Numerical Modeling of a Planar Unconfined Oblique Jet Moving Along the Ground Surface

Abstract

Power-Augmented-Ram (PAR) and Vertical/Short Takeoff and Landing (V/STOL) vehicles use jet support at low speeds when the passive aerodynamic lift is not sufficient. Although V/STOL aircraft have been previously investigated, the PAR concept requires further understanding of the obliquely impinging jet. Previous modeling studies on jet impingement considered jets exiting from domain boundaries. However, many jet applications are not confined in the upward direction and require modeling of airflow entering the jet source. The unconfined jet, modeled as a ducted momentum source, is investigated in this work. The computational approach consists of a two-dimensional, steady, incompressible finite volume method utilizing the k-ε turbulence model. The numerical approach is validated for the planar turbulent free jet, jet normally impinging on the ground, and jet entering a channel under a ground-effect platform. New results are obtained for obliquely impinging jets moving along the ground. Flow structures are studied with focus on the upstream ground vortex, jet entrainment, downstream momentum flow, and effects of jet translating through a stagnant fluid. Beneficial aerodynamic configurations, which reduce ingestion and maximize downstream momentum flow, suggest small impingement angles and moderate ground distances.

Causes and Conditions for Reamer Blade Balling During Hole Enlargement While Drilling

“…The computation results of the improved to the existing reamer (circular nozzle with an angle of 60°) are presented in Figs. [16][17][18]. When adjusting these parameters, the angle of the high speed fluid region remained relatively constant at 21°.…”

Modelling of steady motion of PAR vehicle on solid surfaces

“…It is assumed that the propulsor exit areas, positions and inclination are set to produce a sufficiently thick jet with effective velocity ( )/ T k T bH ρ approaching the channel entrance. Calculation methods for oblique jets in ground effect are discussed by Smithey et al (1977) and Ockfen and Matveev (2009). To evaluate forces on side hulls due to contact with ground, a sectional model of elastic hulls is introduced.…”

Numerical and experimental hydrodynamic study of a coolant distributor for grinding applications

“…Previous studies on different types of impinging-jet cooling systems show that the local heat and mass transfer depends on geometric and hydrodynamic factors such as nozzle location and shape, jet velocity and turbulence level, surface spacing, jet orientation and the surrounding conditions (Aziz, Raiford, & Khan, 2008;Jaramilloa, Pérez-Segarraa, Rodrigueza, & Olivaa, 2008;Ockfen & Matveev, 2009).…”