This study aims to evaluate adiabatic and conjugate effusion cooling effectiveness of combustion chamber liner plate of gas turbines. Validation of the adiabatic model was done by comparing computational fluid dynamics (CFD) result with the experimental results obtained using the subsonic cascade tunnel facility available at Heat Transfer Lab of Council of Scientific and Industrial Research-National Aerospace Laboratories (CSIR-NAL). Computational simulation of the conjugate model is validated against published numerical results. Numerical simulation for the adiabatic cooling effectiveness is carried out for a 1:3 scaled up flat plate test geometry, while the actual flat plate geometry is considered for the conjugate cooling effectiveness analysis. The test plate has 11 rows of cooling holes, and the holes are arranged in staggered manner with each row containing eight holes. For both adiabatic and conjugate cases, the same mainstream conditions are maintained with the inlet temperature of 329 K, velocity of 20 m/s, density ratio 1.3. The coolant to mainstream blowing ratios (BRs) are maintained at 0.4, 1.15, and 1.6. The coolant temperature is 253 K with the flow rates are according to the BRs. Cooling effectiveness is obtained by using CFD simulation with ANSYS fluent package. From the comparison of adiabatic and conjugate results, it is found that conjugate model is giving superior cooling protection than the adiabatic model and effusion cooling effectiveness increases with increase in BR. Investigations on comparison of angle of injection holes show that, 30 deg model give maximum effusion cooling effectiveness as compared to 45 deg and 60 deg models.