Effect of Flow Rate of Side-Type Orifice Intake on Withdrawn Water Temperature
Side-type orifice intake is a type of selective withdrawal facility used in managing reservoirs to mitigate the negative effects of low-temperature water. Based on the temperature data of a thermal stratified reservoir in China, an experiment was conducted in flume to study the influence of intake flow rate on withdrawn water temperature with different temperature distributions. Results indicated that withdrawn water temperature changed with different flow rates. The temperature change was determined by the water temperature gradients above and below the intake, whereas the change trend of temperature depended on the difference between the water temperature gradient above and below the intake. We likewise proposed a new equation with which the withdrawn water temperature of a thermal stratified reservoir using a side-type orifice could be calculated. These findings could be directly applied to the design and operation of side-type orifice intake in thermal stratified reservoirs.
Experiments on Selective Withdrawal of a Codirectional Two-Layer Flow through a Line Sink
For investigating selective withdrawal problems, laboratory experiments were conducted in a horizontal flume with a co-directional two-layer flow of different density into a line sink. Saline water was used as the fluid of the lower layer instead of sediment-laden turbid water for achieving a steady state. In this study, a trend curve was produced using the data of many runs which were taken under varying conditions from aspiration of both layers to only lower-layer aspiration. An adequate parameter for determining the critical condition was obtained from this trend curve. The critical condition is defined as the beginning or ending of aspiration for the upper layer. Suitable variables for the parameter are also discussed. A theoretical formula is suggested and verified, which is better than a traditional empirical formula for calculating the withdrawal concentration. Effects of slot elevation on the lower layer flow and the thickness of the mixing layer are also discussed.
HYPERGOLIC REACTION MECHANISMS OF CATALYTICALLY PROMOTED FUELS WITH ROCKET GRADE HYDROGEN PEROXIDE
Abstract The coupling of the physical and chemical processes controlling the ignition delays (τ ign ) of hypergolic propellants complicates the direct analysis of the transient ignition processes. The transport properties of both the propellants and the ambient gas, and the heat of vaporization and reaction affect τ ign and must be considered experimentally. Furthermore, since hypergolic ignition occurs, by definition, on contact, the mechanics of initial contact and subsequent mixing can affect τ ign and must also be considered. Experimental results from a study of the hypergolic ignition of a catalytically promoted fuel with rocket grade hydrogen peroxide (RGHP) are presented. Statistical analysis of the experimental data was conducted to evaluate the relative effects of RGHP concentration, initial ambient pressure, and the ambient gas on τ ign . At RGHP concentrations of less than 92% in water, stable ignition was difficult to achieve. At sufficiently high Lewis number, an oscillatory ignition process is observed. A phenomenological model comprising mixing, RGHP decomposition, fuel heating and vaporization, and auto-ignition is presented and compared to the experimental results.