{"id":468,"date":"2026-07-10T11:36:51","date_gmt":"2026-07-10T15:36:51","guid":{"rendered":"https:\/\/flumen.clients.cake.fm\/?post_type=cke_article&#038;p=468"},"modified":"2026-07-10T11:36:52","modified_gmt":"2026-07-10T15:36:52","slug":"validating-xstream-for-air-hammer-analysis-in-a-transonic-wind-tunnel","status":"publish","type":"cke_article","link":"https:\/\/flumen.clients.cake.fm\/fr\/articles\/validating-xstream-for-air-hammer-analysis-in-a-transonic-wind-tunnel\/","title":{"rendered":"Validating xStream for Air Hammer Analysis in a Transonic Wind Tunnel"},"content":{"rendered":"\n<div class=\"wp-block-group has-global-padding is-layout-constrained wp-block-group-is-layout-constrained\">\n<ul class=\"wp-block-list\">\n<li>Industry: Aerosapce\u00a0<\/li>\n\n\n\n<li>Region: US<\/li>\n\n\n\n<li>Focus: Hydraulic design of an air tunnel\u00a0<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Challenge<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">North Wind Test LLC needed to evaluate air hammer effects caused by rapid valve actuation in a supersonic wind tunnel\u2019s complex supply piping system. The organization had historically used the legacy GTRAN (developed by NASA) code to model these transients but sought a more modern, user-friendly platform for future work.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Before transitioning, they needed to validate that xStream could accurately replicate legacy GTRAN results\u2014particularly during sudden valve openings that produce significant transient pressure spikes. The test scenario involved tanks initially at 440 psia, transient events from 0\u20132 seconds, and critical valves whose behavior drives the air hammer phenomenon.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Solution<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">North Wind engineers constructed an xStream model of the entire wind tunnel supply system, including storage tanks, manifold, upstream valves, and the PES and sleeve valves. Several methods were evaluated to determine appropriate Cv values for the critical valves\u2014including catalog scaling, back-calculations based on GTRAN results, and adopting GTRAN RESIST values as Cv.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The piping network was iteratively refined, beginning with coarse pipe sectioning for rapid trial runs and increasing resolution for accuracy. The model\u2019s Mach number and temperature settings were adjusted per solver recommendations to ensure stability and accuracy during transient analysis.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Results<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">The comparison between xStream and GTRAN demonstrated excellent agreement, with xStream matching GTRAN\u2019s massflow and pressure-fluctuation magnitudes within approximately 5%. Timing alignment of pressure spikes and troughs was nearly exact across the 0\u20132 second transient.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">This strong correlation provided confidence for North Wind to adopt xStream as their primary tool for future air hammer analyses.<\/p>\n\n\n\n<div class=\"wp-block-buttons is-layout-flex wp-block-buttons-is-layout-flex\">\n<div class=\"wp-block-button\"><a class=\"wp-block-button__link wp-element-button\" href=\"https:\/\/flumen.clients.cake.fm\/wp-content\/uploads\/2026\/07\/CS_xStream_North-Wind-Test-LLC_26_03.pdf\" target=\"_blank\" rel=\"noreferrer noopener\">Read the article<\/a><\/div>\n<\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"Challenge North Wind Test LLC needed to evaluate air hammer effects caused by rapid valve actuation in a supersonic wind tunnel\u2019s complex supply piping system. The organization had historically used the legacy GTRAN (developed by NASA) code to model these transients but sought a more modern, user-friendly platform for future work. Before transitioning, they needed [&hellip;]","protected":false},"featured_media":0,"template":"","cke_solution":[21],"cke_type":[],"class_list":["post-468","cke_article","type-cke_article","status-publish","hentry","cke_solution-xstream"],"acf":{"linked_sector":{"simple_value_formatted":"","value_formatted":"","value":"","field":{"ID":0,"key":"field_691b74ae7b9ed","label":"Secteur d'activit\u00e9","name":"linked_sector","aria-label":"","prefix":"acf","type":"post_object","value":null,"menu_order":0,"instructions":"","required":0,"id":"","class":"","conditional_logic":0,"parent":"group_691b74ade39ea","wrapper":{"width":"","class":"","id":""},"post_type":["cke_secteur"],"post_status":"","taxonomy":"","return_format":"object","multiple":0,"max":"","save_custom":0,"save_post_status":"publish","acfe_add_post":0,"acfe_edit_post":0,"acfe_bidirectional":{"acfe_bidirectional_enabled":"0"},"allow_null":1,"allow_in_bindings":0,"bidirectional":0,"ui":1,"bidirectional_target":[],"save_post_type":"","min":"","_name":"linked_sector","_valid":1}}},"mb":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v28.0 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>Validating xStream for Air Hammer Analysis in a Transonic Wind Tunnel - Flumen<\/title>\n<meta name=\"robots\" content=\"noindex, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<meta property=\"og:locale\" content=\"fr_FR\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Validating xStream for Air Hammer Analysis in a Transonic Wind Tunnel - Flumen\" \/>\n<meta property=\"og:description\" content=\"Challenge North Wind Test LLC needed to evaluate air hammer effects caused by rapid valve actuation in a supersonic wind tunnel\u2019s complex supply piping system. 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