It depends on various factors, including the specific design requirements, operating conditions, and performance objectives. There is no universally applicable value for the minimum and maximum bleed percentages as they can vary based on the turbine's configuration and intended use.

To optimize the design and determine the appropriate bleed percentages, you can consider this steps:

Define Design Objectives

Clearly define the objectives of your gas turbine design, such as maximizing efficiency, minimizing emissions, or optimizing power output. These objectives will guide your optimization process.

Perform Preliminary Analysis

Conduct preliminary analysis and simulations to understand the performance characteristics of the gas turbine under different operating conditions. This will provide insights into the impact of bleed air on the turbine's efficiency, power output, and other key parameters.

Evaluate System Constraints

Consider any system constraints or limitations that may impact the bleed air operation. For example, the availability of bleed air, the capacity of the bleed air system, and the impact on other components within the gas turbine system.

Conduct Sensitivity Analysis

Perform sensitivity analysis by varying the bleed air percentage over a range of values. Evaluate the impact of different bleed percentages on the turbine's performance metrics, such as efficiency, power output, and emissions. This analysis will help identify the optimal bleed air range that balances performance objectives and constraints.

Consider Control and Stability

Take into account the control and stability aspects of the gas turbine system. Ensure that the bleed air operation does not adversely affect the overall stability and control of the system.

Iterative Optimization

Based on the results from the sensitivity analysis, iteratively refine the bleed air percentage within a range that aligns with your design objectives. Evaluate the trade-offs and make adjustments as necessary to achieve the desired performance characteristics.

Validate and Verify

Once you have determined an optimal bleed air range, perform further simulations, analyses, and possibly experimental validation to verify the performance gains and ensure the design meets the desired objectives.

The minimum and maximum percentage of air bleed in a three-shaft gas turbine simulation can vary depending on the specific design and operating conditions of the gas turbine.

Bleed air is typically used to provide cooling and sealing for various components within the gas turbine, such as turbine blades and combustors. The amount of bleed air required depends on the gas turbine's specific design and operating conditions, such as the inlet temperature and pressure, ambient temperature, and power output.

In general, the minimum percentage of air bleed required should be enough to provide adequate cooling and sealing for the gas turbine's components, while the maximum percentage should not exceed the amount required to maintain safe and efficient operation of the turbine.

Therefore, it is essential to consult the gas turbine manufacturer's design specifications or consult with experienced gas turbine engineers to determine the appropriate minimum and maximum percentages of air bleed for a particular gas turbine simulation.

The minimum and maximum percentage of air bleed in three shaft depend on different factors like designe model details and input boundary conditions such as inlet velocity for hot air or could air , inlet hot gas temperature and pressure...

It is difficult to answer this question without knowing your background and the use to which you intend to use the bleed air. It is better to fully understand the application as reputable suppliers will help you with your difficulties if any. Most internal parameters they like to keep to themselves but they will offer guidance. At some stage, to minimise the weight and cost of the topsides of an offshore platform, bleed air from the GT was considered to be used as compressed air supply. One of the difficulties faced was the demand variations of the GT shaft power and the compressed air needs. They do not always go in step and tripping the GT at a critical moment is not appreciated. Stephen.