Sensor of volume and angular position of the liquid mirror in tanks with axial symmetry at an indefinite orientation tanks in space

Abstract

The issues of increasing the accuracy of volume sensors and the angular position of the liquid mirror in the fuel tanks of upper stages of spacecraft are covered. It is shown that the existing sensors of this type do not always meet the stringent requirements for their accuracy and reliability characteristics, especially under conditions of an indefi nite position of the liquid mirror. The principle of construction and design of a sensor for tanks with axial symmetry (spherical, cylindrical, lenticular, etc.) is proposed, which provides simultaneous measurement of the amount and angular position of the liquid mirror with high accuracy under the specifi ed conditions. This sensor consists of one linear and several ring sensing elements immersed in liquid and designed for the primary conversion of the immersion depth into an informative signal. The linear sensing element is installed along an axis passing through the center of the tank and the intake hole, and the ring elements are installed in a plane perpendicular to this axis, at a distance from each other determined by a given error. The operation of linear and ring elements can be based on a thermoresistive or capacitive principle. In the latter case, the sensitive elements may take the form of resonant circuits consisting of one linear and several ring capacitances, to which inductances are connected. Algorithms have been developed for converting the resonant frequencies of at least two sensitive elements into the desired parameters: the volume and angular position of the liquid in the tank. The estimation of the components of the total error of the sensor, due to various factors: the discreteness of the sensor design, the spread of the geometric dimensions of the tank and sensitive elements, as well as the own errors of the sensitive elements, was carried out. It is shown that the main factor limiting the accuracy of the sensors is the reduced errors of the sensitive elements: with the reduced error of these elements of 10 –3 , the similar errors of the sensor are no more than 2.2∙10 –2 in angle and 3.2∙10 –3 in volume. The proposed sensor can be used to measure the specifi ed parameters in objects characterized by an indefi nite position in space (spacecraft, sea vessels during rolling or heel).