RU2085886C1 - Method of check of space vehicle system for tightness - Google Patents

Abstract

FIELD: testing technology. SUBSTANCE: pressure of working medium in system, its temperature and ambient air pressure are measured at the beginning and at the end of holding period; besides that, change in integral temperature of liquid in liquid chamber of system within the same period of time is measured. Untightness of system is judged from volume of liquid contained in liquid chamber and mass of gas in gas chamber measured in filling the system with working medium. EFFECT: enhanced efficiency.

Description

 The invention relates to the field of testing equipment and can be used for testing spacecraft systems for leaks at the final stage of preparation of spacecraft for launch, when the systems (for example, thermal control system) of spacecraft are filled with a working medium.

 Known methods for monitoring the tightness of systems of spacecraft filled with a working medium, which consists in assessing the leakage of the system by measuring the rate of decrease in pressure of the working medium in the system.

 Closest to the technical essence of the proposed is a method for monitoring the tightness of spacecraft systems filled with a working medium, which consists in measuring at the beginning and end of the shutter speed for a given period of time the pressure of the working medium in the system, the temperature and pressure of the ambient air, and an assessment of the measured values of the system leakage .

 This method is adopted as a prototype.

 The disadvantage of the prototype and other known methods is that they are valid only for monitoring systems that are completely charged with a medium homogeneous in physical properties (usually gas), since the geometric volume occupied by the medium coincides with the internal volume of the controlled system, and these methods suggest the invariance of the geometric volume occupied by the medium in a controlled system. Since in most cases the systems are made of materials with small linear temperature expansion coefficients (primarily metals), deformations of the systems over a given period of time associated with temperature changes are negligible. Consequently, the changes in the geometric volume occupied by the medium, which are associated with changes in temperature, are negligible, despite the fact that changes in the pressure of the medium (gas or, to a much greater extent, liquid) caused by temperature changes can be significant.

 These methods become unacceptable in the case of heterogeneous systems, i.e., systems, part of the volume of which is charged with liquid, and part with gas, both of which communicate through a movable separation shell, for example, a membrane or a bellows (the most typical example of such heterogeneous systems is the space temperature control system devices).

 This is due to the fact that the design of such systems is originally designed to compensate for significant changes in the geometric volume occupied by the liquid, and, accordingly, to provide acceptable values for the change in liquid pressure.

 This basic property of the design of the systems under consideration leads to the fact that temperature changes during a given period of time cause significant changes in the geometric volumes occupied by heterogeneous media (liquid and gas) in the controlled system, and these changes, in turn, if they are not taken into account , lead to obviously wrong conclusions about the leakage of the controlled system.

 The technical result is the ability to control heterogeneous spacecraft systems, i.e. spacecraft systems, consisting of liquid and gas cavities separated by a flexible membrane of the compensator, filled with a working medium.

 The technical result is achieved by the fact that in the known method for checking the tightness of spacecraft systems, consisting of liquid and gas cavities separated by a flexible membrane of the compensator, filled with a working medium, which consists in measuring at the beginning and end of exposure for a given period of time the pressure of the working medium in the system, temperature and the ambient air pressure and the assessment of the measured values of the leakage of the system, when filling the system with a working medium, the volume of liquid in the liquid and sous gas in the gas cavities system during exposure further comprises determining a change for the same predetermined time temperature integral fluid cavity in fluid systems and allow for specific values in the evaluation system leaks.

 Thus, when monitoring the proposed method, changes in geometric objects occupied by heterogeneous media (liquid and gas) in the controlled system are taken into account, which allows to ensure the necessary reliability of the control results.

A method for monitoring the tightness of spacecraft systems consisting of liquid and gas cavities separated by a flexible compensator membrane filled with a working medium (for example, a temperature control system, the liquid cavity of which is filled with Temp coolant of volume V _w , and the working medium pressure in the system is created by filling the gas cavity gaseous nitrogen of mass m (r) to an overpressure P _r ) is carried out as follows.

где R универсальная газовая постоянная;
M_r молекулярный вес азота;
B коэффициент линейного расширения теплоносителя.Measure the pressure P _{r (n)} and P _{r (k) of the} working medium in the system, the temperature t _{r (n)} and t _{r (k)} (it is practically equal to the temperature of nitrogen in the gas cavity at the beginning and end of the exposure for a given period of time T system) and the pressure P _{b (n)} and P _{b (k)} of the surrounding air, and also determines the variation in the same lapse vremeniT integral temperaturyt _w coolant cavity in fluid systems and evaluate leakage system Q _{systems are:}

where R is the universal gas constant;
M _{r is the} molecular weight of nitrogen;
B coefficient of linear expansion of the coolant.

Вместе с тем при абсолютной герметичности жидкостной полости системы изменение объема теплоносителя (^V_ж)_темп в ней было бы обусловлено только изменениями интегральной температуры теплоносителя и составило бы:
(^V_ж)_темп B•V_ж•^t_ж. (6)
Поскольку изменение объема теплоносителя (^V_ж)_негерм за счет утечки его из жидкостной полости системы определяется из уравнения: V_ж (^V_ж)_темп + (^V_ж)_негерм, (7)
или,
(^V_ж)_негермV_ж (^V_ж)_темп, (8)
откуда

то, подставляя в уравнение (9) равенства (5) и (6), получим искомое соотношение (1).During a given period of time T, both the leakage of the coolant from the liquid cavity of the system, leading to a decrease in the volume of coolant in the latter, and a change in the volume of coolant in the liquid cavity of the system due to a change in the integral temperature of the coolant. In this case, the total change in the volume of the coolant in the liquid cavity is equal to the change in the volume of nitrogen in the gas cavity of the system, taken with the opposite sign V _W V _r V _{r (n)} V _{r (k)} . (2)
The equation for nitrogen in the gas cavity of the system, written for the state of the beginning of a given time interval T, is as follows:
[P _{r (n)} + R _{b (n)} ] • V _{r (n)} m _(r) • R • t _{r (n)} / M _r , (3)
and, accordingly, recorded for the state of the end of a given period of time T, the following:
[P _{r (k)} + P _{b (k)} ] • V _{r (k)} m _(r) • R • t _{r (k)} / M _r . (4)
Selecting from the equations (3) and (4) the values of V _{r (n)} and V _{r (k)} and substituting them in the expression (2), we obtain:

However, with the absolute tightness of the liquid cavity of the system, a change in the volume of the coolant (^ V _W ) the _rate in it would be due only to changes in the integral temperature of the coolant and would be:
(^ V _w ) _tempo B • V _w • ^ t _w . (6)
Since the change in volume of the coolant (^ V _{w) negerm} due to leakage from its liquid cavity system is defined by the equation: V _w (^ V _{w) rate} + (^ V _{w) negerm,} (7)
or,
(^ V _f ) _negherms V _f (^ V _f ) _tempo , (8)
where from

then, substituting equalities (5) and (6) into equation (9), we obtain the desired relation (1).

 When using the proposed method, it is possible to test systems (for example, thermal control systems) of spacecraft filled with a working medium for leaks during the preparation of spacecraft at the starting position and, therefore, the reliability of the system in flight.

Claims (1)

 A method for monitoring the tightness of spacecraft systems, consisting of liquid and gas cavities separated by a flexible membrane compensator, filled with a working medium, which consists in measuring at the beginning and end of exposure for a given period of time the pressure of the working medium in the system, the temperature and pressure of the ambient air, and the assessment of the measured leakage values of the system, characterized in that when filling the system with a working medium, the volume of liquid in the liquid and the mass of gas in the gas cavities of the system are determined , during the aging process, the change in the same specified period of time is additionally determined for the arithmetic mean temperature of the liquid in the liquid cavity of the system and these values are taken into account when evaluating the leakage of the system.