Investigating Contact Pressure in Combustion Seal Designs for Injectors: Experimental and Finite Element Analysis

This study investigated the contact pressure distribution of three combustion seal designs for fuel injectors using both experimental techniques and finite element analysis (FEA). The designs tested included the baseline seal (Design #1), a conical seal (Design #2), and the current production seal (Design #3). In phase 1, a 2D axisymmetric FEA was conducted under worst-case torque conditions (67.8 Nm) to simulate contact pressure, with an axial load of 10 kN and combustion pressure of 21.3 MPa applied to the injector assembly. Phase 2 employed Fuji films to measure the pressure distribution at higher torques (89.5 and 115.2 Nm) in a more realistic scenario, incorporating challenges such as misalignment and eccentric loading. During this phase, Fuji film shearing was a significant challenge, complicating the accurate assessment of pressure profiles. Design #1 failed to maintain the minimum threshold contact pressure of 70 MPa over a 1 mm length, leading to potential leakage. Design #2 showed improved performance, particularly on the upper surface, but encountered issues with Fuji film shearing at the lower surface. Design #3 exhibited the best performance, maintaining pressures above 70 MPa on both surfaces over more than 1 mm, indicating no expected leakage. These results highlight the efficacy of combining computational and experimental approaches in evaluating seal designs, while also underscoring the need for refinement in experimental methods to address challenges like film shearing and incomplete strain gauge calibration.