The RTAH is quite similar with the space rotor - type superchargers, having used in the space vehicles temperature control systems, by their hydraulic characteristics.
At present, the RTAH designing analytical and calculating basis has been borrowed just from the industrial goods selling centrifugal pumps designing field. The design procedure is rich in a great number of the empirical coefficients and the factors, not having had their physical bases and the grounds, and it, moreover, is not quite being provided the best parameters achievement.
At the flowing in the impeller (which is the RTAH principal element), the flowing in the boundary layer has been become the dominating hydrodynamic factor, because of its diminutiveness. So, the used design procedures are being ignored this peculiarity and the specific feature, and also they are being provided the inefficient, from the power transmission mechanism point of view, the impeller flowing forms, having resulted in the efficiency factor lowering, the vortex formation process increase, and the energy flow pulsation component and the constituent part rise. The existing heart constructions sizes and the required power are being appeared to be the overestimated ones. The above - indicated shortcomings consequence are being become the following:
- the device increased sizes and the weight;
- the increased power consumption;
- the underestimated resource (e.g. action period) for the power unit charging one cycle;
- the construction overheating because of the increased radial sizes;
- the impeller increased traumatic influence upon the blood structure, in which the blood clots are being appeared, having provoked the stroke and the heart attack onset.
It has been turned out historically in our country in such a way, that the main works in the dimunitive rotor - type superchargers field have been carried out in the space - rocket hardware. The technological perfection level, having achieved there, has been considerable exceeded the analogous ground and the terrestrial equipment indicators. The aerospace industry offset rotor - type superchargers are much more compact and smart, and also efficient, than the ground destination their analogues. The challenge is being consisted in the fact, that it is quite impossible mechanically to be turned out to transfer the space ingeneering and the space technology designing experience to the artificial organs field, as these devices operation conditions are being obtained the principal distinctions series.
In particular, the aerospace industry offset rotor - type superchargers must be sustained the heat carrier temperatures considerable drops. The tightened requirements and the raised standards on the anticavitation qualities are being made great demands to them, they must reliably to be worked under the zero gravity conditions. The supply voltage must not be beyond the 24 V...27 airborne voltage values limit. There is also the other specific requirements series to the aerospace industry offset devices.
Many requirements, having conditioned by the application space field, are not quite actual for the land - based pumps, and, at the same time, they are considerably influenced upon the rotor - type supercharger flowing part optimization scheme. That is why, it is quite reasonable to use the knowledge in the field of the flowing hydrodynamics, having received at the space technology and the space engineering making for the medical equipment and the artificial organs development.
The vortex formation zones
and the flow separation
Fig.1. The lines of the flow visualization
on the impeller disk
In particular, it is necessary to be used the data on, that the local vortex structures are being appeared at the impeller miniaturization, having brought the considerable irregularity in the velocity field and the working substance pressures, having passed along the canals, see Fig.1. Consequently, the impeller deflecting characteristics are being lowered, the pressure qualities of the rotor - type artificial heart are being worsen, the construction radial sizes are being increased. One from the rotor - type application main advantages in the artificial blood circulation systems is being lost - that is, the minimum overall dimensions and the mass. If to be used the theory, on which the space pumps designing is being based on, then the above - indicated drawbacks are quite possible to be removed to the considerable extent.
Besides, it is quite possible substantially the impeller pressure qualities to be raised and, as the result of it, the rotor - type artificial heart to be designed more efficient in the operation, with less the impeller traumatic influence upon the blood.
The work was submitted to international scientific conference «Prospects for the development of university science», Dagomys (Sochi), September 21-24, 2009. Came to the editorial office on 03.08.2009.
[1] The"Michael Debeiky Academitian: I rather like it more to be the ordinary physician, than the mature scientist" paper//The "Izvestiya" newspaper, No.72,it is dated from 19.04.2000, p.7, the last passage in the 1-st column.