Wyniki wyszukiwania - BazTech

Ograniczanie wyników

Znaleziono wyników: 2

Liczba wyników na stronie

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych: curvilinear coordinate system

Sortuj według:

Ogranicz wyniki do:

Engineering design of low-head Kaplan hydraulic turbine blades using the inverse problem method

Krzemianowski Z.

Bulletin of the Polish Academy of Sciences. Technical Sciences

2019

Vol. 67, nr 6

1133--1147

The paper concerns the engineering design of guide vane and runner blades of hydraulic turbines using the inverse problem on the basis of the definition of a velocity hodograph, which is based on Wu’s theory [1, 2]. The design concerns the low-head double-regulated axial Kaplan turbine model characterized by a very high specific speed. The three-dimensional surfaces of turbine blades are based on meridional geometry that is determined in advance and, additionally, the distribution of streamlines must also be defined. The principles of the method applied for the hydraulic turbine and related to its conservation equations are also presented. The conservation equations are written in a curvilinear coordinate system, which adjusts to streamlines by means of the Christoffel symbols. This leads to significant simplification of the computations and generates fast results of three-dimensional blade surfaces. Then, the solution can be found using the method of characteristics. To assess usefulness of the design and robustness of the method, numerical and experimental investigations in a wide range of operations were carried out. Afterwards, the so-called shell characteristics were determined by means of experiments, which allowed to evaluate the method for application to the low-head (1.5 m) Kaplan hydraulic turbine model with the kinematic specific speed (»260). The numerical and experimental results show the successful usage of the method and it can be concluded that it will be useful in designing other types of Kaplan and Francis turbine blades with different specific speeds.

The curvilinear coordinates' approach to the smart-designs generation problem

Pietraszek J.

Archives of Materials Science and Engineering

2008

Vol. 34, nr 1

48-51

Purpose: The aim of this paper is to present an alternative approach to the problem of accuracy estimation for smart-designs' class (also named space-filling or intelligent design) by making use of the design’s geometrical properties. Design/methodology/approach: The assumed topographical condition: ‘all design cases have to be on the defined surface' is reversed into a curvilinear coordinate system mapped on this surface. Then a sequence of irregular experimental designs is generated on the surface with various descriptive parameters and sampling from testing function is taken. Next, the identification of a general linear-quadratic model is conducted and various accuracy measures in comparison to a test function are calculated. At last the monotonic correlation analysis between accuracy measures and the design's geometrical properties is conducted. Findings: Significant and strong correlation between the accuracy measures and some of the geometrical properties has been found. Research limitations/implications: The correlations found are a strong suggestion for further research. The future investigations should be provided with various and more complicated testing functions and different topographical conditions. The relations between geometrical properties and accuracy measures need to be identified and their distributions and confidence intervals need to be determined. Practical implications: The results obtained outline the method of the approximation accuracy estimation from geometrical properties of the design. Originality/value: Worked out formulas may be of a significant value for those conducting data mining in technological data warehouses.