Method for Dynamic Stress Design in a Variable Section Blade of a Turbo Machine

2021 ◽  
pp. 75-80
Author(s):  
A.A. Sidorov ◽  
A.S. Golikov
Keyword(s):  
Gas Flow ◽  
Dynamic Stress ◽  
Maximum Amplitude ◽  
Variable Cross Section ◽  
Complex Problem ◽  
Empirical Method ◽  
Variable Cross ◽  
Compressor Blades ◽  
Scientific Publications ◽  
Dynamic Stresses

The problem of assessing the dynamic stresses arising from vibrations of the blades of turbo machines is an urgent and significant problem affecting the overall reliability of the turbo machine. Its solution requires a mathematical study and a physical experiment to determine the intensity of the gas flow impact and the blade reaction.However, there is relatively little information in the scientific publications on this issue. The article considers a semi-empirical method for calculating dynamic stresses at the base of a variable cross-section blade at the first tone resonant vibrations. These vibrations can be considered as the most dangerous because of the maximum amplitude. To perform the calculation a real blade was replaced with a calculated one, composed of separate portions with a constant profile, and the contribution of each part to the stress in the base section was determined. An example of calculating the dynamic stress by the proposed method with a resonant vibration of the first tone of a constant-section blade is given. The calculation showed that the solution to a complex problem can be represented as a sum of solutions to simpler problems. The calculation method can be used in the design of turbine and compressor blades.

The Effect of Gas Evolution on Hydrodynamic Characteristics of Fluid Flow in Pipeline

2016 ◽  
Author(s):  
Geylani M. Panakhov ◽  
Eldar M. Abbasov ◽  
Sayavur I. Bakhtiyarov ◽  
Dennis A. Siginer
Keyword(s):  
Temperature Difference ◽  
Gas Flow ◽  
Variable Cross Section ◽  
Throughput Capacity ◽  
Hydrodynamic Characteristics ◽  
Variable Cross ◽  
Gas Generation ◽  
Two Phase ◽  
Maximum Value ◽  
Oil Gas

A relative motion of different phases leads to formation of certain forces at the interface of transported fluid and pipe walls. In the non-isothermal flow case a thermal interaction between the phases will affect the flow velocity, the pressure and the temperature distributions in variable cross section pipes. Laboratory experiments were conducted in order to study the effects of the gas generation at the pipe walls on the hydrodynamic characteristics of the two-phase oil/gas flow. It is shown that a throughput capacity of the pipe is affected by the temperature difference between the oil and the pipe walls. At certain temperature difference value (∼3°C) the pipe capacity reached a maximum value.

Gas Flow in Microchannels and Nanochannels With Variable Cross Section for All Knudsen and All Mach Number Values

2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Snežana S. Milićev ◽  
Nevena D. Stevanović
Keyword(s):  
Mach Number ◽  
Friction Factor ◽  
Cross Section ◽  
Gas Flow ◽  
Variable Cross Section ◽  
Molecular Flow ◽  
Variable Cross ◽  
General Boundary Condition ◽  
Poiseuille Number ◽  
Isothermal Gas

Abstract The analytical solution for steady viscous pressure-driven compressible isothermal gas flow through micro- and nanochannels with variable cross section for all Knudsen and all Mach number values is presented in this paper. The continuum one-dimensional governing equations are solved using the friction factor that is established in a special way to provide solutions for mass flow rate, pressure, and velocity distribution through the microchannels and nanochannels in the entire rarefaction regime. The friction factor, defined by the general boundary condition and generalized diffusion coefficient proposed by Beskok and Karniadakis (1999, “A Model for Flows in Channels, Pipes, and Ducts at Micro and Nano Scales,” J. Microscale Thermophys. Eng., 3, pp. 43–77), spreads the solution application to all rarefaction regimes from continuum to free molecular flow. The correlation between the product of friction factor and Reynolds number (Poiseuille number) and Knudsen number is established explicitly in the paper. Moreover, the obtained solution includes the inertia effect, which allows the application of the solution to both subsonic and supersonic gas flows, which was not shown earlier. The presented solution confirms the existence of the Knudsen minimum in the diverging, converging, and microchannels and nanochannels with constant cross section. The proposed solution is verified by comparison with experimental, analytical, and numerical results available in literature.

A High Efficient Variable Cross-Section Compound Ultrasonic Wiredrawing Vibration System

2012 ◽  
Vol 157-158 ◽  
pp. 1689-1694 ◽  
Author(s):  
Xiao Biao Shan ◽  
Nai Ming Qi ◽  
Li Li Wang ◽  
Tao Xie
Keyword(s):  
Finite Element ◽  
Cross Section ◽  
Ultrasonic Vibration ◽  
Maximum Amplitude ◽  
Variable Cross Section ◽  
Difficult Problem ◽  
Experimental Result ◽  
Variable Cross ◽  
Vibration System ◽  
High Efficient

To solve the technical difficult problem of difficult-to-draw materials, this work presented a composite ultrasonic vibration system with variable cross-section rods. The four-terminal network method and the finite element method were used to design the conical, the exponential and the catenary transducers. The finite element results of show that the oval trajectory can effectively improve the friction effect between the wire and the tool head. The experimental result showed that the maximum amplitude was about 60 μm. It was 3 times of that in our previous work. These results demonstrated the design of the composite ultrasonic vibration system was feasible.

Simulation of Gas Flow in Channels with Variable Cross-Section at Different Flow Modes using Lattice Boltzmann Method (LBM)

2019 ◽  
pp. 105-115
Author(s):  
A.V. Burmistrov ◽  
S.I. Salikeev ◽  
A.A. Raykov
Keyword(s):  
Lattice Boltzmann Method ◽  
Cross Section ◽  
Lattice Boltzmann ◽  
Gas Flow ◽  
Stokes Equations ◽  
Variable Cross Section ◽  
Variable Cross ◽  
Wide Range ◽  
Boltzmann Method ◽  
Contact Free

All contact-free vacuum pumps operate in a very wide pressure range. Therefore, the calculation of flows through the slot channels is associated with the need to take into account the laws of all three modes of gas flow: viscous, transitional and molecular. Most of channels of contact-free pumps are formed by curved walls, which are slits of variable cross-section in the direction of gas flow, having a minimum gap in some place. The paper considers the basic methods of calculating flows in channels of variable cross-section: the Monte Carlo method for molecular mode, the numerical solution of Navier --- Stokes equations for viscous mode and the Lattice Boltzmann method (LBM) for a wide range of pressures. The results of gas flow simulation calculated in COMSOL Multiphysics with LBM method are presented. The influence of the gas flow mode on the velocity profile in the channel is discussed. Based on the simulation results, the conductivity of channels of different geometries was calculated at various pressures at the inlet and outlet of the channel. The graphs of conductivity dependence on the Knudsen number for the method of angular coefficients, the model of lattice Boltzmann equations and experimental data are presented. It is shown that for slit channels of variable cross-section, the LBM model agrees well with the experiment under any gas flow modes.

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