Ullage

About: Ullage is a research topic. Over the lifetime, 501 publications have been published within this topic receiving 4704 citations. The topic is also known as: headspace.

Systems and methods to provide compliance with structural load requirements for aircraft with additional fuel tankage

Abstract: Methods and systems are provided to comply with structural load requirements applicable to aircraft additional fuel tank systems. A plurality of aircraft fuel tanks (100,200) may be positioned adjacent to one another, preferably within the fuselage (10-1) (e.g., a cargo compartment) of the aircraft so as to be disposed generally along a longitudinal axis of the aircraft. The tank body defining an interior space for holding aircraft fuel, an intercommunication conduit assembly (104,105) between the fuel tank modules configured to refuel and transfer fuel from the tank modules by a cascade mode and an intentional air-filled ullage space are operatively associated with the tank body to prevent an overpressure condition within the interior space of the fuel tank body. The intentional air-filled ullage is obtained through the predetermined positioning of the terminal open end of the intercommunication tube inside the respective fuel tank module. The intentional air-filled ullage can be configured in all or in only some of the fuel tank modules according to the design of the auxiliary fuel tanks or aircraft structural loads requirements.

Microwave apparatus and method for ullage measurement of agitated fluids by spectral averaging

Abstract: A microwave apparatus and method for ullage measurement of agitated materials is provided. The apparatus and method utilize a transformation of the reflected time domain signal into a frequency domain signal. The frequency domain signal is averaged using the natural, inherent weighting associated with the transformation to achieve a unique corrected result. The average frequency domain signal is then used to calculate the average distance for determining the ullage measurement.

Numerical Simulation on Interface Evolution and Pressurization Behaviors in Cryogenic Propellant Tank on Orbit

Abstract: The interface distribution and self-pressurization phenomenon are the most important problems in the storage of cryogenic liquid on orbit, which are difficult to be predicted and assessed exactly due to the complex non-equilibrium thermal behavior. In this paper, one 3-D CFD model based on volume of fluid (VOF) method is established to investigate the interface evolution and self-pressurization process in the liquid oxygen (LOX) tank in microgravity environment with various heat loads and gravitational accelerations. The validity of the model is verified by both the present ground experiments and the drop tower experiments from literature. The impact of microgravity on the gas-liquid interface distribution in the cryogenic tank is analyzed. Different from the ground condition, the distribution behavior of the gas-liquid two-phase fluid in microgravity is that the liquid is covering the tank wall, and the ullage is staying at the top of the tank surrounded by the liquid. Then the pressurization rate of the tank with different gravitational accelerations is obtained. The tank pressure rise rate increases with the reducing of the gravity. The results are beneficial to the optimal design of the cryogenic propellant tank.

Influence of heat transfer rates on pressurization of liquid/slush hydrogen propellant tanks

Abstract: A multi-dimensional computational model of the pressurization process in liquid/slush hydrogen tank is developed and used to study the influence of heat flux rates at the ullage boundaries on the process. The new model computes these rates and performs an energy balance for the tank wall whereas previous multi-dimensional models required a priori specification of the boundary heat flux rates. Analyses of both liquid hydrogen and slush hydrogen pressurization were performed to expose differences between the two processes. Graphical displays are presented to establish the dependence of pressurization time, pressurant mass required, and other parameters of interest on ullage boundary heat flux rates and pressurant mass flow rate. Detailed velocity fields and temperature distributions are presented for selected cases to further illuminate the details of the pressurization process. It is demonstrated that ullage boundary heat flux rates do significantly effect the pressurization process and that minimizing heat loss from the ullage and maximizing pressurant flow rate minimizes the mass of pressurant gas required to pressurize the tank. It is further demonstrated that proper dimensionless scaling of pressure and time permit all the pressure histories examined during this study to be displayed as a single curve.