Product Code:SAE AIR4827
Title:Modeling Techniques for Jet Engine Test Cell Aerodynamics
Issuing Committee:Eg-1e Test Cells Committee
Scope:Research studies focusing on jet engine test cell aerodynamics, acoustics, and cell flow characteristics as affecting engine performance can be conducted with scale models for a variety of test cells. Such studies require the simulation of a number of jet engines in rather accurate detail, both as to geometry and as to flow characteristics. It has been demonstrated that simulators of low-bypass afterburning turbojets, high-bypass turbofans, turboshaft engines (without propellers), and inducted fan engines can be designed, fabricated, and successfully operated using either high-pressure air ejector systems or turbine driven systems for the motive power. The peculiar problems associated with scale model testing and engine simulators and the methods which can be used to attack these problems are described.Product Code:SAE AIR1168/11
Title:Spacecraft Boost and Entry Heat Transfer (STABILIZED Jul 2011)
Issuing Committee:Ac-9 Aircraft Environmental Systems Committee
Scope:The prediction of vehicle temperatures during ascent through the earth?s atmosphere requires an accurate knowledge of the aerodynamic heating rates occurring at the vehicle surface. Flight parameters required in heating calculations include the local airstream velocity, pressure, and temperature at the boundary layer edge for the vehicle location in question. In addition, thermodynamic and transport air properties are required at these conditions.Both laminar and turbulent boundary layers occur during the boost trajectory. Experience has shown that laminar and turbulent heating are of equivalent importance. Laminar heating predominates in importance in the stagnation areas, but the large afterbody surfaces are most strongly affected by turbulent heating. Once the local flow conditions and corresponding air properties have been obtained, the convective heating rate may be calculated for a particular wall temperature. This assumes that the boundary layer flow regime (that is, turbulent, laminar, or transitory) has also been established, so that a heating theory corresponding to the particular flow conditions may be selected.This section presents theoretical methods for computing boost vehicle surface aerodynamic heating rates. First, procedures are given for computing the local flow distributions around the vehicle. Second, methods are given for computing the convective heating rates, using the flow parameters found previously.