In recent years numerical simulations have become an essential tool in the development and optimization of aircraft engine combustion chambers. However, experimental investigations are still very much necessary to gain relevant information of the fundamental fluid mechanics associated with such combustion chambers. These measurements prove to be essential in the establishment of new strategies for a reduction of emissions and to support the development of new models for the numerical simulations. The present work is a contribution focusing on the experimental investigation of flow and mixing behaviour in a rich-lean-staged combustor model, which consists of five swirl nozzles and two opposed rows of secondary air jets. The parameter space covers a variation of the main mass flux, the momentum flux ratio from secondary air jets to the undisturbed main flow as well as the inflow conditions of the secondary air, in form of an increased inflow velocity regulated by a variable bypass blow-off. First the averaged and unsteady base flow is discussed for several parameters and measurement planes without bypass blow-off. Then the influence of the increased inflow velocity on the discharge coefficients of the secondary air is presented and changes in the flow and mixing behaviour within the mixing chamber are presented. The optical measurement techniques LDV (Laser Doppler Velocimetry), PIV (Particle Image Velocimetry) and QLS (Quantitative Light-Sheet) were used to avoid systematic errors associated with intrusive probe measurements in the flow. To ensure the quality of the measurements for the validation of numerical simulations, the accuracy of the experimental results is also discussed. Two ways to address noise treatment in the ‘Unmixedness’ evaluation procedure are presented and applied to the data.