Failures of multifunctional bulkhead caused by high gradient of temperature, pressure and speed of rotation

Analysis and design of the gas generator multifunctional bulkhead considering the thermal and structural loads

“…The idea is to use measuring devices at some points to verify the global stream of operating fluid, through the entire engine, and to lay down to the numerical calculation and predictions to simulate the flow around and inside the bulkhead in order to define its operating conditions. Besides the presented methodology some conclusions can be made in combination with Failure Based Design methodology and previous unsuccessful design solutions as mentioned in Kolarević et al 14…”

“…The last important role is the injection of the cold air onto the turbine disk, thus cooling the turbine root area in order to prevent high reduction of yield stress caused by temperature rise. More details about bulkhead functions could be found in Kolarević et al 14…”

“…The main conclusion is that pressure distribution is not uniform and it cannot be predicted as a linear drop from higher, at the compressor side opening, to lower value, at turbine side opening, around the bulkhead, as it was done in some previous unsuccessful solutions. 14 Depending on the proximity of the impellers to the bulkhead structure there is more or less a Tesla turbine effect on the pressure distribution. This phenomenon significantly changes pressure distribution and in some cases can create lower pressure value than the boundary pressure values, static pressure at compressor and turbine gaps.…”

“…But its operating conditions and complex load state have some similarities with structures in the previously cited papers. In the previous publication, Kolarević et al 14 explained the problems occurred during the development of the structure of the multifunctional bulkhead together with causes and failures during the experimental investigations. Numerical identifications of bulkhead operating conditions for several previous design versions used for Failure-based Design approach in the multifunctional bulkhead design are also presented in the cited article.…”

Reliability‐Based Fatigue Life Prediction for Complex Structure with Time‐Varying Surrogate Modeling

“…Complex structure possesses complex geometric modelling and endures multiple loads during operation in many mechanical systems, such as aircraft engine and spacecraft [1][2][3]. Because of significant cyclic stresses induced by fluid loads, thermal loads, and centrifugal load, as one key failure mode, the fatigue failure seriously affects the security performance of the complex structure [4]. e ever-increasing demands for high-reliability performance and low maintenance cost drive the rising attention to the life prediction approaches.…”