Impinging distance effect

To an extent, the intensity of impingement is dependent on the impinging distance, S, and smaller S implies stronger impingement. Therefore it is also of interest to understand the effect of the impinging distance on the size distribution of droplets. The... 

To examine the reasonableness of the device structure, the effects of impinging distance, S, and placement of the nozzles are studied in certain ranges. 

Interception A special case of impingement, in which a particle is trapped on a fiber due to the effect of Van der Waals forces rather than inertia. The interception of a particle in a particle collection device occurs when the particle follows a gas streamline round a collector at a distance less than the radius of the particle. 

Droplets were collected on 1-inch ethylcellulose strips, placed laterally across the wind tunnel floor at various distances downwind, and on 11-mm. glass rods located 40 inches downwind from the spray nozzle. The effective fall distance for droplets impinging on the wind tunnel floor was 2 feet. Droplet sizes that reach the glass rods will not all impact efficiently, and the efficiency varies with droplet diameter (2, 4). Nonetheless, the size droplet reaching a given glass rod was approximately... 

Fig.4.5.4. A scheme for demonstrating the effect of different penetration distances in impinging streams...

When a photon enters a detector, it may or may not produce a signal or it may produce a signal lower than the discriminator threshold and, therefore, it is not counted. This effect is accounted for by the detector efficiency h, defined as the ratio of the number of photons recorded to the number of photons that impinge upon the detector per unit time. Statistically, the probability that a photon has at least one interaction in the detector Nal crystal is 1 - e r, where m is the linear attenuation coefficient of Nal and r is the distance that the photon travels in the crystal. For an isotropic radioactive point source, the detector efficiency can be expressed as (Tsoulfanidis, 1983)... 

In finite containers, the drag force acting on a particle increases because of two effects. Because the fluid is stationary within a finite distance of the particle, there is a distortion of the flow pattern that reacts back on the particle. The second effect occurs when the fluid streaming around the particle impinges on the container walls and is deflected back on the particle. Considering these two effects, the drag force may be modified as (8)... 

These results [2] suggest that a burner with a 1.5-2.0 mm (three- or four- ribbon) row separation distance and at least four ports is desirable to create a stable and uniform environment above the burner that is resistant to entrainment effects introduced due to impinging surface motion. These results are in agreement with the optimal flame separation distance previously determined by Pearson, Saunders, and Hargreaves [5]. 

PEC device efficiencies as measured by IPCE/EQE or STH implicitly include losses from impinging photons that are reflected or transmitted. To understand the inherent performance of a material, it is often helpful to subtract these losses and measure efficiency based only on photons absorbed. This is known as the absorbed photon-to-current efficiency (APCE), which describes the photocurrent collected per incident photon absorbed. APCE is synonymous with internal quantum efficiency (IQE). This is a particularly useful quantity to measure when studying thin films, since it helps to determine the optimum balance between maximal path-length for photon absorption versus minimal effective e /h" transport distance within the material. 

---