Flowfield of a highly underexpanded jet impinging on a surface.

Bonnema, J. P.; Eastman, Donald W.

doi:10.2514/3.3665

Cited by 5 publications

(2 citation statements)

References 1 publication

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Downstream of the surface shock, the pressure is highest at the centre of the impingement zone as the axial flow velocity must decrease to zero. However, this stagnant, high pressure gas rapidly expands radially, diverting the flow into a wall jet [49,50]. Consequently, the shape of the surface shock is dictated by conservation of mass, energy, and momentum at the interface between the upstream supersonic expansion and the spatial profile of the downstream flow properties (direction, pressure, density, and temperature).…”

Section: Free Jets and Jets Impinging On A Flat Surfacementioning

confidence: 99%

“…Consequently, the shape of the surface shock is dictated by conservation of mass, energy, and momentum at the interface between the upstream supersonic expansion and the spatial profile of the downstream flow properties (direction, pressure, density, and temperature). This can be accurately modelled using numerical techniques [49,50]. The surface shock becomes flattened as it approaches the asymptotic stand-off limit [48,49].…”

Section: Free Jets and Jets Impinging On A Flat Surfacementioning

confidence: 99%

See 1 more Smart Citation

Shock-free ion transmission in a skimmer-based MEMS mass spectrometer vacuum interface

Wright¹,

Syms

2021

J. Micromech. Microeng.

View full text Add to dashboard Cite

Shock-free ion transmission from atmospheric pressure to a microelectromechanical system (MEMS)-based mass spectrometer has been achieved using micro-engineered nickel skimmers. The signal level has increased 70-fold compared with a previous configuration in which the skimmer did not sample the supersonic flow. The skimmers are formed by electroplating internal surfaces of anisotropically etched, pyramidal holes in (100) silicon. Etching from the reverse of the wafer exposes free-standing, open-ended skimmers supported by remaining silicon. High-resolution schlieren imaging has been used to visualise gas flow within the interface. Signal enhancement and increased gas throughput are observed when the skimmer attaches to the supersonic gas expansion via oblique shocks. The silicon back wall interacts with the flow field, causing the free jet Mach disc to evolve into a bowl-shaped surface shock whose position asymptotically approaches a stand-off separation as the interface pressure decreases. Ideally, the skimmer entrance should be located approximately midway between the inlet and the back wall. This development should allow a sensitivity increase in MEMS mass spectrometers using pumps of moderate capacity.

show abstract

Section: Free Jets and Jets Impinging On A Flat Surfacementioning

confidence: 99%