text: The most usual means of water injection is 
  the combustion 
  direct flow of the fluid into 
  chamber. This is illustrated 
  in figure 2.14. 
  The addition of the fluid directly into the com- 
  bustion chamber increases the mass flow and 
  reduces the turbine 
  temperature. The 
  inlet 
  drop in temperature reduces the turbine power 
  and a greater fuel flow is required to maintain 
  engine speed. Thus, the mass flow is increased, 
  more fuel flow is allowed within turbine limits, 
  and greater, energy is imparted to the exhaust 
  gases. 
  
  re- 
  quires additional 
  turbine stages to continue 
  expansion in the turbine section and extract 
  a very large percent of the exhaust gas energy 
  as shaft power. 
  In this sense, the turboprop 
  is primarily a power producing machine and 
  the jet thrust is a small amount of the output 
  propulsive power. Ordinarily, 
  the jet thrust 
  of the turboprop accounts for 15 to 25 percent 
  thrust output. Since the turbo- 
  of the total 
  prop is primarily a power producing machine,  The fluid injected into the combustion cham- 
  bers is generally a mixture of water and alco- 
  hol. The water-alcohol solution has one 