{"id":404510,"date":"2025-01-11T07:42:52","date_gmt":"2025-01-11T07:42:52","guid":{"rendered":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/chamber-pressure-not-reaching-expected-value-2\/"},"modified":"2025-01-11T07:56:34","modified_gmt":"2025-01-11T07:56:34","slug":"chamber-pressure-not-reaching-expected-value-2","status":"publish","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/chamber-pressure-not-reaching-expected-value-2\/","title":{"rendered":"Chamber pressure not reaching expected value"},"content":{"rendered":"

<p><p><p><p><p>My chamber was designed to achieve a chamber pressure of 313.7 psia, and exit pressure of 13.7 psia. I have calculated the required mdot using 2000lbf thrust, C*, thrust coefficient from NASA CEA. My goal is to simulate gaseous ethanol and lox combustion to verify the chemical kinetics before switching to DPM, and model a liquid injection. I set arbitrary inlet areas so that the ethyl alcohol vapor and oxygen have similar velocities. I did not model the exact areas as my actual case will be liquid with much higher densities. I am using a non-premixed steady diffusion flamelet model and mass flow inlet BC. That being said, I am getting a chamber pressure far below what I should be getting despite the combustion working. I am a bit confused why, as the chamber pressure should be set by the throat area and mdot. Is this likely an issue with my rough inlet modelling choices, the fact that gasous combustion has a higher C* than liquids, inconsistencies with the specific heat capacity ratio, or something else? I am also unsure how total pressure in the inlet streams can be close to zero when the static and total pressure at the inlet is 120 psi.<\/p><p><\/p><p><\/p><\/p><\/p><\/p><\/p><\/p>\n","protected":false},"template":"","class_list":["post-404510","topic","type-topic","status-publish","hentry"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_forum_id":["27792"],"_bbp_topic_id":["404510"],"_bbp_author_ip":["172.91.69.229"],"_bbp_last_reply_id":["406558"],"_bbp_last_active_id":["406558"],"_bbp_last_active_time":["2025-01-21 21:53:19"],"_bbp_reply_count":["17"],"_bbp_reply_count_hidden":["0"],"_bbp_voice_count":["4"],"_bbp_engagement":["343144","199","23673","31446"],"_btv_view_count":["426"],"_bbp_topic_status":["unanswered"],"_edit_last":["343144"],"_bbp_revision_log":["a:4:{i:404511;a:2:{s:6:\"author\";i:343144;s:6:\"reason\";s:0:\"\";}i:404512;a:2:{s:6:\"author\";i:343144;s:6:\"reason\";s:0:\"\";}i:404513;a:2:{s:6:\"author\";i:343144;s:6:\"reason\";s:0:\"\";}i:404514;a:2:{s:6:\"author\";i:343144;s:6:\"reason\";s:0:\"\";}}"],"_bbp_subscription":["199","343144","23673","31446"]},"test":"zwernjaydengmail-com"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/404510","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics"}],"about":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/types\/topic"}],"version-history":[{"count":4,"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/404510\/revisions"}],"predecessor-version":[{"id":404514,"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/404510\/revisions\/404514"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=404510"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}