Modeling Gas–Liquid Flow Between Rotating and Nonrotating Annular Disks

2019 ◽  
Vol 141 (12) ◽  
Author(s):  
Irsha Pardeshi ◽  
Tom I-P. Shih
Keyword(s):  
Rotational Speed ◽  
Critical Speed ◽  
Rotating Disk ◽  
Critical Value ◽  
Outer Radius ◽  
Order Model ◽  
Reduced Order ◽  
Gas Liquid Flow ◽  
Gas Penetration ◽  
Annular Disks

When a liquid is forced to flow radially outward in the gap between two coaxial, parallel annular disks—one rotating and one stationary—the liquid occupies the entire gap until the speed of the rotating disk reaches a critical value. Beyond that critical speed, gas from the outer radius starts to enter into the gap, a process referred to as aeration. The higher the rotational speed, the greater is the extent of penetration by the gas into the gap. The extent of gas penetration strongly affects the torque exerted between the two disks because of the large difference in the gas and liquid viscosities. In this study, a reduced-order model is developed to predict the onset of aeration, extent of gas penetration into the gap, and drag torque as a function of the disk's rotational speed, gap between disks, properties of the liquid, and mass flow rate of the liquid forced through the gap. The model developed was validated by comparing predictions with experimental data.

On Transverse Vibrations of Functionally Graded Rotating Hollow Disk

2010 ◽  
Author(s):  
Rui Liu ◽  
Hamid Nayeb-Hashemi ◽  
Masoud Olia ◽  
Ashkan Vaziri
Keyword(s):  
Elastic Modulus ◽  
Critical Speed ◽  
Volume Fraction ◽  
Rotating Disk ◽  
Outer Radius ◽  
Functionally Graded ◽  
Distribution Functions ◽  
Rotating Disks ◽  
Disk Radius ◽  
Power Law Function

We studied the stress field and vibration characteristics of functionally graded rotating disks by solving the governing equation of motion using the finite difference scheme. The material was assumed to have a constant Poisson’s ratio with the elastic modulus varying as a power law function of the disk radius. Such a material could be developed by using particle reinforced composites with various reinforcements or reinforcement volume fraction. The results show that the first critical speed of the rotating disk could be increased by using FGMs. The first critical speed is greater for disks having higher elastic modulus at the outer radius. However, the disk may be unstable for certain distribution functions.

A Reduced Order Model for Transient Analysis of Bladed Disk Forced Response

2005 ◽  
Author(s):  
J. P. Ayers ◽  
D. M. Feiner ◽  
J. H. Griffin
Keyword(s):  
Transient Analysis ◽  
Critical Value ◽  
Forced Response ◽  
Reduced Order Model ◽  
Transient Effects ◽  
Order Model ◽  
Reduced Order ◽  
Bladed Disk ◽  
Vibratory Response ◽  
Acceleration Rate

A method for predicting the vibratory response of bladed disks under high engine acceleration rates is developed. The method is based on the Fundamental Mistuning Model, an existing reduced order model for predicting the steady-state vibratory response. In addition, a criterion is developed for a critical engine acceleration rate, above which transient effects play a large role in the response. It is shown that military engines operate at acceleration rates above this critical value and therefore transient effects are important in practice.

A Reduced-Order Model for Transient Analysis of Bladed Disk Forced Response

2005 ◽  
Vol 128 (3) ◽  
pp. 466-473 ◽  
Author(s):  
J. P. Ayers ◽  
D. M. Feiner ◽  
J. H. Griffin
Keyword(s):  
Transient Analysis ◽  
Critical Value ◽  
Forced Response ◽  
Reduced Order Model ◽  
Transient Effects ◽  
Order Model ◽  
Reduced Order ◽  
Bladed Disk ◽  
Vibratory Response ◽  
Acceleration Rate

A method for predicting the vibratory response of bladed disks under high engine acceleration rates is developed. The method is based on the Fundamental Mistuning Model, an existing reduced order model for predicting the steady-state vibratory response. In addition, a criterion is developed for a critical engine acceleration rate, above which transient effects play a large role in the response. It is shown that military engines operate at acceleration rates above this critical value and therefore transient effects are important in practice.

Model Order Reduction of Transmission Line Model

2020 ◽  
Vol 19 ◽  
Keyword(s):  
Transmission Line ◽  
Large Scale ◽  
Original System ◽  
Reduced Order Model ◽  
Benchmark Problems ◽  
Transmission Line Model ◽  
Order Model ◽  
Line Model ◽  
Reduced Order ◽  
Numerical Effort

Transmission Line model are an important role in the electrical power supply. Modeling of such system remains a challenge for simulations are necessary for designing and controlling modern power systems.In order to analyze the numerical approach for a benchmark collection Comprehensive of some needful real-world examples, which can be utilized to evaluate and compare mathematical approaches for model reduction. The approach is based on retaining the dominant modes of the system and truncation comparatively the less significant once.as the reduced order model has been derived from retaining the dominate modes of the large-scale stable system, the reduction preserves the stability. The strong demerit of the many MOR methods is that, the steady state values of the reduced order model does not match with the higher order systems. This drawback has been try to eliminated through the Different MOR method using sssMOR tools. This makes it possible for a new assessment of the error system Offered that the Observability Gramian of the original system has as soon as been thought about, an H∞ and H2 error bound can be calculated with minimal numerical effort for any minimized model attributable to The reduced order model (ROM) of a large-scale dynamical system is essential to effortlessness the study of the system utilizing approximation Algorithms. The response evaluation is considered in terms of response constraints and graphical assessments. the application of Approximation methods is offered for arising ROM of the large-scale LTI systems which consist of benchmark problems. The time response of approximated system, assessed by the proposed method, is also shown which is excellent matching of the response of original system when compared to the response of other existing approaches .

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