Static port orientation rule for civil aircraft

Static pressure port orientation for civil aircraft was studied in this paper. Static port is one of the most important air data sensors. It is used to measure local static pressure to calculate airspeed and altitude by air data computer, and the measure performance depends on its installed location. In order to fulfill the static port orientation in HB regulations and airworthiness standards, the corresponding requirements were interpreted into analysis objects. The flow field around a wing-body configuration was simulated by computational fluid dynamics (CFD), and the pressure distributions were obtained in various conditions. The root mean square of the pressure coefficients for all the cases was analyzed, and the area where the pressure coefficient is not sensitive to the Mach number and angle of attack (AOA) was found. This area was defined as the C_p steady line. The forward fuselage was simplified as circular cylinder, and the free stream velocity was decomposed into normal and vertical components. The vertical velocity component around the circular cylinder was analyzed theoretically, and the C_p steady line was found as same as that from the simulation result. This behavior means that the C_p steady line is universality. High speed and low speed pressure measurement experiments were conducted to validate the C_p steady line rule. The variation of the pressure coefficient almost equals to zero on the C_p steady line with varying Mach numbers and AOAs. The results have good agreement with the CFD solutions and theoretical results, and it is indicated that the analysis methods and relevant static port installing rule are applicable and possess universality. Furthermore, the obtained method and rule have the potential of applying to other aircrafts with similar configuration.