The goal of a diffuser is to transform kinetic energy into potential energy with minimum losses in total pressure. Existing supersonic diffusers are based on compression through shock waves. This process is inherently inefficient because of the large losses caused by the shocks. We investigate by means of Computational Fluid Dynamics (CFD) the viscous flow in a supersonic diffuser designed by means of inviscid theory to produce a shock-free isentropic compression. The design is based on the combination of elementary flows. Two simple wave regions connected by a sink flow are used to take a uniform supersonic flow at one Mach number to a uniform supersonic flow at a lower Mach number. The theory gives an exact solution for two-dimensional flow. The shape of the diffuser depends on the entrance and exit Mach numbers. For a given inlet Mach number, there is a minimum outlet Mach number determined by a limit line that forms at the throat. Multiple stage diffusers may be used to reduce the Mach number and minimize the shock losses. The results indicate the existence of oblique shock waves and flow separation. Nevertheless, the diffuser efficiency is very high when compared to existing diffuser data. The diffusers may be used for engine inlets or supersonic wind tunnels. Only laminar flows are considered.
","abstract_html":"<p>The goal of a diffuser is to transform kinetic energy into potential energy with minimum losses in total pressure. Existing supersonic diffusers are based on compression through shock waves. This process is inherently inefficient because of the large losses caused by the shocks. We investigate by means of Computational Fluid Dynamics (CFD) the viscous flow in a supersonic diffuser designed by means of inviscid theory to produce a shock-free isentropic compression. The design is based on the combination of elementary flows. Two simple wave regions connected by a sink flow are used to take a uniform supersonic flow at one Mach number to a uniform supersonic flow at a lower Mach number. The theory gives an exact solution for two-dimensional flow. The shape of the diffuser depends on the entrance and exit Mach numbers. For a given inlet Mach number, there is a minimum outlet Mach number determined by a limit line that forms at the throat. Multiple stage diffusers may be used to reduce the Mach number and minimize the shock losses. The results indicate the existence of oblique shock waves and flow separation. Nevertheless, the diffuser efficiency is very high when compared to existing diffuser data. The diffusers may be used for engine inlets or supersonic wind tunnels. Only laminar flows are considered.</p>","abstract_has_math":false,"creators":["A'Rafat, Sa'Ed"],"institution":null,"degree_name":"Master of Science in Aerospace Engineering","degree_level":"Thesis - Open Access","degree_discipline":"Graduate Studies","degree_department":null,"school":null,"contributors":["Jose Rodriguez","George Emanuel","L.L. Narayanaswaml"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":1994,"date_issued":"1994-07-01T07:00:00Z","date_published":"1994-07-01T07:00:00Z","updated_at":"2026-07-27T19:25:16Z","subjects":["supersonic diffusers","shock waves","Computational Fluid Dynamics","flow separation","Aerospace Engineering"],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://commons.erau.edu/db-theses/304","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Jose Rodriguez","George Emanuel","L.L. Narayanaswaml"]},{"key":"dc:creator","label":"Author","values":["A'Rafat, Sa'Ed"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"thesis:degree_discipline","label":"Discipline","values":["Graduate Studies"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Thesis - Open Access"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Master of Science in Aerospace Engineering"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["supersonic diffusers","shock waves","Computational Fluid Dynamics","flow separation","Aerospace Engineering"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://commons.erau.edu/db-theses/304"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["The goal of a diffuser is to transform kinetic energy into potential energy with minimum losses in total pressure. Existing supersonic diffusers are based on compression through shock waves. This process is inherently inefficient because of the large losses caused by the shocks. We investigate by means of Computational Fluid Dynamics (CFD) the viscous flow in a supersonic diffuser designed by means of inviscid theory to produce a shock-free isentropic compression. The design is based on the combination of elementary flows. Two simple wave regions connected by a sink flow are used to take a uniform supersonic flow at one Mach number to a uniform supersonic flow at a lower Mach number. The theory gives an exact solution for two-dimensional flow. The shape of the diffuser depends on the entrance and exit Mach numbers. For a given inlet Mach number, there is a minimum outlet Mach number determined by a limit line that forms at the throat. Multiple stage diffusers may be used to reduce the Mach number and minimize the shock losses. The results indicate the existence of oblique shock waves and flow separation. Nevertheless, the diffuser efficiency is very high when compared to existing diffuser data. The diffusers may be used for engine inlets or supersonic wind tunnels. Only laminar flows are considered.
"]},{"key":"dc:title","label":"Title","values":["Numerical Analysis of the Viscous Flow in a Supersonic Diffuser"]}]}],"canonical_facts":{"dc:contributor":["Jose Rodriguez","George Emanuel","L.L. Narayanaswaml"],"dc:creator":["A'Rafat, Sa'Ed"],"dc:description.abstract":["The goal of a diffuser is to transform kinetic energy into potential energy with minimum losses in total pressure. Existing supersonic diffusers are based on compression through shock waves. This process is inherently inefficient because of the large losses caused by the shocks. We investigate by means of Computational Fluid Dynamics (CFD) the viscous flow in a supersonic diffuser designed by means of inviscid theory to produce a shock-free isentropic compression. The design is based on the combination of elementary flows. Two simple wave regions connected by a sink flow are used to take a uniform supersonic flow at one Mach number to a uniform supersonic flow at a lower Mach number. The theory gives an exact solution for two-dimensional flow. The shape of the diffuser depends on the entrance and exit Mach numbers. For a given inlet Mach number, there is a minimum outlet Mach number determined by a limit line that forms at the throat. Multiple stage diffusers may be used to reduce the Mach number and minimize the shock losses. The results indicate the existence of oblique shock waves and flow separation. Nevertheless, the diffuser efficiency is very high when compared to existing diffuser data. The diffusers may be used for engine inlets or supersonic wind tunnels. Only laminar flows are considered.
"],"dc:identifier":["https://commons.erau.edu/db-theses/304"],"dc:subject":["supersonic diffusers","shock waves","Computational Fluid Dynamics","flow separation","Aerospace Engineering"],"dc:title":["Numerical Analysis of the Viscous Flow in a Supersonic Diffuser"],"thesis:degree_discipline":["Graduate Studies"],"thesis:degree_level":["Thesis - Open Access"],"thesis:degree_name":["Master of Science in Aerospace Engineering"]},"updated_at":"2026-07-27T19:25:16Z"}