The heat exchanger of a regenerative gas turbine is usually calculated for uniform flow distribution. In practice, however, the flow distribution is not uniform. Nonuniformity of flow is caused by the geometry of the flow path and manufacturing tolerances of the regenerator discs themselves. The consequence is a drop in regenerator efficiency.Cold airflow tests were carried out on a model gas turbine to find optimum flow path geometry and data to calculate the drop in heat exchanger efficiency. The entire test was conducted under true Newton number conditions.The efficiency calculation of the heat exchanger based on test results shows that the efficiency drop can be several percent. Suggestions are made as to the shape of the regenerator cover and power turbine diffuser.