International Journal of Heat and Mass Transfer
2020

Experimental investigation of pressure drop of feeding pipes of liquid oxygen in a five-way distribution cavity under different working states

F.S. Xie^a,b, H.W. Mao^a, Y.Z. Li^a,b, E.F. Chen^c, Y. Ma^a
aInstitute of Refrigeration and Cryogenic Engineering, School of Energy and Power Engineering, Xi’an Jiaotong University, Xi’an 710049, China
^bState Key Laboratory of Technologies in Space Cryogenic Propellants, Beijing 100028, China
^cBeijing Institute of Astronautical System Engineering, Beijing 100076, China

摘要：

The uniform distribution of liquid oxygen is essential for design of feeding system in multi-engines of cryogenic rockets. Aiming at a cryogenic launch vehicle with four engines in parallel, a five-way spherical cavity structure was used to evenly distribute liquid oxygen in the multi-branch pipes. These cryogenic rocket engines need to be controlled by opening or closing states for multi-branch pipes to adapt different flight conditions. To study effect of working states on pressure drop in the four branch pipes with the five-way spherical cavity, a large-scale test system was constructed to carry out discharging flow of liquid oxygen. The feeding pipes of full-scale model were adopted, and forty-nine sensors were arranged in the pipes to measure pressure and temperature of liquid oxygen. The constant discharging flow was maintained by a feedback system of tank pressure. The opening or closing states of branch pipes were controlled by cut-off valves at the end of each branch pipe. The liquid oxygen tests were carried out under different actual flight conditions. The results shown that the opening or closing states for four branch pipes had a dramatic effect on the pressure drop in the multi-branch pipes. When the branch pipes all drained at the same time, there was a large pressure drop in two symmetrical branch pipes which enhanced linearly with the increase of Reynolds number. The pressure drop of two branch pipes on the symmetrical sides could exceed 0.1 MPa which was far greater than the normal flow resistance, when the Reynolds number was 5.0 × 10⁶. It was found that there was a regular swirling flow formed in the five-way spherical cavity by using CFD method. When two branch pipes were turned off, whether symmetrical sides or adjacent sides, the large pressure drop still existed, and was positively correlated with the varying Reynolds number. The maximum pressure drop in the branch pipes was close to 0.09 MPa, when the Reynolds number was 3.3 × 10⁶. When three branch pipes were closed, the large pressure drop disappeared, and the flow resistance related positively with the Reynolds number, which accorded with the normal flow resistance. Moreover, according to data of six hot test runs and two verification tests, it was found that the inlet pressure in the main pipe had greatly influence on the pressure drop, which raised sharply as the inlet pressure increased. These results could help to provide a design reference for feeding system of multi-engines in cryogenic rockets.