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.

Device and method for measuring ullage and material level of mine deep-hole chute

Abstract: The invention discloses a device and a method for measuring the ullage and the material level of a mine deep-hole chute and aims at solving the technical problem of accurate online continuous material level measurement when the mine deep-hole chute is blocked by high-concentration dust. The device for measuring the ullage and the material level of the mine deep-hole chute comprises a chute measuring trolley, a laser level meter, an electric rocker arm, a digital display instrument, a PLC and a video sighting system, wherein the electric rocker arm is fixedly connected to the chute measuring trolley; the video sighting system comprises a camera and a liquid crystal monitor; the camera is located on the front end of the electric rocker arm, while the liquid monitor is located on the rear end of the electric rocker arm; the camera is connected with the liquid crystal monitor by use of a transmission cable; the laser level meter is connected with the input end of the PLC; the output end of the PLC is connected with the input end of the digital display instrument. The device for measuring the ullage and the material level of the mine deep-hole chute is integrated with the high-accuracy laser level meter and the auxiliary devices, and is used for measuring by use of a soft measurement method, and the overall measurement accuracy can be +/-1%FS.

Explosive Hydrazine Decomposition Due to Rapid Gas Compression (Adiabatic Heating)

Abstract: : White Sands Test Facility (WSTF) is presently conducting tests to determine the explosive decomposition properties of hydrazine when initiated by rapid gas compression (adiabatic heating). During the development of hydrazine power systems, there have been strong indications that compression of gas bubbles entrained in liquid may have produced explosive decomposition. Testing to identify the conditions that would cause such explosions were initiated at Sundstrand Corporation using a standard U-tube type apparatus. In this apparatus, pressure and/or shock waves were suggested as being the initiation for the observed explosion. The objective of this study was to design an apparatus that would eliminate the contact of the pressure and/or shock waves with hydrazine and then repeat similar tests as conducted by Sunstrand. An apparatus was designed that contained a moveable diaphragm which separated the hydrazine from the pressurant source. In this system a specific gas ullage in the liquid hydrazine can be established and when the diaphragm is depressed during pressurization, the gas ullage is in turn compressed. The results indicated that compression of small gas nitrogen bubbles (0.73 cc) were capable of causing hydrazine to explode. Hydrazine explosions were found to be dependent on the initial hydrazine temperature, gas bubble compression rate, and impurities in the hydrazine.

Parametric Visualization Study of Self-Pressurizing Propellant Tank Dynamics

Abstract: Nitrous oxide is frequently used as a self-pressurizing propellant in hybrid rocket propulsion systems. To study the behavior of these self-pressurized propellant tanks, two different pressure vessels with optical access have been developed that can be filled with nitrous oxide and drained in a way that replicates the conditions of a hybrid rocket motor firing. Carbon dioxide was used as a simulant fluid for nitrous oxide to mitigate explosion and environmental hazards. High speed cameras are used to visualize the internal flow and identify boiling, condensation, and liquid level motion while pressure and temperature sensors are used to determine the thermodynamic state within the tank. Tests have identified two separate temporal regimes that are common to all tests, a transient and steady state, each described by distinct features. The transient regime is characterized by a rapid pressure drop and recovery, with homogeneous condensation of the ullage and heterogeneous nucleation and growth of bubbles in the liquid. The steady state regime begins when a large population of bubbles has been formed in the liquid and a balance is established between nucleation of new bubbles and death of bubbles as they reach the free surface and transfer their mass to the ullage. During this steady state regime the liquid and vapor are both homogeneous two-phase mixtures and the pressure drops in a linear fashion as the liquid drains from the tank. Also presented in this paper are the results of tests of parameter variations, including flow rate, fill level, temperature, initial bubble population, and scaling effects. The same basic features are present in each of these tests.

Measurements of jet-induced pressure decay in a thermally stratified tank

Abstract: Forced mixing may be required for controlling pressure during in-space storage and transfer of cryogenic propellants and life support fluids. To provide applicable data on jet-induced mixing, a l-g experiment was conducted in which an axial jet mixer promoted condensation of the ullage and lowered the pressure in a subscale cylindrical tank partially filled with thermally stratified Freon 11. The experiment objectives were to 1) correlate pressure reduction times with experiment parameters, 2) compare the pressure reduction times to mixing times determined by previous investigations using acid-base neutralization and dye dispersion, and 3) determine the transient condensation and heat transfer rates at the liquid surface as a function of jet parameters. Pressure reduction times were correlated with the rate of jet momentum addition to the bulk fluid. Dimensionless pressure reduction times agreed with comparable acid-base neutralization data, but not with dye dispersion data. The variation of interface heat transfer coefficient with changes in jet Reynolds number was consistent with an existing correlation based on measurements of steady-state rates of mixing-induced condensation of steam.