Influence of the meridional section shape on the external characteristics of hydraulic couplings with a vertical axis of rotation
Abstract Generated abstract
This paper examines how the meridional section shape of working wheels affects the external characteristics of hydraulic couplings with a vertical axis of rotation. Using comparative characteristics for couplings with upper and lower pump wheel arrangements, it varies the section depth of one runner while holding the other unchanged and evaluates the resulting torque behavior, especially at small slips. The study finds that the standard “Vulkan” profile is not optimal for vertical-axis couplings with a lower pump wheel, where increasing the turbine wheel section depth has the strongest effect and a depth about 1.2 times the horizontal-axis profile gives characteristics close to those of horizontal-axis couplings. For upper pump wheel arrangements, the influence is weaker, and conventional horizontal-axis dimensions are considered sufficient.
Full Text
INFLUENCE OF THE SHAPE OF THE MERIDIONAL SECTION ON THE EXTERNAL CHARACTERISTICS OF FLUID COUPLINGS WITH A VERTICAL AXIS OF ROTATION
S. I. Shubovich, Yu. I. Kapustin
(Presented by the scientific seminar of the Department of Applied Mechanics)
The most widespread form of the meridional section of fluid couplings that have symmetrical working wheels and operate with a horizontal axis of rotation is the form recommended by the firm “Vulkan.”
Fig. 1
An investigation of the external characteristics of a fluid coupling with a vertical axis of rotation and a lower location of the pump wheel, having the “Vulkan” form, showed that the torque transmitted by it at small slips is significantly less than the torque of the same fluid coupling with a hori-
with a horizontal axis [1]. This indicates that the “Vulkan” shape does not ensure transmission of maximum torque in fluid couplings with a vertical axis and, consequently, is not optimal for these designs.
Fig. 2. External characteristics of fluid couplings with a vertical axis of rotation and a lower arrangement of the pump wheel: \(a\)—characteristics of fluid couplings having an unchanged section depth of the pump wheel equal to \(0.43B\); \(b\)—characteristics of fluid couplings having an unchanged section depth of the turbine wheel; 1—characteristics of fluid couplings with a section depth of the working wheels equal to \(0.25B\); 2—the same, \(0.43B\); 3—the same, \(0.545B\); 4—the same, \(7.765B\).
Fig. 3. External characteristics of fluid couplings with a vertical axis of rotation and an upper arrangement of the pump wheel: \(a\)—characteristics of fluid couplings having an unchanged section depth of the pump wheel; \(b\)—characteristics of fluid couplings having an unchanged section depth of the turbine wheel; 1—characteristics of fluid couplings with a depth of the meridional sections of the working wheels equal to \(0.25B\); 2—the same, \(0.43B\); 3—the same, \(0.545B\); 4—the same, \(7.765B\).
To determine the optimal shape of the meridional section, the external characteristics of fluid couplings were obtained for different relative positions of the runners, which had the profiles of meridional sections shown in Fig. 1. In this case, the shape of one runner remained unchanged, while the shape of the other runner had a different section depth.
The external characteristics of fluid couplings with a lower arrangement of the pump wheel and different shapes of the meridional sections are given in Fig. 2; with an upper arrangement of the pump wheel, in Fig. 3.
As can be seen from the characteristics presented, the effect produced by changing the depth of the meridional section of the runners on the torque transmitted by the coupling is not the same. This is especially noticeable in fluid couplings with a lower arrangement of the pump wheel. In this case, increasing the section depth of the turbine wheel leads to a more significant increase in torque than increasing the section depth of the pump wheel. When the depth of the meridional section of the turbine wheel is equal to 1.2 times the section depth of the “Vulkan” profile, the external characteristic of the fluid coupling with a vertical axis differs little from the analogous characteristic of a fluid coupling with a horizontal axis.
In fluid couplings with an upper arrangement of the pump wheel, increasing the section depth of both wheels leads to a slight and almost identical increase in torque at small slips. A decrease in the section depth of the runner profile in all cases leads to a significant reduction in the energy capacity of the fluid coupling.
Thus, when designing fluid couplings with a vertical axis of rotation and a lower arrangement of the pump wheel, the shape of the meridional section, in the case of symmetrical wheels, should be taken with a depth equal to 1.2 times the section depth of the runners of fluid couplings with a horizontal axis. In the case of asymmetrical wheels, the depth of the meridional section of the pump wheel may be taken equal to the section depth of fluid couplings with a horizontal axis. For fluid couplings with an upper arrangement of the pump wheel, since their characteristics differ only slightly from the analogous characteristics of fluid couplings with a horizontal axis, the same dimensions as those used for fluid couplings operating with a horizontal axis of rotation may be recommended for the meridional sections of the runners.
REFERENCES
- Yu. I. Kapustin, A. V. Murin. On estimating the influence of the position of the axis of rotation of a fluid coupling on its external characteristic. Izv. TPI, vol. 173, 1968.