Fundamental Research on Method of Characteristics Based on Cubic Interpolated Profile Scheme in Water Hammer Analysis

2016 ◽  
Author(s):  
Yoshikazu Tanaka ◽  
Akie Mukai ◽  
Hiroyuki Taruya ◽  
Kazuhiko Tsuda
Keyword(s):  
Method Of Characteristics ◽  
Spline Interpolation ◽  
Basic Research ◽  
Linear Interpolation ◽  
Water Hammer ◽  
Interpolation Error ◽  
Computational Grids ◽  
Interpolation Scheme ◽  
Courant Number ◽  
The Method Of Characteristics

This paper introduces basic research conducted to develop a numerical analysis technique for water hammer analysis. The CIP (Cubic Interpolated Profile) scheme was applied to obtain more accurate results without greatly causing a spatial interpolation error depending on the Courant number in the method of characteristics. Regarding this technique, the authors derived a well-formed error formula by applying a linear stability analysis. Characteristics of the interpolation error were clarified by comparing existing interpolation schemes with the method of characteristics. The interpolation error of CIP scheme was superior to the Spatial Linear Interpolation Scheme, was approximately equal to the Time Linear Interpolation Scheme and the cubic spline interpolation scheme with sufficient number of computational grids. The calculation efficiency of the CIP scheme was superior to the other schemes excepting the Spatial Linear Interpolation Scheme.

Numerical Simulation and Analysis of Hydraulic Excitation System Based on Water Hammer by the Method of Characteristics

2011 ◽  
Vol 295-297 ◽  
pp. 2210-2215 ◽  
Author(s):  
Hui Xian Zhang ◽  
Zi Ming Kou ◽  
Juan Wu ◽  
Chun Yue Lu
Keyword(s):  
Numerical Simulation ◽  
Method Of Characteristics ◽  
Experimental System ◽  
Water Hammer ◽  
Vibration Exciter ◽  
Transient Pressure ◽  
Excitation System ◽  
The Method Of Characteristics ◽  
System Pressure ◽  
Excitation Pressure

To study artificially produced and actively controlled water hammer wave caused by hydraulic vibration exciter, a mathematical model was established and an experimental system was designed to verify it. Through the given partial differential equations, a computer code based on the method of characteristics was developed to calculate transient pressure distributed along the pipe under different rotational frequency of vibration exciter. The numerical simulation indicates that there is a simple harmonic vibration rising at the cross sections along the pipe, corresponding to different excitation pressure at every cross section. In addition, the excitation pressure can also be adjusted by system pressure via overflow valve. So, this work is expected to serve for the optimum design of the hydraulic excitation system and play a theoretical guiding role to experimental research in future.

Modifications to the Method of Characteristics for the Analysis of the Gas Exchange Process in Internal Combustion Engines

1986 ◽  
Vol 200 (4) ◽  
pp. 259-266 ◽  
Author(s):  
F Payri ◽  
J M Corberán ◽  
F Boada
Keyword(s):  
Gas Exchange ◽  
Internal Combustion Engines ◽  
Method Of Characteristics ◽  
Exchange Process ◽  
Internal Combustion ◽  
Linear Interpolation ◽  
Combustion Engines ◽  
The Method Of Characteristics ◽  
Grid Points ◽  
Gas Exchange Process

Some modifications to the method of characteristics for the analysis of the gas exchange process in internal combustion engines are presented in this paper. The modifications are related to the calculation of the path lines and the Riemann characteristic lines at the grid points. Regarding the path lines, the algorithm for the generation and elimination of path lines has been improved, mainly for the cases in which the fluid motion passes from being null or going out of the pipe to going into the pipe. In those cases the algorithm proposed by Benson can cause some mistakes in the entropy level field of the duct. An alternative method is proposed: the duplication ofpath lines. The other modifcation proposed is related to assuming a linear interpolation for the pressure and the volume flowrate between the nearest grid points, rather than assuming a linear interpolation of the value of the Riemann characteristics. These modijcations substantially improve the results obtained in the calculation of the fluid flow in manifolds of reciprocating internal combustion engines.

IMPROVING EIGENSPACE-BASED FUZZY LOGIC SYSTEM USING A LINEAR INTERPOLATION SCHEME FOR SPEECH PATTERN RECOGNITION

2013 ◽  
Vol 37 (3) ◽  
pp. 611-620
Author(s):  
Ing-Jr Ding ◽  
Chih-Ta Yen
Keyword(s):  
Pattern Recognition ◽  
Fuzzy Logic ◽  
Recognition Performance ◽  
Linear Interpolation ◽  
Fuzzy Logic System ◽  
Interpolation Scheme ◽  
Speech Pattern ◽  
Eigen Value ◽  
Target Speaker ◽  
Logic System

The Eigen-FLS approach using an eigenspace-based scheme for fast fuzzy logic system (FLS) establishments has been attempted successfully in speech pattern recognition. However, speech pattern recognition by Eigen-FLS will still encounter a dissatisfactory recognition performance when the collected data for eigen value calculations of the FLS eigenspace is scarce. To tackle this issue, this paper proposes two improved-versioned Eigen-FLS methods, incremental MLED Eigen-FLS and EigenMLLR-like Eigen-FLS, both of which use a linear interpolation scheme for properly adjusting the target speaker’s Eigen-FLS model derived from an FLS eigenspace. Developed incremental MLED Eigen-FLS and EigenMLLR-like Eigen-FLS are superior to conventional Eigen-FLS especially in the situation of insufficient data from the target speaker.

Non-symmetric flow in Laval type nozzles

1972 ◽  
Vol 273 (1232) ◽  
pp. 185-235 ◽  
Keyword(s):  
Steady State ◽  
Combustion Chamber ◽  
Method Of Characteristics ◽  
Three Dimensions ◽  
Symmetric Flow ◽  
Gaseous Flow ◽  
The Method Of Characteristics ◽  
Lateral Forces

The equations of the steady state, compressible inviscid gaseous flow are linearized in a form suitable for application to nozzles of the Laval type. The procedure in the supersonic phase is verified by comparing solutions so obtained with those derived by the method of characteristics in two and three dimensions. Likewise, the solutions in the transonic phase are com pared with those obtained by other investigators. The linearized equation is then used to investigate the nat re of non-symmetric flow in rocket nozzles. It is found that if the flow from the combustion chamber into the nozzle is non-symmetric, the magnitude and direction of the turning couple produced by the emergent jet is dependent on the profile of the nozzle and it is possible to design profiles such that the turning couples or lateral forces are zero. The optimum nozzle so designed is independent of the pressure and also of the magnitude of the non-symmetry of the entry flow. The formulae by which they are obtained have been checked by extensive static and projection tests with simulated rocket test vehicles which are described in this paper.

Boundary Layer Closure and Heat Transfer in Constant Base Pressure and Simple Wave Guns

1978 ◽  
Vol 100 (4) ◽  
pp. 690-696 ◽  
Author(s):  
A. D. Anderson ◽  
T. J. Dahm
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Layer Thickness ◽  
Boundary Layer Thickness ◽  
Method Of Characteristics ◽  
Simple Wave ◽  
Momentum Equation ◽  
Base Pressure ◽  
Two Dimensional ◽  
The Method Of Characteristics

Solutions of the two-dimensional, unsteady integral momentum equation are obtained via the method of characteristics for two limiting modes of light gas launcher operation, the “constant base pressure gun” and the “simple wave gun”. Example predictions of boundary layer thickness and heat transfer are presented for a particular 1 in. hydrogen gun operated in each of these modes. Results for the constant base pressure gun are also presented in an approximate, more general form.

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