Partial Flow Rate Research Articles

On the Partial Flow Rate Performance of Axial-Flow Compressor and Rotating Stall : 2nd Report, Influences of Impeller Load and a Study of the Mechanism of Unstable Performances

Two experimental investigations of the off-design operations of axial-flow compressor are described. One of them is an investigation of influences of impeller load on both partial flow rate performances and the rotating stall characteristics, the other being an attempt to make clear the mechanism of the unstable performance related with rotating stall. The width of the rotating stall regions and a decrease in discharge pressure in the partial flow rate region become small as the impeller load decreases. When the impeller load becomes so small that rotating stall completely disappears, the slope of the performance curve becomes negative at all flow rates. It is clear that the reverse flow of rotating stall (large stall) reverses from delivery to suction side across the rotor. The mechanism of the reverse flow is discussed and it is shown that the reverse flow is the cause of the unstable performance.

On the Partial Flow Rate Characteristic of Axial-Flow Compressor and Rotating Stall : 3rd Report, On the Devices for Improving the Unstable Characteristic and Their Stall Conditions

On the Partial Flow Rate Characteristic of Axial-Flow Compressor and Rotating Stall : 3rd Report, On the Devices for Improving the Unstable Characteristic and Their Stall Conditions

On the Partial Flow Rate Performance of Axial-Flow Compressor and Rotating Stall : 3rd Report, On the Devices for Improving the Unstable Performance and Stall Condition

Effects of suction and separator, which are used to improve the off-design operations of axial-flow compressors, on the performance curves and stall conditions are studied experimentally. A suction ring has a large effect on the rotating stall characteristics. Application of suction ring with unsuitable geometrical dimensions results in undesirable rotating stall, and the decrease in discharge pressure becomes more remarkable than that of one with out suction ring. On the other hand, a separator has quite useful improving effects on the rotors in which rotating stall occurs. The most effective geometrical dimensions are shown in consideration of partial flow rate performance, stall condition and noise. In addition, the working mechanism of the separator is discussed.

On the Partial Flow Rate Performance of Axial-Flow Compressor and Rotating Stall : 1 st Report, Influences of Hub-Tip Ratio and Stators

On the Partial Flow Rate Performance of Axial-Flow Compressor and Rotating Stall : 1 st Report, Influences of Hub-Tip Ratio and Stators

On the Partial Flow Rate Characteristic of Axial-Flow Compressor and Rotating Stall : 2nd Report, On the Influence of Impeller Load on the Performance and a Study on the Mechanism of Unstable Characteristic

On the Partial Flow Rate Characteristic of Axial-Flow Compressor and Rotating Stall : 2nd Report, On the Influence of Impeller Load on the Performance and a Study on the Mechanism of Unstable Characteristic

On the Partial Flow Rate Characteristic of Axial-Flow Compressor and Rotating Stall : 1st Report, Influence of Hub-tip Ratio and Stators

On the Partial Flow Rate Characteristic of Axial-Flow Compressor and Rotating Stall : 1st Report, Influence of Hub-tip Ratio and Stators

Simulating oxygen transport in the microcirculation by Monte Carlo methods

Oxygen transport in the human cerebral cortex has been simulated previously by considering a single straight capillary and a concentric tissue cylinder as a representa tive sample (the Krogh tissue cylinder). The same geo metric model has been assumed for this study because of its probable accuracy and to allow comparison with previous calculations. Because of the nonlinear equilibrium relationship be tween dissolved and hemoglobin-bound oxygen (the oxy gen dissociation curve), a differential mass balance yields a nonlinear partial differential equation describing oxy gen transport in the capillary. In the tissue a constant consumption rate is assumed and a linear partial differ ential equation results. The tissue equation and the capillary equation are solved simultaneously, to account for capillary-tissue interaction, thus giving axial and radial oxygen partial pressure profiles for the total system. The Monte Carlo method has been employed to solve the resulting set of equations on a digital computer. This technique involves a numerical scheme wherein a process is simulated directly by a random walk phenomenon (Markov process). A particular advantage of this method is that solutions may be obtained for one point in space independently of all others. Therefore, an analysis of the transient response of the "lethal corner" is possible with out solving for the entire mesh. Computation time with the Monte Carlo method was considerably less than that with standard deterministic numerical calculation tech niques. Two models were considered. In the first model the oxygen dissociation curve was linearized, thus giving a linear partial differential equation describing oxygen transport in the capillary. The second model considered the nonlinear nature of the oxygen dissociation curve, and a nonlinear partial differential equation was ob tained. However, because of difficulties with the Monte Carlo method, it was necessary to solve the equations in a quasi-nonlinear manner. For both the linear and the quasi-nonlinear models, solutions were obtained for the steady state with normal conditions and for dynamic cases. Perturbations of ar terial-oxygen partial pressure and blood flow rate were forced, and the behavior of the system was determined. The pure diffusional model checked with previous de terministic calculations demonstrating very rapid re sponse with time constants in the order of 2 seconds. However, the shapes of the intracapillary and tissue oxy gen tension profiles differed somewhat and no allow ances were made for autoregulatory phenomena such as varying flow rates.

Mechanism of Heterogeneous Deposition of Thin Film Rutile

The kinetics of rutile thin film deposition on silicon from the reaction has been studied over a range of temperature (673°–1320°K), titanium tetrachloride partial pressure , and oxygen partial présure in a horizontal flow system with a rf‐heated susceptor. Between 673° and 1120°K the reaction has been found to proceed by a Rideal‐Eley mechanism with the surface reaction rate constant following the relationship exp , over a range of partial pressures and flow rates. Homogeneous reaction becomes appreciable above 1120°K.

Studies on the Characteristics of Axial-Flow Pumps : Part 2, Analytical Method of Determining the Discharge-Theoretical Head Characteristics

In this paper, the flow in an axial-flow pump impeller at partial flow rates is studied by dividing it into two domains ; one is near the casing wall where the radial flow is seriously affected by the wall, another is far from it where the fluid flows along impeller blades and the effect of the wall is negligibly small. By considering about the flow in impeller blades in this way, it becomes possible to analyse an impeller action and to demonstrate the reason for the conspicuous increase of the head at partial quantities. The analytical method to find the relation between the discharge and the theoretical head is obtained. But the complexity of the flow makes it necessary to introduce some coefficients, which should be determined empirically.

Studies on the Characteristics of Axial-Flow Pumps : Part 2, Analytical Method of Determing "Discharge-Theoretical Head" Characteristics

In this paper, the flow in an axial-flow pump impeller at partial flow rates is studied by dividing it into two domains ; one is near the casing wall where the radial flow is seriously affected by the wall, another is far from it where the fluid flows a1ong impeller blades and an effect of the wall is negligibly small. By considering about the flow in impeller blades in this way, it becomes possible to analyse an impeller action and to demonstrate the reason for the conspicuous increase or the head at partia1 quantities. The analytical method to find the relation between the discharge and theoretical head is obtained. But a complexity of the flow makes it necessary to introduce some coefficients, which should be determined empirically.