplitude excitations in the low-frequency range, the hydraulic mounts show strongly frequency-dependent stiffness and damping characteristics, which are related with so-called inertia track dynamics. Since nonlinear damping models based on fluid mechanics are typically used to predict the dynamic characteristics of the hydraulic mounts, relations between various design variables, such as geometry of the inertia track, and resultant stiffness and damping characteristics are understood only by tedious numerical computations. In this paper, the use of an equivalent viscous damping model—derived from a nonlinear model and represented in terms of design variables in an explicit manner—is proposed and, based on the equivalent linear model, are presented simple as well as very useful formulas for an efficient design of the hydraulic mounts.

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